For this reason, the rational selection of substituent on imide nitrogen atoms and/or thiophene α-positions is the key to developing superior n-type organic semiconductors. We here report new NDTI derivatives having N-(2-cyclohexylethyl) groups. Despite their one-dimensional packing structures in the solid state regardless of the presence or absence of chlorine groups at the thiophene α-positions, their FETs show promising performance with electron mobilities higher than 0.1 cm2·V−1·s−1 under ambient conditions. We also discuss how the cyclohexylethyl groups affect the packing structure in comparison with analogous n-octyl derivatives having the same number of carbon atoms.Naphtho[2,3- In fact, with the NDTI core structure, a range of optoelectronic materials, e.g., n-type organic semiconductors, and ambipolar polymers and oligomers for field-effect transistors (FETs) and solar cell applications, have been developed dithiophene (NDTI), to the size of the N-alkyl group, i.e., cyclohexyl (CH) or n-octyl (C8), should be taken into account . The reaction of readily available 2,6-dibromonaphthalene tetracarboxylic anhydride and 2-cyclohexylethylamine gave corresponding diimide (6) in 37% isolated yield. After the introduction of trimethylsilyl (TMS)-acetylene moiety via a Stille coupling reaction to give 7, the sodium-sulfide-induced thiophene annulation reaction afforded desired NDTI derivative (8) with TMS groups at the thiophene α-positions in 27% yield. The TMS groups could be readily desilylated with tetrabutylammonium fluoride or chlorinated with sulfuryl chloride to afford α-unsubstituted (3) or chlorinated NDTI derivative (4), respectively, in reasonable yields. Chlorinated NDTI derivative (4) was synthesized because the corresponding C8-NDTI derivative with two chlorine substituents (2) showed the highest field-effect electron mobility (ca. 0.8 cm2·V−1·s−1) among the NDTI-based organic semiconductors, and it was unveiled that the chlorine groups induced additional intermolecular interaction to realize a 2D π-staking structure in the solid state + 642.0729. Found: 642.0718; IR (KBr) ν = 1653, 1713 cm−1 (C=O).N,N′-Bis(2-cyclohexylethyl)-2,6-bis((trimethylsilyl)ethynyl)-1,4,5,8-naphthalene tetracarboxylic acid diimide (7). A mixture of N,N′-bis(2-cyclohexylethyl)-2,6-dibromo-1,4,5,8-naphthalene tetracarboxylic acid diimide (6) , tributyl(trimethylsilylethynyl)tin , and bis(triphenylphosphine)palladium(II) dichloride  in toluene (400 mL) was stirred under reflux condition for 3 h. After cooling, the solvent was evaporated. Recrystallization of the residue from tetrahydrofuran-methanol gave N,N′-bis(2-cyclohexylethyl)-2,6-bis((trimethylsilyl)ethynyl)-1,4,5,8-naphthalene tetracarboxylic acid diimide (7) as a yellow solid : 1H-NMR  δ 8.96 , 4.20 , 1.86–1.61 , 1.45–1.39 , 1.29–1.01 , 0.38 ; 13C-NMR  δ 162.0, 161.4, 138.1, 127.1, 126.5, 126.4, 125.4, 110.9, 103.6, 39.5, 36.1, 35.5, 33.4, 26.8, 26.4, −0.1; EI-MS (70 eV) = 679 (M+); Mp >269–270 °C; HRMS (EI) m/z calcd for C40H50N2O4Si2 [M]+ 678.3309. Found: 678.3307; IR (KBr) ν = 1669, 1709 cm−1 (C=O).N,N′-Bis(2-cyclohexylethyl)-2,7-bis(trimethylsilyl)naphthodithiophene-4,5,9,10-tetracarboxylic acid diimide (8). Under argon atmosphere, sodium sulfide hydrate  was added to a stirred suspension of N,N′-bis(2-cyclohexylethyl)-2,6-bis((trimethylsilyl)ethynyl)-1,4,5,8-naphthalene tetracarboxylic acid diimide (7)  in ethanol (300 mL) and acetic acid (6 mL) at 60 °C. After stirring at the same temperature for 12 h, the mixture was stirred at room temperature for 12 h under atmospheric condition. Then, the mixture was diluted with water (ca. 300 mL). The resulting precipitate was collected by filtration and washed with methanol. After removal of methanol in vacuo, the crude product was purified by column chromatography . Recrystallization from chloroform-methanol gave N,N′-bis(2-cyclohexylethyl)-2,7-bis(trimethylsilyl)naphthodithiophene-4,5,9,10-tetracarboxylic acid diimide (8) as a maroon solid : 1H-NMR  δ 9.06 , 4.34 , 1.92–1.68 , 1.56–1.47 , 1.36–1.04 , 0.54 ; 13C-NMR  δ 163.2, 163.1, 159.5, 148.1, 144.1, 130.5, 122.4, 118.3, 117.1, 39.7, 36.4, 35.4, 33.3, 26.7, 26.4, −0.3; EI-MS (70 eV) = 742 (M+); Mp 309–311 °C; HRMS (EI) m/z calcd for C40H50N2O4S2Si2 [M]+ 742.2751. Found: 742.2758; IR (KBr) ν = 1649, 1686 cm−1 (C=O).N,N′-Bis(2-cyclohexylethyl)naphthodithiophene-4,5,9,10-tetracarboxylic acid diimide (3). N,N′-Bis(2-cyclohexylethyl)-2,7-bis(trimethylsilyl)naphthodithiophene-4,5,9,10-tetracarboxylic acid diimide (8)  was dissolved in dry tetrahydrofuran (15 mL) and acetic acid (0.15 mL), and then tetra-n-butylammonium fluoride  was added to the solution at 0 °C. After stirring for 2 h at room temperature, the solution was diluted with methanol (ca. 30 mL). The resulting precipitate was collected by filtration and washed with water, methanol, ethyl acetate, and hexane to give N,N′-bis(2-cyclohexylethyl)naphthodithiophene-4,5,9,10-tetracarboxylic acid diimide (3) as a red solid : 1H-NMR  δ 9.11 , 8.21 , 4.47 , 2.00–1.78 , 1.75–1.62 , 1.45–1.21 ; 13C-NMR  δ 163.3, 163.2, 145.2, 143.2, 140.1, 129.5, 124.6, 123.0, 118.4, 36.7, 36.4, 35.6, 33.4, 26.8, 26.3; EI-MS (70 eV) = 599 (M+); Mp 306–309 °C; HRMS (EI) m/z calcd for C34H34N2O4S2 [M]+ 598.1960. Found: 598.1956; IR (KBr) ν = 1645, 1689 cm−1 (C=O).N,N′-Bis(2-cyclohexylethyl)-2,7-dichloronaphthodithiophene-4,5,9,10-tetracarboxylic acid diimide (4). Under argon atmosphere, sulfuryl chloride  was added to a stirred suspension of N,N′-bis(2-cyclohexylethyl)-2,7-bis(trimethylsilyl)naphthodithiophene-4,5,9,10-tetracarboxylic acid diimide (8)  in dichloromethane (50 mL) at 0 °C. After stirring for 2 h, the mixture was diluted with methanol (200 mL). The resulting precipitate was collected by filtration and recrystallized from chloroform to give N,N′-bis(2-cyclohexylethyl)-2,7-dichloronaphthodithiophene-4,5,9,10-tetracarboxylic acid diimide (4) as a red solid : 1H-NMR  δ 8.97 , 4.43 , 1.98–1.75 , 1.64–1.56 , 1.46–1.20 ; EI-MS (70 eV) = 667 (M+); Mp 337–338 °C; HRMS (EI) m/z calcd for C34H32Cl2N2O4S2 [M]+ 666.1181. Found: 666.1179; IR (KBr) ν = 1645, 1686 cm−1 (C=O). Due to the low solubility of 4, 13C-NMR signals were unclear even after 20,000 scans.3 and 4 suitable for X-ray structural analysis were obtained by recrystallization from chlorobenzene. The X-ray crystal structure analyses were carried out on a Rigaku R-AXIS RAPID  or 90 K (4)). The structure was solved by direct methods. Non-hydrogen atoms were refined anisotropically using the SHELXL-2014 program [3 and 4 are available in Supplementary Materials.Single crystals of  program , and hyd3: C34H34N2O4S2 (598.77), red pillar, 0.40 × 0.10 × 0.05 mm3, monoclinic, space group, P21/n (#14), a = 16.370(4), b = 5.455(2), c = 17.688(4) Å, β = 116.037(9)°, V = 1419.2(6) Å3, Z = 2, R(F) = 0.1304 for 929 observed reflections (I > 2σ(I)) and 190 variable parameters, wR(F2) = 0.3434 for all data.Crystallographic data for 4: C34H32Cl2N2O4S2 (667.64), red needle, 0.30 × 0.10 × 0.01 mm3, monoclinic, space group, P21/n (#14), a = 14.349(3), b = 4.927(1), c = 22.110(6) Å, β = 107.11(1)°, V = 1493.9(7) Å3, Z = 2, R(F) = 0.0807 for 1194 observed reflections (I > 2σ(I)) and 225 variable parameters, wR(F2) = 0.2731 for all data.Crystallographic data for 3 and 4 were fabricated in a top-contact-bottom-gate (TCBG) configuration on a heavily doped n+-Si (100) wafer with a 200 nm thermally grown SiO2 (Ci = 17.3 nF·cm−2). The substrate surfaces were treated with octadecyltrichlorosilane (ODTS) as reported previously [2 substrates maintained at 150 or 200 °C at the rate of 1 Å·s−1 under the pressure of ~10−3 Pa. On top of the organic thin film, gold films (80 nm) as drain and source electrodes were deposited through a shadow mask. For a typical device, the drain-source channel length (L) and width (W) are 40 μm and 3.0 mm, respectively. Characteristics of the TFT devices were measured at room temperature under ambient conditions with a Keithley 4200 semiconducting parameter analyzer. Field-effect mobility (μFET) was calculated in the saturation (Vd = Vg = +60) of Id using the following equation,Ci is the capacitance of the SiO2 dielectric layer, and Vg and Vth are the gate and threshold voltages, respectively. Current on/off ratio (Ion/Ioff) was determined from Id at Vg = 0 V (Ioff) and Vg = +60 V. The μFET data of 3- and 4-based devices were typical values from nine different devices.TFT devices based on eviously . Thin fiCalculations of intermolecular transfer integrals of dimers selected from the packing structures elucidated by single-crystal X-ray analysis were performed with the density functional theory (DFT) methods by using the ADF  package  with the


Calocedrus decurrens acclimated to Corsica. The analytical investigation was conducted by GC(RI), GC-MS, pc-GC, and NMR. C. decurrens leaf, old branches, and young branches EOs contained α-pinene , myrcene , Δ-3-carene , limonene , terpinolene , and pin-2-en-8-ol  as major components, respectively. Special attention was paid to purifying and identifying four unusual pinane derivatives: pin-2-en-8-ol, pin-2-en-8-yl Acetate, pin-2-en-8-al, and methyl pin-2-en-8-oate. The last two are reported for the first time.The main objective of this study was to determine the chemical composition of essential oils (EOs) obtained from leaf, old branches, and young branches of a coniferous species  Pinus halepensis  loss from the molecular ion observed at m/z = 194  contained 8.0% of B, which was subsequently isolated by pc-GC with 76% purity (GC).Compound /z = 194 . Compoun13C-NMR spectrum of B displayed twelve signals. Multiple DEPT experiments allowed for differentiating of three quaternary carbons, three CH, three CH2, and three CH3. Moreover, the quaternary carbon at 170.48 ppm and the methylene at 70.58 ppm confirmed the presence of an ester. The presence of a singlet at 1.72 ppm in the 1H spectrum correlated to a methyl signal at 20.53 ppm in the HSQC spectrum suggested an acetate group. This was confirmed by the correlation between H-12 and C-11 in the HMBC spectrum. Altogether, MS and NMR data permitted to envisage a pinane ester having the formula C12H18O2. By comparison of its 13C-NMR data with that of pin-2-en-8-ol (A), we noted that only C-8 and C-6 were impacted by the presence of the acetate. C-8 moved upfield by 1.58 ppm, and C6 moved downfield by 1.76 ppm. Such variations of chemical shifts are commonly encountered when alcohols are compared to their corresponding acetates ) ; EI-MS 70 eV, m/z (rel. int.): 194 , 152 (3), 134 , 119 (96), 105 (60), 93 (76), 92 (86), 91 (100), 84 (28), 79 ( 49), 77 (43), 65 (19), 55 (20), 43 (93), 41 (41). 1H-NMR  and 13C-NMR : see Pin-2-en-8-al (C): C10H14O; HREIMS: m/z 150.1034 ; EI-MS 70 eV, m/z (rel. int.): 150 , 135 (18), 121 , 117 (20), 107 (23), 105 (22), 95 (26), 93 (71), 92 (37), 91 (100), 82 (62), 80 (29), 79 (75), 77 (61), 67 (20), 65 (19), 58 (24), 54 (21), 53 (27), 41 (34). 1H-NMR  and 13C-NMR : see Methyl pin-2-en-8-oate (D): C11H16O2; HREIMS: m/z 180.1137 ; EI-MS 70 eV, m/z (rel. int.): 180 , 165 , 148 , 139 (15), 133 (13), 125 (23), 121 (100), 120 (39), 119 (32), 112 (25), 105 (94), 93 (75), 91 (75), 88 (59), 79 (51), 77 (61), 65 (20), 53 (23), 43 (20). 1H-NMR  and 13C-NMR : see Pin-2-en-8-oicacid (E): C10H14O2; RI (DB-1/DB-WAX) 1288/2286; EI-MS 70 eV, m/z (rel. int.): 166 , 121 (100), 111 (18), 105 (76), 98 (25), 93 (69), 91 (73), 80 (11), 79 (61), 77 (62), 74 (41), 68 (35), 67 (28), 65 (6), 55 (13), 53 (16), 51 (5), 43 (14), 41 (36). 13C-NMR : see


H-chromen-4-one (1) was isolated from the Chinese eaglewood [Aquilariasinensis (Lour.) Gilg]. Its structure was established by detailed MS and NMR spectroscopic analysis, as well as comparison with literature data.A new 2-(2-phenylethyl)chromone, 5,6,7,8-tetrahydroxy-2-(3-hydroxy-4-methoxyphenethyl)-5,6,7,8-tetrahydro-4 Aquilaria sinensis (Lour.) Gilg, which has been used in China as incense as well as a traditional sedative, analgesic and digestive medicine 18D + 12.3 . The [M+Na]+ at m/z 387.1053  in the high-resolution ESI-Mass spectrum corresponded to the molecular formula C18H20O8. This formula can also be validated through 1H-NMR, 13C-NMR and DEPT spectra. Its IR spectrum showed the presence of hydroxyl , unsaturated carbonyl  and phenyl  groups. The 1H-NMR spectrum , four consecutive methine protons , two methylene groups at δH 2.80  and one 1,3,4-trisubstituted phenyl group at δH 6.80 , δH 6.67  and δH 6.60 . The 13C-NMR spectrum . Based on the above evidence, compound 1 was presumed to be 2-(2-phenylethyl)chromone derivative. The 13C-NMR spectra of 1 was similar to that of the 8-chloro-5,6,7-trihydroxy-2-(3-hydroxy-4-methoxyphenethyl)-5,6,7,8-tetrahydro-4H-chromen-4-one 18D + 12.3 . IR (KBr) νmax (cm−1): 3,409, 1,652, 1,570, 1,514, 1,456, 1,285, 1,110, 1,049. 1H- and 13C-NMR spectral data: see m/z: 387.1053 [M+Na]+ . The material of Chinese eaglewood (35.4 Kg) was exhaustively extracted with 95% EtOH three times at room temperature and filtered. After evaporation, the residue was suspended in HAquilariasinensis (Lour.) Gilg], a new 2-(2-phenylethyl)chromone, 5,6,7,8-tetra-hydroxy-2-(3-hydroxy-4-methoxyphenethyl)-5,6,7,8-tetrahydro-4H-chromen-4-one (1) was isolated. Its structure was established on the basis of spectroscopic evidence. The result of bioactive assay showed that compound 1 exhibited no cytotoxic activity against K562, SGC-7901, SMMC-7721 cell lines.As a part of our chemical investigation on Chinese eaglewood [


Mangifera indica leaf decoction (AD), on different experimental models in rodents. The administration of AD up to a dose of 5 g/kg (p.o.) did not produce any signs or symptoms of toxicity in the treated animals, while significantly decreasing the severity of gastric damage induced by several gastroprotective models. Oral pre-treatment with AD  in mice and rats with gastric lesions induced by HCl/ethanol, absolute ethanol, non-steroidal anti-inflammatory drug (NSAID) or stress-induced gastric lesions resulted in a significant decrease of said lesions. Phytochemical analyses of AD composition demonstrated the presence of bioactive phenolic compounds that represent 57.3% of total phenolic content in this extract. Two main phenolic compounds were isolated, specifically mangiferin  and C-glucosyl-benzophenone . These findings indicate the potential gastroprotective properties of aqueous decoction from M. indica leaves. This study was designed to determine the gastroprotective effect of a  Acid related disorders are common conditions in the general population. Furthermore, clinical experience has shown that acid-related symptoms as well as duodenal ulcers return quickly after cessation of drug treatments, raising the possibility of rebound hypersecretion . TherapyMangifera indica L. (Anacardiaceae) is one of the most important tropical plants marketed in the world +; H-NMR (DMSO-d6) δ: 7.36 , 6.84 , 6.36 , 4.60 , 3.19-4,04 (sugar prótons); 13C-NMR (DMSO-d6) δ: 177.1 (C-9), 162.3 (C-3), 160.2 (C-1), 154.8 , 149.5 (C-10a), 142.6 (C-7), 111.2 (C-8a), 107.7 (C-8), 107.3 (C-2), 102.4 (C-5), 101.1 (C-9a), 93.3 (C-4), 81.8 (C-5’), 79.3 (C-3’), 73.5 (C-1’), 71.1 (C-2’), 70.7 (C-4’), 62.2 (C-6’). Mi2: Brown amorphous solid; IR (KBr) νmax: 3.300 (OH), 1.615 (C=O) cm-1. UV (MeOH) λmax 210, 294 nm. EI-MS m/z: 407 [M-H]-, 287 [M-H-120]-; 1H-NMR (DMSO-d6) δ: 7.55 , 6.77 , 5.95 , 4.59 , 3.19-3.58 (sugar protons); 13C-NMR (DMSO-d6) δ: 194.6 (C-7), 161.3 (C-4’), 159.1 (C-4), 157.4 (C-3), 156.8 (C-2), 131.4 , 130.7 (C-1’), 114.6 , 106.9 (C-1), 103.6 (C-5), 94.9 (C-6), 81.0 (C-5’’), 78.3 (C-3’’), 74.6 (C-1’’), 71.9 (C-2’’), 69.6 (C-4’’), 60.5 (C-6’’). ®  diet with free access to tap water under standard conditions of 12 h dark-12 h light, humidity (60 ± 1.0%) and temperature (21 ± 1%). Fasting was used prior to all assays because standard drugs and infusion were always administered orally (by gavage) or intraduodenally using a saline solution (10 mL/Kg) as the vehicle. Moreover, the animals were kept in cages with raised floors of wide mesh to prevent coprophagy. The number of animal was enough the statistical analysis and we reduced number of animals to respect the Ethical Animal Care. The animals were killed by CO2 gas (1 min with outflow 15 L/min) and all experiments following the recommendations of the Canadian Council on Animal Care [Male Swiss albino mice (25-35 g) and male Wistar albino rats (150-250 g) from the Central Animal House of the UNESP were used. The animals were fed a certified Nuvilabmal Care  and all M. indica were performed in mice. In this assay, increasing doses of AD were orally administered to groups of ten animals for each dose after a 12 h fast. Animals receiving the vehicle  served as control. The signs and symptoms associated with the AD administration  were observed at 0, 30, 60, 120, 180 and 240 min after and then once a day for the next 14 days. At the end of the period the number of survivors was recorded. The acute toxicological effect was estimated by the method described by Souza Brito [The acute toxicity studies of za Brito . Gastroprotective effect against different ulcerogenic agents: HCl/ethanol-induced ulcer [ed ulcer  - Mice wed ulcer . Indometed ulcer  - In thied ulcer  - After ed ulcer . After hResults are expressed as mean ± S.E.M. Statistical significance was determined by one-way analysis of variance followed by Dunnett’s or Student’s test, with the level of significance at p < 0.05.


The structures of the synthesized compounds were confirmed by IR, 1H- and 13C-NMR and MS analyses. The phytotoxicity of the 2,5-bis-1,4-benzoquinones was evaluated against two crop species, Cucumis sativus and Sorgum bicolor, at 1.0 × 10-3 mol/L. In general, the quinones displayed inhibitory effects on the dicotyledonous species C. sativus (7–74%). On the other hand stimulatory effects were observed on S. bicolor (monocotyledonous). Similar results were observed in the biological assays carried out with the weed species Ipomoea grandifolia (dicotyledonous) and Brachiaria decumbens (monocotyledonous). In addition, the cytotoxicity of the 2,5-bis-1,4-benzoquinones was assayed against HL-60 (leukemia), MDA-MB-435 (melanoma), SF-295 (brain) and HCT-8 (colon) human cancer cell lines and human peripheral blood mononuclear cells (PBMC), as representatives of healthy cells, using a MTT and an Alamar Blue assay. Compound 12 was the most active, displaying cytotoxicity against all cancer cell lines tested.A series of twelve 2,5-bis-1,4-benzoquinones were prepared in yields ranging from 9–58%  Plant roots perform a variety of functions such as mechanical support, water/nitrogen uptake, and production of exudates. It is known that roots are capable of producing and secreting compounds (exudates) into the rhizosphere. Root exudation includes release of ions, free oxygen and water, enzymes, mucilage, and a range of organic compounds (primary and secondary metabolites) ,2,3,4.1, Sorghum bicolor - cyclohexa-2,5-dien-1,4-dione. Various organic compounds present in root exudates are involved in chemical-mediated plant-plant or allelopathy interactions. Allelopathy is concerned with the chemical interactions that occur among plants and is mediated by the release of allelochemicals into the rhizosphere ,6. The s bicolor  and char1 is a potent inhibitor of chlorophyll formation in Lemma minor L., and it also inhibits the growth of several grass and broadleaf weeds at concentrations as low as 10 μmol/L  for the antitumor activities are presented in 12 and 20 exhibited cytotoxicity against all tumor cell lines tested. Compound 12 was a more potent proliferation inhibitor  than compound 20. The other compounds investigated were not able to significantly inhibit cell growth under the assay conditions, presenting IC50 values higher than 25 µg/mL.The anti-tumor activity of the 2,5-bis-1,4-benzoquinone sorgoleone analogues escribed . To inve12 and 20 against normal cells (PBMC) was assessed by Alamar Blue assay ; 3.16 ; 1.61-1.72 ; 1.54 ; 0.93 ; 13C-NMR δ: 176.1 ; 149.4 ; 90.6 ; 38.9 ; 35.0 ; 23.9 ; 20.4 ; MS, m/z (%): 278 (57) [M+], 235 (87), 222 (100), 221 (51), 208 (15), 194 (14), 179 (27), 163 (23), 152 (15), 138 (14), 125 (18), 82 (17), 68 (27), 55 (24); HRMS (ESI TOF-MS): Calcd. for C16H27N2O2 279.2067; found: 279.2069.To a round-bottomed flask (125 mL) were added 12-16, 18-23 were prepared employing a procedure similar to that described for 17, and yields are presented in 1H- and 13C-NMR and mass spectrometry. The structural characterization of compounds 12, 13, 14, 18, 22, and 23 has already been described ; 2.97 ; 1.90-2.04 ; 0.98 ; 13C-NMR δ: 178.3 ; 151.8  93.0 ; 50.3 ; 28.0 ; 20.5 ; MS, m/z (%): 250 (84) [M+], 235 (13), 207 (100), 193 (40), 165 (28), 164 (31), 151 (60), 138 (23), 123 (20), 67 (21), 53 (46); HRMS (ESI TOF-MS): Calcd. for C14H23N2O2 251.1754; found: 251.1756.2,5-Bis-(pentylamino)-1,4-benzoquinone (16). Red crystals. Purified by column chromatography, eluent hexane/dichloromethane 1:2 (v/v). Mp 134.6–137.1 ºC; IR: 3,263 (NH), 2,957, 2,927, 2,857, 1,644, 1,553, 1,497, 1,463, 1,369, 1271, and 812 cm-1; 1H-NMR (* indicates assignments that could be reversed) δ: 6.62 , 5.28 ; 3.12 ; 1.59-1.68 ; 1.21-1.38 ; 0.86-0.91 ; 13C-NMR δ: 177.1 ; 150.4 ; 91.6 ; 41.6 ; 28.1 *; 27.0 ; 21.3 *; 13.0 ; MS, m/z (%): 278 (100) [M+], 235 (73), 223 (30), 207 (40), 193 (46), 179 (28), 165 (62), 164 (19), 151 (45), 138 (23), 137 (23), 110 (23), 67 (54), 54 (56); HRMS (ESI TOF-MS): Calcd. for C16H27N2O2 279.2067; found: 279.2070.2,5-Bis-(decylamino)-1,4-benzoquinone (19): Red crystals. Purified by column chromatography, eluent hexane/diethylether 2:1 (v/v). Mp 126.4–127.3 ºC; IR: 3,256 (NH), 2,954, 2,917, 2,848, 1,644, 1,554, 1,503, 1,456, 1,365, 1,291, and 683 cm-1; 1H-NMR δ: 6.62 ; 5.30 ; 3.13 ; 1.50-1.70 ; 1.15-1.40 ; 0.88 ; 13C-NMR (* indicates assignments that could be reversed) δ: 178.3 ; 151.6 (C(2), C(5)]; 92.8 ; 42.8 (C(1′), C(1′′)]; 32.1 *; 29.7 *; 29.7 *; 29.5 *; 29.4 *; 28.5 *; 27.2 *; 22.9 *; 14.4 ; MS, m/z (%): 418 (100) [M+], 362 (35), 333 (11), 305 (31), 165 (25), 162 (27), 151 (17), 138 (17), 68 (20), 54 (30). HRMS (ESI TOF-MS): Calcd. for C26H47N2O2 419.3632; found: 419.3637.2,5-Bis-(1-(2-aminoethyl)piperidino)-1,4-benzoquinone (20). Red crystals. Purified by column chromatography, eluent hexane/methanol 1:3 (v/v). Mp 164.2–165.5 ºC; IR: 3,291 (NH), 3,251 (NH), 2,935, 2,849, 1,641, 1,551, 1,493, 1,462, 1,364, 1,289, 1,223, 1,126, 993, and 693 cm-1; 1H-NMR δ: 7.04 ; 5.30 ; 3.19 ; 2.58 ; 2.34-2.42 ; 1.59 ; 1.40-1.44 ; 13C-NMR δ: 178.5 ; 151.6 ; 93.3 ; 56.11 ; 54.5 ; 39.3 (C(1′), C(1′′)]; 26.1 ; 24.5 ; MS, m/z (%): 360 (2) [M+], 99 (11), 98 (100), 70 (6), 55 (14). HRMS (ESI TOF-MS): Calcd. for C20H33N4O2 361.2598; found: 361.2599.2,5-Bis-(4-(2-aminoethyl)morfoline)-1,4-benzoquinone (21). Red crystals. Purified by column chromatography, eluent hexane/ethanol 1:4 (v/v). Mp 186.8–188.0 ºC; IR: 3,354 (NH), 2,869, 2,811, 1,645, 1,613, 1,495, 1,455, 1,354, 1,293, 1,115, 1,026, and 809 cm-1; 1H-NMR δ: 7.00 ; 5.28 ; 3.72 ; 3.20 ; 2.64 ; 2.47 ; 13C-NMR (CDCl3) δ: 178.3 ; 151.0 ; 93.1 ; 66.8 ; 55.5 ; 53.2 ; 38.5 ; MS, m/z (%): 364 (3) [M+], 101 (10), 100 (100), 70 (8), 56 (24); HRMS (ESI TOF-MS): Calcd. for C18H29N4O4 365.2183; found: 365.2186.12-23 was preliminarily evaluated as the ability of these compounds to interfere with the radicle growth of the cultivars Sorghum bicolor and Cucumis sativus. For these biological assays, stock solutions at 1.0 × 10-3 mol/L were prepared as follows: each compound 12-23 was dissolved in xylene (84 μL), Tween 80 surfactant (127 μL) and pentan-3-one (42 μL). The resultant suspension was shaken for 1 min and then transferred to a volumetric flask and the volume supplemented with water to 88 mL. The resultant suspension was sonicated for 5 min.The phytotoxic activity of the 2,5-bis-1,4-benzoquinones S. bicolor  were placed in Petri dishes (i.d. = 9 cm) containing washed sand (660 g) and the solution (88 mL) containing the compound to be evaluated. The Petri dishes were sealed with Parafilm, incubated at 28 °C, and inclinated at 75°. After 24 h and 48 h, the radicle length was measured to the nearest millimeter. All treatments were replicated four times in a completely randomized design. The percentage of radicle growth inhibition was calculated in relation to the root length of the control. Positive values represent inhibition and negative values correspond to stimulation. The data were analyzed using Tukey′s test at 0.05 probability level [C. sativus L. , B. decumbens  and I. grandifolia .This biological assay was carried out as previously described ,53. Grouty level . This biSpinacea oleracea L.) obtained from local market as previously described [2, 10 mmol/L KCl, and buffered with 0.03 mol/L Na+-tricine at pH 8.0. They were stored as a concentrated suspension in the dark for 1 h at 0 °C. Intact chloroplasts were efficiently lysed to yield free thylakoids prior to each experiment by incubating them in the following electron transport medium: 100 mmol/l sorbitol, 10 mmol/L KCl, 5 mmol/L KCN, and 30 mmol/L tricine buffer (pH 8 with the addition of KOH). Chlorophyll concentration was measured spectrophotometrically as reported [Intact chloroplasts were isolated from spinach leaves  was added as electron acceptor for the Hill reaction. The effect of compounds 12, 13 and 23 on the ATP synthesis was evaluated at 100 μmol/L, 200 μmol/L, 300 μmol/L, 400 μmol/L, and 500 μmol/L. All mixtures were illuminated with actinic light of a projector lamp (GAP 2660) passed through a 5 cm aqueous solution of 2% CuSO4 as filter [ATP synthesis was measured as the pH rise from 8.000 to 8.100 using a microelectrode connected to a Corning potentiometer with expanded scale. The pH change was recorded with a Gilson recorder. The reaction medium contained 100 mmol/L sorbitol, 5 mmol/L MgCls filter .12-14 and 16-23 was tested against HL-60 (human leukemia), MDA-MB-435 (human breast cancer), HCT-8 (human colon) and SF-295  cell lines obtained from the National Cancer Institute . Cells cultured in RPMI 1640 medium supplemented with 10% fetal bovine serum, 2 mmol/L glutamine, 100 U/mL penicillin, 100 μg/mL streptomycin at 37 °C under a 5% CO2 atmosphere.The cytotoxicity of compounds 2 atmosphere. Phytohemaglutinin (2 %) was added at the beginning of culture. After 24 h of culture, cells were treated with the test compounds 12-14 and 16-23.Heparinized blood  was collected and Peripheral Blood Mononuclear Cells (PBMC) were isolated by a standard method of density-gradient centrifugation over Histopaque-1077. PBMC were washed and resuspended in RPMI 1640 medium supplemented with 20% fetal bovine serum, 2 mmol/L glutamine, 100 U/mL penicillin, 100 μg/mL streptomycin at 37 °C under a 5% CO5 cells/mL for MDA-MB-435, HCT-8 and SF-295 cell lines, and 0.3 × 106 cells/mL for leukemia cells). After 24 h, the test compounds (0.39 to 25 μg/mL) dissolved in DMSO (0.1%), were added to each well and incubated for 72 h. DMSO (0.1%) and doxorubicin were used as negative and positive controls, respectively. Thereafter, the plates were centrifuged and then the medium was replaced by fresh medium (150 μL) containing 0.5 mg/mL MTT. Three hours later, the MTT formazan product was dissolved in 150 µL DMSO, and absorbance was measured using a multiplate reader . Drug effect was quantified as the percentage of control absorbance of the reduced dye at 595 nm in relation to control wells.Tumor cell growth was quantified by the ability of living cells to reduce the yellow dye 3--2,5-diphenyl-2H-tetrazolium bromide (MTT) to a purple formazan product . For the5 cells/well in 100 µL of medium). After 24 h, the compounds (0.09–25 µg/mL) dissolved in DMSO were added to each well  and incubated for 72 h. Doxorubicin was used as positive control. Twenty four hours before the end of the incubation, 10 µL of stock solution (0.312 mg/mL) of the Alamar Blue  was added to each well. The absorbance was measured using a multiplate reader . The drug effect was quantified as the percentage of control absorbance at 570 nm and 595 nm.In order to investigate selectivity of compounds toward a normal proliferating cell, the Alamar Blue assay was performed with PBMC after 72 h drug exposure . Briefly1) were synthesized and biologically evaluated in terms of their phytotoxicity and cytotoxicity. The assessment of phytotoxicity revealed that the compounds can act as plant growth regulators with various patterns of activity. Moreover, differences were noticed concerning the effects of the compounds on monocotyledonous and dicotyledonous species. Further investigation on the phytotoxicity of the 2,5-bis-1,4-benzoquinones showed that they are capable of inhibiting the ATP synthesis in isolated chloroplasts. The cytotoxicity assays revealed that the compounds 2,5-bis(ethylamino)-1,4-benzoquinone 12 and 2,5-bis(1-(2-aminoethyl)piperidino)-1,4-benzoquinone 20 exhibited activity against all of the human cell lines used in the biological evaluation. The 2,5-bis(ethylamino) derivative 12 exhibited the most selective cytotoxicity against the tumor cell lines tested and is not toxic to normal cells.A series of 2,5-bis-1,4-benzoquinone analogues of sorgoleone (


The results of the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) showed that some of the tested ILs are very promising anti-bacterial agents especially those containing an alkyl chain with a phenyl group .An environmentally-friendly and easy synthesis of a series of novel functionalized imidazolium-based ionic liquids (ILs) is described under both the conventional procedure and microwave irradiation. The structures of newly synthesized room-temperature ionic liquids (RTILs) were established by different spectral analyses. All ILs ( A few decades ago, room-temperature ionic liquids  appeared as an emerging class of ecofriendly compounds alternative to volatile organic compounds (VOCs) due to their outstanding physical and chemical properties such as negligible vapor pressure, excellent thermal and chemical stability, outstanding dissolving capacity, excellent ionic conductivity, non-flammability, and recyclability ,2,3.The above-mentioned characteristics make them strongly attractive for applications in a myriad of different fields and have, therefore, been investigated for a broad range of applications including as potential corrosion inhibitors ,5, in stHowever, possession of these properties does not necessarily make them a greener alternative. Therefore, several works on the biodegradability and toxicity of some ionic liquids (ILs) have recently been published with the aim of understanding the relationship between the molecular structure of ILs and their micro-toxicity ,22,23,24The preparation of these salts by conventional procedures requires a great deal of time and energy (72 h under reflux) ,32. AfteTherefore, the main goal of the present work was the synthesis of a new family of room-temperature functionalized imidazolium-based ionic liquids. The series was selected based on diverse structural features . Additionally, the newly synthesized water-soluble RTILs were investigated for their anti-microbial activity in order to understand the effect of the presence of such functional groups in these new ionic liquids on their toxicity.1–14 using a conventional procedure under microwave-assisted reaction conditions  benzene and (3-bromopropyl) benzene, respectively, in toluene at 80 °C for 18 h , a temperature of 80 °C, and high stirring during the reaction process. This process was implemented in order to shorten the reaction time and to increase the yields obtained under conventional methods. The formation of the IL was monitored as the reaction progressed from a clear homogenous solution to two phases because ILs are insoluble in toluene. The effect of the microwave was investigated and the results indicated that satisfactory yields were obtained in short reaction times compared with the previously mentioned conventional preparation (The microwave-assisted synthesis of the first hexylimidazolium-based derivatives paration .H-imidazol-3-ium bromide (2) was selected as a model IL to discuss the obtained spectroscopic data used to confirm the formation of the imidazolium-based ILs 1 and 2.1-Hexyl-3-(3-phenylpropyl)-1N-alkylation of 1-hexylimidazole with (3-bromopropyl)benzene afforded 1-hexyl-3-(3-phenylpropyl)-1H-imidazol-3-ium bromide (2), which resulted in the appearance of a triplet estimated at around 0.83 ppm due to the methyl protons of the hexyl group. Since IL 2 contains eight methylene groups, three methylene protons appeared as a multiplet at 1.24 ppm and two methylene protons appeared as quintet, respectively, at 2.15 ppm and 2.61 ppm. The three other methylene protons appeared, respectively, as triplets at 2.61 ppm for CH2CH2Ph and at 4.20 ppm and 4.26 ppm for NCH2CH2. The H-NMR spectrum for 2 also contained two doublet signals at 7.91 ppm and 7.93 ppm and one singlet signal at 9.51 ppm, which were attributed to the imidazolium protons. The phenyl protons of the pendent aromatic rings in IL 2 were observed at 7.20 ppm to 7.27 ppm.The 2 contained signals of the eight CH2, which appeared, respectively, at 49.1 ppm and 49.3 ppm for (NCH2) and the six other methylene groups were observed at their usual chemical shifts, which include 22.4, 25.6, 29.8, 31.0, 31.4, and 32.2 ppm. The C-NMR spectrum also displayed the signal of the CH3 group, which appeared at 14.3 ppm. Furthermore, the C-NMR spectrum contained signals corresponding to aromatic carbons including those of the imidazolium ring in the range of δC 122.9 ppm to 141.0 ppm. The obtained results were confirmed without ambiguity by the 13C-DEPT-NMR.The C-NMR spectrum of IL N-alkylation of 1-hexylimidazole was also confirmed by the Fourier transform infrared (FT-IR) spectra of ILs 2 and 3. The FT-IR spectrum of IL 2 contained an absorption band around 2980 cm−1, which indicated the presence of (C=CH). Furthermore, it contained a peak at 2910 cm−1, which was consistent with the presence of CH2 and CH3 groups. Lastly, the mass spectrum of IL 2 contained peaks consistent with the desired mass ions [M − Br]+ known as 271.330 m/z.The success of this new strategy for the After optimization of the reaction conditions, we continued to synthesize novel room-temperature ionic liquids. In this paper, we report the synthesis of a variety of new functionalized imidazolium-based ionic liquids tethered alkyl chain with ester functionality.3–6 in 69–79% yield as viscous liquids after washing with dry ethyl acetate and solvent removal . From this novel series ILs 3–6, 3-(2-ethoxy-2-oxoethyl)-1-hexyl-1H-imidazol-3-ium chloride (3) was selected as a model IL to discuss the obtained spectroscopic data used to confirm its formation.The structures of the halogenated imidazolium-based ionic liquids 3 that were present in the already discussed IL 2, we insisted on new peaks. From the H-NMR spectrum of IL 3, the characteristic singlet at δH 5.36 for two proton units was assigned to the NCH2CO and the characteristic ethyl ester protons appeared as a triplet and quartet at 1.22 ppm and 4.21 ppm, respectively, which confirmed the success of the quaternization step.Since there are some parts of IL 3 contained a signal consistent with the presence of a carbonyl group (CO) at δC 167.4 ppm. The signals of the CH2 and CH3 of the ester group (OCH2CH3) appeared, respectively, at 64.2 ppm and 14.3 ppm. The peak for (NCH2CO) appeared at around 50 ppm, which was confirmed clearly by APT-C-NMR. The five other methylene groups were observed at their usual chemical shifts. The structure of IL 3 was also confirmed by the FT-IR spectrum in which an absorption band at 1745 cm−1 clearly indicated the presence of a carbonyl group (C=O) belonging to an ester. Lastly, the mass spectrum of IL 3 contained a peak consistent with the desired mass ions [M − Cl]+ known as 239.172 m/z.Furthermore, the C-NMR spectrum of IL In the same way, the synthesis of a new series of room-temperature ILs based on an imidazolium moiety and a tethered alkyl chain with alcohol functionality was investigated under both conventional and microwave-assisted procedures .7–9 . The ionic liquid 1-hexyl-3-(2-hydroxyethyl)-1H-imidazol-3-ium bromide (7) was taken as a model compound to discuss the obtained spectroscopic data used to confirm the quaternization reaction of the 1-hexylimidazole by 2-bromoethanol.The previously reported advantages of using microwave irradiation were observed . The suc7 was deduced from its H-NMR spectrum, which confirmed the incorporation of an OH group. Therefore, a broad signal for (CH2CH2OH) was observed at δH 4.84 ppm and two triplets for (2CH2CHOH) appeared respectively at δH 3.81 and 4.28 ppm. The formation of IL 7 was also confirmed by C-NMR and the APT-13C-NMR analysis, which clearly showed the presence of methylene carbons at δC 52.1 ppm and 59.9 ppm belonging to the (CH2CH2OH) group. The FT-IR spectrum of IL 7 contained an absorption band at around 3350 cm−1, which indicated the presence of a hydroxyl group belonging to an alcohol. In addition, the structure of compound 7 was also confirmed by the electron impact mass spectrum, which showed a molecular ion peak [M − Br]+ at 197.064 m/z.Structural elucidation of ionic liquid The synthesis of another series of new functionalized imidazolium-based ionic liquids derivatives was carried out under the same conditions. This time, the focus was on imidazolium-based ionic liquids containing an alkyl chain with ether functionality .The previously reported advantages of using microwave irradiation were observed, which include the short time of reaction and improved yield .10–13 were confirmed by their 1H-NMR, 13C-NMR, FT-IR, and mass spectra. The ionic liquid 1-hexyl-3-(3-phenoxypropyl)-1H-imidazol-3-ium bromide (13) was taken as a model compound to discuss the obtained spectroscopic data used to confirm the quaternization reaction of 1-hexylimidazole by (3-bromopropoxy) benzene.Structures of the desired ionic liquids 13 was first confirmed by H-NMR analysis, which resulted in the appearance of two methylene protons as triplets at 4.45 ppm for NCH2CH2OPh and at 3.98 ppm for CH2CH2OPh. The phenyl protons of the pendent aromatic rings in IL 13 were observed in the range of 6.84 ppm to 7.20 ppm. The C-NMR spectrum of ILs 13 contained signals CH2, which appeared respectively at 65.9 ppm for (CH2CH2O) and at 46.9 for (NCH2CH2O). Furthermore, the C-NMR spectrum contained signals corresponding to aromatic carbons including those of the imidazolium ring in the range of δC 114.8 ppm to 158.5 ppm. The obtained results were confirmed without ambiguity by APT-13C-NMR. The structure of IL 13 was also confirmed by the FT-IR spectrum in which an absorption band around 1250 cm−1 clearly indicated the presence of a (C-O) belonging to an ether group. Furthermore, the mass spectrum of IL 13 displayed molecular ion peak [M − Br]+ at 286.806 m/z.The structure of IL H-imidazol-3-ium chloride (14) -1-hexyl-1ide (14)  was also14, two triplets for NCH2CH2CH2CN appeared, respectively, at δH 2.65 and 4.33 ppm. The C-NMR spectrum of IL 14 contained signals consistent with the presence of a quaternary carbon of a cyano group (CN) at δC 120.1 ppm. The peak for (CH2CN) appeared at δC 14.0 ppm. All other methylene groups were observed at their usual chemical shifts, which were confirmed clearly by APT-13C-NMR. However, the FT-IR clearly indicated a peak at around 2125 cm−1, which was consistent with the presence of a CN group. The mass spectral data revealed the presence of a molecular ion peak [M − Cl]+ at 220.112 m/z, which is shown by the formation of compound 14.From the H-NMR spectrum of IL 1–14 against seven strains of bacteria including four Gram-positive strains  and three Gram-negative strains .Several reports have recently been published showing that ILs possess promising biological activities ,40. EncoE. coli, P. aeruginosa, and S. aureus are most commonly used in clinical studies + 257.26 found for C17H25N2+, .1-Hexyl-3-(3-phenylpropyl)-1H-imidazol-3-ium bromide (2). It was obtained using a yellow viscous liquid. FT-IR (NaCl), cm−1: υ = 1560 (C=N), 2910 and 2980 (Ar-H). H-NMR : δH = 0.83 , 1.24 , 1.79 , 2.15 , 2.61 , 4.20 , 4.26 , 7.20–727 , 7.91–7.93 , 9.51  C-NMR : δC = 14.3 (CH3), 22.4 (CH2), 25.6 (CH2), 29.8 (CH2), 31.0 (CH2), 31.4 (CH2), 32.2 (CH2), 49.1 (CH2), 49.3 (CH2), 122.9 (CH), 123.1 (CH), 126.5 (CH), 128.7 (CH), 128.8 (CH), 136.6 (CH), 141.0 (C), MS [M − Br]+ 271.33 found for C18H27N2+,.3-(2-Ethoxy-2-oxoethyl)-1-hexyl-1H-imidazol-3-ium chloride (3). It was obtained using a brown viscous liquid. FT-IR (NaCl), cm−1: υ = 1210 (C-O), 1550 (C=N), 1750 (C=O), 2850 and 2910 (Ar-H). H-NMR : δH = 0.85 , 1.22 , 1.26 , 1.79 , 4.21 , 4.27 , 5.36 , 7.85 , 7.92 , 9.48 , C-NMR : δC = 14.3 (CH3), 14.4 (CH3), 22.3 (CH2), 25.5 (CH2), 29.8 (CH2), 31.0 (CH2), 49.4 (CH2), 50.0 (CH2), 62.30 (CH2), 122.6 (CH), 124.4 (CH), 137.9 (CH), 167.4 (C=O), MS [M − Cl]+ 239.33 found for C13H23N2O2+, .3-(5-Ethoxy-5-oxopentyl)-1-hexyl-1H-imidazol-3-ium bromide (4). It was obtained using a yellow viscous liquid. FT-IR (NaCl), cm−1: υ = 1150 (C-O), 1550 (C=N), 1735 (C=O), 2910 and 2950 (Ar-H). H-NMR : δH = 0.76 , 1.10 , 1.18 , 1.47 , 1.84 , 2.29 , 3.98 , 4.25 , 4.30 , 8.03 , 9.77 , C-NMR : δC = 14.1 (CH3), 14.4 (CH3), 21.3 (CH2), 22.3 (CH2), 25.6 (CH2), 29.3 (CH2), 29.9 (CH2), 31.0 (CH2), 33.2 (CH2), 48.8 (CH2), 49.2 (CH2), 60.1 (CH2), 122.8 (CH), 122.9 (CH), 136.6 (CH), 172.9 (C=O), MS [M − Br]+ 281.23 found for C16H29N2O2+, .1-Hexyl-3-(6-methoxy-6-oxohexyl)-1H-imidazol-3-ium bromide (5). It was obtained using a yellow viscous liquid. FT-IR (NaCl), cm−1: υ = 1550 (C=N), 1735 (C=O), 2220 (CN), 2910 and 2950 (Ar-H). H-NMR : δH = 0.75 , 1.18–1.23 , 1.49 , 1.79 , 2.22 , 3.50 , 4.26 , 8.01 , 9.77 , C-NMR : δC = 14.1 (CH3), 22.3 (CH2), 24.1 (CH2), 25.3 (CH2), 25.6 (CH2), 29.6 (CH2), 29.9 (CH2), 31.0 (CH2), 33.4 (CH2), 49.0 (CH2), 49.2 (CH3), 51.5 (CH3), 122.8 (CH), 136.5 (CH), 173.4 (C=O), MS [M − Br]+ 281.50 found for C16H29N2O2+, .3-(4-Acetoxybutyl)-1-hexyl-1H-imidazol-3-ium chloride (6). It was obtained using a dark brown viscous liquid. FT-IR (NaCl), cm−1: υ = 1210 (C-O), 1550 (C=N), 1735 (C=O), 2910 and 2950 (Ar-H). H-NMR : δH = 0.60 , 1.05 , 1.45 , 1.66 , 1.78 , 3.25 , 3.84 , 4.08 , 4.20 , 7.35 , 7.51 , 10.05 ; C-NMR : δC = 13.7 (CH3), 20.7 (CH3), 22.1 (CH2), 25.1 (CH2), 25.6 (CH2), 26.8 (CH2), 29.9 (CH2), 30.8 (CH2), 49.1 (CH2), 49.8 (CH2), 63.1 (CH2), 122.1 (CH), 122.4 (CH), 136.7 (CH), 170.9 (C=O), MS [M − Cl]+ 267.18 found for C15H27N2O2+, .1-Hexyl-3-(2-hydroxythyl)-1H-imidazol-3-ium bromide (7). It was obtained through a dark brown viscous liquid. FT-IR (NaCl), cm−1: υ = 1580 (C=N), 2910 and 2950 (Ar-H), 3310 (O-H). H-NMR : δH = 0.77 , 1.21 , 1.75–1.77 , 3.81 , 4.09 , 4.28 , 4.84 , 7.29 , 7.53 , 9.30 . C-NMR : δC = 13.8 (CH3), 22.2 (CH2), 25.7 (CH2), 29.9 (CH2), 31 (CH2), 49.8 (CH2), 52.1 (CH2), 59.9 (CH2), 122.6 (CH), 123.2 (CH), 136.4 (CH), MS [M − Br]+ 197.06 found for C11H21N2O+, .1-Hexyl-3-(3-hydroxypropyl)-1H-imidazol-3-ium bromide (8). It was obtained using a brown viscous liquid. FT-IR (NaCl), cm−1: υ = 1560 (C=N) 2910 and 2950 (Ar-H), 3390 (O-H). H-NMR : δH = 0.68 , 1.12 , 1.73 , 1.97 , 3.42 , 4.11 , 4.34 , 7.37 , 7.66 , 9.72 ; C-NMR : δC = 13.8 (CH3), 22.2 (CH2), 25.7 (CH2), 30.0 (CH2), 30.9 (CH2), 32.6 (CH2), 46.8 (CH2), 49.9 (CH2), 57.1 (CH2), 122.0 (CH), 123.0 (CH), 136.3 (CH), MS [M − Br]+ 211.32 found for C12H23N2O+, .1-Hexyl-3-(2-(2-hydroxyethoxy)ethyl)-1H-imidazol-3-ium chloride (9). It was obtained through a brown viscous liquid. FT-IR (NaCl), cm−1: υ = 1150 (C-O), 1550 (C=N), 3400 (O-H), 2910 and 2950 (Ar-H). H-NMR : δH = 0.83 , 1.24 , 1.78 , 3.45 , 3.77 , 4.22 , 4.39 , 5.77, 7.66 , 7.88 , 9.28 , C-NMR : δ C = 14.3 (CH3), 22.3 (CH2), 25.5 (CH2), 25.6 (CH2), 29.8 (CH2), 29.9 (CH2), 31,0 (CH2), 48.8 (CH2), 49.2 (CH2), 60.4 (CH2), 122.3 (CH), 123.3 (CH), 135.5 (CH), MS [M − Cl]+ 241.04 found for C13H25N2O2+, .1-Hexyl-3-(2-methoxyethyl)-1H-imidazol-3-ium bromide (10). It was obtained using dark brown viscous liquid. FT-IR (NaCl), cm−1: υ = 1150 (C-O), 1550 (C=N), 2910 and 2950 (Ar-H). H-NMR : δH = 0.64 , 1.09 , 1.70 , 3.15 , 3.58 , 4.13 , 4.40 , 7.41, 7.51 , 9.73 , C-NMR : δC = 13.7 (CH3), 22.2 (CH2), 25.6 (CH2), 30.0 (CH2), 30.9 (CH2), 49.6 (CH2), 49.9 (CH2), 58.8 (CH3), 70.1 (CH2), 121.8 (CH), 123.2 (CH), 136.4 (CH), MS [M − Br]+ 211.07 found for C12H23N2O+, .3-(2-Ethoxyethyl)-1-hexyl-1H-imidazol-3-ium chloride (11). It was obtained using a dark brown viscous liquid. FT-IR (NaCl), cm−1: υ = 1110 (C-O), 1560 (C=N), 2910 and 2950 (Ar-H), 3078 (Ar-H). H-NMR : δH = 0.67 , 0.96 , 1.11 , 1.71 , 3.32 , 3.62 , 4.14 , 4.40 , 7.38 , 7.49 , 9.88 , C-NMR : δC = 13.7 (CH3), 14.8 (CH3), 22.2 (CH2), 25.7 (CH2), 30.0 (CH2), 30.9 (CH2), 49.7 (CH2), 49.8 (CH2), 66.5 (CH2), 68.2 (CH2), 121.6 (CH), 123.1 (CH), 136.8 (CH), MS [M − Cl]+ 224.47 found for C13H25N2O+, .3-(5-Ethoxy-5-oxopentyl)-1-hexyl-1H-imidazol-3-ium bromide (12). It was obtained using a dark brown viscous liquid. FT-IR (NaCl), cm−1: υ = 1250 (C-O), 1600 (C=N), 2910 and 2980 (Ar-H). H-NMR : δH = 0.80 , 1.14–1.20 , 1.76–1.79 , 4.25 , 4.38 , 4.68 , 6.94–6.96 , 7.12–7.28 , 7.95 , 7.99  9.60 . C-NMR : δC = 14.2 (CH3), 21.5 (CH2), 22.3 (CH2), 25.5 (CH2), 29.9 (CH2), 31 (CH2), 49.3 (CH2), 66.2 (CH2),115.0 (CH), 121.6 (CH), 122.8 (CH), 128.6 (CH), 129.3 (CH), 129.9 (CH), 137.2 (CH),158.2 (C), MS [M − Br]+ 272.64 found for C17H25N2O+, .1-Hexyl-3-(3-phenoxypropyl)-1H-imidazol-3-ium bromide (13). It was obtained through a yellow viscous liquid. FT-IR (NaCl), cm−1: υ = 1250 (C-O), 1600 (C=N), 2910 and 2980 (Ar-H). H-NMR : δH = 0.76 , 1.14 , 1.71 , 2.29 , 3.98 , 4.20 , 4.45 , 6.84–6.86 , 7.20 , 7.95 , 7.99 , 9.63 . C-NMR : δ C = 14.2 (CH3), 22.3 (CH2), 25.6 (CH2), 29.6 (CH2), 29.9 (CH2), 31.0 (CH2), 46.9 (CH2), 49.3 (CH2), 65.0 (CH2), 114.8 (CH), 121.1 (CH), 122.9 (CH), 123 (CH),129.8 (CH), 136.6 (CH), 158.5 (C), MS [M − Br]+ 286.80 found for C18H27N2O+, .3-(3-Cyanopropyl)-1-hexyl-1H-imidazol-3-ium chloride (14). It was obtained through dark brown viscous liquid. FT-IR (NaCl), cm−1: υ = 1550 (C=N), 2220 (CN), 2910 and 2950 (Ar-H). H-NMR : δH = 0.84 , 1.25 , 1.79 , 2.19 , 2.65 , 4.19 , 4.33 , 7.92, 7.96 , 9.67 , C-NMR : δC = 14.0 (CH2), 14.3 (CH3), 22.3 (CH2), 25.6 (CH2), 25.8 (CH2), 29.7 (CH2), 31.0 (CH2), 48.1 (CH2), 49.3 (CH2), 120.1 (C), 122.9 (CH), 123.0 (CH), 137.0 (CH), MS [M − Cl]+ 220.11 found for C13H22N3+, .Staphylococcus aureus, Bacillus cereus, Acinetobacter baumannii, Escherichia coli, Klebsiella pneumonia, and Pseudomonas aeruginosa as test strains.The antimicrobial activity was initially estimated in terms of inhibition zone (IZ) measurements by using the agar disc diffusion method. The test was performed by sub-culturing 24 h fresh bacterial cultures onto the surface of Muller–Hinton agar plates. The antibacterial activity was assayed using filter paper discs (6 mm i.d.) loaded with 10 μg of a tested compound. Loaded discs were transferred onto the center of inoculated Petri-plates, which were then maintained for 2 h in a refrigerator at 4 °C to allow for the diffusion of the bioactive compound. The diameter of the inhibition zone was measured (in mm) after 24 h incubation at 37 °C. Sterile distilled water was used as a control. All compounds were tested against clinical samples of 8 CFU/mL were prepared from 24 h agar plates with Mueller Hinton broth. Aliquots of 100 µL of each bacterial suspension was mixed with 100 µL serially diluted and tested compound in a microtiter plate [The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) determined by a CLSI microdilution-based method were used to evaluate antibacterial potentials . The teser plate . Un-inoc


Nicotiana tabacum cells to 7-β-glucoside and 7-β-gentiobioside of daidzein, and 3′- and 7-β-glucosides, 3′,7-β-diglucoside, and 7-β-gentiobioside of hesperetin. Daidzein and α-tocopherol were glycosylated by galactosylation with β-glucosidase to give 4′- and 7-β-galactosides of daidzein, which were new compounds, and α-tocopherol 6-β-galactoside. These nine glycosides showed higher anti-allergic activity, i.e., inhibitory activity toward histamine release from rat peritoneal mast cells, than their respective aglycones. In addition, these glycosides showed higher tyrosinase inhibitory activity than the corresponding aglycones. Glycosylation of daidzein, α-tocopherol, and hesperetin greatly improved their biological activities.Daidzein is a common isoflavone, having multiple biological effects such as anti-inflammation, anti-allergy, and anti-aging. α-Tocopherol is the tocopherol isoform with the highest vitamin E activity including anti-allergic activity and anti-cancer activity. Hesperetin is a flavone, which shows potent anti-inflammatory effects. These compounds have shortcomings, i.e., water-insolubility and poor absorption after oral administration. The glycosylation of bioactive compounds can enhance their water-solubility, physicochemical stability, intestinal absorption, and biological half-life, and improve their bio- and pharmacological properties. They were transformed by cultured  Daidzein is the most widely studied isoflavone and is found in beans such as soybean, sweet red bean, and kidney bean. It exhibits anti-oxidative, anti-inflammatory, and anti-aging action and has chemopreventive effects in several biological systems, such as cancer prevention ,7,8,9,10l-tyrosine to l-dopa and the oxidation of l-dopa to dopaquinone. This dopaquinone is highly reactive and can polymerize spontaneously to form melanin in a series of reaction pathways. Accordingly, the regulation of melanin synthesis by the inhibition of tyrosinase to prevent hyperpigmentation has been a recent subject of many studies ..1) was sN. tabacum cells treated with α-tocopherol (6) was obtained. It was not enough for analyses of biological activities.On the other hand, only a small amount of the glycosylation products in the MeOH extracts of 8) with N. tabacum cells was carried out. Products 9–12 were isolated from the MeOH extracts from cultured N. tabacum cells. The structure of compounds 9–12 was identified as hesperetin 3′-β-glucoside (9), hesperetin 7-β-glucoside (10), hesperetin 3′,7-β-diglucoside (11), and hesperetin 7-β-gentiobioside (12), which have been reported before + peak at m/z (439.265), consistent with a molecular formula of C21H20O9 . The 1H-NMR spectrum of 4 had a signal at δ 4.91  corresponding to its attachment to the anomeric carbon (C-1″)  as the product. This finding shows that the product has O-β-galactosylation moiety. The HMBC correlation (δ 4.91 (H-1″) and the carbon signal at δ 159.1 (C-4′) to establish that the galactopyranosyl residue was attached to the 4′-hydroxy group of 1  . The 13C δ 103.0 . This 13relation  was obseoup of 1 . Thus, t5 included a pseudomolecular ion [M + Na]+ peak at m/z (439.248), indicating that the product consisted of one substrate and one hexose. The sugar component in the product was determined to be galactose on the basis of the chemical shifts of their carbon signals , indicating that the galactoside linkage in the compound had β-orientation  and the carbon signal at δ 163.6 (C-7)  . These dion of 1 . Thus, t1), daidzein 7-β-glucoside (2), daidzein 7-β-gentiobioside (3), daidzein 4′-β-galactoside (4), and daidzein 7-β-galactoside (5) for compound 48/80-induced histamine release from rat peritoneal mast cells were investigated (1) with a %inhibition of 58%. On the other hand, the inhibitory activity of daidzein 7-β-glucoside (2) toward histamine release from rat peritoneal mast cells was higher than that of the aglycone daidzein (1). The inhibitory activity of daidzein 7-β-gentiobioside (3) was higher than that of the daidzein glucoside 2. Additionally, daidzein 4′-β-galactoside (4) and daidzein 7-β-galactoside (5) showed higher inhibitory activities toward histamine release than daidzein gentiobioside 3.The anti-allergic activities of daidzein and its glycosides were examined to clarify the effects of glycosylation of daidzein on its physiological activities. The inhibitory activities of daidzein (stigated . Compoun7) had stronger inhibitory activity toward histamine release than α-tocopherol (6).In addition, α-tocopherol 6-β-galactoside (9) and hesperetin 7-β-glucoside (10) was higher than that of hesperetin (8). Furthermore, hesperetin 3′,7-β-diglucoside (11) showed higher inhibitory activity toward histamine release than hesperetin glucosides 9 and 10. The inhibitory activity toward histamine release of hesperetin 7-β-gentiobioside (12) was stronger than hesperetin diglucoside 11. The anti-allergic activities were examined at pH 7.4 and 37 °C according to the reported methods +: m/z 439.265 ; 1H-NMR : 3.58–3.92 , 4.91 , 6.69 , 6.83 , 7.16–7.18 , 7.46–7.48 , 7.97 , 8.10 ; 13C-NMR : 62.4 (C-6″), 70.3 (C-4″), 72.3 (C-2″), 74.9 (C-3″), 77.0 (C-5″), 103.0 (C-1″), 103.8 (C-8), 116.2 (C-10), 117.7 , 119.0 (C-6), 125.3 (C-3), 127.7 (C-1′), 128.0 (C-5), 131.4 , 154.5 (C-2), 159.1 (C-4′), 160.6 (C-9), 169.9 (C-7), 178.0 (C-4).Daidzein 4′-β-galactoside (5): HRESIMS [M + Na]+: m/z 439.248 ; 1H-NMR : 3.62–3.94 , 5.05 , 6.83–6.85 , 7.21 , 7.25 , 7.36–7.38 , 8.13 , 8.18 ; 13C-NMR : 62.5 (C-6″), 70.2 (C-4″), 72.1 (C-2″), 74.8 (C-3″), 77.3 (C-5″), 102.5 (C-1″), 105.0 (C-8), 116.5 , 117.1 (C-6), 120.2 (C-10), 123.8 (C-1′),126.3 (C-3), 128.3 (C-5), 131.4 , 155.0 (C-2), 159.3 , 163.6 (C-7), 178.1 (C-4).Daidzein 7-β-galactoside -1-piperazineethanesulfonic acid (HEPES) (pH 7.4) to give approximately 104 mast cells/mL. Cell viability was always greater than 90% as judged by the trypan blue exclusion test. Mast cells were preincubated with the test compound (1 μM) for 15 min at 37 °C, and subsequently exposed to compound 48/80 at 0.35 μg/mL. Histamine release was determined by a fluorometric assay, and was expressed as a percentage of total histamine [The effects of daidzein, α-tocopherol, hesperetin, and their glycosides on compound 48/80-induced histamine release from rat peritoneal mast cells were examined as follows. Peritoneal mast cells were collected from the abdominal cavities of rats  and purified to a level higher than 95%. The purified mast cells were suspended in a physiological buffered solution (PBS) containing 145 mM NaCl, 2.7 mM KCl, 1.0 mM CaCll-DOPA or l-tyrosine as a substrate. In spectrophotometric experiments, enzyme activity was taken as the initial velocity (Vi) monitored by observing dopachrome formation at 475 nm with a UV spectrophotometer at 30 °C. All samples were dissolved in ethanol at 10 mM. First, 200 μL of a 2.7 mM l-tyrosine or 5.4 mM l-DOPA aqueous solution was mixed with 2687 μL of 0.25 M phosphate buffer (pH 6.8). Next, 100 μL of the sample solution and 13 μL of the same phosphate buffer solution containing mushroom tyrosinase (144 units) were added to the mixture. The inhibitor concentration that gave a 50% loss of activity (IC50) was obtained by fitting the experimental data to the logistic curve.Mushroom tyrosinase (EC 1.14.18.1)  was used for the tyrosinase assay, with either The glycosides of daidzein, α-tocopherol, and hesperetin were synthesized by bioconversion procedures. These two bioconversion systems prepared nine glycosides of these compounds, i.e., daidzein 7-β-glucoside, daidzein 7-β-gentiobioside, hesperetin 3′-β-glucoside, hesperetin 7-β-glucoside, hesperetin 3′,7-β-diglucoside, hesperetin 7-β-gentiobioside, daidzein 4′-β-galactoside, daidzein 7-β-galactoside, and α-tocopherol 6-β-galactoside. Daidzein 4′-β-galactoside and daidzein 7-β-galactoside were two new compounds. Glycosylation of daidzein, α-tocopherol, and hesperetin much improved their biological activities such as suppression activity toward histamine release from rat peritoneal mast cells and tyrosinase inhibitory activity. The diglucoside derivatives showed stronger activity than glucoside derivatives. The gentiobioside derivative had stronger activity than the diglucoside derivative. The galactoside derivative exerted the strongest physiological activity among the glycosides tested.


This is the first report on structure-activity relationships regarding the anti-adhesive potency of proanthocyanidins. In addition, the structures of the first chemically defined proanthocyanidins from Pelargonium sidoides are disclosed. Bacterial adhesion to epithelial cells is a key step in infections, allowing subsequent colonization, invasion and internalization of pathogens into tissues. Anti-adhesive agents are therefore potential prophylactic tools against bacterial infections. The range of anti-adhesive compounds is largely confined to carbohydrate analogues. Tannins are generously recognized as potent antimicrobials, but little data exist on their anti-adherence potency. Using a model for mucosal pathogenesis with labeled group A-streptococci (GAS) and human laryngeal HEp-2 cells, a series of flavan-3-ols  and highly purified and chemically characterized proanthocyanidin samples including procyanidins based on epicatechin, catechin or ‘mixed’ constituent flavanyl units, prodelphinidins made up of (epi)gallocatechin monomeric unts as well as oligomers possessing A-type units in their molecules was evaluated for anti-adhesive effects. Reduced microbial adherence was observed exclusively for prodelphinidins, suggesting that pyrogallol-type elements,  Although there is good evidence for the adaptation of some herbivores and microbes to this constitutive chemical defense, plants may have benefited from accumulating large quantities of polyphenols in their tissues.Proanthocyanidins represent a major group of polyphenols with amazing structural diversity that occur ubiquitously in woody and some herbaceous plants. Their presence in significant amounts in the wood, bark, leaves and fruits of many plant species has suggested a crucial role at the ecological and evolutionary level ,2. One oin vitro and effective antimicrobial protection to plants as well as the claimed efficacy of herbal medicines may plausibly be explained by the large polyphenol concentrations in plants and traditional herbal preparations as well as the chemical heterogeneity. From a clinical point of view, it is highly unlikely that under therapeutic conditions antimicrobial activity at such high MIC values will be significantly effective. Furthermore, the use of high quantities of tannins is therapeutically inappropriate, suggesting that indirect mechanisms may represent a conceivable alternative. Stimulation of the non-specific immune system by ingested polyphenolic metabolites present in herbal preparations may well provide a scientific basis for claimed remedial effects in infectious conditions. That proanthocyanidins have been shown to possess NO inducing and cytokine producing capabilities in infected macrophages strongly support this assumption , 4.21 , 4.55 , 4.63 , 4.87 , 5.78 , 5.84 , 5.98 , 6.56 and 6.59 . 13C-NMR (100 MHz): δC 29.8 [C-4 (F)], 38.9 [C-4 (C)], 67.4 [C-3 (F)], 73.7 [C-3 (C)], 79.9 [C-2 (F)], 84.0 [C-2 (C)], 96.2 [C-6 (A)], 97.5 [C-8 (A)], 97.7 [C-8 (D)], 99.4 [C-4a (D)], 106.7 [C-4a (C)], 107.2 and 107.7 [C-2 and C-6 (B and E)], 108.5 [C-6 (D)], 131.4 and 131.7 [C-1 (B and E)], 133.4 [C-4 (B and E)], 146.7 [C-3 and C-5 (B and E)], 155.2-158.7 . Gallocatechin--gallocatechin (5). 1H-NMR : δ 2.4-2.8 , 3.84 and 4.04* , 4.29* , 4.38 , 4.46* , 4.52 , 4.52 , 4.80* , 5.73 , 5.80, 5.84 and 5.86* , 5.92 and 6.05* , 6.04, 6.35, 6.49*, 6.52* . 13C-NMR (100 MHz): δC 28.0 [C-4 (F)], 38.6 [C-4 (C)], 68.5 [C-3 (F)], 73.7 [C-3 (C)], 82.8 [C-2 (F)], 84.3 [C-2 (C)], 96.3 [C-6 (A)], 96.9 [C-8 (A)], 97.5 [C-8 (D)], 100.5 [C-4a (D)], 107.1 [C-4a (C)], 108.4 and 108.8 [C-2 and C-6 (B and E)], 110.3 [C-6 (D)], 131.7 [C-1 (B and E)], 133.9 [C-4 (B and E)], 146.3 and 146.7 [C-3 and C-5 (B and E)], 154.8-158.8 . Epicatechin--epigallocatechin (6). 1H-NMR data were consistent with those reported [13 C-NMR (100 MHz): δC 29.9 [C-4 (F)], 37.1 [C-4 (C)], 66.8 [C-3 (F)], 73.5 [C-3 (C)], 77.1 [C-2 (C)], 79.7 [C-2 (F)], 96.1 [C-6 (A)], 96.6 [C-8 (A)], 97.4 [C-6 (D)], 100.6 [C-4a (D)], 107.2 [C-4a (C)], 108 - 110 , 109.7 [C-8 (D)], 131.3 and 131.9 [C-1 (B and E)], 134.8 [C-4 (B and E)], 146.7 [C-3 and C-5 (B and E)], 156-159 . reported . 13 C-NMEpigallocatechin--epicatechin (7). 1H-NMR (400 MHz): δ 2.7-2.8 , 4.03 , 4.29 [3-H (C)], 4.79 , 4.91 , 5.07 , 5.91-5.93 , 5.99 , 6.82-6.90 .Vaccinium polyphenols for the prophylaxis of urinary tract infections and, to some extent, to Helicobacter pylori-associated gastritis [Bridelia grandis for microbial adhesion of streptococci suggests tannins as the anti-adhesive principle [in vitro model. This study provided some insight into structure-activity relationships regarding the adhesive potential of proanthocyanidins. The question of specificity deserves further examination. On the other hand, information about the adhesion molecules would significantly contribute to a better understanding of the interactions.Besides carbohydrates ,35,36,37astritis . Apart frinciple . The blorinciple ,11,12. T


N-oxide derivatives were designed, synthesized and evaluated for hypoxic and normoxic cytotoxic activity against human SMMC-7721, K562, KB, A549 and PC-3 cell lines. Many of these new compounds displayed more potent hypoxic cytotoxic activity compared with TX-402 and TPZ in the tumor cells based evaluation, which confirmed our hypothesis that the replacement of the 3-amine with the substituted aryl ring of TX-402 increases the hypoxic anti-tumor activity. The preliminary SAR revealed that 3-chloro was a favorable substituent in the phenyl ring for hypoxic cytotoxicity and 7-methyl or 7-methoxy substituted derivatives exhibited better hypoxic selectivity against most of the tested cell lines. The most potent compound, 7-methyl-3-(3-chlorophenyl)-quinoxaline-2-carbonitrile 1,4-dioxide (9h) was selected for further anti-tumor evaluation and mechanistic study. It also exhibited significant cytotoxic activity against BEL-7402, HepG2, HL-60, NCI-H460, HCT-116 and CHP126 cell lines in hypoxia with IC50 values ranging from 0.31 to 3.16 μM, and preliminary mechanism study revealed that 9h induced apoptosis in a caspase-dependent pathway.A series of 3-aryl-2-quinoxaline-carbonitrile 1,4-di- Hypoxia is an inevitable circumstance in most solid tumors resulting from rapid tumor growth with an inefficient microvascular system. Tumor cells within these regions show resistance to radiotherapy and chemotherapy and present a tremendous challenge to cancer therapy ,2. Hypox1, TPZ, N-oxide  benzotriazine-1,4-dioxide derivatives 6 and 7  through 8, With a similar drug design strategy, we also synthesized a series of 3-phenyl-2-ethylthio- (or 2-ethylsulfonyl)-quinoxaline-1,4-dioxide derivatives through replacement of the 2-cyano and 3-amine moieties with 2-ethylthio (or 2-ethysulfonyl) and the 3-aryl of TX-402. The 2-ethylsulfonyl derivatives displayed moderate to good antiproliferative activity in hypoxia, while the 2-ethylthio derivatives showed almost no activity in the cell-based test. These results implicated that the electron-withdrawing 2-ethylsulfonyl moiety was necessary for hypoxic activity probably due to its modulation of the one-electron reduction potential of molecules. Among all the synthesized compounds, 3-(4-bromophenyl)-2-(ethylsulfonyl)-6-methylquinoxaline-1,4-dioxide Q39, 8,  not onlyN-oxide derivatives 9a–t , K562 (chronic myeloid leukemia), KB (epidermoid carcinoma of the nasopharynx), A549  and PC-3 (prostate cancer) under normoxic and hypoxic conditions. TX-402 and TPZ were employed as positive controls and the antiproliferative activity results are summarized in All the newly synthesized compounds were assayed for N-oxide derivatives showed higher or similar hypoxic cytotoxic activity and selectivity in comparison with those of TX-402 and TPZ against most of the tested cell lines, in particular for the SMMC-7721, K562 and KB cell lines.As shown in 9a–t was highly dependent on the 3-position and 7-position substitutents of the quinoxaline. Such as, compound 9a  exhibited weak to good cytotoxicity against the SMMC-7721, K562, KB, A549 and PC3 cell lines . Compound 9h (7-methyl-3-(3-chlorophenyl)-quinoxaline-2-carbonitrile 1,4-dioxide) showed good hypoxic cytotoxic activity against five cell lines, with IC50 values of 0.76, 0.92, 0.53, 4.91 and 2.25 μM, respectively. By comparison with the IC50 values of the TX-402 , our hypothesis that the replacement of 3-amine with substituted aryl ring of TX-402 increased the hypoxic anti-tumor activity was confirmed.Obviously, the hypoxic cytotoxic potency of 9c and 9h with that of 9a and 9f suggested that an electron-withdrawing 3-chloro group in the 3-phenyl moiety increased cytotoxicity against most tested cell lines, particularly for the SMMC-7721, K562 and KB cell lines. The substituents on the 7-position of the quinoxaline ring also have a significant impact on anti-tumor activity and hypoxia selectivity because of the disparity in the electronic properties of the resulting molecules. As shown in 9p and 9q exhibited better hypoxic antiproliferative activity than the 7-unsubstituted derivative 9a and 9b in most tested cell lines.The substituents on the 3-phenyl moiety affect the anti-tumor activity by changing the electronic and lipophilic properties of the entire molecule. Comparing the cytotoxic activity of 9f and 9n showed very high hypoxic selectivity against SMMC-7721 cell line, with HCR values of 159 and 115, respectively, which were 23- and 16.7-fold more selective than TPZ (HCR = 6.90). The 7-methyl-substituted quinoxaline derivative 9i was the most hypoxic selective cytotoxin against the KB cell line , which is an 11.8-fold improvement compared with TPZ .On the other hand, the introduction of electron-donating methyl or methoxy groups into the 7-position of the quinoxaline ring improved the hypoxic selectivity against most cell lines, in particular for the SMMC-7721, K562 and KB cell lines. For example, 7-methyl and 7-methoxy-substituted quinoxaline derivatives 50 values in the 0.37–5.07 μM range and HCR values between 1.0 and 158.73. The A549 one was the most resistant cell line to the hypoxic cytotoxic effect of these derivatives, with IC50 values in the range of 5.72–36.15μM and HCR values between 0.12 and 5.71. This result was consistent with that of 2-arylcarbonyl-3-trifluoromethylquinoxaline-1,4-di-N-oxide derivatives +.le (11a) . White s3-Methybenzoylacetonitrile (11b) [m/z = 160.6 [M + H]+. le (11b) . White s3-Chlorobenzoylacetonitrile (11c) [m/z = 180.3 [M + H]+.le (11c) . White s4-Bromobenzoylacetonitrile (11d) [m/z = 225.2 [M + H]+.le (11d) . White s4-Nitrobenzoylacetonitrile (11e) [m/z = 191.3 [M + H]+.le (11e) . White s12a–d were synthesized according to a literature method and confirmed by melting point comparison +.ide (9a) . Yellow 3-(3-Methylphenyl)quinoxaline-2-carbonitrile-1,4-dioxide (9b). Yellow solid (48.0%); m.p.: 208–209 °C; IR (KBr): ν 3101, 2235, 1634, 1493, 1340, 1276, 773 cm−1; 1H-NMR (CDCl3) δ 8.68 , 8.61 , 7.99 , 7.93 , 7.49–7.53 , 7.41–7.43 , 2.46 ; HRMS (TOF) calc. for C16H12N3O2 [M + H]+: 278.0924, found: 278.0927.3-(3-Chlorophenyl)quinoxaline-2-carbonitrile-1,4-dioxide (9c). Yellow solid (53.3%); m.p.: 195–197 °C; IR (KBr): ν 3085, 2232, 1647, 1593, 1490, 1436, 1336, 1086, 976, 773 cm−1; 1H-NMR (CDCl3) δ 8.67 , 8.61 , 7.94–8.03 , 7.75 , 7.55–7.61 ; HRMS (TOF) calc. for C15H9ClN3O2 [M + H]+: 298.0378, found: 298.0377.3-(4-Bromophenyl)quinoxaline-2-carbonitrile-1,4-dioxide (9d). Yellow solid (47.2%); m.p.: 230–232 °C; IR (KBr): ν 3102, 2239, 1601, 1515, 1488, 1341, 1272, 1089, 978, 830, 772 cm−1; 1H-NMR (DMSO-d6) δ 8.51–8.55 , 8.07–8.12 , 7.80–7.83 , 7.46–7.49 ; HRMS (TOF) calc. for C15H9BrN3O2 [M + H]+: 341.9873, found: 341.9868.3-(4-Nitrophenyl)quinoxaline-2-carbonitrile-1,4-dioxide (9e). Yellow solid (48.5% yield); m.p.: 240–241 °C; IR (KBr): ν 3105, 2238, 1598, 1515, 1344, 1275, 1089, 979, 855 cm−1; 1H-NMR (DMSO-d6) δ 8.54–8.56 , 8.47–8.49 , 8.11–8.15 , 8.03–8.05 ; HRMS (TOF) calc. for C15H9N4O4 [M + H]+: 309.0618, found: 309.0621.7-Methyl-3-phenylquinoxaline-2-carbonitrile-1,4-dioxide (9f). +.de (9f). . Yellow 7-Methyl-3-(3-methylphenyl)quinoxaline-2-carbonitrile-1,4-dioxide (9g). Yellow solid (43.3% yield); m.p.: 216–217 °C; IR (KBr): ν 3109, 2236, 1613, 1484, 1328, 1275, 1091, 983, 828, 785 cm−1; 1H-NMR (CDCl3) δ 8.40–8.58 , 7.77–7.80 , 7.49–7.52 , 7.42–7.43 , 2.67 , 2.47 ; HRMS (TOF) calc. for C17H14N3O2 [M + H]+: 292.1080, found: 292.1083.7-Methyl-3-(3-chlorophenyl)quinoxaline-2-carbonitrile-1,4-dioxide (9h). Yellow solid (46.5% yield); m.p.: 221–222 °C; IR (KBr): ν 3096, 2233, 1593, 1491, 1333, 1088, 982, 830 cm−1; 1H-NMR (CDCl3) δ 8.50–8.57 , 8.40 , 7.80–7.82 , 7.75 , 7.55–7.60 , 2.67 ; HRMS (TOF) calc. for C16H11ClN3O2 [M + Na]+: 334.0354, found: 334.0352.7-Methyl-3-(4-bromophenyl)quinoxaline-2-carbonitrile-1,4-dioxide (9i). Yellow solid (48.7%); m.p.: 222–223 °C; IR (KBr): ν 3076, 2239, 1602, 1501, 1330, 1231, 1088, 982, 836 cm−1; 1H-NMR  δ 8.39–8.56 , 7.80 , 7.74–7.77 , 7.28–7.31 , 2.67 ; HRMS (TOF) calc. for C16H11BrN3O2 [M + H]+: 356.0029, found: 356.0032.7-Methyl-3-(4-nitrophenyl)quinoxaline-2-carbonitrile-1,4-dioxide (9j). Yellow solid (46.2%); m.p.: 240–241 °C; IR (KBr): ν 3106, 2237, 1602, 1519, 1341, 1092, 981, 936, 828 cm−1; 1H-NMR  δ 8.52–8.58 , 8.46 , 8.43 , 7.95 , 7.82–7.85 , 2.69 ; HRMS (TOF) calc. for C16H10N4NaO4 [M + Na]+: 345.0594, found: 345.0597.7-Methoxy-3-phenylquinoxaline-2-carbonitrile 1,4-dioxide (9k). +.de (9k). . Yellow 7-Methoxy-3-(3-methylphenyl)quinoxaline-2-carbonitrile 1,4-dioxide (9l). Yellow solid (44.5%); m.p.: 203–204 °C; IR (KBr): ν 3101, 2235, 1610, 1504, 1395, 1329, 1258, 1131, 1012, 945, 849 cm−1; 1H-NMR  δ 8.43 , 7.79 , 7.71 , 7.47–7.53 , 7.41–7.43 , 4.03 , 2.40 ; HRMS (TOF) calc. for C17H14N3O3 [M + H]+: 308.1030, found: 308.10337-Methoxy-3-(3-chlorophenyl)quinoxaline-2-carbonitrile-1,4-dioxide (9m). Yellow solid (45.7%); m.p.: 160–162 °C; IR (KBr): ν 3106, 2238, 1616, 1591, 1535, 1494, 1422, 1333, 1250, 1001, 814 cm−1; 1H-NMR (CDCl3) δ 8.56 , 7.87 , 7.74 , 7.54–7.59 , 4.06 ; HRMS (TOF) calc. for C16H11ClN3O3 [M + H]+: 328.0483, found: 328.0485.7-Methoxy-3-(4-bromophenyl)quinoxaline-2-carbonitrile-1,4-dioxide (9n). Yellow solid (45.3%); m.p.: 184–186 °C; IR (KBr): ν 3092, 2238, 1608, 1504, 1332, 1248, 1016, 933, 836 cm−1; 1H-NMR (CDCl3) δ 8.56 , 7.86 , 7.73–7.76 , 7.55 , 7.27–7.31 , 4.05 ; HRMS (TOF) calc. for C16H11BrN3O3 [M + H]+: 371.9978, found: 371.9979.7-Methoxy-3-(4-nitrophenyl)quinoxaline-2-carbonitrile-1,4-dioxide (9o). Yellow solid (45.6%); m.p.: 238–240 °C; IR (KBr): ν 3105, 2235, 1615, 1525, 1361, 1327, 1255, 1013, 939, 858 cm−1; 1H-NMR (CDCl3) δ 8.57 , 8.59 , 7.95  , 7.90 , 7.59 , 4.08 ; HRMS (TOF) calc. for C16H11N4O5 [M + H]+: 339.0724, found: 339.0729.7-Chloro-3-phenylquinoxaline-2-carbonitrile-1,4-dioxide (9p). +.de (9p). . Yellow 7-Chloro-3-(3-methylphenyl)quinoxaline-2-carbonitrile-1,4-dioxide (9q). Yellow solid (46.0%); m.p.: 215–216 °C; IR (KBr): ν 3099, 2235, 1636, 1489, 1400, 1325, 1260, 1095, 893, 831, 787 cm−1; 1H-NMR (DMSO-d6) δ 8.51–8.53 , 8.14 , 7.50–7.52 , 7.44–7.45 , 2.40 ; HRMS (TOF) calc. for C16H11ClN3O2 [M + H]+: 312.0534, found: 312.0536.7-Chloro-3-(3-chlorophenyl)quinoxaline-2-carbonitrile-1,4-dioxide (9r). Yellow solid (45.8%); m.p.: 225–226 °C; IR (KBr): ν 3103, 2234, 1595, 1487, 1401, 1332, 1088, 987, 829 cm−1; 1H-NMR (CDCl3) δ 8.56–8.67 , 7.88–7.94 , 7.74 , 7.56–7.62 ; HRMS (TOF) calc. for C15H8Cl2N3O2 [M + H]+: 331.9988, found: 331.9993.7-Chloro-3-(4-bromophenyl)quinoxaline-2-carbonitrile-1,4-dioxide (9s). Yellow solid (49.4%); m.p.: 223–224 °C; IR (KBr): ν 3102, 2235, 1600, 1492, 1332, 1220, 1091, 989, 835 cm−1; 1H-NMR (DMSO-d6) δ 8.52-8.55 , 8.15 , 7.79–7.82 , 7.46–7.50 ; HRMS (TOF) calc. for C15H8BrClN3O2 [M + H]+: 385.9483, found: 385.9489.7-Chloro-3-(4-nitrophenyl)quinoxaline-2-carbonitrile-1,4-dioxide (9t). Yellow solid (47.9%); m.p.: 238–239 °C; IR (KBr): ν 3107, 2237, 1599, 1519, 1488, 1340, 1094, 987, 830 cm−1; 1H-NMR (DMSO-d6) δ 8.54–8.58 , 8.48–8.50 , 8.17–8.19 , 8.02–8.04 ; HRMS (TOF) calc. for C15H8ClN4O4 [M + H]+: 343.0229, found: 343.0234.2, 5% CO2 at 37 °C or in hypoxic atmosphere with 3% O2, 5% CO2 .The tested eleven human cancer cell lines  were purchased from the Cell Bank of China Science Academy . The above cells were cultured in RPMI-1640  medium with heat-inactivated 10% fetal bovine serum, penicillin (100 units/mL) and streptomycin (100 μg/mL) and incubated in normoxic atmosphere with 20% O2). After 4 h incubation, 200 μL of DMSO was added to each well and optical density (OD) was read at 570 nm by Thermo Multiskan Spectrum (Thermo Electron Corporation). The IC50 values were calculated using the PrismPad computer program  and were defined as concentration of drug causing 50% inhibition in absorbance compared with control (vehicle) cells.Cancer cells were seeded in 96-well microtiter plates , and were cultured in normoxia and hypoxia. The hypoxic cells were allowed to attach 1 day prior to the addition of these compounds (0–50 μM) in complete medium  in replicates of 4 wells per condition. Plates were assayed at 72 h after initiation of drug exposure. Afterwards, 10 μL of stock 3--2,5-diphenyltetrazolium bromide  solution was added to each well (0.5 mg/mL) for another 4 h incubation , 9h (10 μM) alone for 24–48 h in 1% O2 or 20% O2 respectively; 9h (10 μM) +z-VAD-fmk (10.0 μM) for 48 h in hypoxia. Detection of apoptosis by FACS Calibur flow cytometer  was performed using the Propidium iodide (PI) apoptosis detection kit .The SMMC-7721 cells were treated with 9h both in hypoxia and normoxia were extracted in radio-immunoprecipitation assay buffer . Total protein concentrations of whole cell lysates were determined using BioRad BCA method . Equal amounts of protein sampled from whole cell lysates were subjected to electrophoresis on 8%–12% Tris-Glycine pre-cast gels  and electroblottedonto Immobilon-P Transfer Membrane , and probed with primary antibodies and then incubated with a horseradish peroxidase (HRP) conjugated secondary antibodies. Proteins were visualized using enhanced chemiluminescent (ECL) Western Blotting detection reagents .Proteins of SMMC-7721 cells incubated with 10 μM N-oxide derivatives 9a–t have been synthesized and evaluated for their hypoxic and normoxic cytotoxic activity. Many of these 3-aryl-2-quinoxalinecarbonitrile-1,4-di-N-oxide derivatives showed better hypoxic cytotoxic activity and higher hypoxic selectivity than that of TPZCN and TPZ against most tested cancer cell lines, in particular for the SMMC-7721, K562 and KB cell lines. The preliminary SAR study revealed that the 3-(3-chlorophenyl) moiety was favorable for hypoxic cytotoxicity and the 7-methyl or 7-methoxy moiety improved the hypoxic selectivity. Compound 9h decreased the protein levels of procaspase-3 and induced the cleavage of PARP in hypoxia, which suggested it induces apoptosis in a caspase-dependent pathway. In summary, a series of 3-aryl-2-quinoxalinecarbonitrile-1,4-di-


Staphylococcus aureus (MRSA), Acinetobacter baumanni (AC), Klebsiella pneumonie (KB) and Pseudomonas aeruginosa (PA) using the disc diffusion and micro broth dilution assays. Based on the overall results, the complexes showed the highest activities against MRSA while a weak antibacterial activity was observed against A. baumanii and P. aeruginosa.A series of Schiff bases derived from 2-acetylpyridne and their metal complexes were characterized by elemental analysis, NMR, FT-IR and UV-Vis spectral studies. The complexes were screened for anti-bacterial activity against Methicillin-resistant  It is known that the existence of metal ions bonded to biologically active compounds may enhance their activities ethanamine N,N′,N′′}cadmium (5), chlorido(2-{1-[(2-morpholinoethyl)imino]ethyl}-phenolato N,N′,N′′)copper(II) (6), dibromido{2-morpholino-N- ethanamine N,N′,N′′} zinc (8), N,N-dimethyl-N’-[1-(2-pyridyl)ethylidene]ethane-1,2-diamine-3N,N′,N′′}bis(thiocyanate) zinc(II) (9), and aqua{2-morpholino-N-[1-(2-pyridyl)ethylidene]ethanamine to compare the structures of some earlier prepared complexes with the present ones. There are two reported complexes of nickel(II) perchlorate with the similar donor-Schiff base ligand -ethanamine with Zn(II) ion in the presence of potassium bromide. Similar to the structure of the analogous ZnCl2 complex , 144.45 δ(C), 142.62 δ(CH), 136.40 δ(CH), 123.96 δ(CH), , 61.23 , 52.08, 49.67 , 44.57 , 31.82 , 14.52 .The solid product was recrystallized in methanol. Yield: 61.5%. Molecular formula: C2-(Piperazin-1-yl)-N-(1-(pyridin-2-yl)ethylidene)ethanamine (2): A mixture of 4-(2-aminoethyl)-piperazine  and 2-acetylpyridine  in ethanol (50 mL) was refluxed for three hours followed by addition of few drops of glacial acetic acid.1 was applied as the prototype in the isolation of other Schiff bases. Yield: 40.3%. Molecular formula: C13H20N4. Analysis Calculated: C, 67.21; H, 8.68; N, 24.12. Found: C, 68.19; H, 8.89; N, 24.48. IR (ATR cm−1) 3308.37 n(N-H), 2945.30 n(C-H), 1640.05 n(C=N), 1586.63 n(C=N)pyr, 1464.94, 1436.55 n(C-C), 1132.42 n(C-N). UV-Vis (DMSO) 281.00 (n→π*); 224.00 (π→π*). 1H-NMR (DMSO-6d) 8.30–7.85 , 3.98–3.69 (CH2-Pip.), 2.9 (NH-) 2.75–2.55 (NCH2-CH2N), 1.21 (CH3-). 13C-NMR (DMSO-6d) 168.43 , 148.47 δ(C), 140.44 δ(CH), 127.93 δ(CH), 123.79 δ(CH), , 51.72 , 44.19 , 42.04 , 15.79 .The same procedure as for N1,N1-Dimethyl-N2-(1-(pyridin-2-yl)ethylidene)ethane-1,2-diamine (3): An accurately measured amount of 2-acetylpyridine  and N,N-dimethylethyldiamine  in ethanol (25 mL) was refluxed for three hours.11H17N3 (191.27). Analysis Calculated: C, 69.87; H, 8.80; N, 13.58. Found: C, 68.48; H, 8.98; N, 14.98. IR (ATR cm−1) 2925.46 n(C-H) 1639.70 n(C=N) 1566.34 n(C=N)pyr, 1464.83, 1435.25 n(C-C), 1153.71, 1103.38 n(C-N). UV-Vis (DMSO) 321 (n→π*); 233 (π→π*).1H-NMR (DMSO-6d) 8.28–7.87 (CH2-Ar), 2.76–2.68 (NCH2-CH2N), 1.22 (CH3-), 1.9 . 13C-NMR (DMSO-6d) 166.59 , 147.58 δ(C), 145.83 δ(CH), 139.56 δ(CH), 126.82 δ(CH), , 54.43 , 43.44. 43.29 , 14.69 .Yield: 54%. Molecular formula: CAqua{Dithiocyanato- (4): A mixture of 2-acetylpyridine  and 4-(2-aminoethyl)morpholine  in ethanol (20 mL) was refluxed for 2 h followed by addition of a solution of cadmium(II) acetate dihydrate  and sodium thiocyanate  in a minimum amount of water. The mixture was refluxed for 2–3 h resulting in the formation of small amount of precipitate. More precipitate was obtained by removal of some solvent. −1) 2981.09 n(C-H), 2157.91, 2083, n(N=C=S), 1651.16 n(C=N), 1438.25 n(C-C), 1107.15 n(C-N), 659.88 n(OH2) 565.42 n(M-N). UV-Vis (DMSO) 407 (LMCT), 285 (n→π*); 234 (π→π*). 1H-NMR (DMSO-6d) 8.80 , 8.29–8.24 , 7.87–7.85 , 3.80, 3.76 , 3.69 , 2.79–2.77 , 2.69 . 13C-NMR (DMSO-6d) 165.80 , 149.24 δ(C), 140.55 δ(CH), 132.31 δ(CH), 127.68 δ(CH), 124.29 δ(CH) , 64.76, 57.88 , 53.44, 44.36 , 21.98 [δ(SCN)], 15.77 .The product was collected by filtration, washed several times with ethanol until a white colored compound is obtained. It was re-crystallized from the same solvent (ethanol), filtered to remove the suspended impurities. Yield = 75%. Melting point >400 °C. Analysis Calculated: . Found: . IR (ATR cmAqua{Dichlorido Piperazin-4-ium1-(2-pyridyl)ethylidene]ethanamine N,N′,N′′}cadmium (5): A mixture of 2-acetylpyridine  and 4-(2-aminoethyl)piperazine  in ethanol (50 mL) was refluxed for 2 h followed by addition of a solution of cadmium(II) chloride  in a minimum amount of water was added. The mixture was refluxed for 2–3 h resulting in the formation of white precipitate.−1) 3469.07 n(N-H), 2953.13 n(C-H), 1654.02 n(C=N), 1438.11 n(C-C), 1121.21 n(C-N), 652.14 n(OH2) 557.10 n(M-N). UV-Vis (DMSO) 497 (LMCT), 281 (n→π*); 229 (π→π*). 1H-NMR (DMSO-6d) 8.73–7.83 , 3.92, 3.81 , 3.3–3.0 , 2.82–2.80 , 2.76 , 2.38–2.36 , 2.30  2.23 . 13C-NMR (DMSO-6d) 166.938 , 157.942, 146.101, 137.967, 131.059, 124.085  108.095, 106.975 [δ(2CH2)], 69.65 , 40.67 , 46.00 , 18.95 .More precipitate was obtained by removal of some solvent. Analysis Calculated: C, 23.61; H, 3.55; N, 10.14. Found: C, 23.65; H, 3.75; N, 10.24. IR (ATR cmChlorido(2-{1-[(2-morpholinoethyl)imino]ethyl}phenolato N,N′,N′′)copper(II) (6): A mixture of 2-acetylpyridine  and 4-(2-aminoethyl) morpholine  in ethanol (20 mL) was refluxed. After 2 h a solution of copper (II) chloride dihydrate  in a minimum amount of ethanol was added. The mixture was refluxed for 2–3 h resulting in the formation of a small precipitate. More precipitate was obtained by removal of some solvent.−1) 2949.37 n(C-H), 1654.51 n(C=N), 1443.03 n(C-C), 1144.39 n(C-N), 577.38 n(M-N). UV-Vis (DMSO) 645.50 (d→d*); 337.00 (LMCT); 309.00 (n→π*); 223.00, 219.00 (π→π*).The product was collected by filtration, washed several times with ethanol until a green colored compound is obtained. It was re-crystallized from the same solvent (ethanol), filtered to remove the suspended impurities. Yield = 77%. Melting point 375–380 °C. Analysis Calculated: . Found: . IR : A mixture of 4-(2-aminoethyl)morpholine  and 2-acetylpyridine  in ethanol (50 mL) was refluxed for 2 h followed by addition of a solution of cadmium(II) acetate dihydrate  and potassium bromide  in a minimum amount of water was added. The mixture was refluxed for 2–3 h resulting in the formation of a white precipitate. More precipitate was obtained by removal of some solvent.−1) 296202 n(C-H), 1650.04 n(C=N), 1458.80 n(C-C), 1115.11 n(C-N), 556.01 n(M-N). UV-Vis (DMSO) 398 (LMCT), 279 (n→π*); 229 (π→π*). 1H-NMR (DMSO-6d) 8.69–8.68 , 8.29–8.24 , 7.85 , 3.93, 3.80 , 3.73–3.71 , 2.81, 2.80, 2.80, 2.72, 2.70 , 2.55 . 13C-NMR (DMSO-6d) 166.90 , 149.13 δ(C), 147.64 δ(CH), 140.55 δ(CH), 127.72 δ(CH), 124.42 δ(CH), , 64.65 , 53.49 , 36.00 , 30.67 , 15.95 .The product was collected by filtration, washed several times with ethanol until a white colored compound is obtained. It was re-crystallized from the same solvent (ethanol), filtered to remove the suspended impurities. Yield = 81%. Melting point >400 °C. Analysis Calculated: C, 37.48; H, 4.60; N, 10.09. Found: C, 37.28; H, 4.45; N, 10.19. IR (ATR cmDibromido {2-morpholino-N-[1-(2-pyridyl) ethylidene] ethanamine N,N′,N′′}zinc (8): A mixture of 2-acetylpyridine  and 4-(2-aminoethyl) morpholine  in ethanol (20 mL) was refluxed. After 2 h a solution of zinc (II) acetate dihydrate  and potassium bromide  in a minimum amount of water. The mixture was refluxed for 2–3 h resulting in the formation of a small amount of precipitate. More precipitate was obtained by removal of some solvent.−1) 2959.01 n(C-H), 1649.00 n(C=N), 1439.00 n(C-C), 1114.11 n(C-N), 561.12 n(M-N). UV-Vis (DMSO) 498 (LMCT), 289 (n→π*); 229 (π→π*). 1H-NMR (DMSO-6d) 8.78, 8.77 , 8.30–8.25 , 7.89–7.87 , 3.89 , 3.85–3.83 , 2.91–2.90 , 2.62 . 13C-NMR (DMSO-6d) , 168.38 δ(C), 146.49 δ(CH), 140.65 δ(CH), 128.03 δ(CH), 124.05 δ(CH) , 62.88 , 54.55 , 52.09 , 44.12 , 15.86 .The product was collected by filtration, washed several times with ethanol until a milky colored compound is obtained. It was re-crystallized from the same solvent (ethanol), filtered to remove the suspended impurities and a single crystal was obtained suitable for x-ray analysis. Yield = 85%. Melting point >400 °C. Analysis Calculated: C, 30.89; H, 3.79; N, 8.31. Found: C, 30.79; H, 3.49; N, 8.28. IR zinc(II) N,N-Dimethyl-N'-[1-(2-pyridyl)ethylidene]ethane-1,2-diamine-(9): A mixture of 2-acetylpyridine  and N,N-dimethylethyldiamine  in ethanol (50 mL) was refluxed for 2 h followed by addition of a solution of Zinc (II) acetate  and sodium thiocyanate  in a minimum amount of water. The mixture was refluxed for 2–3 h resulting in the formation of a white precipitate. More precipitate was obtained by removal of some solvent.−1) 2949.02 n(C-H), 2070.00 n(N=C=S), 1655.03 n(C=N), 1438.38 n(C-C), 1139.09 n(C-N), 477.06 n(M-N). UV-Vis [λmax (nm) (DMSO)]. UV-Vis (DMSO) 497 (LMCT), 321 (n→π*); 233 (π→π*). 1H-NMR (DMSO-6d) 8.65, 8.64 , 8.35–8.32 , 7.95–7.94, 7.93 , 3.79–3.77 , 2.77–2.75 , 2.59 , 2.39 . 13C-NMR (DMSO-6d) 168.74 , 147.99 δ(C), 147.16 δ(CH), 141.36 δ(CH), 135.03 δ(CH), 128.50 δ(CH) , 56.35 , 44.55 , 44.32 , 22.75 [δ(SCN)], 15.88 .The product was collected by filtration, washed several times with ethanol until a white colored compound is obtained. It was re-crystallized from the same solvent (ethanol), filtered to remove the suspended impurities. Yield = 72%. Melting point 370–375 °C. Analysis Calculated: C, 35.27; H, 4.57; N, 11.22. Found: C, 35.17; H, 4.67; N, 11.21. IR (ATR cmAqua {2-morpholino-N-[1-(2-pyridyl)ethylidene] ethanamine N,N′,N′′}bis(thiocyanato) nickel(II) (10): A mixture of 2-acetylpyridine  and 4-(2-aminoethyl)morpholine in ethanol (20 mL) was refluxed for 2 h followed by addition of a solution of nickel(II) acetate tetrahydrate  and sodium thiocyanate  in a minimum amount of water. The mixture was refluxed for 2–3 h resulting in the formation of a greenish colored precipitate. More precipitate was obtained by removal of some solvent.−1) 2980.11 n(C-H), 2082.19 n(N=C=S), 1651.60 n(C=N), 1441.21 n(C-C), 1106.78 n(C-N), 659.16 n(OH2) 515.83 n(M-N), 461.51 n(M-O). UV-Vis (DMSO) 745.00 (d→d*); 574.00 (LMCT); 279.00 (π→π*).The product was collected by filtration, washed several times with ethanol until a green colored compound is obtained. It was re-crystallized from the same solvent (ethanol), filtered to remove the suspended impurities. Yield = 68%. Melting point 365–370 °C. Analytical Calculated: C, 42.27; H, 4.97; N, 16.43; S, 15.05. Found: C, 42.31; H, 4.98; N, 16.43; S, 15.09. IR . The orientation matrix, unit cell refinement and data reduction were all handled by the APEX II software –MRSA 0804-25, MRSA 0805-21, MRSA 0806-1, MRSA 0807-1, MRSA 0807-7, MRSA 0807-19, MRSA 0808-35, MRSA 0809-15, MRSA 0809-24, MRSA 0809-38; two (2) isolates of Acinetobacter baumannii(AC)–AC 0612-7, AC 0903-21, two (2) isolates of Klebsiella pneumonia (KB)–KB 71, KB 83, and two (2) isolates of Pseudomonas aeruginosa (PA)–P. aeruginosa. All tested bacterial strains of MRSA were of clinical origin and have shown resistance to at least four antibiotics  isolates of methicillin-resistant ibiotics . For eac8 cfu/mL  before inoculated evenly on the entire surface of Mueller Hinton agar (Oxoid) with a sterile cotton swab. Sterilized paper discs , impregnated with 30 µg of respective synthetic Schiff compound, and was placed on the inoculated agar plate. DMSO disc was used as a negative control in the test. The diameter of inhibition zone around the impregnated paper disc was measured after 18 h of incubation at 37 °C. All tests were performed in duplicate. Synthetic Schiff base compounds, in which inhibition zone was observed in any one of the four species tested, were selected for MIC and MBC determination with broth micro-dilution assay. Only compounds with MIC and MBC value lesser than “10 µg/mL” is considered potentially active against the corresponded bacterial species; and further tested against the entire collection of the corresponded bacterial species with disc diffusion assay. This was to determine the variation in the susceptibility responses to the tested compound within the bacterial species tested. The two selected strains for each species in the initial screening were: MRSA 0804-25 and MRSA 0807-7 for MRSA  and further diluted in cation adjusted Mueller Hinton broth  to the concentration of 106 cfu/mL. Two-fold serial dilutions of the tested compound were prepared in CMHB across the 96-well microtiter plate with the highest concentration starting from 750 ppm (750 µL/mL) in duplicate rows. The prepared suspension of the bacteria was added to each well except the negative control wells of the microtitre plate in a 1:1 ratio with final bacteria concentration of approximately “5 × 105” cfu/mL. The inoculated microtitre plates were incubated at 37 °C for 24 h. The MIC was determined as the lowest concentration of the test compound that exhibits no visible growth. A further confirmative test was done by adding 30 µL of MTT dye (Sigma) to each well. Wells with color changes within 30–60 min incubation at room temperature were scored as positive growth. The lowest concentration of the tested compound that exhibits no color changes (yellow) is determined as the MIC value. Minimum inhibition concentrations (MICs) were determined with a 96-well broth micro-dilution assay. The inoculum was prepared by suspending an overnight culture in a sterile 0.85% saline (BDH) to approximate 10The MBC, minimal bactericidal concentration was tested by sub culturing 100 µL from each well of the incubated plate into Mueller Hinton Agar. The MBC was determined as the lowest concentration of the test compound that exhibits no viable microorganism growth on the Mueller Hinton Agar plate. The antimicrobial compound is regarded as bactericidal if the MBC is not more than four times the MIC. In conclusion, Schiff-based complexes were highly inhibitive only against the Gram positive bacterium MRSA, and as such could be potential antibacterial drugs to control MRSA nosocomial infections in hospital settings. 8 and complex 9. These data can be obtained free of charge via http://www.ccdc.cam.ac.uk/conts/retrieving.html, or from the Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-033; or Email: deposit@ccdc.cam.ac.uk.CCDC 851793 and 851794 contain the supplementary crystallographic data for complex


The configurational and conformational behavior of some new 3,3,9,9-tetra-substituted-2,4,8,10-tetraoxaspiro[5.5]undecane derivatives with axial chirality was investigated by conformational analysis and variable temperature NMR experiments.  This conformational equilibrium (flipping of the heterocycle) is an enantiomeric inversion  can be considered and six isomers are possible  the preferred structures (I and IV) exhibit these groups in equatorial orientations. Structures I and IV are considered representative for compounds 3, they cannot be transformed into one other by conformational processes and thus represent separable enantiomers.Compounds with 2,4,8,10-tetraoxaspiro[5.5]undecane skeleton 3,  bearing possible  6,13]. ,13. 3, 33) which exhibit flexible structures. We considered of interest to investigate the stereochemistry  of 3,3,9,9-tetrasubstituted-2,4,8,10-tetraoxaspiro[5.5]undecane derivatives with different substituents at the same position  have very close conformational free enthalpies and 2-CH3,2-CH2X-1,3-dioxane derivatives are flexible compounds  six conformers  detections, were run with compounds 5 and 8. The peaks of the enantiomers are baseline separated , aa; CH1H- and 13C-NMR experiments. The room temperature (rt) 1H-NMR spectrum exhibits for the three diastereoisomers of the compounds only one set of signals at mean values of the chemical shifts. The flexible structure of the compounds was revealed by dynamic 4 run in Et2O-10d at 283 K (1(11) = 3.68 (the beginning of an AB splitting is observed) and δ5(7) = 3.75 ppm] and for those of the substituents located at positions 3 and 9 . Despite the flexible structure of the compound, positions 1,11 and 5,7 are diastereotopic and give different signals, so they are not rendered equivalent by conformational equilibria. The rt spectrum of 4 run in C6D6 reveals the diastereotopicity of protons located at the same position (one is procis and the other one is protrans referred to the substituent with higher precedence located at the closer extremity of the spirane skeleton) so in this case the pattern of the spectrum for the protons of the spirane skeleton consists of two AB systems  and at lower temperature separated groups of signals which correspond to the three frozen diastereoisomers and to the axial and equatorial positions of the protons of the spirane and of the groups located at it. The complete assignment of the signals in the low temperature spectrum was not possible, but the evolution of the pattern of the spectra observed by diminishing the temperature clearly shows the freezing of conformational equilibria and the obtaining at low temperature of frozen diastereoisomers in agreement with the structures shown in schemes 6 and 7. The results obtained in the variable temperature 1H-NMR experiments run with the other compounds of this series are similar with those shown for 4.The variable temperature 13C-NMR experiments (300 – 164 K) were run with compounds 4, 6 and 8 in THF-d8 (6 was observed at lower temperature (Tc=170 K) in comparison with the results in the 1H-NMR variable temperature experiment run with the same compound in the same conditions. Variable temperature n THF-d8 . The coa4 and 8 the coalescences in the 13C-NMR take place at similar or higher temperatures than in 1H-NMR. At low temperature (164 K) the 13C-NMR spectra  belonging to the frozen diastereoisomers appear. For  spectra  are more4 and 8 was not possible. However, these results prove that at rt conformational equilibria between many distereoisomers  and 13C-NMR (75 MHz) spectra were recorded at room temperature in CDCl3 on a Bruker 300 MHz spectrometer, using the solvent line as reference. Variable temperature NMR spectra were recorded on Bruker Avance DMX 500 spectrometer in CD2Cl2, (CD2)4O or (C2D5)2O. Electron impact (70 eV) mass spectra were obtained on Hewlett-Packard MD 5972 GC-MS instrument. GC analyses were performed on a Hewlett-Packard HP 5890 gas chromatograph. A HP-5MS capillary column (30 m x 0.25 mm x 0.33 µm) and helium gas were used for separations.Electrospray ionisation mass spectra ESI (ESI+) were recorded using an Esquire 3000 ion-trap mass spectrometer  equipped with a standard ESI/APCI source. HPLC separations were carried out with a Jasco HPLC system on Chiralcel OD column  termostated at 25 °C with eluent hexane : isopropanol 9:1 and 1 ml/min flow rate. A JASCO MD-910 multiwavelength detector and a JASCO OR-2090 chiral detector were used for detection. Melting points were measured with a Kleinfeld melting point apparatus and are uncorrected. Thin layer chromatography (TLC) was conducted on silica gel 60 F254 TLC plates purchased from Merck. Preparative column chromatography was performed using PharmPrep 60 CC (40–63 µm) silica gel purchased from Merck. Chemicals were purchased from Aldrich, Merck or Acros and were used without further purification.Routine p-toluene-sulfonic acid (0.1 g) was dissolved in 100−150 mL benzene (compounds 4−6 and 8) or toluene (compound 7). The reaction mixture was refluxed and the water was removed by azeotropic distillation using a Dean-Stark trap. When 90 % of the theoretical amount of water had been separated, the mixture was cooled to room temperature and the catalyst was neutralized (under stirring over 1 h) with sodium acetate powder in excess (0.3 g). The reaction mixture was washed with water (2 x 100 mL). After drying with anhydrous sodium sulfate, the solvent was removed in vacuo and the crude product was purified by distillation, column chromatography or by crystallization from methanol.A mixture of ketone (48 mmol) and pentaerythritol (20 mmol) and catalytic amounts of 3,9-Dimethyl-3,9-bis(methoxycarbonylmethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane (4). Yield: 57%; colorless oil; fR = 0.22 (n-hexane / ethyl acetate = 8:2); 1H-NMR: δ/ppm 1.52 , 2.76 , 3.69 , 3.71-3.81 ;13C-NMR: δ/ppm 21.5 [3(9)-CH3], 32.4 (C6), 42.1 [3(9)-CH2-], 51.7 [3(9)-CH2COOCH3], 63.8 , 98.1 , 169.6 [3(9)-COO-]; MS  m/z (%): 317 (16), 259 (69), 143 (14), 117 (31), 101 (22), 83 (50), 43 (100); Anal. Calcd for C15H24O8 (332.15): C, 54.21; H, 7.28; found: C, 54.47; H, 7.09.3,9-bis(Ethoxycarbonylmethyl)-3,9-dimethyl-2,4,8,10-tetraoxaspiro[5.5]undecane (5). Yield: 35%; colorless oil; bp 207 ºC/2 mm; 1H-NMR: δ/ppm 1.25 , 1.52 , 2.75 , 3,77 , 4.14 ; 13C-NMR: δ/ppm 14.0 [3(9)-CH2-COO-CH2CH3] 22.0 [3(9)-CH3], 32.2 (C6), 41.56 [3(9)-CH2-], 60.4 [3(9)-CH2-COO2CH-], 63.7 , 98.0 , 169.1 [3(9)-COO-]; MS (ESI): 383.16 [M + Na+]; MS  m/z (%): 345 (8), 273 (51), 203 (6), 185 (10), 143 (12), 131 (25), 113 (21), 83 (41), 43 (100); Anal. Calcd for C17H28O8 (360.18): C, 56.65; H, 7.83; found: C, 56.38; H, 7.65.3,9-Dibenzyl-3,9-dimethyl-2,4,8,10-tetraoxaspiro[5.5]undecane (6). Yield: 29%; white solid; mp 97−98 ˚C; fR = 0.16 (n-hexane); 1H-NMR: δ/ppm 1.29 , 2.98 , 3.63 , 3.72 , 3.73 , 3.86 , 7.23−7.31 ; 13C-NMR: δ/ppm 19.7 [3(9)-CH3], 33.0 (C6), 44.4 [3(9)-CH2-], 63.9 , 64.0 , 99.9 , 126.4, 127.9, 130.6 (tertiary aromatic carbon atoms), 136.6 (quaternary aromatic carbon atom); MS  m/z (%): 277 (80), 143 (65), 113 (31), 91 (40), 83 (65), 43 (100); Anal. Calcd for C23H28O4 (368.20): C, 74.97; H, 7.66; found: C, 75.20; H, 7.39.3,9-bis(Methoxymethyl)-3,9-dimethyl-2,4,8,10-tetraoxaspiro[5.5]undecane (7). Yield: 36%; white solid; mp 66−67 ºC; fR = 0.40 (dichloromethane / ethyl acetate = 2:1); 1H-NMR: δ/ppm 1.41 , 3.37-3.39 , 3.40 , 3.64 , 3.80 , 3.99 ; 13C-NMR: δ/ppm 17.3 [3(9)-CH3], 32.9 (C6), 59.4 [3(9)-CH2OCH3], 63.6 , 63.7 , 75.9 [3(9)-CH2O-], 98.5 ; MS (ESI): 299.14 [M + Na+]; MS  m/z (%): 261 (3), 231 (63), 143 (31), 113 (25), 83 (67), 43 (100); Anal. Calcd for C13H24O6 (276.16): C, 56.51; H, 8.75; found: C, 56.63; H, 8.98.3,9-bis(Chloromethyl)-3,9-dimethyl-2,4,8,10-tetraoxaspiro[5.5]undecane (8). Yield: 58%; white solid; mp 120−121 ºC; crystallized from methanol; 1H-NMR: δ/ppm 1.47 , 3.56 , 3.69 , 3.81 , 3.91 ; 13C-NMR: δ/ppm 18.7 [3(9)-CH3], 32.8 (C6), 47.2 [3(9)-CH2-Cl], 64.0 , 64.1 , 98.4 ; MS  m/z (%): 269 (11), 235 (77), 143 (22), 113 (26), 83 (73), 43 (100); Anal. Calcd for C11H18Cl2O4 (284.06): C, 46.33; H, 6.36; Cl, 24.86; found: C, 46.08; H, 6.64; Cl, 25.03.