Camphor sulphonic acid mediated quantitative 1,3-diol protection of major Labdane diterpenes isolated from Andrographis paniculata.
Phytochemical survey of the methanol extract of the dried aerial parts of Andrographis paniculata led to the isolation of major labdane diterpenes, namely 14-deoxy-11,12-didehydroandrographolide, andrographolide and neoandrographolide. Andrographolide was found to be the major phytoconstituent of the plant which was biologically active. For better physiochemical characteristics and bioefficacy, andrographolide is subjected to semi-synthetic modifications. However, presence of several free hydroxyl groups associated with this molecule make it quite polar and poorly soluble in many organic solvents and hence unsuitable for synthetic modifications. One way of resolving its solubility issue is to protect 1,3-diol quantitatively under mild reaction condition without effecting other functional groups. Reaction conditions were optimised using different solvent systems and catalysts towards this direction. X-ray structure of 3,19-isopropylidene-14-deoxy-11,12-didehydroandrographolide is being reported here for the first time. Isolated compounds and derivatives were confirmed by spectral analysis or X-ray data analysis.
['Sharma|Venu|V|', 'Kapoor|Kamal K|KK|', 'Mukherjee|Debaraj|D|', 'Gupta|Vivek K|VK|', 'Dhar|Manoj K|MK|', 'Kaul|Sanjana|S|']
D035685:Andrographis D018360:Crystallography, X-Ray D004224:Diterpenes D005960:Glucosides D008515:Medicine, Ayurvedic D035261:Plant Components, Aerial D010936:Plant Extracts D010946:Plants, Medicinal D013451:Sulfonic Acids D013764:Tetrahydronaphthalenes
1,3-diol protection labdane diterpenes andrographolide Natural products quantitative yield