Synthesis and pharmacological evaluation of nucleoside prodrugs designed to target siderophore biosynthesis in Mycobacterium tuberculosis.
The nucleoside antibiotic, 5'-O-[N-(salicyl)sulfamoyl]adenosine (1), possesses potent whole-cell activity against Mycobacterium tuberculosis (Mtb), the etiological agent of tuberculosis (TB). This compound is also active in vivo, but suffers from poor drug disposition properties that result in poor bioavailability and rapid clearance. The synthesis and evaluation of a systematic series of lipophilic ester prodrugs containing linear and α-branched alkanoyl groups from two to twelve carbons at the 3'-position of a 2'-fluorinated analog of 1 is reported with the goal to improve oral bioavailability. The prodrugs were stable in simulated gastric fluid (pH 1.2) and under physiological conditions (pH 7.4). The prodrugs were also remarkably stable in mouse, rat, and human serum (relative serum stability: human∼rat≫mouse) displaying a parabolic trend in the SAR with hydrolysis rates increasing with chain length up to eight carbons (t1/2=1.6 h for octanoyl prodrug 7 in mouse serum) and then decreasing again with higher chain lengths. The permeability of the prodrugs was also assessed in a Caco-2 cell transwell model. All of the prodrugs were found to have reduced permeation in the apical-to-basolateral direction and enhanced permeation in the basolateral-to-apical direction relative to the parent compound 2, resulting in efflux ratios 5-28 times greater than 2. Additionally, Caco-2 cells were found to hydrolyze the prodrugs with SAR mirroring the serum stability results and a preference for hydrolysis on the apical side. Taken together, these results suggest that the described prodrug strategy will lead to lower than expected oral bioavailability of 2 and highlight the contribution of intestinal esterases for prodrug hydrolysis.
['Dawadi|Surendra|S|', 'Kawamura|Shuhei|S|', 'Rubenstein|Anja|A|', 'Remmel|Rory|R|', 'Aldrich|Courtney C|CC|']
D000818:Animals D018938:Caco-2 Cells D004305:Dose-Response Relationship, Drug D015195:Drug Design D006801:Humans D051379:Mice D015394:Molecular Structure D009169:Mycobacterium tuberculosis D009705:Nucleosides D011355:Prodrugs D051381:Rats D017262:Siderophores D013329:Structure-Activity Relationship
Nucleoside Prodrug Tuberculosis Siderophore biosynthesis inhibitor