Synthesis and pharmacological evaluation of nucleoside prodrugs designed to target siderophore biosynthesis in Mycobacterium tuberculosis

Surendra Dawadi, Shuhei Kawamura, Anja Rubenstein, Rory Remmel, Courtney C. Aldrich

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

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 蠑 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.

Original languageEnglish (US)
Pages (from-to)1314-1321
Number of pages8
JournalBioorganic and Medicinal Chemistry
Volume24
Issue number6
DOIs
StatePublished - Mar 15 2016

Bibliographical note

Funding Information:
This work was supported by a grant from the NIH ( AI070219 to C.C.A.).

Publisher Copyright:
© 2016 Elsevier Ltd. All rights reserved.

Keywords

  • Nucleoside
  • Prodrug
  • Siderophore biosynthesis inhibitor
  • Tuberculosis

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