Avoiding Antibiotic Inactivation in Mycobacterium tuberculosis by Rv3406 through Strategic Nucleoside Modification

5′-[N-(d-biotinoyl)sulfamoyl]amino-5′-deoxyadenosine (Bio-AMS, 1) possesses selective activity against Mycobacterium tuberculosis (Mtb) and arrests fatty acid and lipid biosynthesis through inhibition of the Mycobacterium tuberculosis biotin protein ligase (MtBPL). Mtb develops spontaneous resistance to 1 with a frequency of at least 1 × 10–7 by overexpression of Rv3406, a type II sulfatase that enzymatically inactivates 1. In an effort to circumvent this resistance mechanism, we describe herein strategic modification of the nucleoside at the 5′-position to prevent enzymatic inactivation. The new analogues retained subnanomolar potency to MtBPL (KD = 0.66–0.97 nM), and 5′R-C-methyl derivative 6 exhibited identical antimycobacterial activity toward: Mtb H37Rv, MtBPL overexpression, and an isogenic Rv3406 overexpression strain (minimum inhibitory concentration, MIC = 1.56 μM). Moreover, 6 was not metabolized by recombinant Rv3406 and resistant mutants to 6 could not be isolated (frequency of resistance <1.4 × 10–10) demonstrating it successfully overcame Rv3406-mediated resistance.