Figure 3.
Effect of 1,3-diarylpyrazolyl-acylsulfonamides on mycolic acid biosynthesis in Mycobacterium tuberculosis. Mtb H37Rv mc26206 grown in Middlebrook 7H9-OADC-tyloxapol supplemented with casamino acids, pantothenate, and l-leucine at 37 °C was treated with no drug or 2 or 13 (1 to 6× MIC) and metabolically labeled with [1,2-14C]-acetate for 24 h. The same volume of [14C]-acetate-labeled fatty acid and mycolic acid methyl esters (FAMEs and MAMEs) from treated and untreated cells were analyzed by TLC in the solvent system [n-hexanes/ethyl acetate 95:5; by vol.; three developments] and revealed by PhosphorImaging. Compound 2, a potent HadAB inhibitor, inhibited biosynthesis of mycolic acids up to 86% at 3× MIC in 24 h, whereas only 0–49% inhibition was observed with a weaker HadAB inhibitor 13 at 3× MIC.