Discovery of small molecule probe that shows anti-tubercular activity via Mtb bioA (DAPA synthase) enzyme inhibition

Cofactor biosynthetic pathways are a rich source of potential Bacterial drug targets because of their essential nature and lack of corresponding mammalian pathways. The genome sequence of Mycobacterium tuberculosis (Mtb) H37Rv, the model virulent laboratory strain, revealed it has the full metabolic potential to synthesize all Vitamins and cofactors. Biotin (vitamin H) is the cofactor responsible for activation of carbon dioxide in acyl-CoA carboxylases involved in fatty acid metabolism and pyruvate carboxylase in gluconeogenesis. Biotin biosynthesis is required for survival of Mtb in vitro and in vivo. Moreover, biotin starvation of an Mtb biotin auxotroph led to cell death, which is unusual as most Mtb auxotrophs enter a nonreplicating phase when starved for their given nutrient in vitro. In a recent study, Schnappinger and co-workers have demonstrated, using a phenotypically well-regulated bioA knockdown Mtb mutant, that silencing of bioA (DAPA synthase) after establishing an Infection can defeat a chronic Infection in a murine model of TB. These genetic studies provide an unprecedented level of validation for a Mtb target and suggest biotin biosynthesis, BioA in particular, represents an extremely attractive target for the development of new antitubercular agents. We report the discovery of a structurally novel small molecule (CID 1245700) that inhibits bioA and demonstrate antitubercular activity in wild type and Mtb strains that conditionally express bioA.