Synthesis, Structure-Activity Relationship, and Mechanistic Studies of Aminoquinazolinones Displaying Antimycobacterial Activity.

Phenotypic whole-cell screening against () in glycerol-alanine-salts supplemented with Tween 80 and iron (GASTE-Fe) media led to the identification of a 2-aminoquinazolinone hit compound, sulfone which was optimized for solubility by replacing the sulfone moiety with a sulfoxide . The synthesis and structure-activity relationship (SAR) studies identified several compounds with potent antimycobacterial activity, which were metabolically stable and noncytotoxic. Compound displayed favorable properties and was therefore selected for pharmacokinetic (PK) studies where it was found to be extensively metabolized to the sulfone . Both derivatives exhibited promising PK parameters; however, when was evaluated for efficacy in an acute TB infection mouse model, it was found to be inactive. In order to understand the and discrepancy, compound was subsequently retested using different strains cultured in different media. This revealed that activity was only observed in media containing glycerol and led to the hypothesis that glycerol was not used as a primary carbon source by in the mouse lungs, as has previously been observed. Support for this hypothesis was provided by spontaneous-resistant mutant generation and whole genome sequencing studies, which revealed mutations mapping to glycerol metabolizing genes indicating that the 2-aminoquinazolinones kill via a glycerol-dependent mechanism of action.