Synthesis of farinomaleins and their antimicrobial activities

A single-step synthesis of farinomalein A, a naturally occurring maleimide, by the radical-mediated introduction of an isopropyl group to bromomaleic anhydride and one-pot maleimide formation with β-alanine is reported. Antimicrobial testing of natural and unnatural farinomaleins synthesized using this protocol demonstrates that farinomalein A and some unnatural analogs are active against Bacillus subtilis, and one unnatural analog is active against Escherichia coli. The possible inhibitory activity of bacterial membrane and/or cell wall functions of farinomalein A was indicated by cell morphological studies.