– Benastatin B is a polyketide synthase-derived benastatin that has been found in Streptomyces and has diverse biological activities. It inhibits glutathione S-transferase (GST; Ki = 3.7 µM for the rat liver enzyme).2 Benastatin B also inhibits the transglycosylase activity of A. baumannii, C. difficile, E. coli, and S. aureus recombinant penicillin-binding proteins (PBPs; IC50s = 16, 53.3, 30.7, and 31.6 µM, respectively).3 It is active against several bacteria, including methicillin-resistant S. aureus (MRSA; MIC = 3.12 µg/ml).