Benastatin C is a polyketide synthase-derived benastatin that has been found inStreptomycesand has diverse biological activities.1,2It inhibits glutathione S-transferase (GST; IC50= 24 ug/ml for the rat liver enzyme).2Benastatin C also inhibits the esterase activity of isolated porcine pancreatic lipase (IC50= 10 ug/ml). It increases LPS- or concanavalin A-induced blastogenesis of isolated mouse spleen lymphocytes in a concentration-dependent manner.