BEQUINOSTATINS A AND B, NEW INHIBITORS OF GLUTATHIONE S-TRANSFERASE, PRODUCED BY Streptomyces sp. MI384-DF12

PRODUCTION, ISOLATION, STRUCTURE DETERMINATION AND BIOLOGICAL ACTIVITIES

Abstract

New benzo[a]naphthacenequinone metabolites, designated bequinostatins A and B, have been isolated from the culture broth of the benastatin-producing strain Streptomyces sp. MI384-DF12. The structures of bequinostatins A and B were determined by spectral analyses to be 5, 6, 8, 13-tetrahydro-1, 6, 7, 9, 11-pentahydroxy-8, 13-dioxo-3-pentylbenzo[a]naphthacene-2-carboxylic acid and 2-decarboxybequinostatin A, respectively. Bequinostatin A showed considerable inhibitory activity against human pi class glutathione S-transferase (GST π).