New angucyclines and antimicrobial diketopiperazines from the marine mollusk-derived actinomycete Saccharothrix espanaensis An 113

Abstract

Two new angucyclines, saccharothrixmicines A (2) and B (3), together with three known diketopiperazines 4-6 were isolated from the actinomycete Saccharothrix espanaensis An 113 associated with the marine mollusk Anadara broughtoni. Their structures were determined by HRESI-MS and 1D and 2D NMR. Compounds 2 and 3 differ in aglycone and glycosidic bond type. 2 is an alpha-L-6-deoxyaltrose-phenylglycoside of a benz[a]anthraquinone aglycone, while 3 is an O-glycoside of the same sugar linked to C-7 of the known angucyclinone (1). A saccharothrixmicine-containing fraction exhibited activity towards Candida albicans and Xanthomonas sp. pv. badrii whereas the diketopiperazines showed antibiotic activities against Vibrio alginolyticus and Vibrio parahaemolyticus.