Angucycline antibiotics and its derivatives from marine-derived actinomycete Streptomyces sp. A6H.

Vineomycin A (1) and B (2) were isolated from the culture broth of marine actinomycete Streptomyces sp. A6H. Five hydrolysis products were obtained by rational hydrolysis and methanolysis of the fermentation extract. Their structures were characterised as aquayamycin (3), vineomycinone B (4), 9-C--olivosyltetrangulol (5), 7-O-methylgaltamycinone (6) and vineomycinone B methyl ester (7). In addition to these compounds, two ester derivatives, vineolactone A (8) and vineomycinone B benzyl ester (9) of compound 4 were generated semisynthetically. Compound 6 is a new analogue of galtamycinone, while compounds 8 and 9 are new members of vineomycins. Cytotoxic activities and antimicrobial activities were determined for all compounds. The results indicate that only compound 1 showed significant activities with IC value of 0.34 μM against H1975 and MIC value of 4 μg/mL against Staphylococcus aureus.