Himalomycin A and B: Isolation and structure elucidation of new fridamycin type antibiotics from a marine Streptomyces isolate

In our screening of marine Streptomycetes for bioactive compounds, in addition to the known metabolites rabelomycin (1), fridamycin D (2b), N-benzylacetamide and N-(2'-phenylethyl)acetamide, two new anthracycline antibiotics designated as himalomycin A (2c) and B (2d) were isolated from the culture broth of the marine Streptomyces sp. isolate B6921. The structure of the new antibiotics was determined by comparison of the NMR data with those of fridamycin D (2b) and by detailed interpretation of mass, 1D and 2D NMR spectra.