Isolation and structure elucidation of diazaquinomycin C from a terrestrial Streptomyces sp. and confirmation of the akashin structure.

In the screening of terrestrial Streptomycetes for bioactive components, a new antibiotic designated as diazaquinomycin C (2b) was isolated. The new antibiotic was found to be a homologue of diazaquinomycin A (2a) by spectroscopic methods and by comparison of the NMR data with those of 2a. The same strain additionally produced the akashins 1a-1c. The configuration of the N-O acetale bond in these rare glycosylated dichloroindigo derivatives was confirmed to be beta.