Identification of inhibitors of inducible nitric oxide synthase from microbial extracts

A new member of the angucycline family, vineomycin C (3), together with four known metabolites saquayamycin A1 (1), A-7884 (2), rabelomycin (5) and xanthomegnin (6) were isolated from microbial extracts. The structures were determined by 1D and 2D NMR techniques and chemical degradation. Compounds 1 similar to 3 and 5 were isolated from a fermentation of Streptomyces sp., while 6 was isolated from a fungal fermentation extract. All five compounds have shown potent inhibitory activity in the inducible nitric oxide synthase (iNOS) assay.