Detection of phenanthroviridin aglycone in a UV-mutant of Streptomyces murayamaensis

The kinamycin antibiotics, isolated from Streptomyces murayamaensis, were originally characterized by Omura and co-workers as benzo[b]carbazoles (cf. kinamycin D), on the basis of chemical, spectroscopic, and X-ray crystallographic data. We now report the detection of phenanthroviridin aglycone 4, a member of the recently discovered benzo[b]phenanthridine class of natural products, as a minor metabolite of S. murayamaensis.