Pluraflavins, potent antitumor antibiotics from Saccharothrix sp DSM 12931

The new pluramycin-type antibiotics pluraflavin A, C43H54N2O14, pluraflavin B, C43H56N2O15, and pluraflavin E, C36H41NO14 were isolated from cultures of the Saccharothrix species DSM 12931. The structures of the novel compoun ds were elucidated with the aid of 2D NMR and mass spectrometric investigat ions. The characteristic structural element of pluraflavins A and B is an a dditional 4-epi-vancosamine unit at position 13 of the anthraquinone-gamma -pyrone ring system. Pluraflavin E has a carboxyl group in this position. P luraflavin A has a reactive dimethyl epoxide side chain at position 2 of th e anthraquinone-gamma -pyrone aglycon, which may explain the high activity of the antibiotic. The outstanding biological characteristic of pluraflavin A is its powerful, organ-dependent cytostatic action: the IC50 in the colo n carcinoma proliferation assay is in the subnanomolar range.