1,6,11(2H)-Naphthacenetrione, 4-[(6-deoxy-2-O-methyl-.alpha.-L-mannopyranosyl)oxy]-3,4-dihydro-2,5,7-trihydroxy-3,9-dimethoxy-2-methyl- 1,6,11(2H)-Naphthacenetrione, 4-[(6-deoxy-2-O-methylhexopyranosyl)oxy]-3,4-dihydro-2,5,7-trihydroxy-3,9-dimethoxy-2-methyl- 11033-34-4 Antibiotic U 20661 NSC93419 STEFFIMYCIN Steffimycin(USAN Steffisburgensimycin Steffisburgensimycin* Streptomyces steffisburgensis var. steffisburgerensis sp.n. antibiotic U 20661 U-20,661