A-80915 B

New semi-naphthaquinone antibiotics A80915A, B, C, and D were isolated from the fermented broth of Streptomyces aculeolatus A80915 (NRRL 18422). Factors A and C, present in both the broth filtrate and mycelial methanol extract, and factors B and D, found predominantly in the broth filtrate, were recovered by extraction with ethyl acetate. Purification of the individual factors was accomplished by preparative reverse phase high performance liquid chromatograph on C18 bonded silica supports. Factors A through D show antimicrobial activity against Gram-positive aerobic and anaerobic organisms in vitro. Mechanism of action studies demonstrated nearly complete inhibition of macromolecular biosynthesis (protein, RNA, DNA, and cell wall) by A80915 factors A through D. A less highly cyclized semi-naphthaquinone, A80915 factor G, was isolated from the broth of the strain fermented in an alternate medium.