Activity of safracins A and B, heterocyclic quinone antibiotics, on experimental tumors in mice

Safracins A and B, new Antibiotics produced by Pseudomonas fluorescens A2-2, were tested for antitumor activity against mouse tumors. Structurally, these Antibiotics belong to the saframycin family of Antibiotics, and safracin B is 21-hydroxysafracin A. They showed antitumor activity against L1210 and P388 leukemias and B16 melanoma. The toxic and effective doses of safracin B were much lower than those of safracin A. Safracin B also prolonged the life span of tumor-bearing mice to a greater extent than safracin A. These results indicate that the alpha-carbinolamine structure plays an important role in the antitumor action of this type of Antibiotic. Both safracins were, however, ineffective when their administration route differed from that used for inoculating tumor cells.