Streptomyces verticillatus Mitomycins

In Streptomyces verticillatus radioactive glucose has been found to label both the C7N unit of mitomycin C and the remaining atoms, which form a C N unit. ° More directly D-glucosamine is the source of this C N unit (C-1, C-2, C-3, C-9, C-9a, and C-10 and the nitrogen atom of the aziridine ring). ° In order to gain a... 

The mitomycins are potent antibiotics that belong to the family of antitumor quinones. In 1956, mitomycin A (28) and B (34) were isolated from Streptomyces caespitosus, and shortly thereafter, mitomycin C (30) was discovered within the same strain [61, 62]. The A-methyl derivative of (31), porfiromycin, was isolated in 1960 from Streptomyces ardus, which was followed by the discovery of mitiromycin from Streptomyces verticillatus [63, 64]. Among all these different mitomycins, (31) enjoyed early widespread clinical use as a consequence of its uniquely superior activity against solid tumors. Secondly, it possessed reduced toxicity when compared to the natural counterparts (28) and (34). Mitomycin A,... 

Porfiromycin (LXVc), the iV-methyl analogue of mitomycin C, is also a metabolite of Streptomyces verticillatus and has a wide spectrum antitumour activity [300]. It has a therapeutic index of ten against Walker 256, and two against L 1210. In mice it has a LD50 value of 44 mg/kg (i.p.), and in rats 68 mg/kg (oral), which are about four times that of mitomycin C. It has a lower antitumour activity than mitomycin C at comparable toxic dose levels except for ascitic forms of Ehrlich carcinoma in mice [300, 301]. 

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