Some chemotherapeutic properties of two new antitumor antibiotics, saframycins A and C.

The antitumor activity of saframycin was examined against four different experimental tumor systems in mice. Saframycin A and C inhibited the growth of L1210 cells in suspension culture completely at concentrations of 0.02 microgram/ml and 1.0 microgram/ml, respectively. The LD50's of saframycin A for ddY mice were 4.9 mg/kg (ip) and 3.3 mg/kg (iv), respectively. In C3H/He mice, the LD50's were 10.5 mg/kg (ip) and 9.7 mg/kg (iv), respectively. Saframycin A was highly active against Ehrlich ascites carcinoma and P388 leukemia, and moderately active against L1210 leukemia and B16 melanoma. The antitumor activity of saframycin A was 50 to 100 times greater than that of saframycin C. The survivors cured of Ehrlich ascites carcinoma by treatment with saframycin A developed a resistance to rechallenge with the same tumor. On the other hand, when carbazilquinone and adriamycin were used as reference drugs, the cured mice in these cases did not resist rechallenge with the same tumor. When saframycin A (5 mg/kg) was administered intraperitoneally into mice, the blood concentration of saframycin A was 4.6 microgram/ml after 30 min, and 2.8 microgram/ml after 1 hr, and the total recovery within 3 hr from the urine was 30%. Saframycin A was found to be distributed widely, though to different extents, in various organs when injected intraperitoneally into mice.