Thiazostatin A and thiazostatin B, new antioxidants produced by Streptomyces tolurosus.

Sir: During screening for antioxidative substances, which are expected to be useful for chemotherapy of arteriosclerosis and ischemia, we have isolated new potent substances thiazostatins A and B from a culture of an actinomycete, Streptomyces tolurosus 1368-MT1, which was isolated from a soil sample collected at a field in Yamaguchi-city, Japan. Thiazostatin was formerly called AG551} and its producing organism has been deposited at the Fermentation Research Institute, Agency of Industrial Science and Technology, Japan, with an accession No. of FERMP-9144. The fermentation, isolation, structure determination and biological properties ofthiazostatin are described in the present communication. The antioxidant activity was measured by inhibitory effect against erythrocyte hemolysis caused by a radical producing agent, 2,2/-azobisOCT. 1989