New anticoccidial antibiotics, WS-5995 A and B. I. Isolation and characterization.

WS-5995 A, B and C are produced by a new strain of Streptomyces designated Streptomyces auranticolor. These antibiotics were purified by solvent extraction followed by chromatography on silica gel and then crystallized. WS-5995 A (C19H12O6, m.p., 289-291°C) and WS-5995 B (C19H14O6, sublimation at 300°C) protect chickens from infection with Eimeriatenella, a species of coccidia, which produces morbidity or mortality in chickens. WS-5995 C (C19H14O7, m.p., 288-290°C), a biologically inactive component, was found to be converted to WS-5995 A on treatment with trifluoroacetic anhydride.