Retrostatin, a new specific enzyme inhibitor against avian myeloblastosis virus reverse transcriptase

A novel enzyme inhibitor against RNA-directed DNA polymerase of avian myeloblastosis virus was produced by an isolate of a new streptomycete for which the name Streptomyces retrostaticus is proposed. This enzyme inhibitor, which was named retrostatin, did not inhibit DNA-directed DNA polymerase of Escherichia coli and DNA-directed RNA polymerase of Ehrlich ascites tumor cells. Retrostatin was produced by the microorganism together with streptonigrin. These two substances were extracted from the culture broth with ethyl acetate at acidic pH. Retrostatin is an acidic pH indicator and the free acid was recovered as a red powder. Retrostatin had weak antibiotic activities against Gram-positive bacteria and yeasts.