Antitrachoma Activity of Rifamycin B and 8-O-Acetylrifamycin S

Abstract

IT has been found that rifampicin¹ inhibits^2–4 irreversibly^5,6 the development of trachoma agent, and that the effect of rifampicin on trachoma is caused by the inhibition of the agent's DNA dependent RNA polymerase present in the trachoma elementary bodies^7,8 and in the developing inclusion bodies. Thus, rifampicin inhibits trachoma agent and prokaryotic cells by the same mechanism⁹. Studies have shown⁴ that the presence of the hydrazone side chain in the rifamycin SV molecule enhances the antitrachoma activity of the antibiotic. We investigated the antitrachoma activity of rifamycin B. a natural fermentation product of Streptomyces mediterranei, and two other rifamycin derivatives which lack anti-RNA polymerase activity¹⁰: compound VIII (23-dehydroxy-27-demethoxy-23,27-epoxyrifamycin SV) and 8-O-acetylrifamycin S. We found that only 8-O-acetylrifamycin S effectively inhibited the development of trachoma agent in FL cell cultures.