Biosynthesis of less toxic amphotericins

Amphotericin B is a medically important antifungal antibiotic that is also active against human immunodeficiency virus, Leishmania parasites, and prion diseases. The therapeutic use of amphotericin B is restricted by severe side effects that can be moderated by liposomal formulation or structural alteration. Chemical modification has shown that suppression of charge on the exocyclic carboxyl group of amphotericin B substantially reduces toxicity. We report targeted deletions of the amphN cytochrome P450 gene from the chromosome of the amphotericin-producing bacterium Streptomyces nodosus. The mutant strains produced amphotericin analogues in which methyl groups replace the exocyclic carboxyl groups. These compounds retained antifungal activity and had reduced hemolytic activity.Higher Education AuthorityEuropean Unio