ABSTRACT
Pneumocandin D0 (9), a new member of the echinocandin class of antifungal agents, has been isolated as a minor constituent from fermentation broths of the filamentous fungi Zalerion arboricola (ATCC 20957). The structure of 9 has been determined mainly on the basis of spectroscopic analysis and by comparison with published data for similar compounds. To date, pneumocandin D0 has been found to be the most potent inhibitor of Pneumocystis carinii development in vivo within the natural-occurring echinocandin family of antifungal agents.
Subject(s)
Anti-Bacterial Agents/isolation & purification , Anti-Bacterial Agents/pharmacology , Antifungal Agents/isolation & purification , Antifungal Agents/pharmacology , Peptides , Pneumocystis/drug effects , Amino Acid Sequence , Animals , Anti-Bacterial Agents/biosynthesis , Antifungal Agents/biosynthesis , Candidiasis/drug therapy , Echinocandins , Fermentation , Mice , Mice, Inbred Strains , Mitosporic Fungi/metabolism , Molecular Sequence Data , Molecular Structure , Peptides, Cyclic/biosynthesis , Peptides, Cyclic/isolation & purification , Peptides, Cyclic/pharmacology , Pneumonia, Pneumocystis/drug therapy , Spectrometry, Mass, Fast Atom BombardmentABSTRACT
Zalerion arboricola ATCC 20868 produces pneumocandin A0 (L-671,329), a cyclic hexapeptide with a dimethylmyristic acid side chain. This compound has anti-candida and anti-pneumocystis activities. We were interested in looking for other related compounds produced by this organism. To facilitate this search, a simple medium (S2) composed of D-mannitol, peptonized milk, lactic acid, glycine, KH2PO4 and trace elements, which supported the production of a number of such compounds, was designed. For the isolation of mutants, either spores or growing mycelia were treated with N-nitroso-N-methylurethane or N-methyl-N'-nitro-N-nitrosoguanidine and survivors were screened for changes in the product spectrum. From approximately 1,500 survivors tested, 5 mutants were isolated. Mutants ATCC 20957, 74030, 20958 and 20988 exclusively produce various pneumocandins other than A0. These compounds were active against Candida and Pneumocystis carinii. The yield of A0 was found to be increased 2.5-fold over that of the parent in the fifth mutant, MF5415. Further medium studies indicated that the addition of soybean oil to S2 medium improved the yields. Subsequent development of another series of media containing Pharmamedia as a nitrogen source resulted in increase in production by 10- approximately 20-fold. Overall, these studies resulted in substantial improvement in the production of A0 as well as discovery and/or facile production of 7 other related compounds.
