Papyracon Ⅴ

Five new minor metabolites, papyracon D (6), 6-O-methylpapyracon B (9), 6-O-methylpapyracon C (10), lachnumfuran A (11) and lachnumlactone A (12a), together with the known chloromycorrhizinol A (4), have been isolated from extracts of the culture fluids of the ascomycete Lachnum papyraceum. The compounds, which structures were determined by spectroscopic methods, are structurally related to the nematicidal and antibiotic mycorrhizin A (1), which also is produced by the fungus. The nematicidal, antibiotic and cytotoxic activities of the new compounds are weaker compared to those of mycorrhizin A (1). Papyracon D (6) possesses the highest antibiotic activities while lachnumlactone A (12a) is the most nematicidal and cytotoxic.

The structure determination of four new biologically active non-halogenated metabolites isolated from submerged cultures of the ascomycete Lachnum papyraceum is described. The compounds are structurally related to the antibiotic mycorrhizin A: (l'Z)-Dechloromycorrhizin A (12), a stereoisomer of dechloromycorrhizin A (5) previously isolated from the same fungus, as well as papyracon A (13), papyracon B (14) and papyracon C (15) containing an exocyclic double bond. The amounts of the latter three increased significantly when CaBr2 was added to the culture medium. The structures were determined by spectroscopic methods.