Labdane diterpene derivatives from Holwaya mucida.

Clumps of white crystals present in 40-day-old malt agar cultures of Holwaya mucida were isolated as long white needles by crystallization from ethanol following short extraction with chloroform. The levorotary compound ([alpha]21/289 = -193.8 degrees) was recognized as a gamma-lactone (C17H20O5) by infrared and mass spectrometry. It was identified as 7 alpha-methoxy-3a, 10b-dimethyl-1, 2, 3, 3a alpha, 5a alpha, 7, 10b beta, 10c alpha-octahydro-4H, 9H-furo[2', 3', 4': 4, 5]naphthol[2, 1-c]pyran-4, 9-dione, a labdane-derived compound known as antibiotic LL-Z1271 alpha. Preparative thin-layer chromatography of the mother liquor afforded 2 minor metabolites. One was identified as LL-Z1271 gamma, the demethylated analogue of LL-Z1271 alpha. The other one named LL-Z1271 delta, was recognized as a compound related to alpha and gamma: its structure could not be fully elucidated. H. mucida (anamorph: Crinula calciiformis) has no taxonomic relationship with two other LL-Z1271 alpha producing species viz. Acrostalagmus sp. (= Acremonium cf. atrogriseum) and Oidiodendron truncatum.