Three new polyketides produced by Penicillium crustosum, a mycoparasitic fungus from Ophiocordyceps sinensis

A pair of novel benzannulated enantiomers, penilactone C [(+)-1 and (-)-1], a known related analogue 6-acetyl-2α,5-dihydroxy-2-(2-hydroxypropyl)-3α,8-dimethylchroman (3), and a novel polyketide, penilactone D (2), were obtained from the liquid-state and solid-state fermentation broth of Penicillium crustosum, a mycoparasitic fungus isolated from the fruiting body of Ophiocordyceps sinensis. The structures of these compounds were elucidated on the basis of spectroscopic data (HRESIMS, NMR and X-ray crystallography). The absolute configurations of enantiomers (+)-1 and (-)-1 were confirmed by TDDFT ECD calculation, and those of compound 2 were determined using Mo2-induced CD analysis. A plausible biogenetic pathway for 1 is proposed.