Secondary mould metabolites. Part 47. Isolation and structure elucidation of clavilactones A–C, new metabolites from the fungus Clitocybe clavipes

Clavilactones A–C (1, 4 and 5) have been isolated from cultures of the Basidiomycetous fungus Clitocybe clavipes. Their structures and relative configurations have been deduced from 1H and 13C NMR studies, chemical reactions and single-crystal X-ray analysis of the dimethyl ether derivative 3. 1H–1H coupling constants, NOE data and molecular modelling calculations all suggest that the molecules have little conformational mobility and the conformation adopted in solution by clavilactone A 1 and dimethyl ether derivative 3 is essentially identical with that of 3 in the solid state. Clavilactones A–C exhibit antifungal and antibacterial activity and inhibit the growth germination of Lepidium sativum. A possible biogenetic origin of clavilactone A 1 is discussed.