Production of a benzylated flavonoid from 5,7,3′,4′,5′-pentamethoxyflavanone by Penicillium griseoroseum

Penicillium griseoroseum, isolated as an endophytic microorganism from Coffeea arabica seeds, was grown in Czapeckʹs medium containing 5,7,3′,4′,5′-pentamethoxyflavanone. The fungus incorporated a dimethylated tetraketide, clavatol, a typical fungal secondary metabolite, into the flavanone structure at C-6, resulting in a novel benzylated flavonoid. Clavatol was also found free in the fungus extract. The compounds were isolated by chromatographic procedures and identified by extensive spectroscopic studies, including MS/MS and 1D and 2D NMR. The process probably involves enzymes catalyzing C–C bound formation, which is uncommon in fungi. The possibility of fungi participation in the biosynthesis of plant benzylated flavonoids is discussed.