Fungal metabolism of naphthoflavones

• Fungal metabolism of twelve naphthoflavone compounds was investigated.
• Effect of different substituents in B-ring was evaluated.
• Products of 4′-hydroxylation and 4′-O demethylation have been obtained.
• Aspergillus and Verticilium strains were most effective biocatalyst.
• Fungal metabolism do not coincides with human or rodent metabolism.

Naphthoflavones (benzoflavones) are synthetic flavonoids commonly used in drug metabolism studies as selective activators or inhibitors of cytochrome P-450 enzymes. Nowadays they are also used as a component of food supplements for body builders. There is no data regarding naphthoflavone microbial metabolism. In the present studies sixty-three fungal strains have been screened for their ability to transform α-naphthoflavone (7,8-benzoflavone) or β-naphthoflavone (5,6-benzoflavone). Five strains belonging to the genera Penicillium, Cladosporium, Aspergillus and Verticillium transformed α-naphthoflavone and β-naphthoflavone to the corresponding 4′-hydroxy derivatives. These selected fungi have been used in a further study on biotransformation of naphthoflavones with a differently substituted B-ring. Only 4′-methoxy derivatives have been transformed to the related 4′-hydroxy products. Selected strains are good biocatalysts to obtain 4′-hydroxy naphthoflavones in the one step reaction.

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