Biotransformation of 1,8-Dihydroxyanthraquinone into Peniphenone under the Fermentation of Aleurodiscus mirabilis

[Image: see text] The present study verified that 1,8-dihydroxyanthraquinone (1), a common component in some industrial raw materials and dyes, could be converted into peniphenone (2), which possesses immunosuppressive activity and other medicinal potential, by Aleurodiscus mirabilis fermentation. The yield of peniphenone (2) after 7 days of fermentation was 11.05 ± 2.19%. To reveal the transformation mechanism, two secondary metabolites, emodin (3) and monodictyphenone (4), were isolated from the fermentation broth of A. mirabilis, implying that polyketide metabolic pathways from emodin (3) to monodictyphenone (4) might exist in A. mirabilis. 1,8-Dihydroxyanthraquinone (1) was suspected to be converted into peniphenone (2) via the same pathway since emodin (3) and 1,8-dihydroxyanthraquinone (1) share very similar skeletons. The P450 enzyme and Baeyer–Villiger oxidase in A. mirabilis were confirmed to catalyze this biotransformation on the basis of ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) analysis. This novel investigation could shed light on the mechanism and therefore development of peniphenone production from 1,8-dihydroxyanthraquinone by microbial fermentation.