Microbial transformaton of bavachin by Absidia coerulea

Bavachin is one of the major bioactive flavonoid constituents in Fructus Psoraleae (Buguzhi in Chinese), and it displays a broad range of biological activities such as antibacterial, antifungal, anti-inflammatory, antioxidant, antitumor, phytoestrogenic, α-glucosidase inhibitory, and osteoblastic proliferation stimulating activities. In order to improve its bioavailability, we investigated the application of microorganisms as biocatalysts for the transformation of bavachin. Screening studies using twenty two microbes indicated that bavachin could be transformed by several fungal strains including Absidia coerulea, Mucor hiemalis, and Cunninghamella elegans. And our subsequent scale-up fermentation studies of bavachin using A. coerulea resulted in the identification of two novel microbial metabolites together with a recently reported compound bavachinone A. Chemical structures of the three compounds were elucidated on the basis of spectroscopic analysis. This is the first report on the biotransformation of bavachin by microbes, which suggested a potential process to prepare novel derivatives from plant secondary metabolites through microbial enzymes.