Flavonoids Biotransformation by Human Gut Bacterium Dorea sp. MRG-IFC3 Cell-Free Extract

Human gut bacterium sp. MRG-IFC3 is unique in that it is capable of metabolizing puerarin, an isoflavone -glycoside, whereas it shows broad substrate glycosidase activity for the various flavonoid -glycosides. To address the question on the substrate specificity, as well as biochemical characteristics, cell-free biotransformation of flavonoid glycosides was performed under various conditions. The results showed that there are two different enzyme systems responsible for the metabolism of flavonoid -glycosides and -glycosides in the MRG-IFC3 strain. The system responsible for the conversion of puerarin was inducible and comprised of two enzymes. One enzyme oxidizes puerarin to 3"-oxo-puerarin and the other enzyme converts 3"-oxo-puearin to daidzein. The second enzyme was only active toward 3"-oxo-puerarin. The activity of puerarin conversion to daidzein was enhanced in the presence of Mn and NAD . It was concluded that the puerarin -deglycosylation by sp. MRG-IFC3 possibly adopts the same biochemical mechanism as the strain PUE, a species of .