Soy isoflavone-phosphate conjugates derived by cultivating Bacillus subtilis var. natto BCRC 80517 with isoflavone

Daidzein and genistein have many benefits for human health; however, their applications may be restricted because of their low aqueous solubility. In this work, we generated two water soluble isoflavone derivatives, daidzein 7-O-phosphate and genistein 7-O-phosphate, by incubating Bacillus substilis var. natto BCRC 80517 with daidzein and genistein. These two isoflavone derivatives were characterized by HPLC-ESI-MS/MS, 13C NMR and 31P NMR. Genistein was phosphorylated more rapidly than daidzein. In addition, this bacterial strain could transform glucosidic isoflavones via aglucones into the corresponding 7-O-phosphate conjugates. However, despite the production of agluconic daidzein and genistein, cells could not transform malonyl glucosidic isoflavones into the 7-O-phosphate conjugates. Furthermore, alkaline phosphatase activities from human colon carcinoma (Caco-2) cells were found effective in the dephosphorylation of daidzein 7-O-phosphate and genistein 7-O-phosphate into the corresponding aglyconic isoflavones.