Formation mechanism for potent antioxidative o-dihydroxyisoflavones in soybeans fermented with Aspergillus saitoi
1999
Esaki, H. (Sugiyama Jogakuen Univ., Nagoya (Japan)) | Watanabe, R. | Onozaki, H. | Kawakishi, S. | Osawa, T.
The formation mechanism for the potent antioxidative o-dihydroxyisoflavones, 8-hydroxydaidzein (8-OHD) and 8-hydroxygenistein (8-OHG), was studied by incubating whole soybeans in a solid culture and a soybean extract in a liquid culture with Aspergillus saitoi. Analyses of changes in the isoflavone analogue content, beta-glucosidase activity, and isoflavone hydroxylation ability indicated that 8-OHD and 8-OHG were formed from daidzein and genistein, respectively, by microbial hydroxylation, being respectively liberated from daidzein and genistein by beta-glucosidase from A. saitoi during incubation. No selective hydroxylation reaction at the 8-position of daidzein and genistein were apparent during the vegetate stage, but we induced at the stage of sporulation
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