title: Potent Antioxidative Isoflavones Isolated from Soybeans Fermented with Aspergillus saitoi.
abstract: Two potent antioxidative isoflavones were isolated from soybeans fermented with Aspergillus saitoi by silica gel column chromatography and preparative HPLC, using ODS column, or in addition, Toyopearl HW-40 column chromatography. The purified AS-13 and AS-9B compounds were identified as 8-hydroxydaidzein (8-OHD) and 8-hydroxygenistein (8-OHG), respectively, by MS, and (1)H-NMR, (13)C-NMR and HMBC spectra. These isoflavones, which have an o-dihydroxy structure between the 7- and 8-position, each exhibited significantly stronger antioxidative activity than daidzein and genistein in both oil and lipid/aqueous systems. Furthermore, the antioxidative activity and the content of each isoflavone analog in soybeans with different fermentation periods were investigated. It is suggested from these results that AS-13 and AS-9B were produced from daidzein and genistein, respectively, by hydroxylation at the 8-position of each isoflavone structure. In addition, it is concluded that these isoflavones were also the principal antioxidants in potent antioxidative soybeans fermented with A. saitoi.
authors.affiliation: a Department of Food and Nutrition, Sugiyama Jogakuen University.
authors.forename: H
authors.initials: H
authors.lastname: Esaki
authors.affiliation: a Department of Food and Nutrition, Sugiyama Jogakuen University.
authors.forename: H
authors.initials: H
authors.lastname: Onozaki
authors.affiliation: b Department of Applied Biological Sciences, Nagoya University.
authors.forename: Y
authors.initials: Y
authors.lastname: Morimitsu
authors.affiliation: b Department of Applied Biological Sciences, Nagoya University.
authors.forename: S
authors.initials: S
authors.lastname: Kawakishi
authors.affiliation: b Department of Applied Biological Sciences, Nagoya University.
authors.forename: T
authors.initials: T
authors.lastname: Osawa
keywords: 8-hydroxydaidzein; 8-hydroxygenistein; Aspergillus saitoi; antioxidant; fermented soybeans