title: Determination of 15 isoflavone isomers in soy foods and supplements by high-performance liquid chromatography.
abstract: Soy isoflavone is the generic name for the isoflavones found in soy. We determined the concentrations of 15 soy isoflavone species, including 3 succinyl glucosides, in 22 soy foods and isoflavone supplements by high-performance liquid chromatography (HPLC). The total isoflavone contents in 14 soy foods and 8 supplements ranged from 45 to 735 μg/g and from 1,304 to 90,224 μg/g, respectively. Higher amounts of succinyl glucosides were detected in natto, a typical fermented soy product in Japan; these ranged from 30 to 80 μg/g and comprised 4.1-10.9% of the total isoflavone content. In soy powder, 59 μg/g of succinyl glucosides were detected, equivalent to 4.6% of the total isoflavone content. These data suggest that the total isoflavone contents may be underestimated in the previous studies that have not included succinyl glucosides, especially for  Bacillus subtilis -fermented soy food products.
authors.affiliation: Department of Food Function and Labeling, National Institute of Health and Nutrition, Tokyo, Japan.
authors.forename: Kaoru
authors.initials: K
authors.lastname: Yanaka
authors.forename: Jun
authors.initials: J
authors.lastname: Takebayashi
authors.forename: Teruki
authors.initials: T
authors.lastname: Matsumoto
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Ishimi
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D019587:Dietary Supplements / Q000032:analysis*; D007529:Isoflavones / Q000737:chemistry*; D007536:Isomerism; D045730:Soy Foods / Q000032:analysis*
chemical_list: D007529:Isoflavones