ISOFLAVONE COMPOSITION OF AMERICAN AND JAPANESE SOYBEANS IN IOWA - EFFECTS OF VARIETY, CROP YEAR, AND LOCATION

The amounts of 12 isoflavones were measured in 8 American and 3 Japanese soybean varieties by using C-18 reversed-phase high-performance liquid chromatography. In Vinton 81 soybeans of 1989-1991, variation in total isoflavone ranged from 1176 to 3309 mu g/g. Isoflavone amounts of soybeans grown in different locations in 1991 ranged from 1176 to 1749 mu g/g. Crop year seemed to have a much greater influence on isoflavone content in Vinton 81 than did location. Isoflavones in the other seven American varieties (Pioneer 9111, Pioneer 9202, Prize, HP204, LS301, XL72, Strayer 2233) ranged from 2053 to 4216 mu g/g. The major isoflavone constituents were 6''-O-malonylgenistin, genistin, 6''-O-malonyldaidzin, and daidzin. Isoflavone contents in three Japanese varieties (Keburi, Kuro diazu, Raiden) ranged from 2041 to 2343 mu g/g and from 1261 to 1417 mu g/g for soybeans grown in 1991 and 1992, respectively. Compared with American varieties, Japanese varieties had higher 6''-O-malonylglycitin contents and higher ratios of 6''-O-malonyldaidzin to daidzin and 6''-O-malonylgenistin and genistin.