Isoflavones and anthocyanins analysis in soybean (Glycine max (L.) Merill) from three different planting locations in Korea

The analysis of 12 isoflavones in two soybean cultivars, Cheongjakong 3, Taekwangkong and 9 anthocyanins in the black seed coat color Cheongjakong 3 soybean cultivars grown in three different planting locations was conducted. The profiles of 12 isoflavones identified from the soybean seeds were subjected to partial least-squares discriminate analysis (PLS-DA) to evaluate the differences among soybean cultivars and cultivation locations. PLS-DA could fully distinguish between two cultivars. Cheongjakong 3 cultivar was higher in isoflavone than Taekwangkong cultivar. Among the combinations of cultivar and region, Cheongjakong 3 grown in Yesan showed the highest isoflavone contents (2.435 μmole g−1 of malonylgenistin), followed by Cheongjakong 3 (1.940 μmole g−1 of malonylgenistin) grown in Suwon. The environment significantly influenced the isoflavones contents of the soybeans. The total isoflavone contents positively correlated strongly with malonylglycoside [malonyldaidzin + malonylgenistin + malonylglycitin] (r = 0.99***) and glycoside groups [daidzin + genistin + glycitin] (r = 0.89**), while the contents of glycitin, genistin, acetyldaidzin, acetylgenistin, daidzein, glycitein, genistein did not showed significant correlation with total isoflavone. Both isoflavone contents and the content of malonylglycoside groups negatively correlated (r = −0.68*) with the temperature during seed pod development. Malonyldaidzin, malonylglycitin, and malonylgenistin concentrations were also influenced by cultivar and planting region. Between the combinations of cultivar and area, Cheongjakong 3 grown in Suwon exhibited the highest level in the total contents of the anthocyanins, while Cheongjakong 3 grown in Miryang had the lowest. Cyanidin-3-glucoside and the anthocyanin contents were negatively correlated with the temperature in June (r = −0.86*, r = −0.85*) and September (r = −0.85*, r = −0.86*). These results suggest that cooler environments may be more suitable for the production of soybeans with higher isoflavone and anthocyanin content.