Evaluation of isoflavone content and antioxidant activity of selected soy taxa

• Published in: Journal of food composition and analysis 2017-04, Vol.57, p.40-48
• Main Authors: Szymczak, Grażyna, Wójciak-Kosior, Magdalena, Sowa, Ireneusz, Zapała, Karolina, Strzemski, Maciej, Kocjan, Ryszard
• Format: Article
• Language: English
• Subjects: Antioxidant activity; Cultivar differences; Food analysis; Food composition; Glycine max; HPLC-DAD; Isoflavones; Soy cultivars; Soybean
• ISSN: 0889-1575; 1096-0481
• DOI: 10.1016/j.jfca.2016.12.015

•Free and soluble bound isoflavones in various soybean cultivars were analysed.•Antioxidant activity using TPC, DPPH, ABTS, FRAP assay were established.•High variation of isoflavone content in investigated soy taxa was observed.•Cultivars Caloria, Safir, and Brovallia were the richest sources of isoflavones.•Cultivars Caloria, Safir, and Brovallia are the most valuable as functional food. Isoflavones are the main phenolic compounds of soy influencing its biological activity; however, their amount may differ significantly. In this work, the content of isoflavones in various soy taxa was determined using the high performance liquid chromatography with diode array detection (HPLC-DAD) and mass spectrometry (MS) technique. Moreover, the total phenolic content (TPC) and the antioxidant activity of the investigated soybean seeds were analysed using UV–vis spectrophotometric assays. Daidzin (daidzein 7-O-glucoside), malonyldaidzin, genistin (genistein 7-O-glucoside), and malonylgenistin were the dominant isoflavones present in all soybeans seeds. High fluctuations of their content were observed. The cultivars Caloria, Safir, and Brovallia were the richest sources of isoflavones; with total values of 3813, 3198, and 4030μg/g, respectively. All tested soybeans exhibited significant antioxidant activity; however, no correlation between the amount of isoflavones and TPC vs. antioxidant activity was noted.