Determination of Phenolic Content and Antioxidant Activity in Khabarovsk Soybean Cultivars

In this study, total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activity (I) were determined in eight soybean cultivars. Assays were conducted on above-ground parts (AGP) and seeds. Peak areas (STIC+ and STIC−) of major metabolites in the total ion current (TIC) chromatogram, obtained by HPLC–MS/MS, were also calculated. TPC in AGP and seeds ranged from 5.8% to 10.8% and from 2.2% to 4.4%, respectively. TFC was 0.3–1.2% and 0.02–0.07% for AGP and seeds, respectively. The coefficient of variation of I was 42% for AGP and 45% for seeds. The highest I in AGP was observed in Khabarovskij yubilyar (56.5%) and Kobra (54.3%), while that of seeds was observed in Kobra (47.5%). A positive correlation was found in AGP between I and TPC (0.75), as well as between I and STIC+ (0.81). Strong significant correlations were found in seeds between I and TPC (0.90), TFC (0.83), STIC+ (0.78), and STIC− (0.87). Leaf TPC, TFC, and I of the eight cultivars showed no correlation with AGP. These findings indicate that conducting targeted studies on AGP and seeds of food and vegetable varieties can help establish sustainable breeding programs for developing functional food products and animal feed.