Enhancing the Phytochemicals and Antioxidant Abilities of Isoflavone-Enriched Soybean Leaves Through Inoculation with Lacticaseibacillus paracasei LAB47 and Levilactobacillus brevis WCP02

In this study, Lacticaseibacillus paracasei LAB47 (LAB47) and Levilactobacillus brevis WCP02 (WCP02) were selected for the fermentation of isoflavone-enriched soybean leaves (IESLs) according to their survival capability under artificial gastric acid, β-glucosidase activity, γ-aminobutyric acid (GABA) production ability, and isoflavone contents. The strain ratio and fermentation duration with LAB47 and WCP02 for IESLs were 1:1 (per 2.5%, v/v) with a fermentation time of 72 h. Finally, the fermented IESLs (FIESLs) were compared with the raw and steamed IESLs (RIESLs and SIESLs, respectively) to determine the fatty acids, free amino acids, isoflavones, antioxidant activities, digestive inhibitory activities, and DNA protection capacity. The contents of total fatty acids (1295.67 mg/100 g), GABAs (101.39 mg/100 g), total phenolics (33.73 gallic acid equivalents mg/g), total flavonoids (13.93 rutin equivalents mg/g), and isoflavone aglycones (2588.85 μg/g) were higher in FIESLs than in RIESLs and SIESLs. In addition, the IC50 inhibition of glucosidase (2.85 mg/mL) and pancreatic lipase (4.38 mg/mL) and DNA damage protection activities were superior in FIESLs than in RIESLs and SIESLs. Therefore, FIESLs with LAB47 and WCP02 increased the phytochemical and antioxidant activities of IESLs and may be used as functional foods.