Protective Effect of British Red Kidney Bean Peptide Fractions on Ethanol-induced Gastric Mucosal Epithelial Cell Injury

To investigate the protective effects of the peptide fractions of British red kidney beans against ethanol-induced gastric mucosal epithelial cell injury. Peptide fractions were prepared and purified via enzymatic hydrolysis of British red kidney bean protein. Fraction 2 of different concentrations in molecular weight <1 kDa was used to pretreat GES-1 gastric mucosal epithelial cells. GES-1 cells were then exposed to ethanol, and oxidative stress, apoptosis rate, mitochondrial membrane potential, and NLRP3 pathway-related protein expression levels were measured. The enzymatic hydrolysate with a molecular weight of <1 kDa was fractionated on G15 dextran gel to obtain two fractions. Fraction 2 exhibited a stronger 1,1-diphenyl-2-picryl-hydrazyl radical scavenging rate (41.82%±0.93%), hydroxyl radical scavenging rate (67.79%±0.74%), and reducing power (0.23±0.01) than fraction 1. Fraction 2 was thus selected for follow-up experiments. Fraction 2 pretreatment at 50, 100, 200 μg/mL dose-dependently reduced ethanol-induced levels of reactive oxygen species and malondialdehyde in GES-1 cells and increased superoxide dismutase, catalase, and glutathione peroxidase activities (P<0.05). Flow cytometry revealed that fraction 2 pretreatment significantly inhibited ethanol-induced apoptosis and increased mitochondrial membrane potential (P<0.05). Fraction 2 pretreatment also reduced ethanol-induced NLRP3, caspase-1, and IL-1β protein levels in GES-1 cells and IL-1β concentrations in cell fluid. In conclusion, British red kidney bean peptide fractions protected gastric mucosal epithelial cells against ethanol-induced cellular level damage, providing an experimental basis for developing red kidney bean as nutritional and health food.