Inhibitory Effects of Phenolics and Saponins From Commonly Consumed Food Legumes in China Against Digestive Enzymes Pancreatic Lipase andα-Glycosidase

Total phenolic and saponin components were extracted from 13 commonly consumed food legumes produced in China, and then a systematic comparative study was conducted to investigate their inhibitory effects against digestive enzymes, pancreatic lipase, and α-glycosidase, respectively. Saponin extract (1 mg/mL) from black bean exhibited the highest (41.8%) pancreatic lipase inhibitory effect, followed by phenolic extract from adzuki bean with 36.3%, saponin extract from yellow soybean with 34.1%, saponin extract from pinto bean with 32.6%. It is worth mentioning that both phenolic and saponin extracts from the mung bean, adzuki bean, lima bean, and pinto bean exhibited inhibitory effects against pancreatic lipase. Among four beans, the adzuki bean had the highest inhibitory effects against pancreatic lipase activity. In the α-glycosidase assays, phenolic extracts exhibited stronger α-glycosidase inhibitory activity than that of saponins in general. Phenolic extracts of the adzuki bean, black bean, fava bean, lentil, rock bean, and red kidney bean inhibited over 80% of α-glycosidase activity at the concentration of 1 mg/mL. Both phenolic and saponin extracts from the adzuki bean and rock bean exhibited inhibitory effects against α-glycosidase. The results indicate that adzuki bean is one of the best target beans for further study on their anti-obesity and anti-diabetes effects via cell and animal models.