Inhibition of the in vitro activities of α-amylase, α-glucosidase and pancreatic lipase by yellow field pea (Pisum sativum L.) protein hydrolysates

The aim of this work was to produce yellow field pea protein-derived peptides as inhibitors of alpha-amylase, alpha-glucosidase and pancreatic lipase activities. A pea protein concentrate was hydrolysed with alcalase, chymotrypsin, pepsin or trypsin and the hydrolysates separated into different fractions (<1, 1-3, 3-5, 5-10 kDa) by membrane ultrafiltration. Peptide sequence analysis showed that the alcalase hydrolysate had higher levels of di- and tripeptides when compared with the chymotrypsin, pepsin and trypsin hydrolysates. The peptide fractions inhibited alpha-amylase and alpha-glucosidase activities at levels that were similar to the unfractionated hydrolysates. The peptides were more active against alpha-amylase (inhibition at mu g level) than alpha-glucosidase (mg level). In contrast, the fractionated peptides had reduced ability (IC50 >4.2 mg mL(-1)) when compared with the unfractionated hydrolysate (IC50 <4.2 mg mL(-1)) to inhibit lipase activity. Enzyme kinetic studies revealed that the peptides reduced alpha-amylase activity through competitive inhibition. However, inhibition of alpha-glucosidase activity was non-competitive.