In vitro α-amylase inhibitory and antioxidant properties of pancreatin-derived <em>Polyalthia longifolia</em> seed protein hydrolysate

Abstract

Inhibition of α-amylase and free radical scavenging activities are two basic approaches utilized in the management of postprandial hyperglycemia. In recent times, researchers have explored the α-amylase inhibitory and free radical scavenging potentials of plant-derived peptides to circumvent the side effects of synthetic drugs. In this study, proteins from Polyalthia longifolia (P. longifolia) were isolated using alkaline solubilisation-acid precipitation method and the proteins were enzymatically hydrolyzed with pancreatin. The hydrolysate derived was investigated for α-amylase inhibitory property, using starch as the substrate; and antioxidant property, using 2, 20-azinobis-3-ethylbenzothiazoline-6-sulphonate cation radical (ABTS+) scavenging and ferric ion reducing antioxidant power (FRAP) assays. The hydrolysate demonstrated a concentration- dependentα-amylaseinhibitorypotential(IC506.49±0.08mg/ml) exhibiting 64.40 ± 5.58% α-amylase inhibition at the highest concentration considered (9 mg/ml). Kinetics analyses revealed that the hydrolysate exhibited uncompetitive inhibition pattern on α-amylase at 9 mg/ml. The hydrolysate exhibited considerable radical scavenging activity (85.11 ± 2.05%) and reducing ability (35.44 ± 0.13 mM Fe2+ equivalent) at 9 mg/ml. In conclusion, the study suggests that the hydrolysate possesses the ability to manage postprandial hyperglycemia associated with diabetes mellitus via inhibition of α-amylase activity and attenuation of free radical production.

Keywords

• α-amylase, inhibitory properties, antioxidant, p. longifolia, hydrolysate