In vitro inhibitory effects of Pithecellobium dulce (Roxb.) Benth. seeds on intestinal α-glucosidase and pancreatic α-amylase.

This study sought to asses and characterizes the inhibitory action of methanolic extract of Pithecellobium dulce (P. dulce) seeds on α-amylase and α-glucosidase enzymes as well as to characterize compounds responsible for these activities. The methanolic extract was assessed for total phenolic, flavanoid and triterpenoids content by using Folin-Ciocalteu’s reagent, Aluminum chloride (AlCl3) and Vaniline-perchloric acid assay, respectively. The methanolic extract was further quantified with respect to intestinal α-glucosidase (maltase and sucrase) and pancreatic α-amylase inhibition by glucose oxidase method and Dinitrosalicylic acid (DNSA) reagent, respectively. The IC50 values of methanolic extract of P. dulce against maltase and sucrase enzymes was found to be 10.32±1.52 and 2.84±0.96 mg/ml respectively. Furthermore, the IC50 values of methanolic extract of P. dulce against pancreatic α-amylase was found to be 16.75±1.81 mg/ml. The kinetics of glucosidase enzyme was determined by Lineweaver Burk plot and it was found to be non competitive in nature. Reversed phase HPLC analysis revealed oleanolic acid as the main triterpenoid constituent in the extract compared with standard oleanolic acid. Therefore, the enzyme inhibitory activity of P. dulce methanolic extract may be endorsed to the presence of oleanolic acid triterpenoid, thus justifying its traditional use in the management of diabetes.