Identification of α-amylase inhibitory compounds from leaves of Careya arborea Roxb. and in silico docking studies

Abstract

• Chloroform extract of leaves of Careya arborea Roxb. showed strong porcine pancreatic alpha amylase (PPA) enzyme inhibition with respect to positive control: Acarbose. • LC-MS/MS analysis of this chloroform extract showed presence of a number of secondary metabolites especially flavonoids and terpenoids. • Among them, many flavonoids showed effective in silico docking on PPA structure. • Column chromatographic purification of the crude chloroform extract showed further improvement of 1.5 times in PPA inhibition. Diabetes mellitus Type 2 (DM 2) is a lifestyle induced metabolic disease characterized by chronic hyperglycaemia, dyslipidaemia and impaired protein metabolism which leads to multi-organ damage. Pancreatic α-amylase inhibition can control post-prandial hyperglycaemia via deactivation or slow-down of starch breakdown. The current study involved the isolation and analysis of secondary metabolites present in chloroform leaf extract of Careya arborea Roxb. (Family: Lecythidaceae) for their porcine pancreatic α-amylase (PPA) inhibitory activity in vitro and in silico . Total phenolic and flavonoid content was 39.58 ± 0.004 µg/ml and 180 ± 0.2 µg/ml, respectively. IC 50 value of inhibition of PPA by crude chloroform leaf extract was 443.91 µg/ml, while that of the column purified methanol fraction was 294.41 µg/ml, an enhancement of 1.5 times. Secondary metabolites in the chloroform leaf extract were identified with Liquid Chromatography-Mass Spectrometry (LC-MS/MS) and docked with PPA structure (PDB ID: 1OSE) using AutoDock 4.2.6. Program. Hesperidin and Kaempferol 7-O-glucoside had the highest binding energies of -14.62 kcal/mol and -12.7 kcal/mol, respectively and could be the most potential PPA inhibitory secondary metabolites. Since PPA shares high degree of structural and amino acid homology with human pancreatic α-amylase (HPA), our results would be significant for inhibition of HPA as well.