α-Glucosidase Inhibition Kinetics and Molecular Docking Studies with the Bioactive Constituents from Canna indica L. Rhizome Extract

Abstract

The present study investigated the phytochemical constituents from Canna indica rhizome acetone extract, which was earlier reported to possess α-glucosidase inhibiting potential. Different fractions were collected from column chromatography of the acetone extract and the in vitro enzyme inhibition and the kinetic study was performed with the active fraction. The active fraction exhibited competitive inhibition of α-glucosidase. HRLC-MS/MS technique was used to identify the lead compounds from the active fraction. The major compounds were psoromic acid, usnic acid and rosmarinic acid. Molecular docking study of the compounds with the crystal structure of α-glucosidase was performed using ParDOCK. Psoromic acid and usnic acid exhibited strong binding affinity with the active site nucleophiles Asp349 and Asp212, respectively. Usnic acid also stabilized the catalytic residue Glu274. Rosmarinic acid formed multiple hydrogen bonds with the catalytic residue Glu274 and also bonded to non-catalytic residues Gln276, Arg312 and Glu408. The study illustrated informative data on the phytochemical constituents from Canna indica rhizome as α-glucosidase inhibitor and as potential candidates for the development of antidiabetic drugs.