Identification of α-Glucosidase Inhibitors from Cyperus articulatus L. Rhizome extract using HRLC-MS/MS and molecular docking

Abstract

Cyperus articulatus is widely distributed in Indian subcontinent and its rhizome has been used as folk medicine in different geographical regions for treatment of diseases like malaria, epilepsy and dysentery. In present study the rhizome extracts were studied to identify the natural inhibitor compounds for α-amylase and α-glucosidase. Among six different solvent extracts of the rhizome, the acetone extract which showed to have highest phenolics and flavonoids exhibited α-glucosidase inhibition (IC50 9.1 µg/mL). Different fractions were collected using column chromatography and flash chromatography to analyze the active fractions. Two major fractions significantly showed high enzyme inhibitory activity. In HRLC-MS/MS phenolic as well as non-phenolic class of compounds were identified such as quercetrin, dihydroquercetin, mycophenolic acid, koparin-2-methylether, C16-sphinganine, embelin, phytosphingosine, colforsin, 7,8-dihydroxystearic acid and palmitic acid derivative. The two active fractions having IC50 8.38 and 7.65 µg/mL, were shown to exhibit competitive and mixed type inhibition, respectively. Molecular docking analysis of the compounds with the α-glucosidase active site showed that the phenolic class of compounds have efficient binding with one of the aspartate (Asp66, Asp349 and Asp212) residues whereas there was non-polar contacts with other residues in case of non-phenolic compounds such as long chain hydroxyl acids. The results suggest that Cyperus articulatus rhizome is a potential source of drug ingredients for the management of type-II diabetes.