Free radical scavenging and α-glucosidase inhibitory activities of the extracts of Dystaenia takesimana from Ulleung Island

Abstract

In this study, we investigated the free radical scavenging and α-glucosidase inhibitory activities of an aqueous methanolic extract from Dystaenia takesimana sourced from Ulleungdo. Seventy percent of the methanolic extract from D. takesimana was further divided into n-hexane, EtOAc and n-BuOH fractions, which yielded four solvent-soluble portions, namely n-hexane-soluble, EtOAc-soluble, n-BuOH-soluble, and H2O residues. Antioxidant properties were evaluated using the common 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS+) radicals scavenging assays, while the anti-diabetic efficacy of the D. takesimana extract and the solvent-soluble portions were tested using an α-glucosidase assay. All samples exhibited dose-dependent radical scavenging and α-glucosidase inhibitory activities. Among the tested extracts and solvent-soluble fractions, the EtOAc-soluble portion exhibited a much higher radical scavenging activity compared to the other solvent-soluble portions. α-Glucosidase inhibitory IC50 values of 55.5±0.4 and 229.3±2.3 μg/mL were determined for the n-hexane-soluble and EtOAc-soluble portions, respectively. These results suggest that the D. takesimana extract is a potential new source of natural antioxidants and anti-diabetic agents.