Determination of in vitro Antidiabetic and Antioxidant Activities of Dioscorea alata L. Tubers.

Abstract

Background: The tubers of Dioscorea alata L. are used to control blood glucose level of diabetic patients, and these underground edible tubers of D. alata L., commonly known as ‘Raja ala’ in Sri Lanka, were a major dietary constituent in the past and are still consumed today. However, there is no scientific evidence for the antidiabetic properties of D. alata tubers, while only a few studies were based on antioxidant activity. Objectives: To investigate in vitro antidiabetic properties and antioxidant properties of water and ethanolic extracts of D. alata tubers grown in Sri Lanka Methods: D. alata tubers were peeled off, and water and ethanolic extracts of the tubers were prepared using refluxing. To determine the antidiabetic properties, anti-amylase activity and BSA glucose glycation inhibitory activity were performed. In vitro antioxidant activity was determined by 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 2,2-diphenyl-1 picrylhydrazyl (DPPH) assays using standard methods. Student’s t-test was performed for comparisons using Minitab 17. Results: There was no significant antidiabetic activity in the water extract of D. alata. The IC50 values for the anti-amylase and anti-glycation assays of ethanolic extract of D. alata were 178.54±10.41 and 85.68±3.14 µg/mL, respectively. The IC50 values for the ABTS assay of the water and ethanolic extracts of D. alata were 139.69±5.46 and 63.67±3.85 µg/mL, respectively. The IC50 values for the DPPH assay of the water and ethanolic extracts of D. alata were 1102.74±11.51 and 992.99±10.82 µg/mL, respectively.

Conclusions: The present study exhibited that the ethanolic and water extracts of D. alata possess antidiabetic and antioxidant properties, with the ethanolic extract showing more potent in vitro activities.