Comparative study on DPPH free radical scavenging and alpha-glucosidase inhibitory activities of ethanolic extracts from different parts of durian plant (Durio zibethinus murr.)

Abstract

A study on the discovery of traditional medicine has been done for better health. There are so many potential natural resources from Indonesia which can be used for drug discovery. The current study was aimed to (i) quantify the total phenolic and flavonoid contents; (ii) examine the DPPH free radical scavenging (DFRS) and alpha-glucosidase inhibitory (AGI) activities; and (iii) investigate the correlation of the total phenolic and flavonoid contents of different parts of durian plants (Durio zibethinus Murr.) with their activities. Roots, twigs, inner fruit bark and leaves of durian plants (Durio zibethinus Murr.) were macerated with 70% of ethanol. The total phenolic content was measured using Folin-Ciocalteu assay while the total flavonoid content was measured using colorimetric aluminium trichloride assay. The DFRS and AGI activities were determined in vitro and the results were compared with the total phenolic and flavonoid contents. The root (DR), twig (DT), inner fruit bark (DIFB) and leaves (DL) extracts revealed a difference in DFRS and AGI activities. The root and twig extracts revealed the strongest DFRS activity among the samples evaluated with IC50 values of 18.54±0.58 and 96.65±0.14 µg/mL and alpha-glucosidase inhibitory activity with IC50 values of 0.58±0.01 and 1.55±0.02 µg/mL. The root and twig extract also contained the highest phenolic compounds accounting of 94.01±0.018 and 31.65±0.078 mg Gallic Acid Equivalent (GAE)/g dry extract. The total phenolic content of the four extracts has a significant correlation with their DPPH free radical scavenging and alpha-glucosidase inhibitory activity. The different parts of durian plant extracts showed a significant difference (P<0.05) on the level of phenolic and flavonoid contents and the inhibition concentration against DPPH and alpha-glucosidase enzyme. In this study, it was found that the root and twig extract of Durio zibethinus Murr. can be a potential source to be developed as a new antioxidant by their DPPH free radical scavenging activity and alpha-glucosidase inhibitor due to considerable α-glucosidase inhibitory activity.