Delhousie Daniel Jambun
Monash University, Malaysia
Title: Antioxidant Properties of a Near-Threatened Ginger (Etlingera velutina) Endemic to Borneo and the Isolation and Characterization of Its Antioxidant Compounds
Biography
Biography: Delhousie Daniel Jambun
Abstract
Etlingera gingers are known to have beneficial properties to human health. The main focus of this study was Etlingera velutina, a near-threatened ginger endemic to Borneo. Our aim was to determine its antioxidant activity and to isolate and characterize the antioxidant compounds. Crude extracts of E. velutina leaves, stems and rhizomes were obtained via methanol extraction. The extracts were then tested for antioxidant activity using Folin-Ciocalteu, DPPH radical scavenging and oxygen radical antioxidant capacity assays. Our results showed that the leaves of E. velutina possessed significantly better antioxidant activity as compared to the stems and rhizomes. Through bioassay-guided purification work, one compound was successfully isolated and identified as 1,7-Bis(3,4-dihydroxyphenyl)-3-heptanyl acetate (velutinin). This compound exhibited exceptional antioxidant activity (ascorbic acid equivalent antioxidant capacity, oxygen radical antioxidant capacity and cellular antioxidant activity values of 2.18 ± 0.01 µmol AA/ µmol compound, 7.33 ± 0.15 µmol Trolox/ µmol compound and 1.43 ± 0.05 µmol Quercetin/ µmol compound, respectively). In addition, cytotoxicity study against FL83B, HEK-293T and HaCaT cell lines revealed 50 % inhibitory concentration (IC50) values of >100, >100 and 48.34 ± 3.72 µg/mL, respectively. As the cytotoxicity IC50 values were well above the effective concentrations used in the cellular antioxidant assay, this suggest that velutinin possess an exciting potential to be developed as drug to combat oxidative stress in cells.