Study of Total Phenols, Flavonoids, Antioxidant and Antibacterial Activities from Dioscorea hispida Tubers

Abstract

The tubers of Dioscorea hispida Dennst., a Dioscoreaceae plant, contain flavonoid molecules and plant secondary metabolites that are antioxidants and antibacterials. In this study, the total phenolic content and flavonoids from the ethanol extract and fraction (n-hexane and ethyl acetate) of Dioscorea tuber were investigated for their antioxidant and antibacterial properties. Fractionation with n-hexane and ethyl acetate followed by diffusion with 96% ethanol. The Folin-Ciocalteau reagent measured total phenol at 765 nm, and the AlCl3 method measured total flavonoid at 440 nm using a visible spectrophotometer. The DPPH assessed the antioxidant activity, whereas the antibacterial activity against Staphylococcus aureus and Escherichia coli was determined using agar diffusion on paper discs. The extract, n-hexane fraction, and ethyl acetate exhibited total phenolic content of 33.02, 5.95, and 156.33 mg GAE/g extract, respectively. Similarly, the total flavonoid content was measured at 20.26, 14.31, and 74.02 mg QE/g extract. The extract, n-hexane fraction, and ethyl acetate of the Dioscorea tuber exhibited minimum inhibitory concentrations (MICs) of 8.25, 7.76, and 10.30 mg/mL against S. aureus and 8.51, 8.31, and 12.05, against E. coli, respectively. The findings of this study indicate that the ethanol extract and n-hexane fraction derived from Dioscorea tubers exhibited comparatively diminished antioxidant and antibacterial properties in comparison to the ethyl acetate fraction. Furthermore, the ethyl acetate fraction exhibited elevated concentrations of total phenols and total flavonoids in comparison to the remaining fractions.