Antioxidant potency of phenolic phytochemicals from the root extract of Acacia confusa

In the present study, the antioxidant potencies of ethanolic extract and its derived phytochemicals from the root of Acacia confusa, the indigenous Taiwanese species, were investigated and reported for the first time. Among all the soluble fractions of ethanolic extract, the EtOAc soluble fraction exhibited the best antioxidant activity. The bioassay-guided fractionation was carried out and yielded 9 potent antioxidative phytochemicals from EtOAc fraction. Among them, okanin (9) exhibited the lowest IC50 DPPH radical and superoxide anion radical scavenging activity values and the highest TEAC and reducing power activity. Besides, melacacidin (3) was the most abundant antioxidant compound in A. confusa root extract with an absolute content of 109.1 mg/g of crude extract. The structure-activity relationships of antioxidant flavonoids isolated from A. confusa root extract were also discussed. Therefore, with its excellent antioxidant activities, A. confusa root extract has great potential as a source for natural health products.