Antioxidant potential and xanthine oxidase inhibition of flavonol glycosides from Phyllanthus emblica L. leaves

Context: Hyperuricemia is the cause of gout in the inflammatory joint condition. The xanthine oxidase enzyme is a therapeutic target for gout treatment because it plays a role in the generation of uric acid. Allopurinol is used to treat gout. It prevents the xanthine oxidase enzyme from producing as much uric acid. When selecting a medication, one must consider the various adverse effects of allopurinol. Phyllanthus emblica plants are among the medicinal plants that can be used as an alternative treatment for gout. Aims: To evaluate isolated compounds from the Phyllanthus emblica as antihyperuricemia candidates. Methods: The isolated compounds were characterized using High-Performance Liquid Chromatography Analysis and Thin Layer Chromatography-Densitometry. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) and cupric ion (CUPRAC) antioxidant capacity procedures were used to develop the antioxidant activity index. The ability to inhibit xanthine oxidase was determined using a spectrophotometer. Results: Compound 1 was indicated as rutin having antioxidant capacity with an antioxidant activity index (AAI) DPPH value of 7.89 ± 0.03 and AAI CUPRAC value of 15.83 ± 0.04 stronger than compound 2 (quercitrin) with an AAI DPPH value of 3.72 ± 0.01 and AAI CUPRAC 3.24 ± 0.03. The IC50 for quercitrin's inhibition of xanthine oxidase is 23.85 ± 2.04, which was higher than rutin’s IC50 value of 32.77 ± 4.49 µg/mL. Conclusions: Flavonol glycosides present in the ethanol extract of Phyllanthus emblica leaves gave potent xanthine oxidase inhibitory activity stronger than the extract. Quercitrin gave stronger xanthine oxidase inhibitory activity, but this compound has weaker antioxidant capacity compared to rutin.