Phytochemical Investigation and Xanthine Oxidase Inhibitory Effect of Glinus oppositifolius

Gout is a chronic inflammatory disease associated with hyperuricemia and xanthine oxidase (XO) overactivity. The search for natural XO inhibitors with fewer adverse effects has gained increasing interest. This study aimed to evaluate the XO inhibitory potential of Glinus oppositifolius (L.) A. DC., a medicinal plant traditionally used in Vietnam, but with limited scientific validation for anti-gout activity. The whole plant of Glinus oppositifolius were pulverized, then extracted with ethanol, and subsequently fractionated using n-hexane, ethyl acetate, and n-butanol. The fractions were evaluated through phytochemical screening using standard qualitative methods, followed by quantification of total polyphenols and flavonoids based on calibration curves constructed from gallic acid and quercetin standards. In vitro xanthine oxidase inhibition was assessed using the method described by Tadataka Noro, with slight modification. Preliminary phytochemical analysis revealed the presence of flavonoids, saponins, triterpenoids, and phenolic compounds. The ethyl acetate fraction exhibited the highest levels of polyphenols (63.35 ± 1.70 mg GAE/g) and flavonoids (115.50 ± 3.30 mg QE/g), corresponding to the most vigorous XO inhibitory activity (IC50 = 57.41 µg/mL), compared with IC50 =57.41–635.45 µg/mL for the other extracts. The strong correlation between its high bioactive content and potent XO inhibition highlights the ethyl acetate fraction as the most promising anti-gout candidate from G. oppositifolius. These findings demonstrate that G. oppositifolius contains bioactive metabolites with significant XO inhibitory effects, providing scientific support for its traditional use in gout management and highlighting its potential as a natural anti-hyperuricemic candidate.