XANTHINE OXIDASE INHIBITORY ACTIVITY OF METHANOL EXTRACT FRACTIONS OF VARIOUS INDONESIAN ETHNOPHARMACOLOGICAL PLANTS

Abstract

Objective: Hyperuricemia involves an increase in serum uric acid levels, resulting in kidney damage, increased mortality, and reduced quality of life.Inhibitors of xanthine oxidase, which catalyzes the last step in uric acid synthesis, are targets for therapeutic intervention.Methods: An ethnopharmacological approach, screening four native Indonesian herbal medicinal plants with reported activity against hyperuricemia,was used for preliminary studies, fractionating methanolic extracts by solvent partitioning. Fractions were then tested in vitro for xanthine oxidaseinhibitory activity, and the most active fraction was then subjected to preliminary phytochemical screening.Results: The target tissue of the four herbal medicinal plants investigated was Indian bay leaf (Syzygium polyanthum Wight.), God’s crown fruit(Phaleria macrocarpa Boerl.), snake fruit peel (Salacca edulis Reinw.), and Job’s tears tuber (Cyperus rotundus Linn.). Each sample was extracted bymaceration with 80% methanol. The concentrated extract was then fractionated by the liquid-liquid partition method (1:1 v/v) using n-hexane, ethylacetate, butanol, and methanol sequentially as solvents. The results revealed that the ethyl acetate fraction was the most active fraction. S. polyanthumleaf and C. rotundus tuber showed the greatest potential in inhibiting xanthine oxidase, with half-maximal inhibitory concentrations of 18.43 and10.50 μg/ml, respectively. Enzyme kinetics analysis shows that each plant fraction works as a competitive inhibitor of xanthine oxidase.Conclusion: Preliminary screening identified the ethyl acetate fractions of two native Indonesian herbal medicinal plants as showing potential foranti-hyperuricemia activity.