In vitro Study of Xanthine Oxidase Inhibitory of Gambir (Uncaria gambir) Hunter Roxb Extracts

Introduction: Hyperuricemia was a metabolic disorder characterized by high levels of uric acid due to the action of the enzyme xanthine oxidase (XO). Some natural substances with antioxidant activity proved capable of inhibiting the activity of the enzyme XO. Pharmacological benefit of polyphenol compounds had been proved. Gambir (Uncaria gambir) Hunter Roxb, a native plant, had been proved antioxidant activity, so that it had potential to be developed as an inhibitor of the XO. This study aimed to evaluate the activity of Gambir as XO inhibitor. Methods: These extracts of Gambir were preparation from Gambir and Gambir leaf using ethanol 50% and ethanol 96%, respectively. The polyphenol content and Xanthine oxidase inhibitory activity was evaluated by spectrophotometry, meanwhile analysis of (+)catechin was determined by high pressure liquid chromatography (HPLC). Results: Screening XO inhibitory activity in vitro showed that ethanolic 96% extract of Gambir leaf showed the highest activity, i.e. 50% relative to standard allopurinol at the final concentration of 100 ppm. Conclusion: There was no positive correlation between XO inhibitory activity and polyphenol or (+)catechin content.