Abstract

Objective: To evaluate the xanthine oxidase inhibitory activity of the methanol leaf extracts of following Cassia javanica, Cynometra ramiflora, Cassia fistula, Senna siamea, Tamarindus indicus, Intsia bijuga, Cassia spectabilis, Saraca thaipingensis (S. thaipingensis), Caesalpinia pulcherrima (C. pulcherrima) and Bauhinia purpurea. Method: The xanthine oxidase inhibitory activity was tested spectrophotometically under aerobic conditions. Absorption increments was monitored every 30 seconds for 10 min at 295 nm indicating the formation of uric acid. The extracts were also tested for the presence of terpenoids, saponins, tannins, flavonoids, steroids, phenolic compounds, alkaloids and cardiac glycosides. Results: All the extracts inhibited the action of xanthine oxidase. S. thaipingensis and C. pulcherrima exhibited higher than 50% at a concentration 0.05 mg/mL. The IC50 of S. thaipingensis and C. pulcherrima were determined as 0.033 mg/ml and 0.053 mg/mL, respectively while that of allopurinol is 0.004 mg/mL. Conclusion: S. thaipingensis and C. pulcherrima are potentially good sources of xanthine oxidase inhibitors.

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