Antihyperuricemic activity of polar fractions of Pili (Canarium ovatum) leaves

Abstract

Background: One of the causes of inflammatory arthritis is excessive production of uric acid or hyperuricemia. It is a painful disease that is treated with a commercial xanthine oxidase inhibitor to decrease uric acid synthesis. However, the treatment is associated with adverse side effects and thus, there is interest in medicinal plants that could have similar therapeutic effects with minimal side effects. There are many reported indigenous plants and trees in the Philippines that are reported to have therapeutic and bioactive compounds. One such plant is Canarium ovatum or locally called pili. This study aimed to determine the antihyperuricemic activity of the ethanolic extract of the leaves of C. ovatum.

Objective: Determine the antihyperuricemic activity of the crude ethanolic extract of C. ovatum leaves and its partially purified fractions through inhibition of xanthine oxidase and its effect on the blood uric acid level of oxonate-induced hyperuricemic mice.

Methodology: The crude ethanol extract from C. ovatum leaves and its partially purified fractions obtained through column chromatography were tested for their in vitro xanthine oxidase (XO) inhibitory activity by measuring spectrophotometrically the uric acid formation from xanthine as the substrate. The crude ethanol extract and the fraction with the most XO inhibitory activity were then tested for their in vivo XO inhibitory activity in oxonate-induced hyperuricemic mice by measuring their blood uric acid levels using uric acid test strips.

Results: The crude ethanolic extract of C. ovatum leaves at 100ppm showed 83.62±2.05% in vitro inhibition of XO while the most active fraction showed 80.30±4.00% inhibition. Both were comparable (p>0.05) to the positive control, allopurinol, which showed 91.47±5.64% inhibition. In vivo, the crude extract and the fraction that showed the highest XO inhibitory activity at 200 mg/kg significantly (p<0.01 and p<0.05) respectively reduced the serum uric acid levels of the hyperuricemic mice one hour after induction as compared to the negative control. Moreover, their antihyperuricemic activity were not statistically significant as compared to that of allopurinol (p<0.0001).

Conclusion: The crude ethanolic extract of C. ovatum leaves and its most active fraction showed statistically significant in vitro xanthine oxidase inhibition and in vivo antihyperuricemic activity. The activities shown by both crude and active fraction were not statistically different from that determined for allopurinol. Therefore, further studies can be conducted to isolate the most active compound and study its pharmacokinetic properties.

Published online: November 2, 2021