Comparison of Xanthine Oxidase Inhibitory Effect of Swertia chirayita and Febuxostat in Vitro

Abstract

Introduction:Plasma uric acid ? 6.5 to 7.0 mg/dl increases the incidence of gout, hypertension, diabetes mellitus type 2, stroke and heart failure. Low purine diet, use of xanthine oxidase inhibitors allopurinol and febuxostat; or uricosuric agent’s probenecid, sulfinpyrazone and Benzbromarone are being used for treatment. Swertia chirayita extract (SCE) being practiced as anti-inflammatory and anti-oxidant was evaluated for inhibition of xanthine oxidase.

Aims & Objectives: To observe the in vitro effect of Swertia chirayita ethanolic extract on xanthine oxidase inhibition and its comparison with medicine febuxostat.

Place and duration of study: The study was conducted in Pharmacology Department, University of Health Sciences Lahore during June-August 2017.

Material & Methods: Xanthine oxidase (XO) inhibition by ethanolic extract of the herb was compared with febuxostat. Serial dilutions of test compounds ranging from 1.25µg/ml to 100 µg/ml were prepared in absolute ethanol. Fixed volumes of xanthine, xanthine oxidase, phosphate buffer and test compounds were incubated. Uric acid concentration in the reaction mixture was calculated by measuring absorbance at 295nm by using Ultraviolet- Visible Spectrophotometer. Mean values and percent inhibition (± SD) was calculated. EZ Fit Enzyme Kinetic program was also used to calculate inhibitory concentration 50 percent (IC₅₀), Michaelis constant (Km) and maximum rate of reaction (Vmax).

Results: At maximum dose, (100 µg/ml) xanthine oxidase inhibition by febuxostat and Swertia chirayita was 98% and 80% percent respectively (p=0.01). Swertia chirayita extract showed IC₅₀ at 9.15± 1.2 µg/ml whereas IC₅₀ of febuxostat was 7.91± 0.9 µg/ml.

Conclusion: In the light of XO inhibition, Swertia chirayita has potential to be explored as antihyperuricemic agent.