Effects of Pimenta pseudocaryophyllus ethanolic extracts on serum uric acid levels in oxonate-induced mice and xanthine oxidase activity in vitro and in mouse liver

Abstract

Pimenta pseudocaryophyllus is the only species of the Pimenta genus native from Brazil. It is popularly known as “pau-cravo”. In folk medicine, the leaf tea has been used as sedative, diuretic and anti-rheumatism [1,2]. The study aimed examining the efficacy of P. pseudocaryophyllus extracts in reducing serum urate levels in a mouse model of hyperuricemia induced by the uricase inhibitor potassium oxonate, and in inhibiting xanthine oxidase (XO) activity in vitro and in mouse liver [3,4]. In vitro XO inhibitory activity was expressed as the percentage inhibition of XO and in vivo XO activity was expressed as nanomoles of uric acid formed per minute per milligram protein. Statistical evaluation was done using the software GraphPad Prism 5.01. Others statistical evaluations were done using one-way analysis of variance (ANOVA), followed by Dunnett's test. Dried powdered leaves and stems of P. pseudocaryophyllus were extracted by percolation with ethanol. The ethanolic extracts at a concentration of 100 mg/mL inhibited XO in vitro: 76.46% (leaves) and 81.63% (stem). IC50 values of these extracts were 19.91 ± 1.859 mg/mL and 13.72 ± 1.167 mg/mL, respectively. There were significant differences in serum uric acid levels in the animal groups treated with doses of 125, 250 and 500 mg/kg of the ethanolic extracts of leaves and stems compared to the hyperuricemic control group. Positive control group was treated with allopurinol (10 mg/kg). The residual activity of liver XO was inhibited for the ethanolic extracts of leaves and stems. The results obtained in the present study indicate that orally administered extracts of P. pseudocaryophyllus reduce serum urate levels in hyperuricemic mice caused by oxonate. These hypouricemic effects were concluded to be partly due to inhibition of XO activity in mouse liver.