Xanthine Oxidase Inhibitory Activity of Some Vietnamese Remedies Used to Treat Bi Syndrome in Traditional Medicine

Background Hyperuricemia is a metabolic disorder caused by abnormalities in purine metabolism that increase serum uric acid. Some traditional medicine remedies have been proven to cause hypouricemia by inhibiting xanthine oxidase. In Vietnam, some remedies that eliminate wind, cold, and dampness have been used to treat gouty arthritis, but there is still a lack of scientific evidence regarding the underlying biological mechanisms involved. This study aimed to assess the xanthine oxidase inhibitory activity in vitro and the hypouricemic effects of several Vietnamese remedies used to treat Bi syndrome in traditional medicine. Methods The chosen remedies that met our criteria were successively extracted with 70% ethanol. A preliminary investigation of the chemical composition of the extracts was performed by common chemical reactions. The in vitro xanthine oxidase inhibitory activity of the extracts was investigated using the procedure of Noro et al (1983). Acute toxicology and hypouricemic effect of the remedy that showed the highest xanthine oxidase inhibitory activity were investigated in vivo using a potassium oxonate-induced hyperuricemic mouse model. Results Five remedies that met the criteria were chosen. Phytochemical screening of all the extracts revealed the presence of flavonoids, saponins, alkaloids, tannins, and carbohydrates. The Bai nghiem phuong 2 extract did not show xanthine oxidase inhibitory activity whereas the Thang Tri Te Thap extract, which exhibited the highest inhibitory xanthine oxidase activity with an IC 50 value of 48.33 ± 0.41 µg/mL, was selected for the subsequent in vivo experiments. The Thang Tri Te Thap extract did not cause acute toxicity, with a D max of 31.67 g/kg. At doses of 1.5 g/kg and 3 g/kg, Thang Tri Te Thap significantly reduced the serum uric acid concentration by 59.84 ± 5.79% and 65.01 ± 12.73%, respectively (p < 0.05). Conclusions Thang Tri Te Thap showed xanthine oxidase inhibitory activity in vitro and hypouricemic effects in vivo.