Chen Gang, Tan Ming-Liang, Li Kai-Kai, Leung Ping-Chung, Ko Chun-Hay
School of Environmental and Biological Engineering, Chongqing Technology and Business University, Chongqing 400067, China; Chongqing Key Laboratory of Nature Medicine Research, Chongqing Key Lab of Catalysis & Functional Organic Molecules, Chongqing Technology and Business University, Chongqing 400067, China.
School of Environmental and Biological Engineering, Chongqing Technology and Business University, Chongqing 400067, China; Chongqing Key Laboratory of Nature Medicine Research, Chongqing Key Lab of Catalysis & Functional Organic Molecules, Chongqing Technology and Business University, Chongqing 400067, China.
J Ethnopharmacol. 2015 Dec 4;175:14-20. doi: 10.1016/j.jep.2015.08.043. Epub 2015 Sep 3.
Green tea is a Chinese materia medica with the main functions of "inducing urination and quenching thirst". Green tea polyphenols (GTP) are generally acknowledged as the main active fraction with multiple pharmacological functions in green tea. However, the effect of GTP on hyperuricemia is not clear till now.
The present study was carried out to investigate the effect of GTP on serum level of uric acid in potassium oxonate (PO)-induced hyperuricemic mice, and explore the underlying mechanisms from two aspects of production and excretion of uric acid.
PO and GTP were intragastricly administered to mice for consecutive 7 days. Serum level of uric acid, and xanthine oxidase (XOD) activity in serum and liver were examined. Simultaneously, expression of XOD protein in liver was analyzed by Western blot assay. Expressions of urate transporters including urate-anion transporter (URAT) 1, organic anion transporter (OAT) 1 and 3 in kidney were analyzed by immunohistochemistry staining method.
300 and 600 mg/kg GTP significantly decreased serum level of uric acid of hyperuricemic mice in a dose-dependent manner (p<0.05 or p<0.01). Besides, 300 and 600 mg/kg GTP markedly reduced XOD activity in serum and liver of hyperuricemic mice (both p<0.01). Furthermore, 300 and 600 mg/kg GTP clearly reduced XOD expression in liver, as well as reduced URAT1 expression and increased OAT1 and OAT3 expressions in kidney of hyperuricemic mice (p<0.05 or p<0.01).
These results demonstrated that GTP had the effect of lowering uric acid through decreasing the uric acid production and increasing uric acid excretion. Our study suggested that GTP would be a promising candidate as a novel hypouricaemic agent for further investigation.
绿茶是一种中药，主要功能为“利尿解渴”。绿茶多酚（GTP）被公认为是绿茶中具有多种药理功能的主要活性成分。然而，GTP对高尿酸血症的影响目前尚不清楚。
本研究旨在探讨GTP对氧嗪酸钾（PO）诱导的高尿酸血症小鼠血清尿酸水平的影响，并从尿酸生成和排泄两个方面探讨其潜在机制。
将PO和GTP连续7天灌胃给予小鼠。检测血清尿酸水平以及血清和肝脏中的黄嘌呤氧化酶（XOD）活性。同时，通过蛋白质印迹法分析肝脏中XOD蛋白的表达。采用免疫组织化学染色法分析肾脏中尿酸转运蛋白包括尿酸阴离子转运体（URAT）1、有机阴离子转运体（OAT）1和3的表达。
300和600mg/kg GTP能以剂量依赖方式显著降低高尿酸血症小鼠的血清尿酸水平（p<0.05或p<0.01）。此外，300和600mg/kg GTP显著降低高尿酸血症小鼠血清和肝脏中的XOD活性（均p<0.01）。此外，300和600mg/kg GTP明显降低肝脏中XOD的表达，同时降低高尿酸血症小鼠肾脏中URAT1的表达并增加OAT1和OAT3的表达（p<0.05或p<0.01）。
这些结果表明，GTP具有通过减少尿酸生成和增加尿酸排泄来降低尿酸的作用。我们的研究表明，GTP作为一种新型降尿酸药物具有进一步研究的潜力。
