Green tea polyphenols decreases uric acid level through xanthine oxidase and renal urate transporters in hyperuricemic mice.
BACKGROUND
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.


OBJECTIVE
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.


METHODS
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.


RESULTS
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).


CONCLUSIONS
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.
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. Electronic address: gangch_tcm@163.com.
Gang
G
Chen
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.
Ming-Liang
ML
Tan
Institute of Chinese Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China; State Key Laboratory of Phytochemistry and Plant Resources in West China, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
Kai-Kai
KK
Li
Institute of Chinese Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China; State Key Laboratory of Phytochemistry and Plant Resources in West China, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
Ping-Chung
PC
Leung
Institute of Chinese Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China; State Key Laboratory of Phytochemistry and Plant Resources in West China, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China. Electronic address: gohey@cuhk.edu.hk.
Chun-Hay
CH
Ko
D000818:Animals; D006074:Gout Suppressants / Q000494:pharmacology* / Q000627:therapeutic use*; D033461:Hyperuricemia / Q000097:blood / Q000139:chemically induced / Q000188:drug therapy* / Q000378:metabolism; D007668:Kidney / Q000187:drug effects / Q000378:metabolism; D008099:Liver / Q000187:drug effects / Q000201:enzymology; D008297:Male; D051379:Mice; D027362:Organic Anion Transport Protein 1 / Q000378:metabolism; D027361:Organic Anion Transporters / Q000378:metabolism; D029362:Organic Anion Transporters, Sodium-Independent / Q000378:metabolism; D010094:Oxonic Acid; D059808:Polyphenols / Q000494:pharmacology* / Q000627:therapeutic use*; D013662:Tea; D014527:Uric Acid / Q000097:blood; D014969:Xanthine Oxidase / Q000097:blood / Q000378:metabolism
D006074:Gout Suppressants; D027362:Organic Anion Transport Protein 1; D027361:Organic Anion Transporters; D029362:Organic Anion Transporters, Sodium-Independent; D059808:Polyphenols; C109687:Slc22a12 protein, mouse; C105033:Slc22a6 protein, mouse; D013662:Tea; C114338:organic anion transport protein 3; D014527:Uric Acid; C489337:potassium oxonate; D010094:Oxonic Acid; D014969:Xanthine Oxidase
Green tea polyphenols; Hyperuricemia; Urate transporters; Xanthine oxidase