title: Longan seed extract reduces hyperuricemia via modulating urate transporters and suppressing xanthine oxidase activity.
abstract: Hyperuricemia causes gouty arthritis, kidney disease, heart disease, and other diseases. Xanthine oxidase (XOD) and urate transporters play important roles in urate homeostasis. Numerous plants have been identified as XOD inhibitors. Longan seeds are known to contain high levels of polyphenols such as corilagin, gallic acid and ellagic acid. We examined the effect of longan seed extract on XOD inhibition and urate transporters GLUT1 and GLUT9 using both in vitro and in vivo assays. The results showed that dried longan seed extract (LSE) and its active components inhibited XOD dose-dependently in vitro. LSE inhibited uric acid production and XOD activity in normal liver cells (clone-9 cells) and was not cytotoxic under the concentration of 200 μg/ml. For the in vivo study, Sprague-Dawley (SD) rats were given intraperitoneally for thirty minutes with or without allopurinol (a XOD inhibitor, 3.5 mg/kg) or LSE (80 mg/kg) and then injected intraperitioneally with 250 mg/kg of oxonic acid and 300 mg/kg of hypoxanthine intragastrically. LSE was able to reduce serum uric acid level and XOD activity in hyperuricemic rats. However, LSE or allopurinol did not inhibit the liver XOD activities. On the other hand, GLUT1 protein was suppressed in kidney and GLUT9 was induced in liver from experimental rats and LSE or allopurinol decreased GLUT9 but increased GLUT1 protein level in the liver and kidney, respectively. These results confirmed the claimed effect of longan seeds on gout and other complications and suggested that its urate reducing effect might be due to modulation of urate transporters and inhibition of circulating xanthine oxidase.
authors.affiliation: Department of Biotechnology, Yuanpei University, Hsinchu,  Taiwan.
authors.forename: Chien-Wei
authors.initials: CW
authors.lastname: Hou
authors.forename: Ying-Chung
authors.initials: YC
authors.lastname: Lee
authors.forename: Hsiao-Fang
authors.initials: HF
authors.lastname: Hung
authors.forename: Hua-Wen
authors.initials: HW
authors.lastname: Fu
authors.forename: Kee-Ching
authors.initials: KC
authors.lastname: Jeng
mesh_terms: D000493:Allopurinol / Q000494:pharmacology; D000818:Animals; D051272:Glucose Transporter Type 1 / Q000378:metabolism; D006073:Gout / Q000188:drug therapy / Q000378:metabolism; D006074:Gout Suppressants / Q000494:pharmacology / Q000627:therapeutic use; D033461:Hyperuricemia / Q000097:blood / Q000139:chemically induced / Q000517:prevention & control*; D019271:Hypoxanthine; D007668:Kidney / Q000378:metabolism; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D008297:Male; D009004:Monosaccharide Transport Proteins / Q000378:metabolism*; D010094:Oxonic Acid; D008517:Phytotherapy; D010936:Plant Extracts / Q000494:pharmacology / Q000627:therapeutic use; D059808:Polyphenols / Q000494:pharmacology / Q000627:therapeutic use*; D051381:Rats; D017207:Rats, Sprague-Dawley; D029631:Sapindaceae; D012639:Seeds; D014527:Uric Acid / Q000097:blood*; D014969:Xanthine Oxidase / Q000037:antagonists & inhibitors*
chemical_list: C498776:GLUT6 protein, rat; D051272:Glucose Transporter Type 1; D006074:Gout Suppressants; D009004:Monosaccharide Transport Proteins; D010936:Plant Extracts; D059808:Polyphenols; D014527:Uric Acid; D019271:Hypoxanthine; D010094:Oxonic Acid; D000493:Allopurinol; D014969:Xanthine Oxidase