Effects of Oligonol®, an oligomerized polyphenol formulated from lychee fruit, on serum concentration and urinary excretion of uric acid

Abstract Epidemiological observations and laboratory studies have suggested that polyphenols possess anti-inflammatory, anti-microbial, anti-carcinogenic, and antioxidant properties. However, studies assessing the effects of polyphenols on uric acidmetabolism in vivo are scarce. Herein, we investigated whether a phenolic substance, Oligonol®, has effects on uric acidmetabolism. In six healthy male volunteers, Oligonol® significantly decreased 1-h uric acidexcretion and fractional uric acidclearance, which was accompanied by a decreased serum concentration of uric acid. In addition, an in vitro experiment showed that Oligonol® inhibited buttermilk xanthine oxidaseactivity in a dose-dependent manner. Together, these results suggest that Oligonol® lowers serum uric acidthrough inhibition of xanthine oxidase, and may be effective for prevention and treatment of hyperuricemiaand/or gout.