Reduction of the Plasma Uric Acid Level in Potassium Oxoate-Induced Hyperuricemic Rats by Heat-Concentrated Prunus mume Fruit Extract Containing Three Chlorogenic Acid Isomers

Gout is a common rheumatic disease, resulting from hyperuricemia. Prunus mume fruit extract, after being heat-concentrated named mei extract, was empirically found to reduce the risk of gout. While neochlorogenic acid was found as the predominant phenolic compound in the fresh juice of Prunus mume, neochlorogenic acid, chlorogenic acid, and cryptogenic acid were detected as the major phenolic compounds in the mei extract. In vitro testing showed that all the three chlorogenic acid isomers exhibited comparable inhibitory activities on xanthine oxidase. The hypouricemic effects of the mei extract were evaluated in potassium oxonate-induced hyperuricemic rats. Oral administrations of the mei extract significantly reduced the plasma uric acid level in hyperuricemic rats, but did not elevate the urinary uric acid level. The results provide in vivo evidence for the anti-hyperuricemic effects of mei extract for the first time, rationalize its therapeutic usage for the treatment of hyperuricemia and gout, and propose chlorogenic acid isomers as the active ingredients. Mei extract seems to be a potential natural functional food product.