Potential anti-gout constituents as xanthine oxidase inhibitor from the fruits of Stauntonia brachyanthera.

With the aim of finding a better xanthine oxidase inhibitor with potential anti-gout properties, the studies on the fruit of Stauntonia brachyanthera were carried out, which led to the isolation of 12 glycosides, including 4 new nor-oleanane triterpenoids. Their structures were determined by comprehensive spectroscopic (NMR and HR MS) analysis. Two compounds (4 and 11) exhibited significant inhibitory activities on xanthine oxidase with IC50 values of 5.22 and 1.60µM, respectively. Another five compounds (1, 2, 3, 8 and 10) showed qualified activities. The results suggested that the existences of nor-oleanane triterpenoids and flavonoids in the fruits were responsible for the inhibitory activity on xanthine oxidase that could cut off the production of uric acid. Nor-oleanane triterpenoids, a new leading XO inhibitor, is worthy of further studies on molecular biology level for its mechanisms.