Anti-gout nor-oleanane triterpenoids from the leaves of Stauntonia brachyanthera.

With the aim of finding more potential anti-gout compounds from natural resources, a phytochemical study on the leaves of Stauntonia brachyanthera was carried out, which led to the isolation of 11 nor-oleanane triterpenoids, including 4 new ones. Their structures were determined by the comprehensive 1D, 2D NMR, HRMS, and HPLC analysis after acid hydrolysis. Brachyantheraoside B4 (3) and 3-O-α-l-rhamnopyranosyl-(1→2)-α-l-arabinopyranosyl-30-norolean-12,20(29)-dien-28-oic acid (8) exhibited significant inhibitory activities on xanthine oxidase with IC50 values of 0.20 and 18.5μM, respectively. Brachyantheraoside C2 (2) also showed moderate effects on XO. A primary structure-activity relationship was also summarized, which revealed the anti-gout abilities of three nor-oleanane triterpenoids and their potential possibilities as the candidate compounds for the treatment of gout. The discovery of nor-oleanane triterpenoids also widens people's idea for the study of anti-gout agents and promotes the comprehensive development of S. brachyanthera.