Ursane and 24‐Noroleanane‐Type Triterpenoids with Anti‐HIV Activity from the Twigs and Leaves of Antirhea chinensis

Investigations on the twigs and leaves of Antirhea chinensis have led to the discovery of two undescribed pentacyclic triterpenoids (1 and 2) and nine known analogs. Compounds 1 and 2, each assigned as the ursane and 24-noroleanane-type triterpenoids, featuring similar oxidation pattern of 3 beta,6 beta,19 alpha-trihydroxy-28-carboxyl. Their structures were elucidated via comprehensive analyses of spectroscopic data. Compound 1 displayed potent anti-HIV activity (EC50=1.24 mu M) and high selectivity index (SI >32.3).