Investigation of the hooks of Uncaria rhynchophylla resulted in isolation of six phospholipase Cγ1 (PLCγ1) inhibitors (1−6). The structures of these compounds were elucidated as pentacyclic triterpene esters by spectroscopic and chemical analysis. Three of them, namely uncarinic acids C (1), D (2), and E (3), are newly reported as natural products. All the compounds showed dose-dependent inhibitory activities against PLCγ1 in vitro with IC50 values of 9.5−44.6 μM and inhibited the proliferation of human cancer cells with IC50 values of 0.5−6.5 μg/mL.
