Anticancer activity of oleanolic acid and its derivatives modified at A-ring and C-28 position

Oleanolic acid (OA) is a five-ring triterpenoid compound, which is widely present in plants. Due to a wide range of pharmacological activities, oleanolic acid has attracted more and more attention. However, oleanolic acid is insoluble in water and has low bioavailability, which limits its clinical application. In this review, we focus on summarizing the anti-cancer activity and mechanism of the A ring or C-28 carboxyl modified derivatives of OA since 2015, to determine the strength of its anti-cancer effectiveness and evaluate whether it could be used as a clinical anti-cancer drug.