Recent Advances in Enone and NO-Releasing Derivatives of Oleanolic Acid with Anti-cancer Activity

Oleanolic acid (OA) is a natural pentacyclic triterpenoid acid with diverse biological activities including anti-inflammation, suppression of tumor promotion, protection of the liver against toxic injury, and induction of differentiation. However, the potency of OA as an anti-cancer agent is relatively weak. Therefore, remarkable progress has been made in the modification of OA to improve its anti-cancer activity over the past few years. This paper reviews the progress mainly on anti-cancer activity of enone derivatives and nitric oxide (NO)-releasing derivatives of OA over the last decade.