Oleanolic acid or oleanic acid is a naturally occurring pentacyclic triterpenoid with the formula of C30H48O3. It was found in the non-glyceride fraction of olive pomace oil and is widely distributed in food and plants where it exists as a free acid or as an aglycone precursor for triterpenoid saponins, in which it can be linked to one or more sugar chains. It is biosynthesized from lupane. It can rearrange to the isomer, ursolic acid, or be oxidized to taraxasterol and amyrin. Oleanolic acid and its derivatives possess several promising pharmacological activities, such as hepatoprotective effects, and anti-inflammatory, antioxidant, or anticancer activities.