Ursolic acid [(3b)-3-Hydroxyurs-12-en-28-oic acid] rarely occurs without its isomer oleanolic acid [(3b)-3-Hydroxyolean-12-en-28-oic acid] They may occur in their free acid form, as shown in Figure 1, or as aglycones for triterpenoid saponins which are comprised of a triterpenoid aglycone linked to one or more sugar moieties. Ursolic and oleanolic acids are similar in pharmacological activity^1.

Several ursolic acid derivatives, both natural and synthetic, have been reported. Novel ursolic acid derivatives, including ursane-type triterpenoid saponins, naturally occur as secondary metabolites through complex metabolic processes in different parts of the plants^5,8-12. Synthetic derivatives obtained from ursolic acid have been reported and evaluated for their pharmacological action ^3,13-16