Isomers (oleanolic and ursolic acids) differ in their protective effect against isoproterenol-induced myocardial ischemia in rats.

The efficiency and safety of oleanolic acid (OA) and its isomer, ursolic acid (UA) in myocardial ischemia are poorly documented. This study appraised the efficacy of OA and UA in protecting the heart against oxidative damage induced by isoproterenol, since oxidative injury has been investigated as a potential initiator of myocardial necrosis. The level of TBARS increased whereas the antioxidants decreased significantly in the myocardium of ischemic animals. The levels were brought back to near normalcy in OA and UA pre-treated rats by scavenging the free radicals and blocking the induction of lipid peroxidation. These findings provide evidence that OA and UA protect rat myocardium against ischemic insult and the protective effect could be attributed to its antioxidant property and/or to a strengthening of myocardial membrane by its membrane stabilizing action. Among the two isomeric compounds, UA showed higher activity than OA.