CARDIOPROTECTIVE ACTIVITY OF SILYMARIN ON ISCHEMIA-REPERFUSION INDUCED MYOCARDIAL INFARCTION IN RATS

Abstract:

Vigorous global research is underway in an effort to develop pharmacological means to control morbidity and mortality arising from ischemic heart diseases. It has been suggested that the beneficial effects of reperfusing the myocardium might be in part reversed by the occurrence of reperfusion injury. Since reperfusion injury is associated with an imbalance of oxidative stress and antioxidant defense system, it would be possible to limit oxidative damage and ameliorate disease progression by supplementing antioxidants.
Silymarin is an extract of the milk thistle plant Silybium mariamum belongs to the family Compositae. Silymarin consists of a mixture of three bioflavonoids namely silybin, silydianin, and silychristine. Silymarin is known to have antioxidant effect. The present study was designed to study the effects of pretreatment with silymarin in an in vivo rat model on ischemia-reperfusion induced myocardial infarction. The model adapted was that of surgical induced myocardial ischemia, performed by means of the left anterior descending coronary artery occlusion for 30 min followed by reperfusion for another 4 h. Infarct size was measured by using the staining agent, 2,3,5-triphenyl tetrazolium chloride. Lipid peroxide levels in serum and heart tissue were estimated spectrophotometrically. The endogenous antioxidant enzymes superoxide dismutase, catalase, glutathione peroxidase, glutathione S-transferase and reduced glutathione contents were estimated. A dose dependent reduction in infarct size and in lipid peroxide levels of serum and heart tissue, and a dose dependent protection of endogenous antioxidant enzymes were observed with prior treatment of silymarin with various dose levels for 7 days compared to control and sham control animals. Hence the present study suggests the cardioprotective activity of Silymarin in limiting ischemia-reperfusion induced myocardial infarction.