Cardioprotective activity of melatonin and its novel synthesized derivatives on doxorubicin-induced cardiotoxicity.

This study aimed at evaluation of melatonin and some of its novel synthesized derivatives 3, 4, 9 and 10b as cardioprotective agents against doxorubicin-induced acute cardiac toxicity in rats. Also, this work was extended to study the potential role of each synthesized derivative in comparison with the parent compound melatonin. Intraperitoneal injection of a single dose (15mg/kg B.W.) of doxorubicin resulted in significant increase in serum troponin I, leptin, triglycerides, cholesterol and LDL-cholesterol levels with concomitant decrease in serum T(3), T(4) and IL-1alpha levels. In contrast, intraperitoneal injection of melatonin or its synthesized derivatives especially compounds 3 and 10b in a dose of 5mg/kg B.W./day for 10days reversed doxorubicin-induced changes in the above mentioned parameters towards the normal values. The present data revealed that doxorubicin exerts its action mainly through the oxidative stress. This appeared from the significant elevation in serum nitric oxide level and cardiac lipid peroxidation level with concomitant decrease in cardiac antioxidative enzymes activity. Treatment with melatonin and its derivatives 3 and 10b could reduce the markers of oxidative stress and restore the activity of the antioxidative enzymes in the heart tissue. In conclusion, the cardioprotective effect of melatonin and its derivatives may be mediated through the antioxidant and free radical scavenging activity of these compounds.