Quercetin provides greater cardioprotective effect than its glycoside derivative rutin on isoproterenol-induced cardiac fibrosis in the rat

Quercetin exhibits numerous pharmacological effects, including the capacity for cardioprotection. This study aimed to investigate whether quercetin or its glycoside derivative rutin has any protective action against isoproterenol (ISO) induced cardiac fibrosis, and investigate the structure-activity relationship. Male Wistar rats were injected subcutaneously with ISO (15 mg.(kg body mass)(-1)) to induce experimental cardiac fibrosis. The cardioprotective effect of co-treatment with quercetin (25 or 50 mg.kg(-1)) or rutin (25 or 50 mg.kg(-1)) was investigated in ISO-induced cardiac fibrosis in rats. The administration of quercetin and rutin signifcantly decreased the cardiac weight index and myocardial enzyme activity, increased the activity of superoxide dismutase in the serum, and inhibited the ISO-induced increase in angiotensin II and aldosterone in the plasma. Furthermore, overexpression of transforming growth factor beta(1) (TGF-beta(1)), connective tissue growth factor (CTGF), and excessive deposition of extracellular matrix (ECM) in isoproterenol-treated myocardial tissues were normalized by quercetin and rutin. Our results suggest that both quercetin and rutin exhibited cardioprotective effects in cardiac fibrosis induced by ISO in the rat heart. Moreover, the effects of rutin are weaker than quercetin at the same dose. The mechanism of these effects may be related to antioxidative stress, inhibition of the renin-angiotensin-aldosterone system, decrease in the expression of TGF-beta(1) and CTGF, and the subsequent reduction in the deposition of the ECM.