Protective effect of dietary flavonoid quercetin against lipemic-oxidative hepatic injury in hypercholesterolemic rats

Abstract

CONTEXT: Quercetin, a dietary-derived flavonoid, is ubiquitous in fruits and vegetables and plays important roles in human health by virtue of its antioxidant activity. OBJECTIVE: This study was conducted to investigate the possible modulatory effect of quercetin against hepatic lipemic-oxidative injury in rats fed with a high cholesterol diet (HCD), and to highlight the underlying mechanisms of such effect. MATERIALS AND METHODS: Different groups of male Sprague-Dawley rats were used; one group was treated by gavage with HCD cocktail (1 mL/100 g) whereas another group was orally administered HCD-enriched with quercetin (15 mg/kg). Corresponding control animals were also used. RESULTS: Quercetin administration significantly decreased liver triglycerides (24%), liver total cholesterol (TC) (22%), serum TC (20%), serum low-density lipoprotein cholesterol (31%), and duplicated serum high-density lipoprotein cholesterol (HDL-C). This study also revealed that quercetin administration significantly reduced the activity of serum alanine aminotransferase (41%), aspartate aminotransferase (51%), and γ-glutamyl transpeptidase (G-GT) (35%). Significant inhibition of thiobarbituric acid-reacting substances (40%), together with a valuable enhancement of reduced glutathione (GSH) content (53%) in the liver homogenates, was observed. In addition, quercetin-treated hypercholesterolemic animals exhibited a reasonable improvement of hepatic antioxidant enzymes. Moreover, serum and liver content of nitric oxide (NO) were markedly decreased in this model (26 and 25%, respectively), and were almost normalized following quercetin administration. DISCUSSION AND CONCLUSION: These data revealed that quercetin has the ability to ameliorate HCD-induced lipemic-oxidative injury in rat liver possibly through its antioxidant potential and/or increased NO bioavailability.