br Materials and Methods br Results br Discussion

Materials and Methods
Results
Discussion Liver participates in a variety of enzymatic metabolic activities. Administration of ethanol causes elevation of serum ASP, ALT, ALP and total bilirubin levels in rats, indicating that ethanol may induce hepatocellular damages which in turn alters the structure and function of liver hedgehog inhibitor [22,23]. Our study on the ethanol induced hepatic damage are in accordance with previous reports [24]. Silymarin is a standardized extract of the milk thistle (Silybum marianum) chiefly contains flavonoid, includings silybin, silybinin, silydianin and silychristin [25]. Silymarin offers good protection in various toxic models of experimental liver diseases in laboratory animals. It functions through mechanisms of antioxidative, anti-lipid peroxidative, antifibrotic, anti-inflammatory, membrane stabilizing, immunomodulatory and liver regenerating [26]. Silymarin has been applied in alcoholic liver diseases, liver cirrhosis, Amanita mushroom poisoning, viral hepatitis, toxic and drug induced liver diseases and in diabetic patients in clinical settings. Silymarin may also be a useful hepatoprotection drug for hepatobiliary diseases and hepatotoxicity induced by drugs. Moreover, it is used as a standard drug and exhibited potent hepatoprotective activity within the dose range of 25 to 200mg/kg [27,28]. This study demonstrated that A. cepa aqueous bulb extract had reduced levels of AST, ALT and ALP which were elevated by ethanol administration. The results were in accordance with the findings of other investigators [13]. Moreover, it was reported that A. cepa leaf extract also can significantly restored the elevated AST, ALT and ALP enzyme levels to the normal levels [24]. Recently, Riyaz Shaik et al. [29] demonstrated that A. cepa leaves protected hepatocytes by preventing the release of these 3 enzymes. The study of Ogunlade et al. [30] demonstrated that administration of A. cepa by rabbits with alcohol abuse remarkably reduced serum levels of liver biomarker enzymes. Our results are consistent with earlier studies, which strongly suggest that A. cepa may protect the structural integrity of hepatocytes and prevent the release of cytosolic enzymes into bloodstream. Phytochemical screening of aqueous extract of A. cepa bulb showed that it contains abundant carbohydrates, tannins, saponins, and flavanoids, a group of polyphenolic compounds [31]. Approximately 20 types of flavonols were detected ub in onion species, with the two quercetin conjugates:quercetin-3, 40-O-diglucoside (QDG) and quercetin-40-O-monoglucoside (QMG) being the main flavonols representing up to 80–85% of the total flavonoid content [32]. The antioxidant activity in A. cepa bulb is mainly due to the presence of flavonoids [33]. The earlier studies have shown that the presence of organosulphur compounds like dipropyl disulphide, methyl-1-propenyl trisulphide and propyl-1-propenyl trisulphide in the A. cepa bulb [34]. In addition, phenolics, selenium, vitamin C and amino acids were also found to be responsible for antioxidant activity of two Egyptian onion varieties [35]. In the present study, A. cepa showed effective scavenging activities for DPPH, hydroxyl, and super oxide radical, suggesting that it could scavenge the free radicals generated during ethanol metabolism. This finding is consistent with previous studies that the antioxidant activity of A. cepa extract comes from rich sources of bioactive compounds, such as flavanoids [36–38], which quench ROS and regenerate membrane-bound antioxidants at both preventive and curative doses.
Conclusions The present study demonstrated that the aqueous extract of A. cepa bulb protective against ethanol-induced hepatotoxicity which might be due to its antioxidant potential against DPPH, hydroxyl and superoxide radicals. The hepatoprotective role of A. cepa extract (600mg/kg bw) was found to be comparable with Silymarin which might be due to the presence of flavonoid.