Finally, the hepatoprotection of the 50%EtWZ was evaluated using rat model. The results indicated that the 50%EtWZ possessed potent hepatoprotective activities. The protective effect of the extract against hepatotoxicity induced by long-term treatment with ethanol might be attributed to its inhibitory action on oxidative stress. Although multiple factors could be involved in the inhibition of oxidative injury in the liver, the inhibition of CYP2E1 pathway and the enhanced GSH-related antioxidant capacity might be responsible for the protective effect. In addition, the 50%EtWZ also produced anti-inflammatory effect partly by interfering Toll-Like-Receptor-4 (TLR-4)-mediated signal pathway and reducing the production of Tumor Necrosis Factor-alpha (INF-alpha) in Kupffer cells during long-term ethanol exposure. / First, in order to determine which kind of extract possesses the strongest hepatoprotective effect on ethanol-induced cytotoxicity, various extracts were screened for cytochrome P450 2E1 isoenzyme (CYP2E1) inhibitory activity using the fluorogenic CYP2E1 substrate and HepG2 cells overexpressing human CYP2E1. The results showed that all extracts (aqueous, 50% ethanol, and 90% ethanol) of WZ produced inhibitory effect on CYP2E1. The 50% ethanol extract of WZ (50%EtWZ) displayed a stronger CYP2E1 inhibition than the aqueous and 90% ethanol extracts. The aqueous extract and 50%EtWZ showed protective effect against ethanol-induced cytotoxicity at concentrations equivalent to 100 and 1000 mug raw herb/ml. At the same concentration of 100 1.1g/ml, the 50%EtWZ exhibited a more potent protective effect. Higher degree of cytotoxicity was found in the 90% ethanol extract of WZ. Thus, 50%EtWZ was chosen for further study. / In summary, all data suggest that the inhibition of CYP2E1 pathway and the inhibition of oxidative stress by the 50%EtWZ, together with the anti-inflammatory effect on Kupffer cells, may contribute to its hepatoprotection against chronic ethanol-induced liver injury. / Second, the chemical components of the 50%EtWZ were analyzed by chromatographic fingerprints. The fingerprint revealed six hepatoprotective compounds including schisandrin B, schisandrin, deoxyschisandrin, betaine, hyperin, and quercitrin in the formula. / Third, the protective mechanism of the 50%EtWZ was investigated in E47 cells model. The 50%EtWZ protected against CYP2E1-dependent toxicity and oxidative stress induced by ethanol. The mechanism of protection involved the decrease of reactive oxygen species production and the inhibition of lipid peroxidation. The hepataprotection was associated with the maintenance of mitochondrial GSH. Pre-treating E47 cells with the 50%EtWZ significantly inhibited the expression of CYP2E1. Therefore, the protective effect of the 50%EtWZ was most likely attributed to its antioxidant activities and the inhibition of CYP2E1. In addition, the 50%EtWZ prevented ethanol-induced apoptosis and protected against oxidative damage to mitochondria which are critical for maintenance of cell viability. / Wu-Zi-Yan-Zong-Wan (WZ), a traditional medicinal formula, is used for treatment of male sexual dysfunctions. In this study, the hepatoprotection afforded by Wu-Zi-Yan-Zong-Wan treatment and its biochemical mechanism involved against chronic alcohol-induced injury were investigated. / Chen, Mengli. / "May 2008." / Adviser: Che Chun Tao. / Source: Dissertation Abstracts International, Volume: 70-03, Section: B, page: 1609. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (p. 157-179). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.