Background and Aims: Studies have confirmed that the extracts of Eucommia ulmoides have anti-inflammatory and antioxidant effects, and offer a protective effect against organ ischemia-reperfusion injury. However, the pharmacological effects will vary among the extracts from different parts of Eucommia ulmoides and by different extraction methods. This study was conducted to compare the protective effects of the extracts from Eucommia bark and bark as well as by different extraction methods on liver ischemia-reperfusion injury (HIRI), so as to provide reference for the prevention and treatment of HIRI in clinical practice.  
Methods: Forty-eight male SD rats were equally randomized into sham operation group, HIRI model group, and 4 different pretreatment groups. Rats in the 4 pretreatment groups underwent gavage with Eucommia bark water extract, Eucommia bark ethanol extract, Eucommia leaf water extract and Eucommia leaf ethanol extract, respectively, once per day, for 10 d, and the concentration of each extract was 80 g crude drug/kg. Rats in sham operation group and HIRI model group were given the saline of the same volume in the same fashion. On the 11th day, except the rats in sham operation group HIRI was induced in all rats in the other groups by means of 1-h occlusion of the blood supply for the left hepatic lobe and the middle hepatic lobe followed by 4-h reperfusion. After that, the specimens of left hepatic lobe and blood sample from the inferior vena cava were harvested. Then, the pathological changes of the liver were observed by HE staining, and the serum liver function parameters alanine aminotransferase (ALT) and aspartate aminotransferase (AST), and the inflammatory index tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) as well as the oxidative stress variables malondialdehyde (MDA) and superoxide dismutase (SOD) in the liver tissue were determined. 
Results: Except the sham operation group, pathological changes of the liver tissue of different degrees were presented in all remaining groups of rats, but the liver injuries were milder in all pretreatment group that that in HIRI model group, particularly in Eucommia leaf ethanol extract pretreatment group. Compared with sham operation group, the activities of serum ALT and AST were significantly increased, the TNF-α and IL-1β levels and MOD concentrations in the liver tissue were significantly increased, while the SOD activities in the liver tissue were significantly decreased in HIRI group and all pretreatment group, but the changing amplitudes in all above parameters were lower in each pretreatment group than those in HIRI group, particularly those in  Eucommia leaf ethanol extract pretreatment group (all P<0.05). 
Conclusion: The extracts from different parts of Eucommia ulmoides and by different extraction methods all have protective effects against HIRI, especially, the ethanol extract from Eucommia leaves has most evident protective effect, suggesting that the flavonoids in the Eucommia leaves is the most effective compounds against HIRI, which deserves to be further explored and developed.