| Aim:Carnosic acid (CA), a natural strong antioxidant, has widely pharmacological and biologic actions.But this is no report about the effect of CA on liver injury at now.The aims of the present study were to systemically observe the protective effect of CA on liver cells in CCl4-induced human liver cell line L-02 injury in intro and in CCl4-induced rat acute liver injury in vivo and to study such effect of CA is related to inhibiting lipid peroxidation and pro-inflammatory factor production. Methods:The present study included two parts:animal experiment in vivo and cell experiment in vitro.(1)Animal experiment:SD rats were intraperitoneal injected with 10% CCl4 in the dose of 0.7 ml/100g and then were divided into six groups:normal control group, CCl4-induced liver injury model group, three different dose CA treated group (25,50 and 100 mg/kg) and positive drug group bifendatatum (BD,100 mg/kg). These drugs were orally treated for 4 days (once a day) before 10%CCl4 was injected. At the 24 hour of 10% CCl4 injection, the activities of both alanine aminotransferase (ALT) and aspartate aminotransferase (AST) and the level of interleukin-6 (IL-6) as well as the content of malondialdehyde (MDA) in liver tissue were determined. At the end of the experiment, the liver tissues were collected to pathological histology.(3)Cell experiment:Human liver cell line L-02 were cultured and treated as follows:normal control, CCl4-treated group (cells were treated with 60% CCl4-medium for 6 h), three different concentration CA-treated groups (cells were added with 5,10 or 25μg/ml, respectively,1 h before treatment with CCl4) and positive drug group (cells were added with BD 25μg/ml 1 h treatment with CCl4). There cells were incubated for 6 hours after CCl4 or/and drugs treatment and then cultured medium were collected to determine the activities of both ALT and AST as well as the content of MDA.Results:Animal experiment:the plasma activities of ALT and AST were 49.6±7.9 and 182.4±19.8 U/L in normal rats. Intraperitoneal injection with 10% CC14 for 24 h could increase the activities of ALT and AST to 1243.1±325.4 and 795.4±94.3 U/L, respectively.The level of IL-6 in plasma and the content of MDA in liver tissue were 210.8±57.4 ng/ml and 0.77±0.08 nmol/mg in normal rats, and them were markedly increased after treatment with CC14 (392.5±71.3 ng/ml and 2.46±0.73 nmol/mg, respectively). Both P< 0.01 vs control. Different dose of CA which orally treated rat before 10%CCl4 was injected could differently lessen the increasing activities of AST and ALT,decrease the level of IL-6 in plasma and the content of MDA in liver tissue by CC14(ALT were 788.9±124.6,456.7±98.5,234.8±79.7 U/L;AST were 525.5±112.5,351.3±76.9,276.5±69.4 U/L; IL-6 were 324.8±61.7,265.8±31.8,239.0±51.4 ng/ml; MDA awere 1.63±0.51,0.98±0.75,0.85±0.62 nmol/ml; respectively). The results of the pathological histology showed that oral administration of CA markedly improved the injury of liver tissue induced by CCl4.Cell experiment:MTT results showed that CA (25μg/ml) and BD (25μg/ml) had no effect on normal liver cell viability. Treatment with 60% CCl4-medium for 6 h could markedly decrease cell viability to 78.5±4.3%(both P< 0.01 vs control). Pretreatment with CA could markedly decrease CCl4-induced decrease in cell viability (hepitical cell viability were 84.9±4.1; 90.1±3.2,97.4±6.8, respectively). The activities of ALT and AST were 32.1±11.3 and 59.6±12.1 U/L in cultured medium of normal cells, the level of IL-6 and the content of MDA were 412.5±61.4 ng/ml and 4.1±1.80 nmol/ml, respectively. Treatment with 60% CCl4-medium for 6 h could increase the activities of AST and ALT to 186.8±25.1 and 141.2±27.8 U/L,and increase the level of IL-6 and the content of MDA to 798.6±45.8 ng/ml and 17.5±4.4nmol/ml respectively (both P< 0.01 vs control). However, pre-treatment with CA could concentration-dependently decrease the loss of hepatic cell viability,the activities of AST and ALT as well as the level of IL-6 in medium and the content of MDA in cells(ALT were 104.9±23.3,63.7±14.5,53.9±9.6 U/L；AST were 125.3±20.4,85.5±14.2,64.9±11.4 U/L；IL-6 were 614.9±79.0,538.9±31.9,469.9±51.7 ng/ml；MDA were 11.2±1.65,6.5±1.7l,5.0±1.65 nmol/ml；respectively).Conclusion:These present results in vivo and in cells suggest that CA exhibit a significant protective effect on CCl4-induced liver injury,which may be related to inhibiting lipid peroxidation and pro—inflammatory factor production.
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