The aim of this study was to investigate the effect of Cynara scolymus extract alone or in combination with silymarin on the carbon tetrachloride (CCl4)-induced hepatic injury in rats. Cynara extract (30, 60, or 120 mg/kg), silymarin (25 mg/kg), or Cynara extract (30, 60, or 120 mg/kg) combined with silymarin was given once daily orally simultaneously with CCl4 and for 2 weeks thereafter. Liver damage was assessed by determining serum enzyme activities and hepatic histopathology. Cynara extract given at the above doses conferred significant protection against the hepatotoxic actions of CCl4 in rats, reducing serum alanine aminotransferase (ALT) levels by 21 %, 24.3 %, and 35.8 %, respectively, compared to CCl4 control group. Serum aspartate aminotransferase (AST) levels decreased by 15.5 %, 39.6 %, and 44.3 %, respectively. Alkaline phosphatase (ALP) decreased by 21 % and 25 % by Cynara extract at 60 and 120 mg/kg, respectively. In rats treated with silymarin combined with Cynara extract (30, 60, or 120 mg/kg), ALT decreased by 32.6 %, 34.5 %, and 51.6 %, and AST decreased by 20 %, 50.6 %, and 58.3 %, respectively. Meanwhile, ALP decreased by 22.4 % and 29.7 % after treatment with silymarin combined with Cynara extract (60 or 120 mg/kg). On the other hand, the administration of silymarin alone reduced ALT, AST, and ALP levels by 55.3 %, 67.1 %, and 52.5 %, respectively. The administration of CCl4 resulted in marked increase in nitric oxide level in serum (the concentrations of nitrite/nitrate) as well as marked decrease in blood levels of reduced glutathione (GSH). Treatment with Cynara extract resulted in a dose-dependent decrease in serum nitric oxide level and increased GSH in blood compared with CCl4 control group. Silymarin showed an additive effect resulting in further decrease in serum nitric oxide. Silymarin only treatment caused a marked reduction in serum nitric oxide level and increased GSH in blood. Histopathological studies also indicated that CCl4-induced liver injury was less severe in Cynara extract-treated groups. Metabolic perturbations caused by CCl4 in hepatocytes such as reduced protein and mucopolysaccharide content were markedly improved by the Cynara extract given at the dose of 120 mg/kg. Intracellular protein and mucopolysaccharide contents were normalized upon treatment with silymarin. The effect of Cynara–silymarin combination was, however, less than that of Cynara extract alone. These results suggest that treatment with Cynara extract protects against CCl4-induced hepatic injury in rats and might prove of value in treating chronic liver disease in man, although the combination of Cynara–silymarin is not superior to either Cynara extract or silymarin alone.
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