Résumé
Several compounds and extracts isolated from a brown alga, Ishige (I.) okamurae, exhibit anti-oxidant and anti-inflammatory effects. The present study investigated whether the ethyl acetate (EtOAc) fraction of I. okamurae (EFIO) could ameliorate carbon tetrachloride (CCl4)-induced hepatotoxicity in rats. Sprague-Dawley rats were intraperitoneally (i.p.) administered with EFIO at 10 or 50 mg/kg per day for 2 consecutive days before CCl4 injection (3.3 mL/kg, i.p.). Twenty four hours later, the rats were anesthesized with diethyl ether and dissected. Pretreatment with EFIO significantly reduced the increased serum levels of alanine aminotransferase and aspartate aminotransferase in CCl4-treated rats. Pretreatment with EFIO also significantly inhibited the reduced activities of superoxide dismutase and catalase in the CCl4-injured liver. Histopathological evaluations showed that hemorrhage, hepatocyte necrosis, inflammatory cell infiltration, and fatty degeneration induced by CCl4 treatment were ameliorated by the administration of EFIO. Additionally, liver immunohistochemical analyses revealed the marked reduction in ED1-positive monocyte-like macrophages in EFIO-pretreated rats given CCl4. These results suggest that EFIO ameliorates CCl4-induced liver injury, possibly through the inhibition of oxidative stress.