摘要Background:Complementary medicine is an interesting field for extracting bio-active compounds from various plant and animal sources.The hepatoprotective effect of the methanolic extract of a species of sea cucumber called Holothuria leu-cospilota in an animal model of liver cancer caused by dimethyl nitrosamine (DMN) was studied.Methods:Wistar female rats were randomly divided into five groups ( n=12):control (intact),positive control (received 1% DMN[10 mg/kg/week,intraperitoneally]for 12 weeks),and three treatment groups (received 50,100,and 200 mg/kg/day H.leu-cospilota extract orally for 12 weeks along with intraperitoneal administration of 1% DMN[10 mg/kg/week]).In all groups,ultrasound was performed on the liver every week to check its density.Blood sampling and liver isolation were performed on three occasions,at 4,8,and 12 weeks,to check liver enzymes and the histopathological condition of the liver tissue (every week,four animals from each group were randomly selected).Results:Liver density changes were evident from the eighth week onward in the positive control group.Histopathological results indicated pathologic changes in the positive control group after 4 weeks.The increase in liver enzymes in the posi-tive control group was significantly different from that in the treatment and control groups.Conclusions:We demonstrated the hepatoprotective effect of H.leucospilota on DMN-induced liver damage in rats using biochemical and histological parameters and ultrasonography.More additional research (in silico or in vitro) is needed to find the exact mechanism and the main biological compound in H .leucospilota .