Objective:To compare the protective effect of 18α-and 18β-glycyrrhizic acid on acute liver injury in mice

and screen out their optimal combination proportion. Method:The mice were randomly divided into normal group

model group

high dose group (60 mg·kg-1)

middle dose group (30 mg·kg-1)

low dose group (15 mg·kg-1) of 18α-and 18β-glycyrrhizic acid. With the drug dose of combined medication groups of 60 mg·kg-1

combined medication 1 groups (18α-glycyrrhizic acid-18β-glycyrrhizic acid 1:3)

combined medication 2 groups (18α-glycyrrhizic acid-18β-glycyrrhizic acid 2:3)

combined medication 3 groups (18α-glycyrrhizic acid-18β-glycyrrhizic acid 1:1). Before the modeling

the drugs were injected once everyday for 7 days

the same volume of saline was given to normal group and model group. At 1 h after the last administration

the treated groups and model group were ip given 0.1%CCl4 peanut oil (20 mL·kg-1) to establish mouse model of acute liver injury induced by CCl4 .The samples of blood and liver from high does group

middle dose group

low dose group and three combination proportion groups of 18α-and 18β-glycyrrhizic acid were analyzed

and level of alanine aminotransferase (ALT)

aspartate aminotransferase (AST)

superoxide dismutase (SOD) and malondialdehyde (MDA) were measured. Result:Compared with the normal group

the serum levels of AST

liver homogenate levels of AST

ALT

MDA in model group were remarkably higher (P<0.01)

levels of SOD was remarkably lower. Compared with the model group

18α-and 18β-glycyrrhizic acid remarkably reduced the serum levels of AST

reduced liver homogenate levels of AST

ALT and MDA

and increased liver homogenate content of SOD. 18β-glycyrrhizic acid had a better effect on liver homogenate levels of AST

ALT than 18α-glycyrrhizic acid

and showed no significant difference in other indexes compared with 18β-glycyrrhizic acid. The optimal combination proportion of 18α-and 18β-glycyrrhizicacid is 2:3

with a better effect on liver homogenate levels of AST

MDA than simple 18α-or 18β-glycyrrhizic acid. Conclusion:18α-and 18β-glycyrrhizic acid can protect acute liver injury in mice. The latter had a better protective effect than the former. Their optimal combination proportion is 2:3

with a better effect on liver homogenate levels of AST

MDA than simple 18α-or 18β-glycyrrhizic acid.