Objective: To study the modulatory effect of the water extract of Ziziphus jujaba Mill.var. spinosa (Bunge) Hu ex H.F.Chou(SZR)

Polygala tenuifolia Willd.(YZ)and Platycodon grandiflorum (Jacq.)A.DC.(JG)on the activity and mRNA expression of cytochrome P450 isoenzymes in rat liver. Method: The rats were killed after the animals were administred medicines once daily for consecutive 7 days

the livers were removed rapidly and weighed

and then

liver microsomes were prepared with ultra-centrifuge method

the contents of liver microsomal cytochrome P450(CYP450)

cytochrome b5 (Cytb5) and the activities of erythromycin N -demethylase(ERD) were examined by ultraviolet spectrophotometry

the activities of phenacetin O-deethylase (PHD) and p-nitrophenol-hydroxylase (pNPH) were determined by high performance liquid chromatography (HPLC).The mRNA expression level of five CYP isoenzymes CYP1A1

CYP1A2

CYP2E1

CYP3A1 and CYP3A2 were detected by semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR). Result: All groups were no difference in the levels of liver index compared with the blank control. SZR obviously decreased the b5 contents and CYP3A activity of liver microsomes

markedly increased the activity of p NPH. YZ obviously increased p NPH

and significantly decreased ERD activity

JG obviously decreased the b5 contents of liver microsomes

and significantly increased the activity of PHD and p NPH. At the mRNA level.The CYP1A1 gene was not detected in these groups. SZR induced the expression of CYP2E1

CYP3A1 and CYP3A2. YZ inhibited the expression of CYP3A1

induced the expression of CYP3A2. JG induced the expression of CYP1A2

CYP2E1 and CYP3A2.The mRNA level of CYP2E1 in SZR group

and the mRNA level of CYP1A2 and CYP2E1 in JG group were largely consistent with the results of the enzyme activity. Conclusion: The water extract of SZR induced the activity of CYP2E1

the water extract of JG could induce the activity of CYP1A2 and CYP2E1. The change in enzyme activity might be attributed to the increase in mRNA level. It indicates that if drugs metabolized by CYP2E1 and CYP3A are taken simultaneously with SZR and YZ

or drugs metabolized by CYP1A2

CYP2E1 and CYP3A are taken with JG

the efficacy of the above drugs will be influenced. So

the cases should be careful considered in clinical application.