Abstract: Abstract: Objective To observe the effect of magnesium isoglycyrrhizinate on the expressions of UGT1A, MRP2 protein and mRNA of L- 02 cells damaged by triptolide, and to investigate hepatoprotective mechanism of magnesium isoglycyrrhizinate in terms of drug metabolism. Methods L-02 cells were divided into 4 groups: normal group, triptolide group, magnesium isoglycyrrhizinate group and rifampicin group. Magnesium isoglycyrrhizinate group and rifampicin group were pretreated by magnesium isoglycyrrhizinate and rifampicin for 24 h and the remaining two groups added medium. Triptolide were added for 18 h except normal group. Cell survival rate was tested by MTT. The expression levels of UGT1A, MRP2 protein and mRNA were detected by Western blot assay and RT-PCR. Results Compared with triptolide group, cell survival rate was significantly higher in magnesium isoglycyrrhizinate group (P＜0.05). Meanwhile, the expression levels of UGT1A, MRP2 protein and mRNA were significantly lower in triptolide group compared with those of control group (P＜ 0.05). The expression levels of UGT1A, MRP2 protein and mRNA were significantly up- regulated in magnesium isoglycyrrhizinate pretreatment group than those of triptolide group (P＜0.05). The UGT1A protein and mRNA expressions were significantly decreased in rifampicin pretreatment group than those of magnesium isoglycyrrhizinate group (P＜0.05), but there were no significant differences in MRP2 protein and mRNA expressions between the two groups. Conclusion Magnesium isoglycyrrhizinate shows protective effects on triptolide induced L-02 cell injury, which may be involved with the activation of UGT1A and MRP2.

Key words: tripterygium, multidrug resistance- associated proteins, magnesium isoglycyrrhizinate, triptolide, uridine, diphosphate glucuronyltransferase 1A, MRP2, L-02 cell