Abstract: OBJECTIVE:To investigate the influence of Yin-tonification herbal formulas Jaeumganghwa-tang(Ziyin Jianghuo Tang,JEGHT),Ssanghwa-tang(Shuanghe Tang,SHT) and Yukmijihwang-tang(Liuwei Di huang Tang,YMJHT) on the activities of human major cytochrome P450(CYP450 s) and UDP-glucuronosyltransferases isozymes(UGTs) in vitro.METHODS:The activities of CYP450 s(CYP1 A2,CYP3 A4,CYP2 B6,CYP2 C9,CYP2 C19,CYP2 D6 and CYP2 E1) and UGTs(UGT1 A1,UGT1 A4 and UGT2 B7)were assessed using in vitro fluorescence-and luminescence-based enzyme assays,respectively.The effects of herbal formulas on the activities of CYP450 s and UGTs were presented as IC50 values.RESULTS:JEGHT showed the potent inhibition of the CYP2 D6 activity,with weak inhibition on the activities of CYP1 A2,CYP2 B6,CYP2 C9,CYP2 C19,CYP2 E1,CYP3 A4,UGT1 A1,UGT1 A4 and UGT2 B7.SHT inhibited the activities of CYP1 A2 and CYP2 E1,whereas the negligible inhibition of the activities of CYP2 B6,CYP2 C9,CYP2 C19,CYP2 D6,CYP3 A4,UGT1 A1,UGT1 A4 and UGT2 B7 through SHT was observed.YMJHT inhibited CYP2 E1 activity,with a negligible inhibition on the activities of CYP1 A2,CYP2 B6,CYP2 C9,CYP2 C19,CYP2 D6,CYP3 A4,UGT1 A1,UGT1 A4 and UGT2 B7.CONCLUSION:These findings provide information about the potential interactions between three Yin-tonification herbal formulas and conventional drugs.

Key words: Yin reinforcing agents, Cytochrome P-450 enzyme system, Uridine diphosphate glucuronic acid, Transferases, Herb-drug interactions