ABSTRACT
OBJECTIVE: To observe the metabolism-based interaction of diphenytriazol and flavone compounds. METHODS: Flavone compounds kaempferol, isoharmnten and Elsholtzia blanda benth extract were chosen as the substrate of glucuronidation in the phase II metabolism. The metabolism was investigated in different rat liver microsome incubates pretreated with beta-naphthoflavone (BNF), diphenytriazol and tea oil (control). The concentrations of residual substrate were determined by HPLC. Quercetin and kaempferol were coincubated with diphenytriazol in control microsome to evaluate the inhibition for phase I metabolism. The concentration of diphenytriazol was determined by HPLC. RESULT: The phase II metabolic activity of kaempferol, isoharmnten and Elsholtzia blanda benth extract in diphenytriazol-treated microsome was more potent than that in BNF-treated microsome (P<0.01). The phase I metabolism of diphenytriazol was markedly inhibited by quercetin and kaempferol, with the inhibition constants (Ki) (12.41 +/-0.26)microg . ml(-1) and (7.97 +/-0.08)microg . ml(-1), respectively. CONCLUSION: Diphenytriazol demonstrates metabolism-based interaction with flavone compounds in vitro.