OBJECTIVETo explore the interaction between herbal medicines and western drugs based on CYP3A4 enzyme metabolism by using testotesrone as a probe in liver microsome metabolism system in vitro.

METHODThe mixed liver microsome enzymatic system consisting of rat liver microsomes by ultra-high-speed centrifuge was established. The substrate testosterone was added into the system and enzyme CYP3A4 metabolic activity was expressed by the output of 6beta-hydroxy-testosterone which was measured by HPLC method. The proper conditions for testotesrone metabolism in liver microsome system included substrate concentration, incubation time, pH and incubation temperature. When the conditions in vitro were determined, three kinds of Chinese herbal medicinal ingredients (Tetrahydropalmatine, neferine, panax notoginseng saponins) were diluted into different concentrations and incubated with testotesrone in the liver microsomes incubation system, respectively. The results were measured through metabolite production with or without the presence of Chinese medicines. We assessed the Chinese herbal medicinal ingredients effect on the metabolism of CYP3A4 enzyme through 6beta-hydroxy metabolite of testosterone production.

RESULTLiver microsomes were incubated in the system, the testosterone metabolited into 6beta-hydroxy testosterone. The metabolism conditions were proper at the concentration of testosterone 200 micromol x L(-1) which was incubated for 3.5 hours at 37 degrees C in pH 7.0, PBS 0.1 mol x L(-1). The inhibition of tetrahydropalmatine and panax notoginseng saponins on testotesrone were weak with IC50 > 100 micromol x L(-1). The neferine had a little inhibition on testotesrone metabolism, IC50 < 100 micromol L(-1).

CONCLUSIONTetrahydropalmatine and panax notoginseng saponins had no obvious effect on testotesrone metabolism. Neferine had a little effect on testotesrone metabolism. It prompted that drug-interaction could not be apparent between two kinds of Chinese medicines and the CYP3A4 enzyme substrate, Neferine could bring about drug-interaction.