CYP450 enzyme inhibition of berberine in pooled human liver microsomes by cocktail probe drugs / 中国中药杂志

<p><b>OBJECTIVE</b>To investigate the effect of CYP450 enzyme inhibition of berberine in pooled human liver microsomes by cocktail probe drugs.</p><p><b>METHOD</b>Cocktail probe drugs method has been established, an LC-MS/MS analytical method has been established to determine the five probes of midazolam, phenacetin, dextromethorphan, tolbutamide, chlorzoxazone and the internal standard was benzhydramine to evaluate the effect of CYP450 activity following administration of berberine in pooled human liver microsomes.</p><p><b>RESULT</b>Compared with control group, the pharmacokinetics of midazolam, phenacetin and tolbutamide were no significant differences, but the pharmacokinetics of chlorzoxazone was significantly decreased. There were no significant differences for the pharmacokinetics of dextromethorphan when the concentration of berberine was 50 microg x L(-1). The pharmacokinetics of dextromethorphan was significantly decreased when the concentration of berberine was exceed 200 microg x L(-1).</p><p><b>CONCLUSION</b>Berberine has no influence on the activities of CYP3A4, CYP1A2 and CYP2C19 below 2 000 microg x L(-1), but can inhibit the activity of CYP2E1 and CYP2D6 in concentration-dependent.</p>

Enzyme reaction kinetics, metabolic enzyme phenotype, and metabolites of berberine / 中草药

Objective: To study the metabolic characteristics of berberine using the pooled human liver microsomes and recombinant human cytochrome enzymes P450 (CYP) isozymes, to identify CYP isozymes responsible for berberine metabolism and its contribution, and to determine the structures of metabolism. Methods: Pooled human liver microsomes were incubated with berberine (20, 100, 200, 400, 600, 800, and 1 200 ng/mL). The Michaelis-Menten parameters (Km), maximum velocity (Vmax), and clearance (CLint) of pooled liver microsomes were initially estimated by analyzing Lineweave-Brurk plot. Various selective CYP inhibitors were used to investigate their inhibitory effects on the metabolism of berberine and the certain concentration of berberine was incubated with recombinant human CYP isozymes (CYP3A4, CYP1A2, CYP2D6, and CYP2C9). The concentration of berberine and metabolites in the incubation pool was determined by UPLC method. The P450 isozymes were ranked with the method of total normalized rate (TNR) and the related metabolites were identified by LC-MS/MS. Results: The Vmax, Km, and CLint of berberine in pooled human liver microsomes were 1.51 nmol·mg-1·h-1, 2.69 nmol/mL, and 0.56 mL·mg-1·h-1, respectively. Quinidine (the specific inhibitor of CYP2D6) and Furafylline (the specific inhibitor of CYP1A2) could significantly inhibit the berberine metabolism, and the other CYP inhibitors had no significant effect on the metabolism of berberine. CYP2D6 and CYP1A2 were responsible for 75.253 9% and 23.323 6% of the berberine metabolite M1 (demethyleneberberine), and responsible for 46.893 8% and 8.679 5% of M2 (thalifendine or berberrubine). The major metabolic pathway of berberine in pooled human liver microsomes incubation system is O-demethylated, demethyleneberberine, thalifendine, or berberrubine could be generated in vitro. Conclusion: Bererine is metabolized by CYP2D6 and CYP1A2 in human liver, the metabolites of berberine are demethyleneberberine and thalifendine or berberrubine.