Development and validation of a sensitive liquid chromatography-tandem mass spectrometry method for the determination of paeoniflorin in rat brain and its application to pharmacokinetic study.

A sensitive and specific method was developed and validated for the determination of paeoniflorin in rat brain with liquid chromatography-tandem mass spectrometry. Sample pretreatment involved protein precipitation following solid-phase extraction. Paeoniflorin and geniposide (internal standard) were separated isocratically on a Waters Symmetry C18 column (150 mm x 2.

Heme-reversible impairment of CYP2B1/2 induction in heme-depleted rat hepatocytes in primary culture: translational control by a hepatic alpha-subunit of the eukaryotic initiation factor kinase?

The role of heme in the phenobarbital-mediated induction of CYP2B1/2 was reexamined in rat hepatocytes in monolayer culture, acutely depleted of heme by treatment with either 3,5-dicarbethoxy-2,6-dimethyl-4-ethyl-1,4-dihydropyridine (DDEP) or N-methylprotoporphyrins (NMPP). The findings revealed that such acute hepatic heme depletion markedly impaired CYP2B1/2 protein induction, an effect that was reversible by heme resupplementation. However, TaqMan analyses of hepatic mRNA isolated from these heme-depleted cells revealed that this impairment was not due to faulty transcriptional activation of either CYP2B1 or CYP2B2 gene expression as previously proposed, thereby confirming literature reports that heme is not a transcriptional regulator of the CYP2B1/2 gene.

Phenotype distribution and gender-related differences of CYP2E1 activity in a Chinese population.

1. The aim was to investigate the phenotype distribution characteristic and gender-related differences of CYP2E1 activity in a healthy Chinese population. 2.

Inducibility of CYP1A2 by omeprazole in vivo related to the genetic polymorphism of CYP1A2.

Aims: To evaluate the effect of the CYP1A2*1C and CYP1A2*1F polymorphisms on the inducibility of CYP1A2 by omeprazole in healthy subjects.

Methods: Mutations of CYP2C19 and CYP1A2 were identified by PCR-RFLP. Omeprazole, 120 mg day-1, was given to 12 extensive metabolizers (EM) with respect to CYP2C19 (six CYP1A2*1F/CYP1A2*1F and six CYP1A2*1C/CYP1A2*1F of CYP1A2) for 7 days.

Phenotypic polymorphism of CYP2A6 activity in a Chinese population.

Aims: To investigate the distribution characteristics of CYP2A6 activity in a Chinese population and to examine the sex-related differences in CYP2A6 activities.

Methods: One hundred and twenty healthy volunteers, 63 men and 57 women, were included in the study. Cytochrome P450 (CYP) 2A6 activity was measured using the ratio of urinary 7-hydroxycoumarin (7-OHC) excreted in 8 h after a coumarin dose.