Identification of novel CYP4F2 genetic variants exhibiting decreased catalytic activity in the conversion of arachidonic acid to 20-hydroxyeicosatetraenoic acid (20-HETE).

CYP4F2 is an enzyme involved in the formation of 20-hydroxyeicosatetraenoic acid (20-HETE) from arachidonic acid and metabolizes vitamin K into an inactive form. Our objectives were to identify new CYP4F2 genetic variants and to characterize the functional consequences of the conversion of arachidonic acid into 20-HETE. We used direct DNA sequencing to identify a total of 20 single-nucleotide polymorphisms (SNPs) including four coding variants, A27V, R47C, P85A, and V433M, in 50 randomly selected subjects.

Identification of cytochrome P450s involved in the metabolism of arachidonic acid in human platelets.

Although cytochrome P450s (CYPs) have been identified in most human cells, identification of CYPs in human platelets remains poorly explored. CYP expressions in human platelets were screened by using reverse transcriptase-polymerase chain reaction and western blot analysis followed by functional assays using arachidonic acid (ARA). CYP1A1, 2U1, 2J2, 4A11, 4F2, and 5A1 were expressed as both proteins and mRNAs in platelets.

The tyrosine kinase inhibitor nilotinib selectively inhibits CYP2C8 activities in human liver microsomes.

The tyrosine kinase inhibitor nilotinib was examined for its inhibition of cytochrome P450s (CYPs) in human liver microsomes and in human CYPs expressed in a baculovirus-insect cell system. Nilotinib demonstrated preferential inhibition of CYP2C8-mediated paclitaxel 6α-hydroxylation, rosiglitazone hydroxylation and amodiaquine N-deethylation in human liver microsomes, with IC₅₀ values of 0.4, 7.

LC-MS/MS for the simultaneous analysis of arachidonic acid and 32 related metabolites in human plasma: Basal plasma concentrations and aspirin-induced changes of eicosanoids.

Eicosanoids play an important role in various biological responses and can be used as biomarkers for specific diseases. Therefore, we developed a highly selective, sensitive, and robust liquid chromatography-tandem mass spectrometric method to measure arachidonic acid and its 32 metabolites in human plasma. Sample preparation involved solid phase extraction, which efficiently removed sources of interference present in human plasma.

High-sensitivity liquid chromatography-tandem mass spectrometry for the simultaneous determination of five drugs and their cytochrome P450-specific probe metabolites in human plasma.

A sensitive liquid chromatography-tandem mass spectrometric (LC-MS/MS) method with electrospray ionization was developed for the simultaneous quantitation of five probe drugs and their metabolites in human plasma for assessing the in vivo activities of cytochrome P450 (CYP). CYP isoform specific substrates and their metabolites of CYP1A2 (caffeine), CYP2C9 (losartan), CYP2C19 (omeprazole), CYP2D6 (dextromethorphan) and CYP3A (midazolam) were all simultaneously analyzed using LC-MS/MS after administration of a mixture of five drugs (i.e.