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Liu, Kwang-Hyeon,Kim, Min-Jung,Jung, Woo Moon,Kang, Wonku,Cha, In-June,Shin, Jae-Gook American Society for Pharmacology and Experimental 2005 Drug metabolism and disposition: the biological fa Vol.33 No.2
<P>We recently proposed a possible stereoselective activation by lansoprazole of CYP2C9-catalyzed tolbutamide hydroxylation, as well as stereoselective inhibition of several cytochrome P450 (P450) isoforms. This study evaluated the effects of lansoprazole enantiomers on CYP2C9 activity in vitro, using several probe substrates. For tolbutamide 4-methylhydroxylation and phenytoin 4-hydroxylation, R-lansoprazole was an activator (140 and 550% of control at 100 microM R-lansoprazole, EC50 values of 19.9 and 30.2 microM, respectively). R-Lansoprazole-mediated activation of the formation of 4-hydroxyphenytoin was also seen with recombinant human CYP2C9. R-Lansoprazole increased the Michaelis-Menten-derived V(max) of phenytoin 4-hydroxylation from 0.024 to 0.121 pmol/min/pmol P450, and lowered its K(m) from 20.5 to 15.0 microM, suggesting that R-lansoprazole activates CYP2C9-mediated phenytoin metabolism without displacing phenytoin from the active site. Kinetic parameters were also estimated using the two-site binding equation, with alpha values <1 and beta values >1, indicative of activation. Additionally, phenytoin at 10 to 200 microM had no reciprocal effect on the hydroxylation of R-lansoprazole. Meanwhile, R-lansoprazole had no activation effect on diclofenac and S-warfarin metabolism in the incubation study using both recombinant CYP2C9 and human liver microsomes. These substrate-dependent activation effects suggest that phenytoin has a different binding orientation compared with diclofenac and S-warfarin. Overall, these results suggest that R-lansoprazole activates CYP2C9 in a stereospecific and substrate-specific manner, possibly by binding within the active site and inducing positive cooperativity. This is the first report to describe stereoselective activation of this cytochrome P450 isoform.</P>
Characterization of Pyribenzoxim Metabolizing Enzymes in Rat Liver Microsomes
Liu Kwang-Hyeon,Moon Joon-Kwan,Seo Jong-Su,Park Byeoung-Soo,Koo Suk-Jin,Lee Hye-Suk,Kim Jeong-Han Korean Society of ToxicologyKorea Environmental Mu 2006 Toxicological Research Vol.22 No.1
The primary metabolism of pyribenzoxim was studied in rat liver microsomes in order to identify the cytochrome P450 (CYP) isoform(s) and esterases involved in the metabolism of pyribenzoxim. Chemical inhibition using CYP isoform-selective inhibitors such as ${\alpha}$-naphthoflavone, tolbutamide, quinine, chlorzoxazone, troleandomycin, and undecynoic acid indicated that CYP1A and CYP2D are responsible for the oxidative metabolism of pyribenzoxim. And inhibitory studies using eserine, bis-nitrophenol phosphate, dibucaine, and mercuric chloride indicated pyribenzoxim hydrolysis involved in microsomal carboxylesterases containing an SH group (cysteine) at the active center.
Characterization of Pyribenzoxim Metabolizing Enzymes in Rat Liver Microsomes
Kwang-Hyeon Liu,Joon-Kwan Moon,Jong-Su Seo,Byeoung-Soo Park,Suk Jin Koo,Hye-Suk Lee,Jeong-Han Kim 한국독성학회 2006 Toxicological Research Vol.22 No.1
The primary metabolism of pyribenzoxim was studied in rat liver microsomes in order to identify the cytochrome P450 (CYP) isoform(s) and esterases involved in the metabolism of pyribenzoxim. Chemical inhibition using CYP isoform-selective inhibitors such as α-naphthoflavone, tolbutamide, quinine, chlorzoxazone, troleandomycin, and undecynoic acid indicated that CYP1A and CYP2D are responsible for the oxidative metabolism of pyribenzoxim. And inhibitory studies using eserine, bis-nitrophenol phosphate, dibucaine, and mercuric chloride indicated pyribenzoxim hydrolysis involved in microsomal carboxylesterases containing an SH group (cysteine) at the active center.
Liu, Kwang-Hyeon,Kim, Mi-Gyung,Lee, Dong-Jun,Yoon, Yune-Jung,Kim, Min-Jung,Shon, Ji-Hong,Choi, Chang Soo,Choi, Young Kil,Desta, Zeuresenay,Shin, Jae-Gook American Society for Pharmacology and Experimental 2006 Drug metabolism and disposition: the biological fa Vol.34 No.11
<P>Ebastine undergoes extensive metabolism to form desalkylebastine and hydroxyebastine. Hydroxyebastine is subsequently metabolized to carebastine. Although CYP3A4 and CYP2J2 have been implicated in ebastine N-dealkylation and hydroxylation, the enzyme catalyzing the subsequent metabolic steps (conversion of hydroxyebastine to desalkylebastine and carebastine) have not been identified. Therefore, we used human liver microsomes (HLMs) and expressed cytochromes P450 (P450s) to characterize the metabolism of ebastine and that of its metabolites, hydroxyebastine and carebastine. In HLMs, ebastine was metabolized to desalkyl-, hydroxy-, and carebastine; hydroxyebastine to desalkyl- and carebastine; and carebastine to desalkylebastine. Of the 11 cDNA-expressed P450s, CYP3A4 was the main enzyme catalyzing the N-dealkylation of ebastine, hydroxyebastine, and carebastine to desalkylebastine [intrinsic clearance (CL(int)) = 0.44, 1.05, and 0.16 microl/min/pmol P450, respectively]. Ebastine and hydroxyebastine were also dealkylated to desalkylebastine to some extent by CYP3A5. Ebastine hydroxylation to hydroxyebastine is mainly mediated by CYP2J2 (0.45 microl/min/pmol P450; 22.5- and 7.5-fold higher than that for CYP3A4 and CYP3A5, respectively), whereas CYP2J2 and CYP3A4 contributed to the formation of carebastine from hydroxyebastine. These findings were supported by chemical inhibition and kinetic analysis studies in human liver microsomes. The CL(int) of hydroxyebastine was much higher than that of ebastine and carebastine, and carebastine was metabolically more stable than ebastine and hydroxyebastine. In conclusion, our data for the first time, to our knowledge, suggest that both CYP2J2 and CYP3A play important roles in ebastine sequential metabolism: dealkylation of ebastine and its metabolites is mainly catalyzed by CYP3A4, whereas the hydroxylation reactions are preferentially catalyzed by CYP2J2. The present data will be very useful to understand the pharmacokinetics and drug interaction of ebastine in vivo.</P>
( Kwang Hyeon Liu ) 한국피부장벽학회 2014 한국피부장벽학회지 Vol.16 No.2
Lipids are important components in all biological tissues. They play important roles associated with the proper function of the organism. Lipidomics, a branch of metabolomics, is a systems-based study of all lipids and their function within the cell. Shotgun lipidomics provide rapid semi-quantitative snapshots of the composition of complex lipidomes in samples. In this study, we developed lipidomics methodology for skin lipid profiling and identification using chip-based direct infusion nanoelectrospray tandem mass spectrometry. Skin ceramides are produced by coupling fatty acid acyl chains onto sphingoid bases by an amide binding. The MS/MS fragmentation pattern of skin ceramides was characterized through the interpretation of product ion scan mass spectra of them. Based on the MS fragmentation pattern of skin ceramides, an in silico MS/MS library for the annotation and identification of unknown lipids from skin samples has generated. This lipidomic platform was applied to identify the ceramide signatures in db/db mice as well as T2DM and allergic contact dermatitis patients. This study was supported by a grant of the Korean Health Technology R&D Project, Ministry of Health & Welfare, Republic of Korea (HN13C0076).
Screening of Potential Anticancer Compounds from Marketed Drugs
류광현(Kwang-Hyeon Liu) 한국생명과학회 2011 생명과학회지 Vol.21 No.11
CYP2J2는 치료약물 및 아라키돈산과 같은 내인성 화합물의 대사에 중요한 역할을 수행하고 있는 효소이다. 최근, CYP2J2 단백질이 인체 종양 조직이나 종양 세포주에 과발현되어 있고, CYP2J2 효소의 작용에 의해 생성된 에폭시에이코사트리에논산(EETs)이 세포사멸을 방지한다는 것이 보고되었다. 본 연구는 시판중인 약물 120종을 대상으로 시토크롬 2J2 동종효소에 저해능을 가지는 화합물을 발굴하고자 하였다. 인체 간 마이크로솜 시료에 아스테미졸과 NADPH 재생성계 및 약물(50 μM)을 첨가한 후 15분간 반응시켜 생성된 대사물을 LC/MS/MS를 이용하여 분석하여 시토크롬 2J2 동종효소 활성의 변화를 평가하였다. 그 결과 할로페리돌, 터페나딘, 아리피프라졸, 미코나졸의 순으로 CYP2J2 효소 활성 저해능을 보였다. 미코나졸은 CYP2J2에 의해 매개되는 에바스틴(IC50=11.2 μM) 및 터페나딘(IC50=2.2 μM) 대사를 강력하게 저해하였다. 터페나딘 또한 CYP2J2 매개 에바스틴 대사를 농도 의존적으로 저해하였다(IC50=13.6 μM). 향후, 이들 약물을 대상으로 한 항암 활성 평가가 필요할 것으로 판단된다. Cytochrome P450 2J2 (CYP2J2) plays important roles in the metabolism of endogenous metabolites such as arachidonic acid as well as therapeutic drugs. CYP2J2 is overexpressed in human cancer tissues and cancer cell lines, as well as in epoxyeicosatrienoic acids (EETs) and CYP2J2-mediated metabolites, and prevent apoptosis of cancer cells. This study aimed to screen marketed drugs for inhibitory potential on CYP2J2 isoforms using human liver microsomes. The initial screen isolated 4 compounds, from 120 marketed drugs, that inhibited the CYP2J2-mediated astemizole O-demethylation more than 50% in the following the order: haloperidol (75%) > terfenadine (56%) > aripiprazole (55%) > miconazole (52%). Miconazole strongly inhibited CYP2J2-mediated ebastine hydroxylation (IC50=11.2 μM) and terfenadine hydroxylation (IC50=2.2 μM), and terfenadine also inhibited CYP2J2-mediated ebastine hydroxylation (IC50=13.6 μM) in a dose dependent manner. The present data suggest that these drugs are potential candidates for further evaluation for their anti-cancer activities.