• 대한약학회:학술대회논문집
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• 대한약학회 2003년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2-2
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• pp.85.3-86
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• 2003

Oltipraz, a cancer chemopreventive agent, induces CYP1A1 to a certain extent by transactivation of the gene via the Ah receptor (AhR)-xenobiotic response element (XRE) pathway. Previously, we showed that oltipraz promoted CCAAT/enhancer binding protein (C/EBP ) activation, which leads to the induction of glutathione S-transferase. Given that oltipraz activates C/EBP for gene transactivation and that the putative C/CBP binding site is located in CY)1A1 promoter region, this study investigated the effect of oltipraz on CYP1A1 induction by 3-methylcholanthrene (3-MC). (omitted)

• Biomolecules & Therapeutics
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• 제18권2호
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• pp.226-232
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• 2010

The aim of this study was to investigate the effect of atrovasatatin on the pharmacokinetics of nicardipine after oral and intravenous administration of nicardipine to rats. Nicardipine was administered orally (12 mg/kg) or intravenously (i.v., 4 mg/kg) without or with oral administration of atrovasatatin (0.3 or 1.0 mg/kg) to rats. The effect of atorvastatin on the P-glycoprotein (P-gp) as well as CYP3A4 activity was also evaluated. Atorvastatin inhibited CYP3A4 enzyme activity in a concentration-dependent manner with 50% inhibition concentration ($IC_{50}$) of 48 ${\mu}M$. Compared to the controls (nicardipine alone), the area under the plasma concentration-time curve (AUC) of nicardipine was significantly (1.0 mg/kg, p<0.05) greater by 16.8-45.4%, and the peak plasma concentration ($C_{max}$) was significantly (1.0 mg/kg, p<0.05) higher by 28.0% after oral administration of nicardipine with atorvastatin, respectively. Consequently, the relative bioavailability (R.B.) of nicardipine was increased by 1.17- to 1.45-fold and the absolute bioavailability (A.B.) of nicardipine with atrovasatatin was significantly greater by 16.7-20.9% compared to that of the controls (14.3%). Compared to the i.v. control, atrovasatatin did not significantly change pharmacokinetic parameters of i.v. administration nicardipine. The enhanced oral bioavailability of nicardipine by atorvastatin suggests that CYP3A subfamily-mediated metabolism were inhibited in the intestine and/or in the liver rather than P-gp-mediated efflux of nicardipine. Based on these results, modification of nicardipine of dosage regimen is required in the patients. Human studies are required to prove the above hypothesis.

• Biomolecules & Therapeutics
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• 제16권3호
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• pp.190-196
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• 2008

Deoxypodophyllotoxin (DPT) is a medicinal herb product isolated from Anthriscus sylvestris. DPT possesses beneficial activities in regulating immediate-type allergic reaction and anti-inflammatory activity through the dual inhibition of cyclooxygenase-2 and 5-lipoxygenase. In the present study, the metabolism of DPT was further characterized in rat liver microsomes isolated from male Sprague Dawley rats. The metabolism of DPT was NADPH-dependent. In addition, when liver microsomes were incubated with SKF-525A, a well-known CYP inhibitor, in the presence of $\beta$-NADPH, the metabolism of DPT was significantly inhibited. Using enriched rat liver microsomes, the anticipated isoforms of cytochrome P450s (CYPs) in the metabolism of DPT were partially characterized. Phenobarbital-induced microsomes increased in the formation of metabolite M1. The metabolite M3 was only produced in the enriched microsomes isolated from dexamethasone-treated rats. The results indicated that the metabolism of DPT would be CYP-dependent and that CYP2B and CYP3A might be important in the metabolism of DPT in rats.

• Toxicological Research
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• 제15권1호
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• pp.95-101
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• 1999

Cytochrome P450 (CYP) 3A4 metabolizes aflatoxin B1 (AFB1) to AFB1-exo-8,9-epoxide (8,9-epoxidation) and aflatoxin Q1 (AFQ1; 3$\alpha$-hydroxylation) simultaneously. We investigated whether each metabolite was formed via its own binding site of CAP3A4 active site. Kinetics of the formation of the two metabolites were sigmoidal and consistent with the kinetics of substrate activation. The HIll model predicted that two substrate binding wites are involved in the oxidationof AFB1 by CYP3A4. Dehydronifedipine, a metabolite of nifedipine generated by CYP3A4, inhibited the formation of AFQ1 without any inhibition in the formation of AFB1-exo-8,9-epoxidation. Dehydronifedipine was found to act as a reversible competitive inhibitor against 3$\alpha$-hydroxylation of AFB1. Vmax and S0.5 of the 8,9-epoxidation were not changed in the presence of 0, 50, or 100 $\mu\textrm{M}$ dehydronifedipine. S0.5 of 3$\alpha$-hydroxylation was increased from 58$\pm$4 $\mu\textrm{M}$ to 111$\pm$8 $\mu\textrm{M}$ in the presence of 100 $\mu\textrm{M}$ nifedipine whereas Vmax was not changed. These results suggest that there exist two independent binding sites in the active site of CAP3A4 . One binding site is responsible for AFB1-exo-8,9-epoxidation and the other is involved in 3$\alpha$-hydroxylation of AFB1. Dehydronifedipine might selectively bind to the site which is responsible for the formation of AFQ1 in the active site of CYP3A4.

• Parasites, Hosts and Diseases
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• 제51권2호
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• pp.165-175
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• 2013

The fear that schistosomes will become resistant to praziquantel (PZQ) motivates the search for alternatives to treat schistosomiasis. The antimalarials quinine (QN) and halofantrine (HF) possess moderate antischistosomal properties. The major metabolic pathway of QN and HF is through cytochrome P450 (CYP) 3A4. Accordingly, this study investigates the effects of CYP3A4 inhibitor, ketoconazole (KTZ), on the antischistosomal potential of these quinolines against Schistosoma mansoni infection by evaluating parasitological, histopathological, and biochemical parameters. Mice were classified into 7 groups: uninfected untreated (I), infected untreated (II), infected treated orally with PZQ (1,000 mg/kg) (III), QN (400 mg/kg) (IV), KTZ (10 mg/kg)+QN as group IV (V), HF (400 mg/kg) (VI), and KTZ (as group V)+HF (as group VI) (VII). KTZ plus QN or HF produced more inhibition (P<0.05) in hepatic CYP450 (85.7% and 83.8%) and CYT b5 (75.5% and 73.5%) activities, respectively, than in groups treated with QN or HF alone. This was accompanied with more reduction in female (89.0% and 79.3%), total worms (81.4% and 70.3%), and eggs burden (hepatic; 83.8%, 66.0% and intestinal; 68%, 64.5%), respectively, and encountering the granulomatous reaction to parasite eggs trapped in the liver. QN and HF significantly (P<0.05) elevated malondialdehyde levels when used alone or with KTZ. Meanwhile, KTZ plus QN or HF restored serum levels of ALT, albumin, and reduced hepatic glutathione (KTZ+HF) to their control values. KTZ enhanced the therapeutic antischistosomal potential of QN and HF over each drug alone. Moreover, the effect of KTZ+QN was more evident than KTZ+HF.

• Biomolecules & Therapeutics
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• 제19권2호
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• pp.255-260
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• 2011

The purpose of this study was to investigate the effect of ticlopidine on the pharmacokinetics of diltiazem and its active metabolite, desacetyldiltiazem, in rats. Pharmacokinetic parameters of diltiazem and desacetyldiltiazem were determined in rats after oral administration of diltiazem (15 $mg{\cdot}kg^{-1}$) with ticlopidine (3 or 9 $mg{\cdot}kg^{-1}$). The effects of ticlopidine on P-glycoprotein (P-gp) and cytochrome P450 (CYP) 3A4 activities were also evaluated. Ticlopidine inhibited CYP3A4 enzyme activity in a concentrationdependent manner with a 50% inhibition concentration ($IC_{50}$) of 35 ${\mu}M$. In addition, ticlopidine did not significantly enhance the cellular accumulation of rhodamine-123 in NCI/ADR-RES cells overexpressing P-gp. Compared with the control (given diltiazem alone), ticlopidine significantly altered the pharmacokinetic parameters of diltiazem. The peak concentration ($C_{max}$) and the area under the plasma concentration-time curve (AUC) of diltiazem were significantly (9 $mg{\cdot}kg^{-1}$, p<0.05) increased in the presence of ticlopidine. The AUC of diltiazem was increased by 1.44-fold in rats in the presence of ticlopidine (9 $mg{\cdot}kg^{-1}$). Consequently, the absolute bioavailability (A.B.) of diltiazem in the presence of ticlopidine (9.3-11.5%) was signifi cantly higher (9 $mg{\cdot}kg^{-1}$, p<0.05) than that in the control group (8.0%). Although ticlopidine significantly (p<0.05) increased the AUC of desacetyldiltiazem, the metabolite-parent AUC ratio (M.R.) in the presence of ticlopidine (9 $mg{\cdot}kg^{-1}$) was significantly decreased compared to that in the control group, implying that ticlopidine could effectively inhibit the metabolism of diltiazem. In conclusion, the concomitant use of ticlopidine significantly enhanced the oral bioavailability of diltiazem in rats by inhibiting CYP3A4-mediated metabolism in the intestine and/or liver rather than by inhibiting intestinal P-gp activity or renal elimination of diltiazem.

• 생명과학회지
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• 제18권3호
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• pp.381-386
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• 2008

동해에서 취수한 해양심층수의 암예방 효능을 얄아보고자 암발생 억제물질의 생화학적 표식자(biochemical markers)인 CYP 1A2 활성, phase II 효소인 QR과 GST의 활성, GSH 함량 및 ODC 활성에 미치는 영향을 살펴보았다. 해양심층수는 암의 개시단계(initiation)를 유발시키는 것으로 알려진 CYP 1A2 활성을 경도의존적으로 저해시켰다. 해양심층수를 Hepa 1clc7 세포에 경도별$(100{\sim}1,000)$로 처리하였을 때 phase II 생체 해독효소인 QR과 GST의 활성은 최대 20%의 증가를 나타내었고, 외부의 독성물질이나 대사산물로부터 세포를 보호하는 역할을 하는 GSH의 함량은 $26{\sim}40%$의 증가를 나타내었다. 그리고 발암과정의 촉진/진행단계에 관여하는 ODC의 활성은 해양심층수의 경도 800과 1,000에서 20%와 35%의 저해율을 나타내었으며, 경도 1,000을 처리한 군에서는 양성대조군인 DFMO와 같은 저해율을 나타내었다. 그러므로 본 연구 결과에 의하면 동해 해양심층수는 발암과정과 관련된 개시 및 촉진/진행단계를 저해시켜 암예방 효능을 나타낼 것으로 사료된다.

• 환경생물
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• 제21권1호
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• pp.18-25
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• 2003

본 연구는 내분비교란물질로 알려진 TBTC가 해양생물에게 미치는 영향을 조사하는 연구의 일환으로, 이 화합물에 노출시킨 어류의 간장 MFO 효소계의 반응을 in vitro로 조사하였다. 대상 어류는 개복치(Mola mola), 숭어(Mugil cephalus), 강도다리(Ptatichthys stellatus), 청어(Clupeu pallasii), 붕장어(Astroconger myriaster), 조피볼락 (Sebastes schlegeli), 참돔(Pugrus major), 넙치(Paralichthys olivaceus)이며, 이들의 간장 미크로좀을 2mM의 TBTC와 in vitro (3$0^{\circ}C$, 20분)로 배양하고 cytoch-rome P45O (CYP), cytochrome b5, NAD(P)H -cytochro-me c 환원효소를 비롯한 탈알킬화 효소들(EROD, PROD, MROD, ECOD)의 변화를 조사하였다. TBTC는 환원효소의 측정 시에는 DMSO에, 그리고 그 밖의 효소 측정시에는 메탄올에 녹여 2% 농도로. 첨가하였다. 어류의 간장 CYP 함량은 TBTC와 배양 후 대부분(6 어류/8어류)에서 10% 이하로 크게 저해되었으나, cyto-chrome b5함량은 변함이 없었다. 하지만 NAD(P)H 의존성 환원효소의 반응은 어류에 따라 달랐고, CYP 외에 두 환원효소도 모두 영향을 받아 저해되는 타입 1(개복치, 조피볼락, 청어, 강도다리, 참돔), CYP 외에 NADH 의존성 환원효소만 저해되는 타입 2(붕장어, 숭어)및 CYP 저해되지만 두 환원효소는 영향을 받지 않거나 오히려 유도되는 타입 3 (넙치)으로 구분되었다. 그리고 대부분(7/8)의 어류에서는 NADH 의존성 환원효소가 NADPH 의존성 환원효소에 비해 더욱 저해되는 경향을 보였다. TBTC는 어류의 탈알킬화 효소에도 영향을 미쳤고, 어류별 EROD활성의 저해는 개복치, 참돔, 붕장어, 조피볼락(잔존율 1~7%)>숭어, 청어 (14~30%)>넙치, 강도다리(56~65%)의 순이었으며, ECOD 활성의 저해도 개복치, 참돔, 붕장어 (36~38%)>조피볼락(63%))숭어, 청어, 넙치, 강도다리(90%)의 순으로 비슷한 경향이었다. 한편, 넙치와 강도다리에서는 PROD가 MROD보다 더욱 심하게 저해되었다. 이처럼 어류 간장의 약물대사 효소계는 TBTC에 의한 저해 정도가 어류에 따라 심한 차이를 보였다.

• 한국환경성돌연변이발암원학회:학술대회논문집
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• 한국환경성돌연변이발암원학회 2002년도 Molecular and Cellular Response to Toxic Substances
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• pp.100-105
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• 2002

• BMB Reports
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• 제41권5호
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• pp.358-362
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• 2008

RNA interference (RNAi) is the process of sequence-specific gene silencing. However, RNAi efficiency still needs to be improved for effective inhibition of target genes. We have developed an effective strategy to express multiple shRNAs (small hairpin RNA) simultaneously using multiple RNA Polymerase III (Pol III) promoters in a single vector. Our data demonstrate that multiple shRNAs expressed from Pol III promoters have a synergistic effect in repressing the target gene. Silencing of endogenous cyclophilin A (CypA) or key HIV viral genes by multiple shRNAs results in significant inhibition of the target gene.