• Proceedings of the PSK Conference
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• 2002.10a
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• pp.312.3-313
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• 2002

Recently we have reported that various hydroxystilbenes show strong inhibition of human P450 1 activity. A series of synthetic trans-stilbene derivatives were prepared and their inhibitory potentials were evaluated with the bacterial membrane of recombinant human P450 1A1, 1A2 or 1B1 coexpressed with human NADPH-P450 reductase to find new candidates for cancer chemoprevention, Of the compounds tested. SY-021 (3.5-dimethoxyphenyl vinyl thiophene) exhibited a potent inhibition of human P450 181 with an IC$_{50}$ value of 2 nM. SY-021 also showed the inhibitrion of P450 1A1 with IC$_{50}$ value of 61 nM and P450 1A2 with IC$_{50}$ value of 11 nM. SY-021 showed 31-fold selectivity for P450 1B1 over P450 1A1 and 6-fold selectivity for P450 1B1 over 1A2. We have further investigated the inhibition kinetics of P450 1A1. 1A2 and 1B1 by SY-021. The modes of inhibition by SY-021were non-compeitive for all three P450 1 enzymes. Effect of preincubation with NADPH on inhibition of P450 1B1 by SY-021 was determined. These results suggest that SY-021 is one of the mostj potent inhibitor of human P450 1 enzymes and may be considered as a good candidate for a cancer chemopreventive agent in human

• Biomolecules & Therapeutics
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• v.30 no.1
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• pp.1-18
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• 2022

Drug-drug interactions are a major cause of hospitalization and deaths related to drug use. A large fraction of these is due to inhibition of enzymes involved in drug metabolism and transport, particularly cytochrome P450 (P450) enzymes. Understanding basic mechanisms of enzyme inhibition is important, particularly in terms of reversibility and the use of the appropriate parameters. In addition to drug-drug interactions, issues have involved interactions of drugs with foods and natural products related to P450 enzymes. Predicting drug-drug interactions is a major effort in drug development in the pharmaceutical industry and regulatory agencies. With appropriate in vitro experiments, it is possible to stratify clinical drug-drug interaction studies. A better understanding of drug interactions and training of physicians and pharmacists has developed. Finally, some P450s have been the targets of drugs in some cancers and other disease states.

• Proceedings of the PSK Conference
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• 2003.10b
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• pp.148.2-149
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• 2003

Recently we have reported that various hydroxystilbenes show strong inhibition of human cytochrome P450 1 enzyme activities. A series of syntheic trans-stilbene derivatives were prepared and their inhibitory potentials were evaluated with the bacterial membrane of recombinant human cytochrome P450 1A1, 1A2 and 1B1 coexpressed with hyman NADPH-P450 reductase to find a new inhibitor of cytochrome P450 enzymes. Of the compounds tested, SY-081 exhibited a potent inhibition of human cytochrome P450 1B1 with an $IC_50$ value of 2.6 nM. (omitted)

• Archives of Pharmacal Research
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• v.27 no.2
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• pp.199-205
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• 2004

Cytochrome P450 (P450) 1 enzymes such as P450 1A1, 1A2, and 181 are known to be involved in the oxidative metabolism of various procarcinogens and are regarded as important target enzymes for cancer chemoprevention. Previously, several hydroxystilbene compounds were reported to inhibit P450 1 enzymes and were rated as candidate chemopreventive agents. In this study, we investigated the inhibitory effect of 2-[2-(3,5-dimethoxyphenyl)vinyl]-thiophene (DMPVT), produced from the chemical modification of oxyresveratrol, on the activities of P450 1 enzymes. The inhibitory potential by DMPVT on the P450 1 enzyme activity was evaluated with the Escherichia coli membranes of the recombinant human cytochrome P450 1A1, 1A2, or 1B1 coexpressed with human NADPH-P450 reductase. DMPVT significantly inhibited ethoxyresorufin O-deethylation (EROD) activities with $IC_{50}$ values of 61, 11, and 2 nM for 1A1, 1A2, and 1B1, respectively. The EROO activity in OMBA-treated rat lung microsomes was also significantly inhibited by OMPVT in a dose-dependent manner. The modes of inhibition by DMPVT were non-competitive for all three P450 enzymes. The inhibition of P450 1B1-mediated EROD activity by OMPVT did not show the irreversible mechanism-based effect. The loss of EROD activity in P450 1B1 with OMPVT incubation was not blocked by treatment with the trapping agents such as glutathione, N-acetylcysteine, or dithiothreitol. Taken together, the results suggested DMPVT to be a strong noncompetitive inhibitor of human P450 1 enzymes that should be considered as a good candidate for a cancer chemopreventive agent in humans.

• Journal of the Korean Applied Science and Technology
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• v.29 no.3
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• pp.435-442
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• 2012

The cytochrome P-450 enzymes (CYP 2A6) regulate many endogenous signaling molecules and drugs. Aryl alkynes such as 2-ethynylnaphthalene are important P450 inhibitors which have been extensively studied as medicines or as an effective chemical probes for profiling mouse liver microsomal P-450. Here we have synthesized indole-based novel P450 inhibitor, 5-ethynyl indole 3, and showed that it has successfully inhibited CYP 2A6 by chemical inhibition reaction. By using HPLC equipped with a photo diode array(PDA) detector, all of the peaks derived from the enzymatic reaction have been characterized.

• Korean Journal of Acupuncture
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• v.21 no.2
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• pp.139-145
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• 2004

Objectives : Inhibition of phase I enzymes such as cytochrome P450 (CYP) 1A1 or 1A2 is considered a major mechanism of protection against initiation of carcinogenesis. The inhibition of toxic enzymes and CYP were studied with so many oriental herbral medicine. Recently, numerous polysaccharides and polysaccharide-protein complexes have been isolated from mushrooms and used as a source of therapeutic agents. The most promising biopharmacological activities of these polymers are their immunomodulation and anti cancer. But, in this study the inhibitory effect was on the aqua-acupuncture of Lentinus edodes. Materials : Lentinus edodes aqua-acupuncture solution (LEAS) was prepared and tested for the inhibition of cytochrome P450 (CYP) 1A1 and 1A2 activities. LEAS type I from fruit body of these mushrooms. Type II was extracted from cultured broth of Lentinus edodes mycelum. Results : LEAS type I and type II were significantly inhibited CYP 1A1 and 1A2 enzymes at concentration of 5.0 and 10.0 mg/ml. Conclusion : These results suggested that LEAS may act as block agent against carcinogenesis by inhibition of phase I enzymes.

• Proceedings of the Korean Society of Toxicology Conference
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• 2002.05a
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• pp.92-92
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• 2002

Recently we have reported that various hydroxystilbenes show strong inhibition of human P450 1 activity. A series of synthetic trans-stilbene derivatives were prepared and their inhibitory potentials were evaluated with the bacterial membrane of recombinant human P450 1A1, 1A2 or 1B1 coexpressed with human P450/NADPH-450 reductase to find new candidates for cancer chemoprevention.(omitted)

• Proceedings of the Korean Biophysical Society Conference
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• 2002.06b
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• pp.53-53
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• 2002

Inhibitory effects of Cu$\^$2＋/ on the cytochrome P450 (P450)-catalyzed reactions of liver microsomes and reconstituted systems containing purified P450 and NADPH-P450 reductase (NPR) were seen. However, Zn$\^$2＋/, Mg$\^$2＋/, Mn$\^$2＋/, Ca$\^$2＋/, and Co$\^$2＋/ had no apparent effects on the activities of microsomal P450s. Cu$\^$2＋/ inhibited the reactions catalyzed by purified P450s lA2 and 3A4 with IC$\sub$50/ values of 5.7 and 8.4 ${\mu}$M, respectively.(omitted)

• Journal of Microbiology and Biotechnology
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• v.15 no.1
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• pp.183-187
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• 2005

Abstract The cancer chemopreventive potential of chitosanoligosaccharides was investigated by measuring the induction of quinone reductase and glutathione S-transferase activities and inhibition of cytochrome P450 1A1, 2B1, and 2E1 activities. Chitosanoligosaccharide I (1-${\kappa}$Da${\kappa}$Da) significantly induced glutathione S-transferase activity with a maximal 1.5-fold increase at 500 ${\mu}$g/ml, while chitosanoligosaccharide II (3-${\kappa}$Da${\kappa}$Da) (500 ${\mu}$g/ml) strongly induced quinone reductase (p<0.01) and glutathione S-transferase (p<0.005) activities. The in vitro incubation of rat liver microsomes with chitosanoligosaccharides I and II (2.5, 5, 50, and 500 ${\mu}$g/ml) showed a dose-dependent inhibiton of cytochrome P450 1A1, 2B1, and 2E1 activities. Chitosanoligosaccharide II was a more potent inhibitor of cytochrome P450 2B1 activity than chitosanoligosaccharide I. Accordingly, these findings suggest that chitosanoligosaccharides are potential chemopreventive agents.

• Applied Biological Chemistry
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• v.41 no.4
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• pp.213-217
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• 1998

An assay for cytochrome P450 monooxygenase activity by determination of the products of organophosphate oxidation via inhibition of acetylcholinesterase was described. Extracts from strains of Oryzaephilus surinamensis selected for resistance to chlorpyrifos-methyl (QVOS 102), fenitrothion (VOS F) and malathion (VOS 3), and a standard susceptible strain VOS 48, were incubated with an organophosphate in the presence of a NADPH-generating system and acetylcholinesterase. The degree of inhibition of the acetylchoinesterase activity was converted to manooxygenase activity using standard curves for the inhibition of acetylcholiesterase by chlorpyrifos-methyl-oxon, fenitrooxon and malaoxan. Activity was detectable in VOS 48 and was present at different increased levels with the different organophosphates in the three resistant strains, suggesting that different forms of P450 might be involved in organophosphate oxidation in these insects. The assays were carried out using crude insect homogenates and much smaller samples of insect material than the standard aldrin to dieldrin assay. It should be possible to use the method for determination of monooxygenase activity in single insert.