BioAssay record AID 1340971 submitted by ChEMBL: Hepatic extraction ratio in mouse liver microsomes at 1 uM in presence of NADPH by LC-MS/MS method.
TY - JOUR. T1 - Selective deficiency of debrisoquine 4-hydroxylase activity in mouse liver microsomes. AU - Masubuchi, Yasuhiro. AU - Iwasa, Takashi. AU - Hosokawa, Shin. AU - Suzuki, Tokuji. AU - Horie, Toshiharu. AU - Imaoka, Susumu. AU - Funae, Yoshihiko. AU - Narimatsu, Shizuo. PY - 1997/9. Y1 - 1997/9. N2 - Cytochrome P450 enzymes belonging to the CYP2D subfamily have been shown to be one of determinants of the polymorphic drug oxidations in the human and the rat. Debrisoquine 4-hydroxylation is a typical reaction catalyzed by these enzymes. However, various strains of mice were observed to have much lower debrisoquine 4-hydroxylase activity than Wistar rats, whereas other monooxygenase activities in mice toward bunitrolol, propranolol, imipramine and amitriptyline, which are mediated by the CYP2D enzymes in the rat, were comparable to those of the rats. Immunoblot analysis of mouse liver microsomes with an antibody raised against a rat CYP2D enzyme indicated that the mouse liver contained ...
The results obtained in the current study demonstrate that ABT-378 undergoes CYP-dependent biotransformation to three major metabolites (M-1, M-3, and M-4) as well as several minor metabolites in human liver microsomes, consistent with a previous human liver microsomal metabolism study (Kumar et al., 1999). Members of the CYP3A subfamily (CYP3A4 and CYP3A5) were found to be the enzymes responsible for the formation of all the metabolites of ABT-378. Ritonavir was found to be a very potent inhibitor of CYP3A-mediated biotransformation of ABT-378 with a very lowKi value (0.013 μM).. The high metabolic lability precludes the use of ABT-378 alone as an effective antiviral agent for the treatment of HIV infection. The potent in vitro inhibition of the metabolism of ABT-378 by ritonavir indicates that on coadministration of ritonavir with ABT-378, the former would potentially inhibit the metabolism of the latter, thereby reducing the clearance of ABT-378. This has been demonstrated to be true in a ...
female wistar hepatic microsomes female wistar rat hepatic microsomes | order female wistar hepatic microsomes female wistar rat hepatic microsomes | How to use: female
1. Guanosine 5′-[gamma-thio]triphosphate (GTP[S]), if added before GTP, blocks both Ca2+ efflux promoted by GTP and the effect of GTP on enhancement of inositol 1,4,5-triphosphate (IP3)-promoted Ca2+ release from preloaded microsomal vesicles. If, however, GTP[S] is added after GTP, it does not reverse the Ca2+ efflux promoted by GTP, nor does it inhibit IP3-promoted Ca2+ release. 2. The effect of GTP in enhancing IP3-promoted Ca2+ release is maintained after washing the microsomal vesicles free of added GTP. After this treatment, enhancement of IP3-promoted Ca2+ efflux can be observed in the absence of poly(ethylene glycol). 3. Electron microscopy shows that during GTP treatment of microsomal vesicles there is rapid production of very large vesicular structures, apparently produced by fusion of smaller vesicles. 4. Light-scattering changes are detectable during the fusion process. 5. Both Ca2+ efflux promoted by GTP and the enhancement of IP3-promoted Ca2+ release seen in the presence of GTP ...
When one wishes to scale in vitro metabolic kinetic data to in vivo clearances, the issue of nonspecific microsomal binding needs to be addressed in addition to the plasma or blood binding that is more frequently incorporated into the scaling method. It has been demonstrated that eq. 2 could be of more general utility in the prediction of clearance than either the well stirred model containing no free fraction corrections, or only the fupcorrection (Obach, 1999). Cancellation of the fup/fuinc ratios cannot be relied upon, particularly because fuinc can depend strongly on the microsomal protein concentration that one chooses to use as shown in Table 1 and by other studies (Obach, 1996,1997; Mclure et al., 2000; Venkatakrishnan at. al., 2000). If eq. 2 is to become more widely used for in vivo clearance prediction, a better understanding of how nonspecific microsomal binding depends on microsomal protein concentration and on chemical structure is required. The ultimate goal would be to predict the ...
BioAssay record AID 510137 submitted by ChEMBL: Ratio of IC50 for CYP3A4 in human liver microsomes measured immediately to IC50 for CYP3A4 in human liver microsomes measured after incubation.
1. A partially purified UDP-glucuronyltransferase was obtained by extracting rat liver microsomal preparations with Lubrol, a non-ionic detergent. 2. The soluble enzyme catalysed conjugation of both o-aminophenol and p-nitrophenol and was extremely stable when compared with untreated microsomal preparations. 3. The characteristics of the conjugation of the two phenols were found to differ with respect to pH optimum, bivalent cation requirement and Michaelis constants, suggesting that more than one enzyme is involved in the conjugation reaction.. ...
hepatic microsomes female wistar hepatic microsomes female wistar rat | order hepatic microsomes female wistar hepatic microsomes female wistar rat | How to use: hepati
There are various subcellular fractions and they include homogenate, s9, microsomes and cytosol. These products are valuable tools in drug discovery for studying the metabolism of your compounds. Human Subcellular Products InVitroCYP™ 150-Donor Human Liver Microsomes InVitroCYP™ H-Class Human Liver Microsomes InVitroCYP™ M-Class Human Liver Microsomes Human Microsomes - Other Tissues Human Liver S9
Thank you for your interest in spreading the word about Biochemical Society Transactions.. NOTE: We only request your email address so that the person you are recommending the page to knows that you wanted them to see it, and that it is not junk mail. We do not capture any email address.. ...
Human liver microsomes are subcellular fractions that contain drug-metabolizing enzymes including CYP enzymes, flavin monooxygenases, and UDP glucuronyl transferases. InVitroCYP M-class microsomes are designed to exhibit moderate CYP activity, ideal for clearance and metabolite identification studies. BioreclamationIVT extensive characterization and tissue profiling process guarantees that each lot of InVitroCYP M-class microsomes will provide consistent and reproducible results for your metabolism and clearance studies.
In cell biology, microsomes are heterogenous vesicle-like artifacts (~20-200 nm diameter) re-formed from pieces of the endoplasmic reticulum (ER) when eukaryotic cells are broken-up in the laboratory; microsomes are not present in healthy, living cells.[1] Microsomes can be concentrated and separated from other cellular debris by differential centrifugation. Unbroken cells, nuclei, and mitochondria sediment out at 10,000 g, whereas soluble enzymes and fragmented ER, which contains cytochrome P450 (CYP), remain in solution (g is the Earths gravitational acceleration). At 100,000 g, achieved by faster centrifuge rotation, ER sediments out of solution as a pellet but the soluble enzymes remain in the supernatant. In this way, cytochrome P450 in microsomes is concentrated and isolated. Microsomes have a reddish-brown color, due to the presence of the heme. Because of the need for a multi-part protein-system, microsomes are necessary to analyze the metabolic activity of CYPs. These CYPs are highly ...
In the obersvation of Evidence for the involvement of human liver microsomes CYP1A2 in the mono-hydroxylation of daidzein by Peng WX, Wang LS, Li HD, Abd El-Aty AM, Chen GL, Zhou HH., posted in US National Library of Medicine National Institutes of Health, researchers found that Michaelis-Menten kinetic parameters were best fitted to a one-component enzyme kinetic model. The mean K(m) (micromol/l) and V(max) (micromol/g min) values (+/-S.D.) were 26.86 (10.45) and 4.76 (2.07), 53.83 (22.25) and 2.29 (1.04), 51.48 (29.32) and 2.21(0.82), for the formation rates of 7,8,4-THI, 7,3,4-THI and 6,7,4-THI, respectively. Furafylline, the CYP1A2-specific inhibitor, estrogen and monoclonal antibody raised against human CYP1A2 (MAB-1A2) substantially inhibited the formation rates of mono-hydroxylated metabolites. The IC(50) of Fur for the formation of 7,3,4-THI, 6,7,4-THI and 7,8,4-THI was 1.0, 0.9 and 0.8 micromol/l, respectively. The IC(50) of estrogen for the formation of 7,3,4-THI, ...
Magnolin, epimagnolin A, dimethyllirioresinol, eudesmin, and fargesin are pharmacologically active tetrahydrofurofuranoid lignans found in Flos Magnoliae. The inhibitory potentials of dimethyllirioresinol, epimagnolin A, eudesmin, fargesin, and magnolin on eight major human cytochrome P450 (CYP) enzyme activities in human liver microsomes were evaluated using liquid chromatography-tandem mass spectrometry to determine the inhibition mechanisms and inhibition potency. Fargesin inhibited CYP2C9-catalyzed diclofenac 4-hydroxylation with a Ki value of 16.3 μM, and it exhibited mechanism-based inhibition of CYP2C19-catalyzed [S]-mephenytoin 4-hydroxylation (Ki, 3.7 μM; kinact, 0.102 min−1), CYP2C8-catalyzed amodiaquine N-deethylation (Ki, 10.7 μM; kinact, 0.082 min−1), and CYP3A4-catalyzed midazolam 1-hydroxylation (Ki, 23.0 μM; kinact, 0.050 min−1) in human liver microsomes. Fargesin negligibly inhibited CYP1A2-catalyzed phenacetin O-deethylation, CYP2A6-catalyzed coumarin 7-hydroxylation,
Thank you for your interest in spreading the word about Biochemical Society Transactions.. NOTE: We only request your email address so that the person you are recommending the page to knows that you wanted them to see it, and that it is not junk mail. We do not capture any email address.. ...
Cytochrome P-450 (P-450) 2A6 was purified by chromatography of human liver microsomes. The final preparation was electrophoretically homogeneous and contained 16 nmol of P-450/mg of protein. The amino-terminal amino acid sequence of the protein (first 13 residues) matched that of the reported cDNA exactly. The UV-visible spectrum indicated that the isolated hemoprotein was in the low-spin form. The protein was recognized by rabbit antibodies raised against rat P-450 2A1, and a rabbit antiserum against the P-450 2A6 preparation was also prepared. With these antibodies, it was estimated that P-450 2A6 accounted for a maximum of 1% of the total P-450 present in the human liver microsomes; the level varied greater than 100-fold among the 20 samples examined. Purified P-450 2A6 catalyzed coumarin 7-hydroxylation and 7-ethoxycoumarin O-deethylation at rates similar to those measured in the human liver sample used to prepare P-450 2A6, and these two microsomal activities were strongly inhibited by the ...
Gentaur molecular products has all kinds of products like :search , SeraLab \ Beagle Liver Microsomes \ MIC-114 for more molecular products just contact us
AB - Steroid glucuronidation was investigated in solubilized female rat and rabbit liver microsomes and in preparations of UDP-glucuronsyltransferase (UDPGT) activity resolved from these organelles. Solubilized rabbit liver microsomes possessed
Initial studies aimed to characterize the effect of BSA on COD glucuronidation by HLM and confirm the contributions of UGT2B4 and UGT2B7 to C6G formation. Kinetic parameters for C6G formation in HLM in the absence of BSA were similar to those reported previously by Court et al. (2003). Addition of BSA (2%) to incubations resulted in an 88% reduction in Km without an effect on Vmax. A similar effect has been reported for the glucuronidation of several other UGT2B7 substrates by HLM (Rowland et al., 2007; Kilford et al., 2009), confirming that Km or microsomal intrinsic clearance values for UGT2B7 substrates are overestimated and underestimated, respectively, by approximately an order of magnitude when HLM are used as the enzyme source in the absence of albumin supplementation.. Also consistent with previous published data (Court et al., 2003), the screening of 13 recombinant enzymes demonstrated that only UGT2B4 and UGT2B7 glucuronidated COD. In contrast to the Michaelis-Menten (or weak substrate ...
We screened thousands of compounds and identified several drugs with improved anti-MRSA activities after they undergo human liver microsomal metabolism or in presence of Cefoxitin, a known antibacterial agents which has a high MIC against MRSA F-182. We used liquid handling workstations and LC-MS based analysis to screen and characterize active agents. We further extended screening some of the hits from the screening against additional MRSA strain, one VRE and one E. coli strain for spectrum of activity and frequency of resistance. This approach can be adopted for exploring other biological activities of these library of compounds with modifications. We are in the process of exploring the mechanism of action of these interesting agents using multi-omics study consisting of metabolomics, proteomics and genomics ...
The involvement of human cytochrome P450 (CYP) 2E1 in the hydroxylation of 4-nitrophenol (4NP) to 4-nitrocatechol (4NC) has been investigated using cDNA expression and liver microsomal kinetic and inhibitor techniques. 4NP hydroxylation by human liver microsomes and cDNA-expressed human CYP2E1 exhib …
1-Chloro-2-hydroxy-3-butene (CHB) is an in vitro metabolite of 1,3-butadiene, a rodent/human carcinogen. To search for an approach detecting CHB in vivo, it is vital to obtain a full understanding of CHB metabolism. Previously, we demonstrated that CHB was bioactivated to 1-chloro-3-buten-2-one (CBO) by alcohol dehydrogenase. However, CHB metabolism by cytochrome P450s has not been reported. Thus, in the present study, CHB metabolism by rat liver microsomes was investigated. The results showed that CHB was converted to 1-chloro-3,4-epoxy-2-butanol (CEB) and CBO. 4-Methylpyrazole, a cytochrome P450 2E1-specific inhibitor, inhibited the formation of both CEB and CBO, while 1-benzylimidazole, a generic cytochrome P450 inhibitor, completely abolished the formation of CEB and CBO, suggesting that CHB metabolism was mediated by cytochrome P450s. Because the molecules have two chiral centers, CEB was detected as two stereoisomers, which were designated D-CEB and M-CEB, and were characterized as ...
Rodent skin (extrahepatic) subcellular fractions, including matching pooled IGS Sprague-Dawley rat microsomes and S9 from dermal tissue, characterized for in vitro ADME studies to test the biotransformation of transdermal xenobiotics.
Our CYP and UGT inhibition services are conducted with Corning UltraPool® HLM 150 pooled human liver microsomes, drug probe substrates and validated LC/MS/MS methods. Options include direct and time-dependent inhibition studies with flexible endpoints. Kinetic results reported include IC50, IC50 shift (dilution and non-dilution methodology), as well as KI and kinact. Assays are also available using hepatocytes or recombinant enzyme study models.. To request a study quotation call: 781.938.2546 or send a request to: [email protected].. ...
Gentaur molecular products has all kinds of products like :search , SeraLab \ Bovine Microsomes \ MIC-202 for more molecular products just contact us
Caltag Medsystems is a UK distributor of diagnostic and research reagents for cell biology, flow cytometry, immunology, histology and neuroscience. We offer over 200,000 high quality products at competitive prices
Download Free Full-Text of an article EFFECTS OF 3 - METHYL CHOLANTHEREN ON LIVER MICROSOMAL MIXED FUNCTION OXIDASE ACTIVITIES OF ACIPENSER PERSICUS
TY - JOUR. T1 - Oxygen concentrations required for reductive defluorination of halothane by rat hepatic microsomes. AU - Lind, R. C.. AU - Gandolfi, A. J.. AU - Sipes, I. G.. AU - Brown, B. R.. AU - Waters, S. J.. PY - 1986/10/22. Y1 - 1986/10/22. N2 - The free oxygen concentrations required for reductive defluorination of halothane by rat hepatic microsomes from control and phenobarbital- (PB) and polychlorinated biphenyl- (PCB) treated animals were determined. Halothane-exposed microsomes from treated rats generated measurable levels of fluoride ion after 30 min incubations with oxygen concentrations of 5% or less. Microsomes from control animals produced fluoride only if the free oxygen concentration was 2% or less. During anoxic (0% oxygen) incubations, defluorination rates of 2.10 ± 0.17, 5.55 ± 0.38, and 5.46 ± 0.30 nmol fluoride·mg protein-1·30 min-1 were observed for microsomes from control, PB, and PCB rats, respectively. Normalizing the maximal rates of defluorination to the ...
1. Cimetidine pretreatment of male Sprague-Dawley rats caused a significant increase in the specific content of total hepatic cytochrome P-450, supporting the hypothesis that this H2-receptor antagonist has monooxygenase induction effects. 2. Quantitative ultrastructural studies of liver of cimetidine-pretreated animals also supported this hypothesis in showing a significant proliferation of smooth endoplasmic reticulum. These ultrastructural changes were qualitatively similar to those produced by treatment of rats with phenobarbital, a well-characterized monooxygenase-inducing agent whose effects were studied for comparative purposes. 3. Competitive inhibition of metoprolol αhydroxylation by cimetidine in liver microsomes prepared from untreated animals (Ki = 18.8 μM) was also demonstrated. 4. These results allowed testing of the hypothesis (Burnet el al. 1986) that inhibition of a defined monooxygenase should lead to induction of the synthesis of the relevant cytochrome P-450 isozyme. 5. The ...
hepatic microsomal mixed function oxidase system의 중추인 cytochrome p-450은 주위환경, 약물, 식이 및 영양 상태에따라 활성이 변화하는것으로 알려져있다. 또한 이 효소계를 통하여 대사되는 2-acetylaminofluorene은 guinea pig를 제외한 모든 동물에서 간암을 일으키는 물질이라는것이 밝혀져서 연구의 대상이 되고있다. 최근 cholesterol은 성인병에 있어 그 원인 인자로서 중요성이 알려지고 있으며 cytochrome p-450과 b_(5)와의 연관성이 보고된바있다. 한편 인삼은 항암작용, 대사촉진, 간조직에서의 해독작용등 여러가지 기능이 보고되어 있다. 이에 저자는 cholesterol을 투여한 흰쥐에서 hepatic microsomal cytochrome p-450 및 b_(5)의 활성에대한 영향과 2-AAF의 ring-hydroxylation과 N-hydroxylation의 변화를 관찰하고, cholesterol과 인삼을 통시에 투여한 군과 비교관찰하여 다음과 같은 결론을 얻었다. 1) 정상 ...
TY - JOUR. T1 - Liver microsomes contain multiple forms of inositol 1,4,5-trisphosphate binding proteins. T2 - Identification by nitrocellulose blot overlay. AU - Ali, Nawab. AU - Agrawal, Devendra K.. PY - 1992. Y1 - 1992. N2 - A group of proteins binding to inositol 1,4,5-trisphosphate (IP3) has been identified in rat liver microsomes by a nitrocellulose blot-overlay technique. Proteins were resolved by SDS-PAGE, blotted on nitrocellulose and incubated with [32P]IP3 followed by autoradiography. Approximately eight IP3-binding polypeptides ranging Mr 23-50 kDA were present exclusively in microsomes; these were absent from plasma membrane and mitochondrial fractions. Binding of [32P]IP3 to these proteins was displaceable to a great extent by 5 μM unlabeled IP3 but not by 10 μM IP1, IP2, IP4, ATP, or GTPγS. These results suggest that liver microsomes contain multiple forms of IP3-binding proteins that can be detected by this new method.. AB - A group of proteins binding to inositol ...
Dive into the research topics of Characterization of paracetamol UDP-glucuronosyltransferase activity in human liver microsomes. Together they form a unique fingerprint. ...
Caco-2 cell lysate, and intestinal and liver microsomes derived from female humans and rats were used to compare and contrast the metabolism and disposition of raloxifene. In Caco-2 cell lysate, raloxifene 6-β-glucuronide (M1) was the main metabolite, although raloxifene 4′-β-glucuronide (M2) was formed in comparable abundance (58% versus 42%). In rat liver and intestinal microsomes, M1 represented about 76 to 86% of glucuronidated metabolites. In contrast, raloxifene 4′-β-glucuronide (M2) was the predominant metabolite in expressed UGT1A10 (96%) and human intestinal (92%) microsomes. Intrinsic clearance for M2 (CLint, M2) in human intestinal microsomes was 33- to 72-fold higher than in rat microsomes, whereas intrinsic clearance for M1 (CLint, M1) was 3- to 4-fold lower. Taken together, total intrinsic clearance (CLint, M1 + CLint, M2) in human intestinal microsomes was 3- to 6-fold higher than that in rat intestinal microsomes, but was similar in liver microsomes. In addition, intrinsic
Buy our Recombinant Human Cytochrome P450 2A6 protein. Ab114776 is a protein fragment produced in Wheat germ and has been validated in WB, ELISA, SDS-PAGE…
Buy our Recombinant Human Cytochrome P450 3A4 protein. Ab114327 is a full length protein produced in Wheat germ and has been validated in WB, ELISA, SDS-PAGE…
1. Paeonol, the primary active component of a traditional Chinese medicine Moutan Cortex, has a wide range of pharmacological activities. In the present study, the metabolism of paeonol by cytochrome P450s (CYPs) was investigated in human liver microsomes ...
The endocannabinoid system is important for many physiological and pathological processes, but its role in the regulation of liver cytochromes P450 (CYPs) is still unknown.We studied the influence of the endocannabinoid oleamide on rat and human liver CYPs. Oleamide was administered i.p. to rats at doses of 0.1, 1 and 10 mg/kg/day for 7 days. The content and activity of key CYPs was evaluated in rat liver microsomes. Moreover, its interactions with nuclear receptors regulating CYP genes and serum levels of their ligands (prolactin, corticosterone, and free triiodothyronine) were tested in vitro CYP inhibition assays. Decreased protein levels and metabolic activities of CYP1A2, CYP2B, and CYP2C11 along with a drop in metabolic activity of CYP2D2 were observed in animals treated with oleamide (10 mg/kg/day). The activities of CYP2C6, CYP2A, and CYP3A and the levels of hormones were not altered. In vitro, oleamide exhibited a weak inhibition of rat CYP1A2, CYP2D2, and CYP2C6. The activities of rat ...
Tirilazad mesylate (Freedox), a potent inhibitor of membrane lipid peroxidation in vitro, is under clinical development for the treatment of subarachnoid hemorrhage. In humans, tirilazad is cleared almost exclusively via hepatic elimination. Characterization of three major microsomal metabolites of tirilazad by mass spectrometry indicated that hydroxylation had occurred in the pyrrolidine ring(s) and at the 6 beta-position of the steroid domain. A role for CYP3A4 in the formation of the three major metabolites (tirilazad hydroxylase activity) was established in human liver microsomal preparations: 1) Tirilazad hydroxylation was potently inhibited by troleandomycin and ketoconazole, specific inhibitors of CYP3A4. 2) The rates of tirilazad hydroxylation within a population of 14 human livers displayed a 9-fold interindividual variation and a significant correlation (r2 = .95) between tirilazad hydroxylation and testosterone 6 beta-hydroxylation. 3) Kinetic analysis of tirilazad hydroxylase ...
Publication year 1996. Abstract The oxidative biotransformation of 1, 2-dichlorobenzene (1, 2-DCB) was investigated using hepatic microsomes from male Wistar, Fischer-344 and Sprague-Dawley (SD) rats, phenobarbital (PB)- and isoniazid (ISO) pretreated male Wistar rats and from man. In addition, microsomes from cell lines selectively expressing one cytochrome P450 (P4502E1, 1A1, 1A2, 2B6, 2C9, 2D6, 2A6 and 3A4) were used. The rate of conversion was 0.09 nmol/min/mg, protein for both Wistar and Fischer-344 rat microsomes, 0.04 for SD-microsomes and 0.14 for human microsomes. Induction of Wistar rats with isoniazid (ISO, a P4502E1 inducer) or phenobarbital (PB, a P4502B1/2 inducer) resulted in an increased conversion rate of 0.20 and 0.42 nmol/min/mg, protein, respectively. Covalent binding of radioactivity to microsomal protein was similar for Wistar, Fischer and ISO-pretreated rats (16-17% of total metabolites), whereas induction with PB resulted in an increased covalent binding of 23% of total ...
TY - JOUR. T1 - Activation of propranolol and irreversible binding to rat liver microsomes. T2 - strain differences and effects of inhibitors. AU - Masubuchi, Yasuhiro. AU - Narimatsu, Shizuo. AU - Suzuki, Tokuji. PY - 1992/2/4. Y1 - 1992/2/4. UR - http://www.scopus.com/inward/record.url?scp=0026584689&partnerID=8YFLogxK. UR - http://www.scopus.com/inward/citedby.url?scp=0026584689&partnerID=8YFLogxK. U2 - 10.1016/0006-2952(92)90587-9. DO - 10.1016/0006-2952(92)90587-9. M3 - Article. C2 - 1540217. AN - SCOPUS:0026584689. VL - 43. SP - 635. EP - 637. JO - Biochemical Pharmacology. JF - Biochemical Pharmacology. SN - 0006-2952. IS - 3. ER - ...
Hepatic microsomal cytochrome P450s, which are involved in the metabolism of drugs, hormones, prostaglandins and fatty acids, change when animals develop diabetes. We studied changes in cytochrome P450 isozymes in both hepatic and renal microsomes of rats with diabetes caused by streptozocin, and co …
TY - JOUR. T1 - Identification and characterization of human cytchrome P450 (CYP) isoforms interacting with cisapride. AU - Desta, Zeruesenay. AU - Thacker, David. AU - Soukhova, Nadia. AU - Shin, Jae Gook. AU - Flockhart, David A.. PY - 1999/1/1. Y1 - 1999/1/1. N2 - Using human liver microsomes (HLMs) and recombinant CYP450s, we characterized the metabolism of cisapride and documented its inhibitory effect on CYP450s. Two cisapride enantiomers (EI and EII) were separated and fractions collected for study. HPLC chromatograms of HLM incubates of cisapride separated 3 metabolite peaks, M1-M3. The identity of M1 is consistent with norcisapride, while M2 and M3 may represent oxidative hydroxylation of the fluorophenyl ring. The formation rate of M1 and 10μM cisapride in 15 HLMs significantly correlated with the activities of CYP3A, 2C19 and 1A2. Of CYP isoform specific inhibitors tested, ketoconazole potently inhibited the formation of M1, M2 and M3. Of the 10 recombinant CYP450s tested, CYP3A4, ...
Hi Methods, I am fractionating baculovirus-infected Sf9 and Sf21 insect cells, using differential centrifugation to isolate microsomal membranes. The problem is that the microsomes (50,000 x g) are very particulate, and remain clumpy even after homogenization with hand-held glass/Teflon Potter-Elvehjem tissue grinder. Even mechanical disruption of the final microsomal pellet using a small polytron leaves clumps of unresuspended membranes that are visible by eye. The insect cell microsomes are clumpy when isolated either in solutions containing high salt (0.6 M KCl, 250 mM sucrose, 3 mM MgCl2) or low salt (10 mM NaHCO3, 0.1 mM CaCl2). The two different preparative protocols are listed below. Following centrifugation, the microsomal pellets are typically resuspended in 250 mM sucrose buffered with MOPS or histidine. Why do the microsomes clump so much? Are there solutes to add (pyrophosphate, NaI, etc) that would allow easy and complete resuspension of insect cell microsomes? Thanks, Mike Autry ...
Abstract OBJECTIVE: In order to evaluate the inhibitory effects of isoniazid on cytochrome P450 (CYP) mediated drug metabolism, the in vitro inhibitory potency and specificity as w..
Lu, A.Y.H., Kuntzman, S.W., Jacobson, M. and Conney, A.H. (1972). Reconstituted liver microsomal enzyme system that hydroxylates drugs, other foreign compounds, and endogenous substrates. II. Role of the cytochrome P-450 and P-448 fractions in drug and steroid hydroxylations. J. Biol. Chem. 247: 1727-1734. PMID 4401153. ...
Rat and human liver microsomes oxidized ranitidine to its N−oxide(66−76%)and S−oxide(13−18%)and desmethylranitidine(12−16%).N− and S−oxidations of ranitidine were inhibited by metimazole [flavin−containing monooxygenase(FMO)inhibitor] to 96−97% and 71−85%, respectively, and desmethylation of ranitidine was inhibited by SKF525A [cytochrome P450(CYP)inhibitor] by 71−95%.Recombinant FMO isozymes like FMO1, FMO2, FMO3 and FMO5 produced 39, 79, 2180 and 4 ranitinine N−oxide and 45, 0, 580 and 280 ranitinine S−oxide pmol·min,SUP,-1,/SUP,·nmol,SUP,-1,/SUP, FMO, respectively.Desmethyranitinine was not produced by recombinant FMOs.Production of desmethylranitidine by rat and human liver microsomes was inhibited by tranylcypromine, α−naphthoflavon and quinidine, which are known to inhibit CYP2C19, 1A2 and 2D6, repectively.FMO3, the major form in adult liver, produced both ranitidine N− and S−oxides at a 4 to 1 ratio.FMO1, expressed primarily in human kidney, was 55− ...
Sigma-Aldrich offers abstracts and full-text articles by [Ramakrishna Nirogi, Raghava Choudary Palacharla, Abdul Rasheed Mohammed, Arunkumar Manoharan, Ranjith Kumar Ponnamaneni, Gopinadh Bhyrapuneni].
Unfavorable drug metabolism is the main reason for attrition of new chemical entities and withdrawal of drugs from the market, costing pharmaceutical companies a great deal of money and time. Therefore, obtaining information about the drug metabolism of a new chemical entity via the hepatic clearance in the early stages ... read more of the drug development process is crucial in guaranteeing its success. Human-based in vitro systems, especially liver microsomes, hepatocytes and liver slices are increasingly applied in the drug development process for this purpose. The aim is to determine which of these commonly used systems is the most appropriate for predicting hepatic clearance in humans. Although there is no perfect in vitro system, primary hepatocytes and the HepaRG cell line are the most representative systems of the liver at present. However, it has to be kept in mind that besides their potential to accurately predict in vivo clearance other influencing factors that may interfere with ...
Uncontrolled cell proliferation is the hall mark of many cancers, and is typically manifested by a deregulation of the cell-division cycle. CDKs play critical roles in regulating cell cycle, apop- tosis and cell differentiation. AG-024322 is a multitargeted CDK inhibitor that has been shown to induce cancer cell apoptosis and de- monstrate significant antitumor activity in hu-man tumor xenograft models. This compound is under clinical development as an intravenous anticancer agent. AG-024322 exhibited moder-ate to high systemic clearance across preclini-cal species. In vitro metabolism in human liver microsomes and hepatocytes demonstrates that glucuronidation and oxidation represent the major metabolic pathways of AG-024322. The experiments of chemical inhibition and micro-somes containing individual CYP or UGT iso-forms revealed that CYP3A and UGT1A1 appear to predominantly mediate AG-024322 oxidation and glucuronidation, respectively. Formation kinetics of the two pathways in human liver mi-crosomes
PubMed comprises more than 30 million citations for biomedical literature from MEDLINE, life science journals, and online books. Citations may include links to full-text content from PubMed Central and publisher web sites.
If you are a society or association member and require assistance with obtaining online access instructions please contact our Journal Customer Services team ...
Drugs are eliminated from the body either as unchanged parent or as metabolite. Metabolic stability plays a major role in drug clearance, with the liver being the primary site for drug biotransformation via two major enzymatic reactions: Phase I (modifications to the molecular structure itself) and Phase II reactions (conjugation reactions). A common system for measuring hepatic metabolism in early drug discovery, restricted to Phase I reactions, uses liver microsomes, a subcellular fraction containing major drug-metabolizing enzymes, including the cytochrome P450 (CYP) family and flavin monooxygenase (FMO). ...
Goal: Uridine diphospho-glucuronosyltransferases (UGTs) are membrane-bound enzymes that catalyze the conjugation of glucuronic acid onto a varied set of xenobiotics. Horses successfully and extensively glucuronidate numerous xenobiotics, along with opioids, making UGTs an very important group of drug-metabolizing enzymes for the clearance of remedy. Recombinant enzymes have allowed researchers to characterize the metabolism of a variety of remedy. The first purpose was to clone, particular and characterize equine UGTs using remedy characterised as UGT substrates in numerous species. A secondary purpose was to characterize the in vitro metabolism of morphine in horses.. Examine design: In vitro drug metabolism look at using liver microsomes and recombinant enzyme strategies.. Animals: Liver microsomes and RNA from tissue collected from two Thoroughbred mares euthanized for various causes.. Strategies: Primarily based mostly on homology to the human UGT2B7, Four equine UGT variants have been ...