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Łyżwa P, Mikołajczyk M. Chiral Sulfinimines in Asymmetric Synthesis of Enantiomeric Aminophosphonic Acids. PHOSPHORUS SULFUR 2014. [DOI: 10.1080/10426507.2014.906426] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Piotr Łyżwa
- Centre of Molecular and Macromolecular Studies, Department of Heteroorganic Chemistry, Polish Academy of Sciences, Sienkiewicza Str. 112, 90-363 Łódź, Poland
| | - Marian Mikołajczyk
- Centre of Molecular and Macromolecular Studies, Department of Heteroorganic Chemistry, Polish Academy of Sciences, Sienkiewicza Str. 112, 90-363 Łódź, Poland
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Łyżwa P, Błaszczyk J, Sieroń L, Mikołajczyk M. Asymmetric Synthesis of Structurally Diverse Aminophosphonic Acids by Using EnantiopureN-(p-Tolylsulfinyl)cinnamaldimines as Reagents. European J Org Chem 2013. [DOI: 10.1002/ejoc.201201589] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Inhibitors of fatty acid synthesis in prokaryotes and eukaryotes as anti-infective, anticancer and anti-obesity drugs. Future Med Chem 2012; 4:1113-51. [PMID: 22709254 DOI: 10.4155/fmc.12.62] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
There is a large range of diseases, such diabetes and cancer, which are connected to abnormal fatty acid metabolism in human cells. Therefore, inhibitors of human fatty acid synthase have great potential to manage or treat these diseases. In prokaryotes, fatty acid synthesis is important for signaling, as well as providing starting materials for the synthesis of phospholipids, which are required for the formation of the cell membrane. Recently, there has been renewed interest in the development of new molecules that target bacterial fatty acid synthases for the treatment of bacterial diseases. In this review, we look at the differences and similarities between fatty acid synthesis in humans and bacteria and highlight various small molecules that have been shown to inhibit either the mammalian or bacterial fatty acid synthase or both.
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Ceccarelli SM, Chomienne O, Gubler M, Arduini A. Carnitine Palmitoyltransferase (CPT) Modulators: A Medicinal Chemistry Perspective on 35 Years of Research. J Med Chem 2011; 54:3109-52. [DOI: 10.1021/jm100809g] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Simona M. Ceccarelli
- Pharmaceuticals Division, F. Hoffmann-La Roche Ltd., CH- 4070 Basel, Switzerland
| | - Odile Chomienne
- Pharmaceuticals Division, F. Hoffmann-La Roche Ltd., CH- 4070 Basel, Switzerland
| | - Marcel Gubler
- Pharmaceuticals Division, F. Hoffmann-La Roche Ltd., CH- 4070 Basel, Switzerland
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Conti R, Mannucci E, Pessotto P, Tassoni E, Carminati P, Giannessi F, Arduini A. Selective reversible inhibition of liver carnitine palmitoyl-transferase 1 by teglicar reduces gluconeogenesis and improves glucose homeostasis. Diabetes 2011; 60:644-51. [PMID: 21270274 PMCID: PMC3028366 DOI: 10.2337/db10-0346] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVE We have developed a new antihyperglycemic agent (teglicar) through the selective and reversible inhibition of the liver isoform of carnitine palmitoyl-transferase 1 (L-CPT1). RESEARCH DESIGN AND METHODS Glucose production was investigated in isolated hepatocytes and during pancreatic clamps in healthy rats. Chronic treatments on C57BL/6J, db/db, high-fat fed mice, and rats were performed to understand glucose metabolism and insulin sensitivity. RESULTS In isolated hepatocytes, teglicar concentration dependently reduced ketone bodies and glucose production up to 72 and 50%, respectively. In rats, teglicar reduced the endogenous glucose production (-62%) without affecting peripheral glucose utilization. Heart 2-[(3)H]deoxyglucose uptake in mice was also not affected, confirming in vivo the drug selectivity toward L-CPT1. Chronic treatment in db/db mice (50 mg/kg/bid; 45 days) reduced postabsorptive glycemia (-38%), water consumption (-31%), and fructosamine (-30%). Such antidiabetic activity was associated with an improved insulin sensitivity assessed by the insulin tolerance test. A significant 50% increase in hepatic triglyceride content (HTGC) was found, although plasma alanineaminotransferase was not altered. In addition, long-term teglicar administration to high-fat fed C57BL/6J mice normalized glycemia (-19%) and insulinemia (-53%). Long-term teglicar administration (30 days, 80 mg/kg) in healthy overnight-fasted rats slightly reduced basal glycemia (-20%, ns), reduced basal insulin levels by 60%, doubled triglycerides, and increased free-fatty acids (+53%). HTGC was markedly increased, but liver and peripheral insulin sensitivity assessed by hyperinsulinemiceuglycemic clamp were not affected. CONCLUSIONS Teglicar, in vitro and in animal models, reduces gluconeogenesis and improves glucose homeostasis, refreshing the interest in selective and reversible L-CPT1 inhibition as a potential antihyperglycemic approach.
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Affiliation(s)
- Roberto Conti
- Department of Endocrinology and Metabolism, sigma-tau s.p.a, Rome, Italy.
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Tassoni E, Conti R, Gallo G, Vincenti S, Dell'Uomo N, Mastrofrancesco L, Ricciolini R, Cabri W, Carminati P, Giannessi F. Aminocarnitine Ureidic Derivatives as Inhibitors of Carnitine Palmitoyltransferase I. ChemMedChem 2010; 5:666-9. [DOI: 10.1002/cmdc.200900535] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Rufer AC, Thoma R, Hennig M. Structural insight into function and regulation of carnitine palmitoyltransferase. Cell Mol Life Sci 2009; 66:2489-501. [PMID: 19430727 PMCID: PMC11115844 DOI: 10.1007/s00018-009-0035-1] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2009] [Revised: 03/18/2009] [Accepted: 04/09/2009] [Indexed: 01/07/2023]
Abstract
The control of fatty acid translocation across the mitochondrial membrane is mediated by the carnitine palmitoyltransferase (CPT) system. Modulation of its functionality has simultaneous effects on fatty acid and glucose metabolism. This encourages use of the CPT system as drug target for reduction of gluconeogenesis and restoration of lipid homeostasis, which are beneficial in the treatment of type 2 diabetes mellitus and obesity. Recently, crystal structures of CPT-2 were determined in uninhibited forms and in complexes with inhibitory substrate-analogs with anti-diabetic properties in animal models and in clinical studies. The CPT-2 crystal structures have advanced understanding of CPT structure-function relationships and will facilitate discovery of novel inhibitors by structure-based drug design. However, a number of unresolved questions regarding the biochemistry and pharmacology of CPT enzymes remain and are addressed in this review.
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Affiliation(s)
- Arne C. Rufer
- F. Hoffmann-La Roche AG, Pharma Research Discovery Technologies, 4070 Basel, Switzerland
| | - Ralf Thoma
- F. Hoffmann-La Roche AG, Pharma Research Discovery Technologies, 4070 Basel, Switzerland
| | - Michael Hennig
- F. Hoffmann-La Roche AG, Pharma Research Discovery Technologies, 4070 Basel, Switzerland
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8
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Vickers AEM. Characterization of hepatic mitochondrial injury induced by fatty acid oxidation inhibitors. Toxicol Pathol 2009; 37:78-88. [PMID: 19234235 DOI: 10.1177/0192623308329285] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Impairment of liver mitochondrial beta-oxidation is an important mechanism of drug-induced liver injury. Four inhibitors of fatty acid oxidation were compared in short-term rat in vivo studies in which the rats were administered one or four doses. The hepatocellular vacuolation represented ultra-structural mitochondrial changes. Urine nuclear magnetic resonance (NMR) spectroscopy revealed that both FOX988 and SDZ51-641 induced a persistent dicarboxylic aciduria, suggesting an inhibition of mitochondrial beta-oxidation and incomplete fatty acid metabolism. Etomoxir caused minimal mitochondrial ultrastructural changes and induced only transient dicarboxylic aciduria. CPI975 served as a negative control, in that there were no significant perturbations to the mitochondrial ultrastructural morphology or in the urine NMR composition; however, compound exposure was confirmed by the up-regulation of liver gene expression compared to vehicle control. The liver gene expression changes that were altered by the compounds were indicative of mitochondria, general and oxidative stress, and peroxisomal enzymes involved in beta-oxidation, suggestive of a compensatory response to the inhibition in the mitochondria. In addition, both FOX988 and SDZ51-641 up-regulated ribosomal genes associated with apoptosis, as well as p53 pathways linked with apoptosis. In summary, metabonomics and liver gene expression provided mechanistic information on mitochondrial dysfunction and impaired fatty acid oxidation to further define the clinical pathology and histopathology findings of hepatotoxicity.
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9
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Vickers AEM, Bentley P, Fisher RL. Consequences of mitochondrial injury induced by pharmaceutical fatty acid oxidation inhibitors is characterized in human and rat liver slices. Toxicol In Vitro 2006; 20:1173-82. [PMID: 16545538 DOI: 10.1016/j.tiv.2006.01.021] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2005] [Revised: 01/03/2006] [Accepted: 01/24/2006] [Indexed: 11/29/2022]
Abstract
Inhibition of liver mitochondrial beta-oxidation by pharmaceuticals may lead to safety concerns including mitochondrial dysfunction, lipid accumulation, inflammation and necrosis. In this study, the consequences of mitochondrial beta-oxidation inhibition by pharmaceuticals is investigated in human and rat liver slices. The fatty acid oxidation inhibitors Etomoxir and CPI975, inhibit the rate limiting mitochondrial beta-oxidation enzyme carnitine palmitoyltransferase I, while FOX988 and SDZ51-641, sequester mitochondrial coenzyme A to inhibit carnitine palmitoyltransferase II. Mitochondrial dysfunction was evident by a significant decrease of liver slice ATP levels and mitochondrial injury was verified by ultrastructural changes in morphology, manifested as enlarged mitochondria, C- or O-shaped mitochondria, and granular or crystalline inclusions. Gene expression changes were evident prior to changes in mitochondrial morphology. Time- and concentration dependent changes in mitochondrial genes linked with respiration and mitochondrial fatty acid beta-oxidation were associated with an up-regulation of peroxisome fatty acid oxidation genes, likely as a compensatory mechanism for the inhibition of the mitochondrial pathways. Gene expression changes preceding the decline of liver slice ATP and GSH levels included an up-regulation of stress response and oxidative stress gene expression, as well as genes linked with transcription, transporters, proliferation, cell matrix and signaling. In association with the decline of liver slice ATP and GSH was increased apoptosis and inflammation. Caspase activity, a functional indicator of apoptosis, was significantly increased as well as an up-regulation of genes linked with apoptosis. The increased gene and protein expression of the pro-inflammatory cytokine IL-8, produced by endothelial cells, is likely in response to the manifestation of oxidative stress and GSH depletion; further amplifying the oxidative stress response induced by the fatty acid oxidation inhibitors and triggering an inflammatory response. In summary, human and rat liver slices exhibited similar effects to the inhibitors of mitochondrial beta-oxidation, and the mitochondrial injury is associated with apoptosis and inflammation in the liver slices.
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Affiliation(s)
- A E M Vickers
- Novartis Pharmaceuticals Corporation, One Health Plaza, E. Hanover, NJ 07936, United States.
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10
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Gandour RD. Rationalizing the Solution Properties of Zwitterions by Means of Computational Chemistry. Chem Biodivers 2005; 2:1580-94. [PMID: 17191957 DOI: 10.1002/cbdv.200590129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
This short review describes our computational studies of carnitine, acetylcarnitines, and betaines over the past two decades. Interspersed among the three computational studies--a molecular mechanics study of the conformer population of carnitine and acetylcarnitine, an AM1 study of the energetics of hydrolysis of acetylcarnitine, and an HF 6-31G* study of the solvation energies and structures of a homologous series of betaines--are brief overviews of our research in designing and testing new therapeutic agents for non-insulin dependent diabetes and for protection against sexually transmitted diseases. The three studies also show how computational chemistry has evolved during this time to enable an evaluation of the structure and energetics of zwitterions in aqueous solution.
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Affiliation(s)
- Richard D Gandour
- Department of Chemistry (MC 0212), Virginia Tech, Blacksburg, VA 24061, USA.
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11
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Proietto J, Andrikopoulos S. Molecular Mechanisms of Increased Glucose Production: Identifying Potential Therapeutic Targets. J Investig Med 2004. [DOI: 10.1177/108155890405200633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/16/2023]
Abstract
Many patients with type 2 diabetes go on to require insulin therapy to achieve adequate control. A need remains to develop new classes of oral hypoglycemic agents to complement those already in use. A useful target is the inappropriately elevated endogenous glucose production present in patients with type 2 diabetes. This review discusses mechanisms of increased glucose production and possible strategies and targets for its suppression. Several approaches are being investigated, including inhibitors of glycogenolysis and gluconeogenesis, inhibitors of stimulatory hormones or their receptors, metabolic modulators, and agents that alter gene expression. There is a high probability that one of these approaches will soon result in a safe and effective inhibitor of glucose production.
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Affiliation(s)
- Joseph Proietto
- Department of Medicine (J.P., S.A.), Repatriation Hospital, Heidelberg, Australia
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12
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Cabrero A, Merlos M, Laguna JC, Carrera MV. Down-regulation of acyl-CoA oxidase gene expression and increased NF-kappaB activity in etomoxir-induced cardiac hypertrophy. J Lipid Res 2003; 44:388-98. [PMID: 12576521 DOI: 10.1194/jlr.m200294-jlr200] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Activation of nuclear factor-kappaB (NF-kappaB) is required for hypertrophic growth of cardiomyocytes. Etomoxir is an irreversible inhibitor of carnitine palmitoyltransferase I (CPT-I) that activates peroxisome proliferator-activated receptor alpha (PPARalpha) and induces cardiac hypertrophy through an unknown mechanism. We studied the mRNA expression of genes involved in fatty acid oxidation in the heart of mice treated for 1 or 10 days with etomoxir (100 mg/kg/day). Etomoxir administration for 1 day significantly increased (4.4-fold induction) the mRNA expression of acyl-CoA oxidase (ACO), which catalyzes the rate-limiting step in peroxisomal beta-oxidation. In contrast, etomoxir treatment for 10 days dramatically decreased ACO mRNA levels by 96%. The reduction in ACO expression in the hearts of 10-day etomoxir-treated mice was accompanied by an increase in the mRNA expression of the antioxidant enzyme glutathione peroxidase and the cardiac marker of oxidative stress bax. Moreover, the activity of the redox-regulated transcription factor NF-kappaB was increased in heart after 10 days of etomoxir treatment. Overall, the findings here presented show that etomoxir treatment may induce cardiac hypertrophy via increased cellular oxidative stress and NF-kappaB activation.
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Affiliation(s)
- Agatha Cabrero
- Unitat de Farmacologia, Departament de Farmacologia i Química Terapeùtica, Facultat de Farmàcia, Universitat de Barcelona, Spain
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Ramsay RR, Gandour RD, van der Leij FR. Molecular enzymology of carnitine transfer and transport. BIOCHIMICA ET BIOPHYSICA ACTA 2001; 1546:21-43. [PMID: 11257506 DOI: 10.1016/s0167-4838(01)00147-9] [Citation(s) in RCA: 257] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Carnitine (L-3-hydroxy-4-N-trimethylaminobutyric acid) forms esters with a wide range of acyl groups and functions to transport and excrete these groups. It is found in most cells at millimolar levels after uptake via the sodium-dependent carrier, OCTN2. The acylation state of the mobile carnitine pool is linked to that of the limited and compartmentalised coenzyme A pools by the action of the family of carnitine acyltransferases and the mitochondrial membrane transporter, CACT. The genes and sequences of the carriers and the acyltransferases are reviewed along with mutations that affect activity. After summarising the accepted enzymatic background, recent molecular studies on the carnitine acyltransferases are described to provide a picture of the role and function of these freely reversible enzymes. The kinetic and chemical mechanisms are also discussed in relation to the different inhibitors under study for their potential to control diseases of lipid metabolism.
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Affiliation(s)
- R R Ramsay
- Centre for Biomolecular Sciences, University of St Andrews, North Haugh, St Andrews KY16 9ST, UK.
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Yotsumoto T, Naitoh T, Kitahara M, Tsuruzoe N. Effects of carnitine palmitoyltransferase I inhibitors on hepatic hypertrophy. Eur J Pharmacol 2000; 398:297-302. [PMID: 10854842 DOI: 10.1016/s0014-2999(00)00288-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
We investigated the effect of two types of carnitine palmitoyltransferase I inhibitors, ethyl 2-(6-(4-chlorophenoxy)hexyl)oxirane-2-carboxylate (etomoxir) and (R)-3-carboxy-N,N, N-trimethyl-2-¿[hydroxy(tetradecyloxy)phosphinyl]oxy¿-1-propana minium hydroxide (SDZ CPI 975), on cardiac and hepatic hypertrophy in ddY mice. One-week administration of etomoxir caused cardiac and hepatic hypertrophy, 19% and 22% as a ratio to body weight, respectively. Although 4-week administration of etomoxir caused hepatic hypertrophy, there was no significant change in liver triglyceride content in the first or second week. In cultured HepG(2) cells, etomoxir treatment (1 week) did not cause triglyceride to accumulate. One-week administration of SDZ CPI 975 caused neither cardiac nor hepatic hypertrophy. In vitro, neither drug had selectivity for carnitine palmitoyltransferase I isozymes. These findings suggest that the hepatic hypertrophy following 1- or 2-week treatment with etomoxir is caused by mechanisms different from those responsible for triglyceride accumulation, and that inhibition of carnitine palmitoyltransferase I may not necessarily induce hepatic hypertrophy.
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Affiliation(s)
- T Yotsumoto
- Shiraoka Research Station of Biological Science, Nissan Chemical Industries Ltd., 1470, Shiraoka, Minamisaitama, Saitama, 349-0294, Japan
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Savle PS, Pande SV, Lee TS, Gandour RD. Stereoisomeric acylamidomorpholinium carnitine analogues: selective inhibitors of carnitine palmitoyltransferase I and II. Bioorg Med Chem Lett 1999; 9:3099-102. [PMID: 10560732 DOI: 10.1016/s0960-894x(99)00543-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Acylamidomorpholinium carnitine analogues, 6-(tetradecanamidomethyl- and -hexadecanamidomethyl)-4,4-dimethylmorpholin-4-ium-2-a cetate, 1, synthesized as complete sets of stereoisomers, were assayed as inhibitors for isozymes of carnitine palmitoyltransferase (CPT). Microsomal CPT isoymes showed modest discrimination among the stereoisomers; while rat-liver mitochondrial CPT-I and CPT-II showed distinct differences. The tetradecanamidomethyl analogue of (2R,6S)-1 activated CPT-I but inhibited CPT-II.
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Affiliation(s)
- P S Savle
- Department of Chemistry, Virginia Tech, Blacksburg 24061-0212, USA
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16
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Zhou YP, Cockburn BN, Pugh W, Polonsky KS. Basal insulin hypersecretion in insulin-resistant Zucker diabetic and Zucker fatty rats: role of enhanced fuel metabolism. Metabolism 1999; 48:857-64. [PMID: 10421226 DOI: 10.1016/s0026-0495(99)90219-6] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The biochemical mechanisms responsible for basal hyperinsulinemia in insulin-resistant states have not been fully defined. We therefore studied pancreatic beta-cell function in vitro to characterize the relative importance of fuel metabolism or secretion via a constitutive pathway in the maintenance of high basal insulin secretion in Zucker diabetic fatty (ZDF) and Zucker fatty (ZF) rats. Insulin secretion from ZF (10+/-1.8 v 5+/-0.6 pmol/ng DNA/h) and ZDF (30+/-4 v 7+/-0.8 pmol/ng DNA/h) islets at 2.8 mmol/L glucose was two to four times greater than secretion from islets of lean littermate control rats. In response to a decreasing glucose concentration (from 12 to 0 mmol/L), a paradoxical increase in insulin secretion was observed in perfused ZDF rat pancreas. Insulin secretion at 2.8 mmol/L glucose was suppressed approximately 70% to 80% in islets from ZDF and ZF rats following exposure to diazoxide, a K+-adenosine triphosphate (K(ATP)) channel opener that inhibits membrane depolarization, or rotenone and oligomycin, agents that inhibit ATP production, or by incubation at 23 degrees C. Inhibition of glycolysis with mannoheptulose, 2-deoxyglucose, and iodoacetate or fatty acid oxidation with a carnitine palmitoyltransferase I inhibitor also significantly inhibited basal insulin secretion in islets of ZDF and ZF rats but not their lean littermates. Furthermore, the glycolytic flux at 2.8 mmol/L glucose was significantly higher in ZDF islets versus ZDF lean littermate (ZLC) islets (2.2+/-0.1 v 3.7+/-0.3 pmol/ng DNA/2 h, P < .01) and was suppressed by mannoheptulose. In ZDF and ZF islets, high basal insulin secretion was maintained despite a 50% reduction in the rate of proinsulin/insulin biosynthesis at 2.8 mmol/L glucose. The rate of proinsulin to insulin conversion and the ratio of proinsulin to insulin secretion by islets of ZDF rats were similar to the values in the lean littermates. Thus, basal hypersecretion in these two insulin-resistant models appears to be related to enhanced fuel metabolism rather than the contribution of a constitutive pathway of secretion.
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Affiliation(s)
- Y P Zhou
- Department of Medicine, The University of Chicago, IL 60637, USA
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Szczepaniak LS, Babcock EE, Schick F, Dobbins RL, Garg A, Burns DK, McGarry JD, Stein DT. Measurement of intracellular triglyceride stores by H spectroscopy: validation in vivo. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 276:E977-89. [PMID: 10329993 DOI: 10.1152/ajpendo.1999.276.5.e977] [Citation(s) in RCA: 298] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We validate the use of 1H magnetic resonance spectroscopy (MRS) to quantitatively differentiate between adipocyte and intracellular triglyceride (TG) stores by monitoring the TG methylene proton signals at 1.6 and 1.4 ppm, respectively. In two animal models of intracellular TG accumulation, intrahepatic and intramyocellular TG accumulation was confirmed histologically. Consistent with the histological changes, the methylene signal intensity at 1.4 ppm increased in both liver and muscle, whereas the signal at 1.6 ppm was unchanged. In response to induced fat accumulation, the TG concentration in liver derived from 1H MRS increased from 0 to 44.9 +/- 13.2 micromol/g, and this was matched by increases measured biochemically (2.1 +/- 1.1 to 46.1 +/- 10.9 micromol/g). Supportive evidence that the methylene signal at 1.6 ppm in muscle is derived from investing interfascial adipose tissue was the finding that, in four subjects with generalized lipodystrophy, a disease characterized by absence of interfacial fat, no signal was detected at 1.6 ppm; however, a strong signal was seen at 1.4 ppm. An identical methylene chemical shift at 1.4 ppm was obtained in human subjects with fatty liver where the fat is located exclusively within hepatocytes. In experimental animals, there was a close correlation between hepatic TG content measured in vivo by 1H MRS and chemically by liver biopsy [R = 0.934; P <.0001; slope 0.98, confidence interval (CI) 0.70-1.17; y-intercept 0.26, CI -0.28 to 0. 70]. When applied to human calf muscle, the coefficient of variation of the technique in measuring intramyocellular TG content was 11.8% in nonobese subjects and 7.9% in obese subjects and of extramyocellular (adipocyte) fat was 22.6 and 52.5%, respectively. This study demonstrates for the first time that noninvasive in vivo 1H MRS measurement of intracellular TG, including that within myocytes, is feasible at 1.5-T field strengths and is comparable in accuracy to biochemical measurement. In addition, in mixed tissue such as muscle, the method is clearly advantageous in differentiating between TG from contaminating adipose tissue compared with intramyocellular lipids.
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Affiliation(s)
- L S Szczepaniak
- Center for Diabetes Research, University of Texas Southwestern Medical Center, Dallas, Texas 75235, USA
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Affiliation(s)
- M J Reed
- Shaman Pharmaceuticals, Inc, South San Francisco, CA, USA.
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Hutchison TL, Brouillette WJ. Synthesis of 2-[6-(2,4-dinitrophenoxy)hexyl]oxiranecarboxylic acid: a selective carnitine palmitoyltransferase-1 inhibitor. Bioorg Med Chem 1998; 6:2133-8. [PMID: 9881103 DOI: 10.1016/s0968-0896(98)00175-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Carnitine palmitoyltransferases 1 and 2 (CPT-1 and CPT-2) catalyze the transfer of long chain fatty acids between carnitine and coenzyme A. Unlike CPT-2, CPT-1 exists in at least two isoforms with different physical and kinetic properties. Liver and skeletal muscle each contain a different isoform of CPT-1. Cardiac muscle contains both isoforms, and the minor component is identical to the isoform found in the liver. 2-[6-(2,4-Dinitrophenoxy)hexyl]oxiranecarboxylic acid (2) was reported to be a selective inhibitor for the liver isoform of CPT-1. A synthesis of 2 is described here which involves the reaction of diethyl malonate with 1-bromo-6-phenoxyhexane.
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Affiliation(s)
- T L Hutchison
- Department of Chemistry, University of Alabama at Birmingham 35294, USA
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Deems RO, Anderson RC, Foley JE. Hypoglycemic effects of a novel fatty acid oxidation inhibitor in rats and monkeys. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 274:R524-8. [PMID: 9486313 DOI: 10.1152/ajpregu.1998.274.2.r524] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Increased fatty acid oxidation contributes to hyperglycemia in patients with non-insulin-dependent diabetes mellitus. To improve glucose homeostasis in these patients, we have designed a novel, reversible inhibitor of carnitine palmitoyl-transferase I (CPT I) that potently inhibits fatty acid oxidation. SDZ-CPI-975 significantly lowered glucose levels in normal 18-h-fasted nonhuman primates and rats. In rats, glucose lowering required fatty acid oxidation inhibition of > or = 70%, as measured by beta-hydroxybutyrate levels, the end product of beta-oxidation. In cynomolgus monkeys, comparable glucose lowering was achieved with more modest lowering of beta-hydroxybutyrate levels. SDZ-CPI-975 did not increase glucose utilization by heart muscle, suggesting that CPT I inhibition with SDZ-CPI-975 would not induce cardiac hypertrophy. This was in contrast to the irreversible CPT I inhibitor etomoxir. These results demonstrate that SDZ-CPI-975 effectively inhibited fatty acid oxidation and lowered blood glucose levels in two species. Thus reversible inhibitors of CPT I represent a class of novel hypoglycemic agents that inhibit fatty acid oxidation without inducing cardiac hypertrophy.
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Affiliation(s)
- R O Deems
- Novartis Pharmaceuticals Corporation, East Hanover, New Jersey 07936, USA
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Recent Advances in the Development of Agents for the Treatment of Type 2 Diabetes. ANNUAL REPORTS IN MEDICINAL CHEMISTRY 1998. [DOI: 10.1016/s0065-7743(08)61086-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
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Britton CH, Mackey DW, Esser V, Foster DW, Burns DK, Yarnall DP, Froguel P, McGarry JD. Fine chromosome mapping of the genes for human liver and muscle carnitine palmitoyltransferase I (CPT1A and CPT1B). Genomics 1997; 40:209-11. [PMID: 9070950 DOI: 10.1006/geno.1996.4539] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- C H Britton
- Department of Internal Medicine, University of Texas Southwestern Medical Center at Dallas 75235, USA
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McGarry JD, Brown NF. The mitochondrial carnitine palmitoyltransferase system. From concept to molecular analysis. EUROPEAN JOURNAL OF BIOCHEMISTRY 1997; 244:1-14. [PMID: 9063439 DOI: 10.1111/j.1432-1033.1997.00001.x] [Citation(s) in RCA: 1163] [Impact Index Per Article: 43.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
First conceptualized as a mechanism for the mitochondrial transport of long-chain fatty acids in the early 1960s, the carnitine palmitoyltransferase (CPT) system has since come to be recognized as a pivotal component of fuel homeostasis. This is by virtue of the unique sensitivity of the outer membrane CPT I to the simple molecule, malonyl-CoA. In addition, both CPT I and the inner membrane enzyme, CPT II, have proved to be loci of inherited defects, some with disastrous consequences. Early efforts using classical approaches to characterize the CPT proteins in terms of structure/function/regulatory relationships gave rise to confusion and protracted debate. By contrast, recent application of molecular biological tools has brought major enlightenment at an exponential pace. Here we review some key developments of the last 20 years that have led to our current understanding of the physiology of the CPT system, the structure of the CPT isoforms, the chromosomal localization of their respective genes, and the identification of mutations in the human population.
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Affiliation(s)
- J D McGarry
- Department of Internal Medicine and Biochemistry, University of Texas Southwestern Medical Center, Dallas 75235-9135, USA
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