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Xie J, Wang S, Ma P, Ma F, Li J, Wang W, Lu F, Xiong H, Gu Y, Zhang S, Xu H, Yang G, Lerner RA. Selection of Small Molecules that Bind to and Activate the Insulin Receptor from a DNA-Encoded Library of Natural Products. iScience 2020; 23:101197. [PMID: 32544667 PMCID: PMC7298650 DOI: 10.1016/j.isci.2020.101197] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Revised: 02/21/2020] [Accepted: 05/21/2020] [Indexed: 12/11/2022] Open
Abstract
Although insulin is a life-saving medicine, administration by daily injection remains problematic. Our goal was to exploit the power of DNA-encoded libraries to identify molecules with insulin-like activity but with the potential to be developed as oral drugs. Our strategy involved using a 104-member DNA-encoded library containing 160 Traditional Chinese Medicines (nDEL) to identify molecules that bind to and activate the insulin receptor. Importantly, we used the natural ligand, insulin, to liberate bound molecules. Using this selection method on our relatively small, but highly diverse, nDEL yielded a molecule capable of both binding to and activating the insulin receptor. Chemical analysis showed this molecule to be a polycyclic analog of the guanidine metformin, a known drug used to treat diabetes. By using our protocol with other, even larger, DELs we can expect to identify additional organic molecules capable of binding to and activating the insulin receptor. Annotation of natural products via complementary bifunctional linkers Function-guided DEL selection using the natural ligand for competitive elution Identification of Rutaecarpine as a binder and activator of insulin receptor
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Affiliation(s)
- Jia Xie
- Department of Chemistry, Scripps Research Institute, La Jolla, CA 92037, USA
| | - Shuyue Wang
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai 201210, China; School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China; Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Peixiang Ma
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai 201210, China
| | - Fei Ma
- Department of Chemistry, Scripps Research Institute, La Jolla, CA 92037, USA
| | - Jie Li
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai 201210, China; School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China; Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wei Wang
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai 201210, China
| | - Fengping Lu
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai 201210, China
| | - Huan Xiong
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai 201210, China
| | - Yuang Gu
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai 201210, China; School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China; Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Shuning Zhang
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai 201210, China; School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China; Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Hongtao Xu
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai 201210, China.
| | - Guang Yang
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai 201210, China.
| | - Richard A Lerner
- Department of Chemistry, Scripps Research Institute, La Jolla, CA 92037, USA.
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Discovery of potent and orally active 1,4-disubstituted indazoles as novel allosteric glucokinase activators. Bioorg Med Chem Lett 2017; 27:2678-2682. [DOI: 10.1016/j.bmcl.2017.04.041] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Revised: 04/10/2017] [Accepted: 04/12/2017] [Indexed: 01/23/2023]
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Cheruvallath ZS, Gwaltney SL, Sabat M, Tang M, Feng J, Wang H, Miura J, Guntupalli P, Jennings A, Hosfield D, Lee B, Wu Y. Design, synthesis and SAR of novel glucokinase activators. Bioorg Med Chem Lett 2013; 23:2166-71. [DOI: 10.1016/j.bmcl.2013.01.093] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2012] [Revised: 01/17/2013] [Accepted: 01/22/2013] [Indexed: 10/27/2022]
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Bonn P, Brink DM, Fägerhag J, Jurva U, Robb GR, Schnecke V, Svensson Henriksson A, Waring MJ, Westerlund C. The discovery of a novel series of glucokinase activators based on a pyrazolopyrimidine scaffold. Bioorg Med Chem Lett 2012; 22:7302-5. [DOI: 10.1016/j.bmcl.2012.10.090] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Revised: 10/16/2012] [Accepted: 10/19/2012] [Indexed: 10/27/2022]
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Waring MJ, Clarke DS, Fenwick MD, Godfrey L, Groombridge SD, Johnstone C, McKerrecher D, Pike KG, Rayner JW, Robb GR, Wilson I. Property based optimisation of glucokinase activators – discovery of the phase IIb clinical candidate AZD1656. MEDCHEMCOMM 2012. [DOI: 10.1039/c2md20077e] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Song HP, Tian K, Lei L, Shen ZF, Liu SX, Zhang LJ, Song HR, Jin XF, Feng ZQ. Novel N-(pyrimidin-4-yl)thiazol-2-amine derivatives as dual-action hypoglycemic agents that activate GK and PPARγ. Acta Pharm Sin B 2011. [DOI: 10.1016/j.apsb.2011.07.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
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Pike KG, Allen JV, Caulkett PW, Clarke DS, Donald CS, Fenwick ML, Johnson KM, Johnstone C, McKerrecher D, Rayner JW, Walker RP, Wilson I. Design of a potent, soluble glucokinase activator with increased pharmacokinetic half-life. Bioorg Med Chem Lett 2011; 21:3467-70. [DOI: 10.1016/j.bmcl.2011.03.093] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2011] [Revised: 03/21/2011] [Accepted: 03/22/2011] [Indexed: 01/23/2023]
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Waring MJ, Johnstone C, McKerrecher D, Pike KG, Robb G. Matrix-based multiparameter optimisation of glucokinase activators: the discovery of AZD1092. MEDCHEMCOMM 2011. [DOI: 10.1039/c1md00092f] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Waring MJ, Brogan IJ, Coghlan M, Johnstone C, Jones HB, Leighton B, McKerrecher D, Pike KG, Robb GR. Overcoming retinoic acid receptor-α based testicular toxicity in the optimisation of glucokinase activators. MEDCHEMCOMM 2011. [DOI: 10.1039/c1md00090j] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Wu CF, Xu Y, Tao Y, Yang JY. Establishment of hypoglycemic agent screening method based on human glucokinase. BIOMEDICAL AND ENVIRONMENTAL SCIENCES : BES 2009; 22:62-69. [PMID: 19462690 DOI: 10.1016/s0895-3988(09)60024-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
OBJECTIVE To establish a reliable platform for screening glucokinase activators (GKAs) in vitro. METHODS Pancreatic glucokinase (PGK) protein expressed in a prokaryotic expression system as a histidine-tagged fusion protein from Homo sapiens was produced. Then, response surface methodology (RSM) was used to optimize the microplate-based GKA screening platform. In the first step of optimization with Plackett-Burman design (PBD), initial pH, reaction time and MgCl2 were found to be important factors affecting the activity ratio of GKA (RO-28-1675) significantly. In the second step, a 2(3) full factorial central composite design (CCD) and RSM were applied to the optimal condition determination of each significant variable. A second-order polynomial was determined by a multiple regression analysis of the experimental data. RESULTS The following optimal values for the critical factors were obtained: initial pH 0 (7.0), reaction time-0.63 (13.7 min) and MgCl2 0.11 (2.11 mmol/L) with a predicted value of the maximum activity ratio of 34.1%. CONCLUSION Under the optimal conditions, the practical activity ratio is 34.8%. The determination coefficient (R2) is 0.9442, ensuring adequate credibility of the model. LLAE3, extracted from Folium nelumbinis in our laboratory, has prominently activated effects on PGK.
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Affiliation(s)
- Chou-Fei Wu
- Key Laboratory of State Food Science and Technology, Jiangxi-OAI Joint Research Institute, Nanchang University, Nanchang 330047, Jiangxi, China
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Wyne KL. Management of type 2 diabetes mellitus: is it time for a paradigm shift? Metab Syndr Relat Disord 2008; 2:251-62. [PMID: 18370694 DOI: 10.1089/met.2004.2.251] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Type 2 diabetes mellitus is a multi-organ disease that results from the combination of insulin resistance and a beta-cell secretory defect. The worldwide prevalence of type 2 diabetes has increased substantially during the past decade, and patients with this disease continue to experience a high incidence of morbidity and mortality. Because the complications associated with this disease affect multiple organ systems and have a dramatic impact on daily life, the importance of lowering glycosylated hemoglobin (HbA(1c)) levels to within the normal range cannot be overemphasized. The introduction in the past decade of several new classes of pharmacological agents to treat patients with type 2 diabetes now provides the opportunity to focus therapy on treating the underlying disease process instead of just reacting to the blood glucose levels. The thiazolidinediones are unique in their ability to modulate free fatty acid metabolism and to improve insulin sensitivity. These agents also exert numerous nonglycemic effects on the vasculature and lipid metabolism and may improve many of the risk factors associated with metabolic syndrome. Data from the United Kingdom Prospective Diabetes Study (UKPDS) group showed that conventional methods of managing type 2 diabetes, including the use of sulfonylureas or biguanides, do not provide long-term glycemic control. Consequently, new treatment paradigms stressing the earlier use of thiazolidinediones, either alone or in combination with metformin, may lead to more durable glycemic control, thus facilitating the reduction of complications in patients with type 2 diabetes.
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Affiliation(s)
- Kathleen L Wyne
- Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas
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12
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Chen L, Li H, Liu J, Zhang L, Liu H, Jiang H. Discovering benzamide derivatives as glycogen phosphorylase inhibitors and their binding site at the enzyme. Bioorg Med Chem 2007; 15:6763-74. [PMID: 17719791 DOI: 10.1016/j.bmc.2007.08.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2007] [Revised: 07/31/2007] [Accepted: 08/01/2007] [Indexed: 12/14/2022]
Abstract
A series of novel benzamide derivatives was designed, synthesized, and their inhibitory activities against glycogen phosphorylase (GP) in the direction of glycogen synthesis by the release of phosphate from glucose-1-phosphate were evaluated. The structure-activity relationships (SAR) of these compounds are also presented. Within this series of compounds, 4m is the most potent GPa inhibitor (IC(50)=2.68 microM), which is nearly 100 times more potent than the initial compound 1. Analysis of mapping between pharmacophores of different binding sites and each compound demonstrated that these benzamide derivatives bind at the dimer interface of the rabbit muscle enzyme, and possible docking modes of compound 4m were explored by molecular docking simulation.
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Affiliation(s)
- Ling Chen
- Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, PR China
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Poucher SM, Freeman S, Loxham SJG, Convey G, Bartlett JB, De Schoolmeester J, Teague J, Walker M, Turnbull AV, Charles AD, Carey F, Berg S. An assessment of the in vivo efficacy of the glycogen phosphorylase inhibitor GPi688 in rat models of hyperglycaemia. Br J Pharmacol 2007; 152:1239-47. [PMID: 17934512 DOI: 10.1038/sj.bjp.0707502] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND AND PURPOSE Studies in cultured hepatocytes demonstrate glycogen synthase (GS) activation with glycogen phosphorylase (GP) inhibitors. The current study investigated whether these phenomena occurred in vivo using a novel GP inhibitor. EXPERIMENTAL APPROACH An allosteric GP inhibitor, GPi688, was evaluated against both glucagon-mediated hyperglycaemia and oral glucose challenge-mediated hyperglycaemia to determine the relative effects against GP and GS in vivo. KEY RESULTS In rat primary hepatocytes, GPi688 inhibited glucagons-mediated glucose output in a concentration dependent manner. Additionally GP activity was reduced and GS activity increased seven-fold. GPi688 inhibited glucagon-mediated hyperglycaemia in both Wistar (65%) & obese Zucker (100%) rats and demonstrated a long duration of action in the Zucker rat. The in vivo efficacy in the glucagon challenge model could be predicted by the equation; % glucagon inhibition=56.9+34.3[log ([free plasma]/rat IC50)], r=0.921). GPi688 also reduced the blood glucose of obese Zucker rats after a 7 h fast by 23%. In an oral glucose tolerance test in Zucker rats, however, GPi688 was less efficacious (7% reduction) than a glycogen synthase kinase-3 (GSK-3) inhibitor (22% reduction), despite also observing activation (by 45%) of GS in vivo. CONCLUSIONS AND IMPLICATIONS Although GP inhibition can inhibit hyperglycaemia mediated by increased glucose production, the degree of GS activation induced by allosteric GP inhibitors in vivo, although discernible, is insufficient to increase glucose disposal. The data suggests that GP inhibitors might be more effective clinically against fasting rather than prandial hyperglycaemic control.
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Affiliation(s)
- S M Poucher
- Cardiovascular & Gastrointestinal Discovery Department, AstraZeneca Pharmaceuticals, Alderley Park, Macclesfield, Cheshire, UK.
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. JO, . CA. Evaluation of Hypoglycemic Activity of Glycosides and Alkaloids Extracts of Picralima nitida Stapf (Apocynaceae) Seed. INT J PHARMACOL 2007. [DOI: 10.3923/ijp.2007.505.509] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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McKerrecher D, Allen JV, Caulkett PWR, Donald CS, Fenwick ML, Grange E, Johnson KM, Johnstone C, Jones CD, Pike KG, Rayner JW, Walker RP. Design of a potent, soluble glucokinase activator with excellent in vivo efficacy. Bioorg Med Chem Lett 2006; 16:2705-9. [PMID: 16503142 DOI: 10.1016/j.bmcl.2006.02.022] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2006] [Revised: 02/07/2006] [Accepted: 02/07/2006] [Indexed: 10/25/2022]
Abstract
The optimisation of a series of glucokinase activators is described, including attempts to uncouple the relationship between potency and plasma protein binding, and to better understand the key pharmacokinetic properties of the series. The use of unbound clearance as an optimisation parameter facilitated the identification of GKA50, a compound which combines excellent potency and pharmacokinetics with good free drug levels and solubility, and exhibits in vivo efficacy at 1mg/kg po in an acute rat OGTT model.
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Affiliation(s)
- Darren McKerrecher
- Cardiovascular and Gastrointestinal Research Area, AstraZeneca R&D, Mereside, Alderley Park, Macclesfield, Cheshire SK10 4TG, UK.
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Sawa M, Tateishi H, Mizuno K, Harada H, Oue M, Tsujiuchi H, Furutani Y, Kato S. Tryptamine-based human beta3-adrenergic receptor agonists. Part 2: SAR of the methylene derivatives. Bioorg Med Chem Lett 2005; 14:5963-6. [PMID: 15546708 DOI: 10.1016/j.bmcl.2004.09.054] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2004] [Revised: 09/14/2004] [Accepted: 09/17/2004] [Indexed: 11/20/2022]
Abstract
A series of tryptamine derivatives with modified sulfonamide were designed, synthesized, and evaluated for their ability to stimulate cAMP accumulation in CHO cells expressing the cloned human beta3-adrenergic receptor (AR). For this series of compounds, our objective was to symmetrize the alpha-position of the tryptamine moiety maintaining its activity and reducing the cost of production. Compound 11h, having m-aminobenzene, exhibited excellent agonistic activity for beta3-AR with excellent subtype selectivity.
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Affiliation(s)
- Masaaki Sawa
- Chemistry Research Laboratories, Dainippon Pharmaceutical Co., Ltd, 33-94 Enoki-cho, Suita, Osaka 564-0053, Japan.
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McKerrecher D, Allen JV, Bowker SS, Boyd S, Caulkett PW, Currie GS, Davies CD, Fenwick ML, Gaskin H, Grange E, Hargreaves RB, Hayter BR, James R, Johnson KM, Johnstone C, Jones CD, Lackie S, Rayner JW, Walker RP. Discovery, synthesis and biological evaluation of novel glucokinase activators. Bioorg Med Chem Lett 2005; 15:2103-6. [DOI: 10.1016/j.bmcl.2005.01.087] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2004] [Revised: 01/04/2005] [Accepted: 01/12/2005] [Indexed: 11/28/2022]
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Xu S, Zhu B, Teffera Y, Pan DE, Caldwell CG, Doss G, Stearns RA, Evans DC, Beconi MG. METABOLIC ACTIVATION OF FLUOROPYRROLIDINE DIPEPTIDYL PEPTIDASE-IV INHIBITORS BY RAT LIVER MICROSOMES. Drug Metab Dispos 2004; 33:121-30. [PMID: 15486074 DOI: 10.1124/dmd.104.001842] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The current study evaluated the potential for two dipeptidyl peptidase-IV (DPP-IV) inhibitor analogs (1S)-1-(trans-4-([(4-trifluoromethoxyphenyl)sulfonyl]amino)cyclohexyl)-2-[(3S)-3-fluoropyrrolidin-1-yl]-2-oxoethanaminium chloride and (1S)-1-(trans-4-([(2,4-difluorophenyl)sulfonyl]amino)cyclohexyl)-2-[(3S)-3-fluoropyrrolidin-1-yl]-2-oxoethanaminium chloride (MRL-A and MRL-B), containing a fluoropyrrolidine moiety in the structure, to undergo metabolic activation. The irreversible binding of these tritium-labeled compounds to rat liver microsomal protein was time- and NADPH-dependent and was attenuated by the addition of reduced glutathione (GSH) or N-acetylcysteine (NAC) to the incubation, indicating that chemically reactive intermediates were formed and trapped by these nucleophiles. Mass spectrometric analyses and further trapping experiments with semicarbazide indicated that the fluoropyrrolidine ring had undergone sequential oxidation and defluorination events resulting in the formation of GSH or NAC conjugates of the pyrrolidine moiety. The bioactivation of MRL-A was catalyzed primarily by rat recombinant CYP3A1 and CYP3A2. Pretreatment of rats with prototypic CYP3A1 and 3A2 inducers (pregnenolone-16alpha-carbonitrile and dexamethasone) enhanced the extent of bioactivation which, in turn, led to a higher degree of in vitro irreversible binding to microsomal proteins (5- and 9-fold increase, respectively). Herein, we describe studies that demonstrate that the fluoropyrrolidine ring is prone to metabolic activation and that GSH or NAC can trap the reactive intermediates to form adducts that provide insight into the mechanisms of bioactivation.
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Affiliation(s)
- Shiyao Xu
- Department of Drug Metabolism, Merck Research Laboratories, P.O. Box 2000, RY80E-200, Rahway, NJ 07065-0900, USA.
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Welters HJ, McBain SC, Tadayyon M, Scarpello JHB, Smith SA, Morgan NG. Expression and functional activity of PPARgamma in pancreatic beta cells. Br J Pharmacol 2004; 142:1162-70. [PMID: 15237101 PMCID: PMC1575182 DOI: 10.1038/sj.bjp.0705844] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Rosiglitazone is an agonist of peroxisome proliferator activated receptor-gamma (PPARgamma) and ameliorates insulin resistance in type II diabetes. In addition, it may also promote increased pancreatic beta-cell viability, although it is not known whether this effect is mediated by a direct action on the beta cell. We have investigated this possibility. Semiquantitative real-time reverse transcription-polymerase chain reaction analysis (Taqman) revealed that freshly isolated rat islets and the clonal beta-cell line, BRIN-BD11, express PPARgamma, as well as PPARalpha and PPARdelta. The levels of expression of PPARgamma were estimated by reference to adipose tissue and were found to represent approximately 60% (islets) and 30% (BRIN-BD11) of that found in freshly isolated visceral adipose tissue. Western blotting confirmed the presence of immunoreactive PPARgamma in rat (and human) islets and in BRIN-BD11 cells. Transfection of BRIN-BD11 cells with a PPARgamma-sensitive luciferase reporter construct was used to evaluate the functional competence of the endogenous PPARgamma. Luciferase activity was modestly increased by the putative endogenous ligand, 15-deoxy-Delta12,14 prostaglandin J2 (15dPGJ2). Rosiglitazone also caused activation of the luciferase reporter construct but this effect required concentrations of the drug (50-100 microm) that are beyond the expected therapeutic range. This suggests that PPARgamma is relatively insensitive to activation by rosiglitazone in BRIN-BD11 cells. Exposure of BRIN-BD11 cells to the lipotoxic effector, palmitate, caused a marked loss of viability. This was attenuated by treatment of the cells with either actinomycin D or cycloheximide suggesting that a pathway of programmed cell death was involved. Rosiglitazone failed to protect BRIN-BD11 cells from the toxic actions of palmitate at concentrations up to 50 microm. Similar results were obtained with a range of other PPARgamma agonists. Taken together, the present data suggest that, at least under in vitro conditions, thiazolidinediones do not exert direct protective effects against fatty acid-mediated cytotoxicity in pancreatic beta cells.
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Affiliation(s)
- Hannah J Welters
- Institute of Biomedical and Clinical Science, Peninsula Medical School, Plymouth, Devon
| | | | | | | | | | - Noel G Morgan
- Institute of Biomedical and Clinical Science, Peninsula Medical School, Plymouth, Devon
- Author for correspondence:
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Brocklehurst KJ, Payne VA, Davies RA, Carroll D, Vertigan HL, Wightman HJ, Aiston S, Waddell ID, Leighton B, Coghlan MP, Agius L. Stimulation of hepatocyte glucose metabolism by novel small molecule glucokinase activators. Diabetes 2004; 53:535-41. [PMID: 14988235 DOI: 10.2337/diabetes.53.3.535] [Citation(s) in RCA: 118] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Glucokinase (GK) has a major role in the control of blood glucose homeostasis and is a strong potential target for the pharmacological treatment of type 2 diabetes. We report here the mechanism of action of two novel and potent direct activators of GK: 6-[(3-isobutoxy-5-isopropoxybenzoyl)amino]nicotinic acid(GKA1) and 5-([3-isopropoxy-5-[2-(3-thienyl)ethoxy]benzoyl]amino)-1,3,4-thiadiazole-2-carboxylic acid(GKA2), which increase the affinity of GK for glucose by 4- and 11-fold, respectively. GKA1 increased the affinity of GK for the competitive inhibitor mannoheptulose but did not affect the affinity for the inhibitors palmitoyl-CoA and the endogenous 68-kDa regulator (GK regulatory protein [GKRP]), which bind to allosteric sites or to N-acetylglucosamine, which binds to the catalytic site. In hepatocytes, GKA1 and GKA2 stimulated glucose phosphorylation, glycolysis, and glycogen synthesis to a similar extent as sorbitol, a precursor of fructose 1-phosphate, which indirectly activates GK through promoting its dissociation from GKRP. Consistent with their effects on isolated GK, these compounds also increased the affinity of hepatocyte metabolism for glucose. GKA1 and GKA2 caused translocation of GK from the nucleus to the cytoplasm. This effect was additive with the effect of sorbitol and is best explained by a "glucose-like" effect of the GK activators in translocating GK to the cytoplasm. In conclusion, GK activators are potential antihyperglycemic agents for the treatment of type 2 diabetes through the stimulation of hepatic glucose metabolism by a mechanism independent of GKRP.
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Affiliation(s)
- Katy J Brocklehurst
- Cardiovascular and Gastrointestinal Department, AstraZeneca, Macclesfield, Cheshire, U.K
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