51
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Caporale A, Doti N, Monti A, Sandomenico A, Ruvo M. Automatic procedures for the synthesis of difficult peptides using oxyma as activating reagent: A comparative study on the use of bases and on different deprotection and agitation conditions. Peptides 2018; 102:38-46. [PMID: 29486214 DOI: 10.1016/j.peptides.2018.02.006] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Revised: 01/31/2018] [Accepted: 02/16/2018] [Indexed: 12/17/2022]
Abstract
Solid-Phase Peptide Synthesis (SPPS) is a rapid and efficient methodology for the chemical synthesis of peptides and small proteins. However, the assembly of peptide sequences classified as "difficult" poses severe synthetic problems in SPPS for the occurrence of extensive aggregation of growing peptide chains which often leads to synthesis failure. In this framework, we have investigated the impact of different synthetic procedures on the yield and final purity of three well-known "difficult peptides" prepared using oxyma as additive for the coupling steps. In particular, we have comparatively investigated the use of piperidine and morpholine/DBU as deprotection reagents, the addition of DIPEA, collidine and N-methylmorpholine as bases to the coupling reagent. Moreover, the effect of different agitation modalities during the acylation reactions has been investigated. Data obtained represent a step forward in optimizing strategies for the synthesis of "difficult peptides".
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Affiliation(s)
- A Caporale
- IBB-CNR, Via Mezzocannone 16, 80134 Napoli, Italy; CIRPeB, Via Mezzocannone 16, 80134 Napoli, Italy
| | - N Doti
- IBB-CNR, Via Mezzocannone 16, 80134 Napoli, Italy; CIRPeB, Via Mezzocannone 16, 80134 Napoli, Italy.
| | - A Monti
- IBB-CNR, Via Mezzocannone 16, 80134 Napoli, Italy; DiSTABiF, Università degli Studi della Campania "Luigi Vanvitelli", Via Vivaldi 43, 81100, Caserta, Italy
| | - A Sandomenico
- IBB-CNR, Via Mezzocannone 16, 80134 Napoli, Italy; CIRPeB, Via Mezzocannone 16, 80134 Napoli, Italy
| | - M Ruvo
- IBB-CNR, Via Mezzocannone 16, 80134 Napoli, Italy; CIRPeB, Via Mezzocannone 16, 80134 Napoli, Italy.
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52
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Sharma A, Kumar A, Abdel Monaim SAH, Jad YE, El-Faham A, de la Torre BG, Albericio F. N-methylation in amino acids and peptides: Scope and limitations. Biopolymers 2018. [PMID: 29528112 DOI: 10.1002/bip.23110] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Active pharmaceutical ingredients (APIs) can be divided into two types, namely chemical and biological entities. Traditionally, the former has been associated with the so-called small molecules. The revival of peptides in pharmaceutical industry results from their importance in many biological roles. However, low metabolic stability and the lack of oral availability of most peptides is the main drawback for peptide to fulfill that paradigmatic situation. In this regard, efforts are being channeled into addressing this issue by introducing restrictions into the flexible peptide backbone, mainly through N-methyl amino acids (NMAAs) or development of small cyclic peptides. In many cases, both the above restrictions are combined with the aim to enhance oral availability. The synthesis of NMAAs is complex and their introduction into the peptide chain brings additional synthetic challenges and also sometimes leads to side-reactions. Here we discuss the most efficient methods for the synthesis of NMAAs (either in solution or in solid phase) and also their introduction into peptide sequences. Special attention is also given to the detection of side reactions and the most efficient way to prevent them.
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Affiliation(s)
- Anamika Sharma
- Catalysis and Peptide Research Unit, School of Health Sciences, University of KwaZulu-Natal, Westville, Durban, 4001, South Africa
| | - Ashish Kumar
- Catalysis and Peptide Research Unit, School of Health Sciences, University of KwaZulu-Natal, Westville, Durban, 4001, South Africa.,School of Chemistry and Physics, University of KwaZulu-Natal, Westville, Durban, 4001, South Africa
| | - Shimaa A H Abdel Monaim
- Catalysis and Peptide Research Unit, School of Health Sciences, University of KwaZulu-Natal, Westville, Durban, 4001, South Africa
| | - Yahya E Jad
- Catalysis and Peptide Research Unit, School of Health Sciences, University of KwaZulu-Natal, Westville, Durban, 4001, South Africa
| | - Ayman El-Faham
- Department of Chemistry, College of Science, King Saud University, Riyadh, 11451, Saudi Arabia.,Department of Chemistry, Faculty of Science, Alexandria University, Ibrahimia, Alexandria, 21321, Egypt
| | - Beatriz G de la Torre
- Catalysis and Peptide Research Unit, School of Health Sciences, University of KwaZulu-Natal, Westville, Durban, 4001, South Africa.,KRISP, College of Health Sciences, University of KwaZulu-Natal, Westville, Durban, 4001, South Africa
| | - Fernando Albericio
- Catalysis and Peptide Research Unit, School of Health Sciences, University of KwaZulu-Natal, Westville, Durban, 4001, South Africa.,School of Chemistry and Physics, University of KwaZulu-Natal, Westville, Durban, 4001, South Africa.,Department of Chemistry, College of Science, King Saud University, Riyadh, 11451, Saudi Arabia.,Department of Organic Chemistry, University of Barcelona, Martí i Franqués 1-11, Barcelona, 08028, Spain.,CIBER-BBN, Networking Centre on Bioengineering, Biomaterials and Nanomedicine, Barcelona Science Park, Baldiri Reixac 10, Barcelona, 08028, Spain
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53
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Purohit S, Li T, Guan W, Song X, Song J, Tian Y, Li L, Sharma A, Dun B, Mysona D, Ghamande S, Rungruang B, Cummings RD, Wang PG, She JX. Multiplex glycan bead array for high throughput and high content analyses of glycan binding proteins. Nat Commun 2018; 9:258. [PMID: 29343722 PMCID: PMC5772357 DOI: 10.1038/s41467-017-02747-y] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Accepted: 12/22/2017] [Indexed: 12/28/2022] Open
Abstract
Glycan-binding proteins (GBPs) play critical roles in diverse cellular functions such as cell adhesion, signal transduction and immune response. Studies of the interaction between GBPs and glycans have been hampered by the availability of high throughput and high-content technologies. Here we report multiplex glycan bead array (MGBA) that allows simultaneous analyses of 384 samples and up to 500 glycans in a single assay. The specificity, sensitivity and reproducibility of MGBA are evaluated using 39 plant lectins, 13 recombinant anti-glycan antibodies, and mammalian GBPs. We demonstrate the utility of this platform by the analyses of natural anti-glycan IgM and IgG antibodies in 961 human serum samples and the discovery of anti-glycan antibody biomarkers for ovarian cancer. Our data indicate that the MGBA platform is particularly suited for large population-based studies that require the analyses of large numbers of samples and glycans.
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Affiliation(s)
- Sharad Purohit
- Center for Biotechnology and Genomic Medicine, Medical College of Georgia, Augusta University, 1120 15th Street, Augusta, GA, 30912, USA
- Department of Obstetrics and Gynecology, Medical College of Georgia, Augusta University, 1120 15th Street, Augusta, GA, 30912, USA
- Department of Medical Laboratory, Imaging and Radiologic Sciences, College of Allied Health Sciences Augusta University, 1120 15th Street, Augusta, GA, 30912, USA
| | - Tiehai Li
- Department of Chemistry, Georgia State University, Atlanta, GA, 30303, USA
| | - Wanyi Guan
- Department of Chemistry, Georgia State University, Atlanta, GA, 30303, USA
| | - Xuezheng Song
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, 30322, USA
| | - Jing Song
- Department of Chemistry, Georgia State University, Atlanta, GA, 30303, USA
| | - Yanna Tian
- Department of Obstetrics and Gynecology, Medical College of Georgia, Augusta University, 1120 15th Street, Augusta, GA, 30912, USA
| | - Lei Li
- Department of Chemistry, Georgia State University, Atlanta, GA, 30303, USA
| | - Ashok Sharma
- Center for Biotechnology and Genomic Medicine, Medical College of Georgia, Augusta University, 1120 15th Street, Augusta, GA, 30912, USA
| | - Boying Dun
- Center for Biotechnology and Genomic Medicine, Medical College of Georgia, Augusta University, 1120 15th Street, Augusta, GA, 30912, USA
- Department of Obstetrics and Gynecology, Medical College of Georgia, Augusta University, 1120 15th Street, Augusta, GA, 30912, USA
| | - David Mysona
- Center for Biotechnology and Genomic Medicine, Medical College of Georgia, Augusta University, 1120 15th Street, Augusta, GA, 30912, USA
| | - Sharad Ghamande
- Department of Obstetrics and Gynecology, Medical College of Georgia, Augusta University, 1120 15th Street, Augusta, GA, 30912, USA
| | - Bunja Rungruang
- Department of Obstetrics and Gynecology, Medical College of Georgia, Augusta University, 1120 15th Street, Augusta, GA, 30912, USA
| | - Richard D Cummings
- Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, 02115, USA
| | - Peng George Wang
- Department of Chemistry, Georgia State University, Atlanta, GA, 30303, USA
| | - Jin-Xiong She
- Center for Biotechnology and Genomic Medicine, Medical College of Georgia, Augusta University, 1120 15th Street, Augusta, GA, 30912, USA.
- Department of Obstetrics and Gynecology, Medical College of Georgia, Augusta University, 1120 15th Street, Augusta, GA, 30912, USA.
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54
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Fraczyk J, Kaminski ZJ, Katarzynska J, Kolesinska B. 4-(4,6-Dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium Toluene-4-sulfonate (DMT/NMM/TsO−
) Universal Coupling Reagent for Synthesis in Solution. Helv Chim Acta 2017. [DOI: 10.1002/hlca.201700187] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Justyna Fraczyk
- Institute of Organic Chemistry; Lodz University of Technology; 90-924 Lodz Poland
| | - Zbigniew J. Kaminski
- Institute of Organic Chemistry; Lodz University of Technology; 90-924 Lodz Poland
| | - Joanna Katarzynska
- Institute of Organic Chemistry; Lodz University of Technology; 90-924 Lodz Poland
| | - Beata Kolesinska
- Institute of Organic Chemistry; Lodz University of Technology; 90-924 Lodz Poland
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55
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Jaradat DMM. Thirteen decades of peptide synthesis: key developments in solid phase peptide synthesis and amide bond formation utilized in peptide ligation. Amino Acids 2017; 50:39-68. [PMID: 29185032 DOI: 10.1007/s00726-017-2516-0] [Citation(s) in RCA: 133] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Accepted: 11/21/2017] [Indexed: 12/27/2022]
Abstract
A historical overview of peptide chemistry from T. Curtius to E. Fischer to M. Bergmann and L. Zervas is first presented. Next, the fundamentals of peptide synthesis with a focus on solid phase peptide synthesis by R. B. Merrifield are described. Immobilization strategies to attach the first amino acid to the resin, coupling strategies in stepwise peptide chain elongation, and approaches to synthesize difficult peptide sequences are also shown. A brief comparison between tert-butyloxycarbonyl (Boc)/benzyl (Bzl) strategy and 9-fluorenylmethoxycarbonyl (Fmoc)/tert-butyl (t -Bu) strategy utilized in solid phase peptide synthesis is given with an emphasis on the latter. Finally, the review focuses on the discovery and development of peptide ligation and the latest advances in this field including native amide bond formation strategies, these include the native chemical ligation, α-ketoacid-hydroxylamine ligation, and serine/threonine ligation which are the most commonly used chemoselective ligation methods that provide amide bond at the ligation site. This review provides an overview of the literature concerning the most important advances in the chemical synthesis of proteins and peptides covering the period from 1882 to 2017.
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Affiliation(s)
- Da'san M M Jaradat
- Department of Chemistry, Faculty of Science, Al-Balqa Applied University, P.O. Box 19117, Al-Salt, Jordan.
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56
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Konwar M, Boruah PR, Saikia PJ, Khupse ND, Sarma D. ESP-Promoted Suzuki-Miyaura Cross-Coupling and Peptide Bond Formation Reactions in Water at Room Temperature. ChemistrySelect 2017. [DOI: 10.1002/slct.201700638] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Manashjyoti Konwar
- Department of Chemistry; Dibrugarh University; Dibrugarh- 786004, Assam India
| | - Preeti Rekha Boruah
- Department of Chemistry; Dibrugarh University; Dibrugarh- 786004, Assam India
| | - Prakash J. Saikia
- Analytical Chemistry Division; CSIR-North East Institute of Science & Technology; Jorhat- 785006, Assam India
| | | | - Diganta Sarma
- Department of Chemistry; Dibrugarh University; Dibrugarh- 786004, Assam India
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57
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Rad-Malekshahi M, Fransen MF, Krawczyk M, Mansourian M, Bourajjaj M, Chen J, Ossendorp F, Hennink WE, Mastrobattista E, Amidi M. Self-Assembling Peptide Epitopes as Novel Platform for Anticancer Vaccination. Mol Pharm 2017; 14:1482-1493. [PMID: 28088862 PMCID: PMC5415879 DOI: 10.1021/acs.molpharmaceut.6b01003] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Revised: 12/29/2016] [Accepted: 01/14/2017] [Indexed: 12/17/2022]
Abstract
The aim of the present study was to improve the immunogenicity of peptide epitope vaccines using novel nanocarriers based on self-assembling materials. Several studies demonstrated that peptide antigens in nanoparticulate form induce stronger immune responses than their soluble forms. However, several issues such as poor loading and risk of inducing T cell anergy due to premature release of antigenic epitopes have challenged the clinical success of such systems. In the present study, we developed two vaccine delivery systems by appending a self-assembling peptide (Ac-AAVVLLLW-COOH) or a thermosensitive polymer poly(N-isopropylacrylamide (pNIPAm) to the N-terminus of different peptide antigens (OVA250-264, HPV-E743-57) to generate self-assembling peptide epitopes (SAPEs). The obtained results showed that the SAPEs were able to form nanostructures with a diameter from 20 to 200 nm. The SAPEs adjuvanted with CpG induced and expanded antigen-specific CD8+ T cells in mice. Furthermore, tumor-bearing mice vaccinated with SAPEs harboring the HPV E743-57 peptide showed a delayed tumor growth and an increased survival compared to sham-treated mice. In conclusion, self-assembling peptide based systems increase the immunogenicity of peptide epitope vaccines and therefore warrants further development toward clinical use.
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Affiliation(s)
- Mazda Rad-Malekshahi
- Department
of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands
- Department
of Pharmaceutical Biomaterials and Medical Biomaterials Research Center,
Faculty of Pharmacy, Tehran University of
Medical Sciences, Tehran, Iran
| | - Marieke F. Fransen
- Department
of Immunohematology and Blood Transfusion, Leiden University Medical Center, Leiden, The Netherlands
| | - Małgorzata Krawczyk
- Department
of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands
| | - Mercedeh Mansourian
- Department
of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands
| | - Meriem Bourajjaj
- Department
of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands
| | - Jian Chen
- Department
of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands
| | - Ferry Ossendorp
- Department
of Immunohematology and Blood Transfusion, Leiden University Medical Center, Leiden, The Netherlands
| | - Wim E. Hennink
- Department
of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands
| | - Enrico Mastrobattista
- Department
of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands
| | - Maryam Amidi
- Department
of Pharmaceutics, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands
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58
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Scrivanti A, Bortoluzzi M, Sole R, Beghetto V. Synthesis and characterization of yttrium, europium, terbium and dysprosium complexes containing a novel type of triazolyl–oxazoline ligand. CHEMICAL PAPERS 2017. [DOI: 10.1007/s11696-017-0174-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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59
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de Figueiredo RM, Suppo JS, Midrier C, Campagne JM. Sequential One-Pot Synthesis of Dipeptides through the Transient Formation of CDI-N
-Protected α-Aminoesters. Adv Synth Catal 2017. [DOI: 10.1002/adsc.201700034] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Renata Marcia de Figueiredo
- Institut Charles Gerhardt Montpellier; UMR 5253 CNRS-UM-ENSCM; Ecole Nationale Supérieure de Chimie de Montpellier; 8 Rue de l'Ecole Normale 34296 Montpellier Cedex 5 France
| | - Jean-Simon Suppo
- Institut Charles Gerhardt Montpellier; UMR 5253 CNRS-UM-ENSCM; Ecole Nationale Supérieure de Chimie de Montpellier; 8 Rue de l'Ecole Normale 34296 Montpellier Cedex 5 France
| | - Camille Midrier
- Institut Charles Gerhardt Montpellier; UMR 5253 CNRS-UM-ENSCM; Ecole Nationale Supérieure de Chimie de Montpellier; 8 Rue de l'Ecole Normale 34296 Montpellier Cedex 5 France
| | - Jean-Marc Campagne
- Institut Charles Gerhardt Montpellier; UMR 5253 CNRS-UM-ENSCM; Ecole Nationale Supérieure de Chimie de Montpellier; 8 Rue de l'Ecole Normale 34296 Montpellier Cedex 5 France
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60
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Landeros JM, Juaristi E. Mechanochemical Synthesis of Dipeptides Using Mg-Al Hydrotalcite as Activating Agent under Solvent-Free Reaction Conditions. European J Org Chem 2017. [DOI: 10.1002/ejoc.201601276] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- José M. Landeros
- Departamento de Química; Centro de Investigación y de Estudios Avanzados; Instituto Politécnico Nacional; Avenida IPN No. 2508 07360 Ciudad de México Mexico
| | - Eusebio Juaristi
- Departamento de Química; Centro de Investigación y de Estudios Avanzados; Instituto Politécnico Nacional; Avenida IPN No. 2508 07360 Ciudad de México Mexico
- El Colegio Nacional; Luis González Obregón No. 23, Centro Histórico 06020 Ciudad de México Mexico
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61
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Mekhail GM, Kamel AO, Awad GA, Mortada ND, Rodrigo RL, Spagnuolo PA, Wettig SD. Synthesis and evaluation of alendronate-modified gelatin biopolymer as a novel osteotropic nanocarrier for gene therapy. Nanomedicine (Lond) 2016; 11:2251-73. [PMID: 27527003 DOI: 10.2217/nnm-2016-0151] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
AIM To synthesize an osteotropic alendronate functionalized gelatin (ALN-gelatin) biopolymer for nanoparticle preparation and targeted delivery of DNA to osteoblasts for gene therapy applications. MATERIALS & METHODS Alendronate coupling to gelatin was confirmed using Fourier transform IR, (31)PNMR, x-ray diffraction (XRD) and differential scanning calorimetry. ALN-gelatin biopolymers prepared at various alendronate/gelatin ratios were utilized to prepare nanoparticles and were optimized in combination with DNA and gemini surfactant for transfecting both HEK-293 and MG-63 cell lines. RESULTS Gelatin functionalization was confirmed using the above methods. Uniform nanoparticles were obtained from a nanoprecipitation technique. ALN-gelatin/gemini/DNA complexes exhibited higher transfection efficiency in MG-63 osteosarcoma cell line compared with the positive control. CONCLUSION ALN-gelatin is a promising biopolymer for bone targeting of either small molecules or gene therapy applications.
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Affiliation(s)
- George M Mekhail
- School of Pharmacy, University of Waterloo, 200 University Avenue West, Waterloo, ON, N2L 3G1, Canada.,Department of Pharmaceutics & Industrial Pharmacy, Faculty of Pharmacy, Ain Shams University, Khalifa El-Maamon Street, Abbasiya Square, Cairo 11566, Egypt
| | - Amany O Kamel
- School of Pharmacy, University of Waterloo, 200 University Avenue West, Waterloo, ON, N2L 3G1, Canada.,Department of Pharmaceutics & Industrial Pharmacy, Faculty of Pharmacy, Ain Shams University, Khalifa El-Maamon Street, Abbasiya Square, Cairo 11566, Egypt
| | - Gehanne As Awad
- Department of Pharmaceutics & Industrial Pharmacy, Faculty of Pharmacy, Ain Shams University, Khalifa El-Maamon Street, Abbasiya Square, Cairo 11566, Egypt
| | - Nahed D Mortada
- Department of Pharmaceutics & Industrial Pharmacy, Faculty of Pharmacy, Ain Shams University, Khalifa El-Maamon Street, Abbasiya Square, Cairo 11566, Egypt
| | - Rowena L Rodrigo
- School of Pharmacy, University of Waterloo, 200 University Avenue West, Waterloo, ON, N2L 3G1, Canada
| | - Paul A Spagnuolo
- School of Pharmacy, University of Waterloo, 200 University Avenue West, Waterloo, ON, N2L 3G1, Canada
| | - Shawn D Wettig
- School of Pharmacy, University of Waterloo, 200 University Avenue West, Waterloo, ON, N2L 3G1, Canada.,Waterloo Institute for Nanotechnology, University of Waterloo, 200 University Avenue West, Waterloo, ON, N2L 3G1, Canada
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62
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El Dine TM, Rouden J, Blanchet J. Borinic acid catalysed peptide synthesis. Chem Commun (Camb) 2016; 51:16084-7. [PMID: 26390250 DOI: 10.1039/c5cc06177f] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The catalytic synthesis of peptides is a major challenge in the modern organic chemistry hindered by the well-established use of stoichiometric coupling reagents. Herein, we describe for the first time that borinic acid is able to catalyse this reaction under mild conditions with an improved activity compared to our recently developed thiophene-based boronic acid. This catalyst is particularly efficient for peptide bond synthesis affording dipeptides in good yields without detectable racemization.
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Affiliation(s)
- Tharwat Mohy El Dine
- Laboratoire de Chimie Moléculaire et Thio-organique, ENSICAEN, Université de Caen Normandie, CNRS, 6 boulevard du Maréchal Juin, 14050 Caen, France.
| | - Jacques Rouden
- Laboratoire de Chimie Moléculaire et Thio-organique, ENSICAEN, Université de Caen Normandie, CNRS, 6 boulevard du Maréchal Juin, 14050 Caen, France.
| | - Jérôme Blanchet
- Laboratoire de Chimie Moléculaire et Thio-organique, ENSICAEN, Université de Caen Normandie, CNRS, 6 boulevard du Maréchal Juin, 14050 Caen, France.
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63
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Ben Haj Salah K, Legrand B, Das S, Martinez J, Inguimbert N. Straightforward strategy to substitute amide bonds by 1,2,3-triazoles in peptaibols analogs using Aibψ[Tz]-Xaa dipeptides. Biopolymers 2016; 104:611-21. [PMID: 25784277 DOI: 10.1002/bip.22641] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Revised: 03/02/2015] [Accepted: 03/07/2015] [Indexed: 02/04/2023]
Abstract
Structured peptides gained more attention over a decade because of their biological properties, biocompatibility and ability to act as modulators of protein/protein interactions, antibiotics, analgesics, immunosuppressants or as imaging agents to cite a few relevant applications. However, their poor bioavalability due in part to the susceptibility of the peptide bond to proteolytic cleavages often impaired their development and considerably limited their therapeutic use. To circumvent these problems, many efforts are undertaken to discover stable amide bond mimics resistant to proteolytic degradation. Among them the 1,2,3-triazole emerged as a highly stable analogue of the trans-peptide bond to generate bioactive peptides. Here we report a convenient approach to readily substitute amide bonds by triazole rings in Aib-containing peptides using Aibψ[Tz]-Xaa dipeptide-like units. We defined their application in solid phase synthesis and generated short model peptide sequences to study the impact of the triazole incorporation on their conformations in solution by circular dichroism and nuclear magnetic resonance spectroscopies.
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Affiliation(s)
- Khoubaib Ben Haj Salah
- Université de Perpignan Via Domitia, Centre de Recherche Insulaire et Observatoire de l'Environnement (CRIOBE), USR CNRS 3278, centre de phytopharmacie, bâtiment T, 58 avenue P. Alduy, 66860, Perpignan, France
| | - Baptiste Legrand
- Institut des Biomolécules Max Mousseron (IBMM), UMR 5247 CNRS, Université de Montpellier, 15 avenue Charles Flahault, BP 14491, 34093, Montpellier Cedex 5, France
| | - Sanjit Das
- Université de Perpignan Via Domitia, Centre de Recherche Insulaire et Observatoire de l'Environnement (CRIOBE), USR CNRS 3278, centre de phytopharmacie, bâtiment T, 58 avenue P. Alduy, 66860, Perpignan, France
| | - Jean Martinez
- Institut des Biomolécules Max Mousseron (IBMM), UMR 5247 CNRS, Université de Montpellier, 15 avenue Charles Flahault, BP 14491, 34093, Montpellier Cedex 5, France
| | - Nicolas Inguimbert
- Université de Perpignan Via Domitia, Centre de Recherche Insulaire et Observatoire de l'Environnement (CRIOBE), USR CNRS 3278, centre de phytopharmacie, bâtiment T, 58 avenue P. Alduy, 66860, Perpignan, France
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64
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Sabatino G, Guryanov I, Rombecchi A, Zanon J, Ricci A, Cabri W, Papini AM, Rovero P. Production of peptides as generic drugs: a patent landscape of octreotide. Expert Opin Ther Pat 2016; 26:485-95. [DOI: 10.1517/13543776.2016.1158810] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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65
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Dunetz JR, Magano J, Weisenburger GA. Large-Scale Applications of Amide Coupling Reagents for the Synthesis of Pharmaceuticals. Org Process Res Dev 2016. [DOI: 10.1021/op500305s] [Citation(s) in RCA: 411] [Impact Index Per Article: 51.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Joshua R. Dunetz
- Process
Chemistry, Gilead Sciences, 333 Lakeside Drive, Foster City, California 94404, United States
| | - Javier Magano
- Chemical Research & Development, Pfizer Worldwide Research & Development, Eastern Point Road, Groton, Connecticut 06340, United States
| | - Gerald A. Weisenburger
- Chemical Research & Development, Pfizer Worldwide Research & Development, Eastern Point Road, Groton, Connecticut 06340, United States
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66
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Freimuth L, Christoffers J. Bifunctional Diaminoterephthalate Scaffolds as Fluorescence Turn-On Probes for Thiols. Chemistry 2015; 21:8214-21. [DOI: 10.1002/chem.201500494] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Indexed: 11/12/2022]
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67
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Sevilla P, Vining KV, Dotor J, Rodriguez D, Gil FJ, Aparicio C. Surface immobilization and bioactivity of TGF-β1 inhibitor peptides for bone implant applications. J Biomed Mater Res B Appl Biomater 2015; 104:385-94. [DOI: 10.1002/jbm.b.33374] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Revised: 11/21/2014] [Accepted: 01/17/2015] [Indexed: 12/17/2022]
Affiliation(s)
- Pablo Sevilla
- Department of Mechanical Engineering; Escola Universitària Salesiana de Sarrià. Pg. Sant Joan Bosco 74; 08017 Barcelona Spain
- Biomaterials, Biomechanics and Tissue Engineering Group, Department of Materials Science and Engineering, Technical University of Catalonia, Pav. E; Av. Diagonal 647 Barcelona Spain
| | - Kyle V. Vining
- MDRCBB-Minnesota Dental Research Center for Biomechanics and Biomaterials, Department of Restorative Sciences, University of Minnesota School of Dentistry; 16-250A Moos Tower 515 Delaware St. SE Minneapolis MN 55455 USA
| | - Javier Dotor
- DIGNA Biotech, R+D Department. Calle Orense 85, Edificio Lexington; 28020 Madrid Spain
| | - Daniel Rodriguez
- Biomaterials, Biomechanics and Tissue Engineering Group, Department of Materials Science and Engineering, Technical University of Catalonia, Pav. E; Av. Diagonal 647 Barcelona Spain
| | - F. Javier Gil
- Biomaterials, Biomechanics and Tissue Engineering Group, Department of Materials Science and Engineering, Technical University of Catalonia, Pav. E; Av. Diagonal 647 Barcelona Spain
| | - Conrado Aparicio
- MDRCBB-Minnesota Dental Research Center for Biomechanics and Biomaterials, Department of Restorative Sciences, University of Minnesota School of Dentistry; 16-250A Moos Tower 515 Delaware St. SE Minneapolis MN 55455 USA
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68
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Hernández-Fernández E, Sánchez-Lara PP, Ordóñez M, Ramírez-Marroquín OA, Avalos-Alanís FG, López-Cortina S, Jiménez-Pérez VM, Ibarra-Rivera TR. Synthesis of β-hydroxyacetamides from unactivated ethyl acetates under base-free conditions and microwave irradiation. ACTA ACUST UNITED AC 2015. [DOI: 10.1016/j.tetasy.2014.11.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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69
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Giust S, La Sorella G, Sperni L, Strukul G, Scarso A. Substrate selective amide coupling driven by encapsulation of a coupling agent within a self-assembled hexameric capsule. Chem Commun (Camb) 2015; 51:1658-61. [DOI: 10.1039/c4cc08833f] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Encapsulation of a cationic carbodiimide condensing agent within a self-assembled hexameric capsule made of resorcin[4]arene units provides a nano-environment that efficiently steers the substrate selectivity in the amide synthesis reaction between carboxylic acids and primary amines.
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Affiliation(s)
- Sonia Giust
- Dipartimento di Scienze Molecolari e Nanosistemi
- Università Ca' Foscari di Venezia
- Venezia
- Italy
| | - Giorgio La Sorella
- Dipartimento di Scienze Molecolari e Nanosistemi
- Università Ca' Foscari di Venezia
- Venezia
- Italy
| | - Laura Sperni
- Dipartimento di Scienze Molecolari e Nanosistemi
- Università Ca' Foscari di Venezia
- Venezia
- Italy
| | - Giorgio Strukul
- Dipartimento di Scienze Molecolari e Nanosistemi
- Università Ca' Foscari di Venezia
- Venezia
- Italy
| | - Alessandro Scarso
- Dipartimento di Scienze Molecolari e Nanosistemi
- Università Ca' Foscari di Venezia
- Venezia
- Italy
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70
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Paradís-Bas M, Tulla-Puche J, Albericio F. 2-Methoxy-4-methylsulfinylbenzyl: a backbone amide safety-catch protecting group for the synthesis and purification of difficult peptide sequences. Chemistry 2014; 20:15031-9. [PMID: 25280354 DOI: 10.1002/chem.201403668] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Indexed: 01/08/2023]
Abstract
The use of 2-methoxy-4-methylsulfinylbenzyl (Mmsb) as a new backbone amide-protecting group that acts as a safety-catch structure is proposed. Mmsb, which is stable during the elongation of the sequence and trifluoroacetic acid-mediated cleavage from the resin, improves the synthetic process as well as the properties of the quasi-unprotected peptide. Mmsb offers the possibility of purifying and characterizing complex peptide sequences, and renders the target peptide after NH4 I/TFA treatment and subsequent ether precipitation to remove the cleaved Mmsb moiety. First, the "difficult peptide" sequence H-(Ala)10-NH2 was selected as a model to optimize the new protecting group strategy. Second, the complex, bioactive Ac-(RADA)4-NH2 sequence was chosen to validate this methodology. The improvements in solid-phase peptide synthesis combined with the enhanced solubility of the quasi-unprotected peptides, as compared with standard sequences, made it possible to obtain purified Ac-(RADA)4-NH2. To extend the scope of the approach, the challenging Aβ(1-42) peptide was synthesized and purified in a similar manner. The proposed Mmsb strategy opens up the possibility of synthesizing other challenging small proteins.
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Affiliation(s)
- Marta Paradís-Bas
- Institute for Research in Biomedicine (IRB Barcelona), Baldiri Reixac 10, Barcelona, 08028 (Spain), Fax: (+34) 93-4037126; CIBER-BBN, Networking Centre on Bioengineering, Biomaterials and Nanomedicine, Barcelona Science Park, Baldiri Reixac 10, Barcelona, 08028 (Spain)
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71
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Guan X, Chaffey PK, Zeng C, Tan Z. New Methods for Chemical Protein Synthesis. Top Curr Chem (Cham) 2014; 363:155-92. [DOI: 10.1007/128_2014_599] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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72
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Fernandes C, Masawang K, Tiritan ME, Sousa E, de Lima V, Afonso C, Bousbaa H, Sudprasert W, Pedro M, Pinto MM. New chiral derivatives of xanthones: synthesis and investigation of enantioselectivity as inhibitors of growth of human tumor cell lines. Bioorg Med Chem 2013; 22:1049-62. [PMID: 24411197 DOI: 10.1016/j.bmc.2013.12.042] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Revised: 12/10/2013] [Accepted: 12/17/2013] [Indexed: 11/16/2022]
Abstract
A highly efficient and practical methodology for synthesis of new chiral derivatives of xanthones (CDXs) in enantiomerically pure form has been developed. According to this approach, thirty CDXs (3-32) were synthesized by coupling a carboxyxanthone (1) and a carboxymethoxyxanthone (2) with both enantiomers of commercially available chiral building blocks, namely six amino alcohols, one amine and one amino ester. The activation of the carboxylic acid group of the xanthonic scaffold was carried out with the coupling reagent O-(benzotriazol-1-yl)-N-N-N'-N'-tetramethyluronium tetrafluoroborate (TBTU), in the presence of a catalytic amount of TEA in anhydrous THF. The coupling reactions with the chiral blocks were performed at room temperature with short reactions times, excellent yields (ranging from 94% to 99%), and very high enantiomeric excess. The synthesized CDXs were evaluated for their effect on the in vitro growth of three human tumor cell lines, namely A375-C5 (melanoma), MCF-7 (breast adenocarcinoma), and NCI-H460 (non-small cell lung cancer). The most active compound was CDX 15 being active in all human tumor cell lines with values of GI50 of 32.15±2.03μM for A375-C5, 22.55±1.99μM for MCF-7, and 14.05±1.82μM for NCI-H460. Nevertheless, some CDXs showed cell-type selectivity. Furthermore, the growth inhibitory effects, in some cases, demonstrated to be depending on the stereochemistry of the CDXs. An interesting example was observed with the enantiomers 3 and 4, which demonstrated high enantioselectivity for MCF-7 and NCI-H460 cell lines. It can be inferred that the effects on the growth of the human tumor cell lines can be ascribed not only to the nature and positions of substituents on the xanthonic scaffold but also to the stereochemistry of the CDXs. Some considerations regarding structure-activity relationship within this class of compounds will be highlighted.
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Affiliation(s)
- Carla Fernandes
- Centro de Química Medicinal da Universidade do Porto (CEQUIMED-UP), Rua de Jorge Viterbo Ferreira 228, 4050-313 Porto, Portugal; Laboratório de Química Orgânica e Farmacêutica, Departamento de Ciências Químicas, Faculdade de Farmácia, Universidade do Porto, Rua de Jorge Viterbo Ferreira 228, 4050-313 Porto, Portugal; Centro Interdisciplinar de Investigação Marinha e Ambiental (CIIMAR/CIMAR), Universidade do Porto, Rua dos Bragas 289, 4050-123 Porto, Portugal
| | - Kamonporn Masawang
- Centro de Química Medicinal da Universidade do Porto (CEQUIMED-UP), Rua de Jorge Viterbo Ferreira 228, 4050-313 Porto, Portugal; Faculty of Science, Kasetsart University, 10900 Bangkok, Thailand
| | - Maria Elizabeth Tiritan
- Centro de Química Medicinal da Universidade do Porto (CEQUIMED-UP), Rua de Jorge Viterbo Ferreira 228, 4050-313 Porto, Portugal; Centro Interdisciplinar de Investigação Marinha e Ambiental (CIIMAR/CIMAR), Universidade do Porto, Rua dos Bragas 289, 4050-123 Porto, Portugal; Cooperativa de Ensino Superior, Politécnico e Universitário (CESPU), Centro de Investigação em Ciências da Saúde, Instituto Superior de Ciências da Saúde-Norte (CICS-ISCS-N), Rua Central de Gandra 1317, 4585-116 Gandra PRD, Portugal
| | - Emília Sousa
- Centro de Química Medicinal da Universidade do Porto (CEQUIMED-UP), Rua de Jorge Viterbo Ferreira 228, 4050-313 Porto, Portugal; Laboratório de Química Orgânica e Farmacêutica, Departamento de Ciências Químicas, Faculdade de Farmácia, Universidade do Porto, Rua de Jorge Viterbo Ferreira 228, 4050-313 Porto, Portugal; Centro Interdisciplinar de Investigação Marinha e Ambiental (CIIMAR/CIMAR), Universidade do Porto, Rua dos Bragas 289, 4050-123 Porto, Portugal
| | - Virgínia de Lima
- Universidade Federal do Rio de Janeiro, Instituto de Química, LADETEC-LAB RES, Rio de Janeiro, RJ, Brazil
| | - Carlos Afonso
- Centro de Química Medicinal da Universidade do Porto (CEQUIMED-UP), Rua de Jorge Viterbo Ferreira 228, 4050-313 Porto, Portugal; Laboratório de Química Orgânica e Farmacêutica, Departamento de Ciências Químicas, Faculdade de Farmácia, Universidade do Porto, Rua de Jorge Viterbo Ferreira 228, 4050-313 Porto, Portugal; Centro Interdisciplinar de Investigação Marinha e Ambiental (CIIMAR/CIMAR), Universidade do Porto, Rua dos Bragas 289, 4050-123 Porto, Portugal
| | - Hassan Bousbaa
- Centro de Química Medicinal da Universidade do Porto (CEQUIMED-UP), Rua de Jorge Viterbo Ferreira 228, 4050-313 Porto, Portugal; Centro Interdisciplinar de Investigação Marinha e Ambiental (CIIMAR/CIMAR), Universidade do Porto, Rua dos Bragas 289, 4050-123 Porto, Portugal; Cooperativa de Ensino Superior, Politécnico e Universitário (CESPU), Centro de Investigação em Ciências da Saúde, Instituto Superior de Ciências da Saúde-Norte (CICS-ISCS-N), Rua Central de Gandra 1317, 4585-116 Gandra PRD, Portugal
| | | | - Madalena Pedro
- Centro de Química Medicinal da Universidade do Porto (CEQUIMED-UP), Rua de Jorge Viterbo Ferreira 228, 4050-313 Porto, Portugal; Cooperativa de Ensino Superior, Politécnico e Universitário (CESPU), Centro de Investigação em Ciências da Saúde, Instituto Superior de Ciências da Saúde-Norte (CICS-ISCS-N), Rua Central de Gandra 1317, 4585-116 Gandra PRD, Portugal.
| | - Madalena M Pinto
- Centro de Química Medicinal da Universidade do Porto (CEQUIMED-UP), Rua de Jorge Viterbo Ferreira 228, 4050-313 Porto, Portugal; Laboratório de Química Orgânica e Farmacêutica, Departamento de Ciências Químicas, Faculdade de Farmácia, Universidade do Porto, Rua de Jorge Viterbo Ferreira 228, 4050-313 Porto, Portugal; Centro Interdisciplinar de Investigação Marinha e Ambiental (CIIMAR/CIMAR), Universidade do Porto, Rua dos Bragas 289, 4050-123 Porto, Portugal.
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73
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Würdemann M, Christoffers J. Nitrile Oxide versus Nitrone - Switching Regioselectivity of Intramolecular 1,3-Dipolar Cycloadditions towards the Preparation of Aminopiperidinecarboxylates. European J Org Chem 2013. [DOI: 10.1002/ejoc.201301039] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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74
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75
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Jastrzabek K, Bednarek P, Kolesinska B, Kaminski ZJ. Bis(4,6-dimethoxy-1,3,5-triazin-2-yl) ether as coupling reagent for peptide synthesis. Chem Biodivers 2013; 10:952-61. [PMID: 23681736 DOI: 10.1002/cbdv.201200369] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2012] [Indexed: 02/01/2023]
Abstract
Bis(4,6-dimethoxy-1,3,5-triazin-2-yl) ether (4) was prepared by treatment of 2-hydroxy-4,6-dimethoxy-1,3,5-triazine with 2-chloro-4,6-dimethoxy-1,3,5-triazine in 61% yield. Ether 4, isoelectronic with pyrocarbonates, was found capable to activate carboxylic acids in the presence of 1,4-diazabicyclo[2.2.2]octane (DABCO) to yield, under mild reaction conditions, superactive triazine esters. Versatility of this new coupling reagent was confirmed by condensation of lipophilic and sterically hindered carboxylic acids with amines in 71-98% yield, and by synthesis of peptides, including those containing Aib-Aib sequence, in solution with high yield and high enantiomeric purity.
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Affiliation(s)
- Konrad Jastrzabek
- Institute of Organic Chemistry, Technical University of Lodz, Zeromskiego 116, PL-90-924 Lodz
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76
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Fernandes C, Oliveira L, Tiritan ME, Leitao L, Pozzi A, Noronha-Matos JB, Correia-de-Sá P, Pinto MM. Synthesis of new chiral xanthone derivatives acting as nerve conduction blockers in the rat sciatic nerve. Eur J Med Chem 2012; 55:1-11. [PMID: 22819594 DOI: 10.1016/j.ejmech.2012.06.049] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2012] [Revised: 06/18/2012] [Accepted: 06/25/2012] [Indexed: 11/29/2022]
Abstract
The synthesis and structure elucidation of three new chiral xanthone (9H-xanthon-9-one) derivatives (2-4) are fully reported. The coupling reactions of the synthesized building block 6-methoxy-9-oxo-9H-xanthene-2-carboxylic acid (1) with two enantiomerically pure amino alcohols ((S)-(+)-valinol and (S)-(+)-leucinol) and one amine ((S)-(-)-α-4-dimethylbenzylamine), were carried out using the coupling reagent O-(benzotriazol-1-yl-)-N,N,N',N'-tetramethylluronium tetrafluoroborate (TBTU). The coupling reactions were performed with yields higher than 97% and enantiomeric excess higher than 99%. The structures of the compounds were established by IR, MS, and NMR ((1)H, (13)C, HSQC, and HMBC) techniques. Taking into account that these new chiral xanthone derivatives have molecular moieties structurally very similar to local anaesthetics, the ability to block compound action potentials (CAP) at the isolated rat sciatic nerve was also investigated. Nerve conduction blockade might result from a selective interference with Na(+) ionic currents or from a non-selective modification of membrane stabilizing properties. Thus, the mechanism, by which the three chiral xanthone derivatives cause conduction blockade in the rat sciatic nerve and their ability to prevent hypotonic haemolysis, given that erythrocytes are non-excitable cells devoid of voltage-gated Na(+) channels, are also described. Data suggest that nerve conduction blockade caused by newly-synthesized xanthone derivatives might result predominantly from an action on Na(+) ionic currents. This effect can be dissociated from their ability to stabilize cell membranes, which became apparent only upon increasing the concentration of compounds 2-4 to the higher micromolar range.
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Affiliation(s)
- Carla Fernandes
- Centro de Química Medicinal da Universidade do Porto (CEQUIMED-UP), Portugal
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77
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New aldehyde and vinylsulfone proteasome inhibitors for targeted melanoma therapy. Eur J Med Chem 2011; 46:5705-10. [DOI: 10.1016/j.ejmech.2011.07.037] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2011] [Revised: 07/19/2011] [Accepted: 07/20/2011] [Indexed: 11/23/2022]
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