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He JH, Cheng WW, Zhang AQ, Qin SY. Tandem "One-Shot" Measurement of Residual Chemical Shift Anisotropy and Residual Dipolar Coupling using Biphasic Supramolecular Peptide Liquid Crystals. Anal Chem 2024; 96:11881-11889. [PMID: 38976239 DOI: 10.1021/acs.analchem.4c01558] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/09/2024]
Abstract
Both solitary and tandem applications of residual chemical shift anisotropy (RCSA) and residual dipolar coupling (RDC) show great potential for the structural and configurational determination of organic molecules. A critical component of both RDC and RCSA methodologies is the alignment medium, whose availability is limited, especially for RCSA measurement. Moreover, reported RDC and RCSA acquisitions mainly rely on two experiments conducted under two different conditions, which are relatively time-consuming and easily cause experimental errors. Herein, a biphasic supramolecular lyotropic liquid crystalline (LLC) system was developed through the self-assembly of C21H43-CONH-V4K3-CONH2, which could act as an alignment medium for not only RDC but also RCSA extraction in DMSO-d6. Notably, the RCSA extraction was easily achieved via one-shot measurement from a single one-dimensional 13C NMR experiment, with no need for special instruments, devices, and correction. Relying on the biphasic LLC medium, meanwhile, RDC data were simply extracted from a single F1-coupled HSQC experiment, different from the standard protocol that requires two spectral acquisitions corresponding to the isotropic and anisotropic conditions. Collectively, the biphasic LLC medium is applicable for tandem RCSA and RDC measurements in one single sample, advancing the stereochemical elucidation of molecules of interest.
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Affiliation(s)
- Jin-Hao He
- Hubei Engineering Technology Research Centre of Energy Polymer Materials, South-Central Minzu University, Wuhan 430074, P. R. China
| | - Wei-Wei Cheng
- Hubei Engineering Technology Research Centre of Energy Polymer Materials, South-Central Minzu University, Wuhan 430074, P. R. China
| | - Ai-Qing Zhang
- Hubei Engineering Technology Research Centre of Energy Polymer Materials, South-Central Minzu University, Wuhan 430074, P. R. China
| | - Si-Yong Qin
- Hubei Engineering Technology Research Centre of Energy Polymer Materials, Key Laboratory of Analytical Chemistry of the State Ethnic Affairs Commission, South-Central Minzu University, Wuhan 430074, P. R. China
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2
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Silva Elipe MV, Ndukwe IE, Murray JI. Cryogen-free 400-MHz nuclear magnetic resonance spectrometer as a versatile tool for pharmaceutical process analytical technology. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2024; 62:512-534. [PMID: 38369696 DOI: 10.1002/mrc.5434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 01/15/2024] [Accepted: 01/16/2024] [Indexed: 02/20/2024]
Abstract
The discovery of new ceramic materials containing Ba-La-Cu oxides in 1986 that exhibited superconducting properties at high temperatures in the range of 35 K or higher, recognized with the Nobel Prize in Physics in 1987, opened a new world of opportunities for nuclear magnetic resonance (NMRs) and magnetic resonance imaging (MRIs) to move away from liquid cryogens. This discovery expands the application of high temperature superconducting (HTS) materials to fields beyond the chemical and medical industries, including electrical power grids, energy, and aerospace. The prototype 400-MHz cryofree HTS NMR spectrometer installed at Amgen's chemistry laboratory has been vital for a variety of applications such as structure analysis, reaction monitoring, and CASE-3D studies with RDCs. The spectrometer has been integrated with Amgen's chemistry and analytical workflows, providing pipeline project support in tandem with other Kinetic Analysis Platform technologies. The 400-MHz cryofree HTS NMR spectrometer, as the name implies, does not require liquid cryogens refills and has smaller footprint that facilitates installation into a chemistry laboratory fume hood, sharing the hood with a process chemistry reactor. Our evaluation of its performance for structural analysis with CASE-3D protocol and for reaction monitoring of Amgen's pipeline chemistry was successful. We envision that the HTS magnets would become part of the standard NMR and MRI spectrometers in the future. We believe that while the technology is being developed, there is room for all magnet options, including HTS, low temperature superconducting (LTS) magnets, and low field benchtop NMRs with permanent magnets, where utilization will be dependent on application type and costs.
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Affiliation(s)
| | - Ikenna Edward Ndukwe
- Department of Attribute Sciences, Process Development, Amgen Inc., Thousand Oaks, California, USA
| | - James I Murray
- Pivotal and Commercial Drug Substance Technologies, Process Development, Amgen Inc., Thousand Oaks, California, USA
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3
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Qin SY, He JH, Zhao Y, Yang YL, Zhang AQ, Lei X. Programming Peptide Liquid Crystal Media to Acquire Independent Sets of Residual Dipolar Couplings and Enantiodiscrimination in Multiple Solvent Systems. Anal Chem 2023; 95:17759-17765. [PMID: 37996077 DOI: 10.1021/acs.analchem.3c03777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2023]
Abstract
Multiple independent sets of residual dipolar couplings (RDCs) acquired by relying on different alignment media show the great potential for de novo structure determination of organic compounds. However, this methodology is severely compromised by the limited availability of multialignment media. In this work, an engineering strategy was developed to program the oligopeptide amphiphiles (OPAs) to create different peptide liquid crystal (LC) media for the acquisition of independent sets of RDCs. With no need for de novo design on peptide sequences, the molecular alignment can be simply modulated by varying the length of the hydrophobic tails within OPAs. Relying on these programmed peptide LC media, five independent sets of RDCs were extracted in a highly efficient and accurate manner. Because of the similar bulk composition of OPAs, this approach offers the significant advantage in circumventing the possible incompatibilities of analytes with one or several different alignment media, therefore avoiding the analysis complication. Notably, these peptide LC media show enantiodifferentiating properties, and the enantiodiscriminating capabilities could also be optimized through the programmed strategy. Furthermore, we show that these media are compatible with different polar solvents, allowing the possible de novo structure elucidation of organic compounds with varied polarities and solubilities.
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Affiliation(s)
- Si-Yong Qin
- Hubei Engineering Technology Research Centre of Energy Polymer Materials, School of Chemistry and Materials Science, South-Central Minzu University, Wuhan 430074, China
- Key Laboratory of Analytical Chemistry of the State Ethnic Affairs Commission, School of Chemistry and Materials Science, South-Central Minzu University, Wuhan 430074, China
| | - Jin-Hao He
- Hubei Engineering Technology Research Centre of Energy Polymer Materials, School of Chemistry and Materials Science, South-Central Minzu University, Wuhan 430074, China
| | - You Zhao
- Hubei Engineering Technology Research Centre of Energy Polymer Materials, School of Chemistry and Materials Science, South-Central Minzu University, Wuhan 430074, China
| | - Yan-Ling Yang
- School of Pharmaceutical Sciences, South-Central Minzu University, Wuhan 430074, P. R. China
| | - Ai-Qing Zhang
- Hubei Engineering Technology Research Centre of Energy Polymer Materials, School of Chemistry and Materials Science, South-Central Minzu University, Wuhan 430074, China
| | - Xinxiang Lei
- School of Pharmaceutical Sciences, South-Central Minzu University, Wuhan 430074, P. R. China
- State Key Laboratory of Applied Organic Chemistry, Lanzhou Magnetic Resonance Center, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, China
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Silva Elipe MV, Ndukwe IE, Navarro-Vázquez A. Anisotropic NMR data acquisition with a prototype 400 MHz cryogen-free NMR spectrometer. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2023; 61:530-543. [PMID: 37530063 DOI: 10.1002/mrc.5380] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 06/22/2023] [Accepted: 06/26/2023] [Indexed: 08/03/2023]
Abstract
High-temperature superconducting (HTS) materials have recently been incorporated into the construction of HTS cryogen-free magnets for nuclear magnetic resonance (NMR) spectroscopy. These HTS NMR spectrometers do not require liquid cryogens, thereby providing significant cost savings and facilitating easy integration into chemistry laboratories. However, the optimal performance of these HTS magnets against standard cryogen NMR magnets must be evaluated, especially with demanding modern NMR applications such as NMR in anisotropic media. The stability of the HTS magnets over time and their performance with complex pulse sequence experiments are the main unknown factors of this new technology. In this study, we evaluate the utility of our prototype 400 MHz cryogen-free power-driven HTS NMR spectrometer, installed in the fumehood of a chemistry laboratory, for stereochemical analysis of three commercial natural products (artemisinin, artemether, and dihydroartemisinin) via measurement of anisotropic NMR data, in particular, residual dipolar couplings. The accuracy of measurement of the anisotropic NMR data with the HTS magnet spectrometer is evaluated through the CASE-3D fitting protocol, as implemented in the Mestrenova-StereoFitter software program.
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Affiliation(s)
| | | | - Armando Navarro-Vázquez
- Departmento de Química Fundamental, Centro de Ciências Exatas e da Natureza, Universidade Federal de Pernambuco, Recife, Pernambuco, Brazil
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Zhao Y, Qin H, Yang YL, Li JQ, Qin SY, Zhang AQ, Lei X. Weakly aligned Ti 3C 2T x MXene liquid crystals: measuring residual dipolar coupling in multiple co-solvent systems. NANOSCALE 2023; 15:7820-7828. [PMID: 37051680 DOI: 10.1039/d3nr00204g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Residual Dipolar Coupling (RDC), acquired relying on weakly alignment media, is highly valuable for the structural elucidation of organic molecules. Arising from the striking features of no background signals and low critical concentrations, two-dimensional (2D) liquid crystals (LCs) show the clear advantages of acting as alignment media to measure RDCs. So far, creating multisolvent compatible 2D LC media through a simple and versatile method is still formidably challenging. Herein, we report the rapid creation of aligned media based on the Ti3C2Tx MXene, which self-aligned in multiple co-solvents including CH3OH-H2O, DMSO-H2O, DMF-H2O, and acetone-H2O. We demonstrated the applicability of these aligned media for the RDC measurement of small organic molecules with different polarities and solubilities. Notably, Ti3C2Tx MXene LCs without chemical modification enabled RDC measurements on aromatic molecules. The straightforward preparation of Ti3C2Tx media and its compatibility with multiple solvents will push RDC measurement as a routine methodology for structural elucidation. It may also facilitate the investigation of solvation effects on conformational dynamics.
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Affiliation(s)
- You Zhao
- Hubei Engineering Technology Research Centre of Energy Polymer Materials, School of Chemistry and Materials Science, South-Central Minzu University, Wuhan 430074, China.
- Key Laboratory of Catalysis and Energy Materials Chemistry of Ministry of Education and Hubei Key Laboratory of Catalysis and Materials Science, South-Central Minzu University, Wuhan, China
| | - Huan Qin
- Hubei Engineering Technology Research Centre of Energy Polymer Materials, School of Chemistry and Materials Science, South-Central Minzu University, Wuhan 430074, China.
- Key Laboratory of Catalysis and Energy Materials Chemistry of Ministry of Education and Hubei Key Laboratory of Catalysis and Materials Science, South-Central Minzu University, Wuhan, China
| | - Yan-Ling Yang
- School of Pharmaceutical Sciences, South-Central Minzu University, Wuhan, China.
| | - Jia-Qian Li
- School of Pharmaceutical Sciences, South-Central Minzu University, Wuhan, China.
| | - Si-Yong Qin
- Hubei Engineering Technology Research Centre of Energy Polymer Materials, School of Chemistry and Materials Science, South-Central Minzu University, Wuhan 430074, China.
- Key Laboratory of Catalysis and Energy Materials Chemistry of Ministry of Education and Hubei Key Laboratory of Catalysis and Materials Science, South-Central Minzu University, Wuhan, China
| | - Ai-Qing Zhang
- Hubei Engineering Technology Research Centre of Energy Polymer Materials, School of Chemistry and Materials Science, South-Central Minzu University, Wuhan 430074, China.
- Key Laboratory of Catalysis and Energy Materials Chemistry of Ministry of Education and Hubei Key Laboratory of Catalysis and Materials Science, South-Central Minzu University, Wuhan, China
| | - Xinxiang Lei
- School of Pharmaceutical Sciences, South-Central Minzu University, Wuhan, China.
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6
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Wesp S, Wolf K, Immel S, Reggelin M. Poly(arylisocyanides) as Versatile, Enantiodiscriminating Alignment Media for Small Molecules. Chempluschem 2022; 87:e202100507. [PMID: 35072980 DOI: 10.1002/cplu.202100507] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 01/02/2022] [Indexed: 11/08/2022]
Abstract
Lyotropic liquid crystalline (LLC) phases of amino acid derived polyarylisocyanides were employed as chiral alignment media for the measurement of residual dipolar couplings (RDCs) of small chiral organic molecules. Anisotropic samples in CDCl3 displayed quadrupolar splittings of the deuterium signal in the range of several hundreds of Hertz. The LLC phases showed excellent orienting properties for a broad range of analytes bearing various functional groups. The precise extraction of RDCs in the range of up to ±40 Hertz from F2-coupled HSQC spectra was possible. Additionally, the chiral environment offers the opportunity for diastereomorphous interactions with the enantiomers of chiral analytes leading to two different sets of RDCs. This differential order effect was particularly pronounced with ketones and alcohols.
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Affiliation(s)
- Svenja Wesp
- Technische Universität Darmstadt, Clemens Schöpf Institut für Organische Chemie und Biochemie, Alarich-Weiss-Str. 4, 64287, Darmstadt, Germany
| | - Kai Wolf
- Technische Universität Darmstadt, Clemens Schöpf Institut für Organische Chemie und Biochemie, Alarich-Weiss-Str. 4, 64287, Darmstadt, Germany
| | - Stefan Immel
- Technische Universität Darmstadt, Clemens Schöpf Institut für Organische Chemie und Biochemie, Alarich-Weiss-Str. 4, 64287, Darmstadt, Germany
| | - Michael Reggelin
- Technische Universität Darmstadt, Clemens Schöpf Institut für Organische Chemie und Biochemie, Alarich-Weiss-Str. 4, 64287, Darmstadt, Germany
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7
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Elyashberg M, Argyropoulos D. Computer Assisted Structure Elucidation (CASE): Current and future perspectives. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2021; 59:669-690. [PMID: 33197069 DOI: 10.1002/mrc.5115] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 10/31/2020] [Accepted: 11/08/2020] [Indexed: 06/11/2023]
Abstract
The first efforts for the development of methods for Computer-Assisted Structure Elucidation (CASE) were published more than 50 years ago. CASE expert systems based on one-dimensional (1D) and two-dimensional (2D) Nuclear Magnetic Resonance (NMR) data have matured considerably by now. The structures of a great number of complex natural products have been elucidated and/or revised using such programs. In this article, we discuss the most likely directions in which CASE will evolve. We act on the premise that a synergistic interaction exists between CASE, new NMR experiments, and methods of computational chemistry, which are continuously being improved. The new developments in NMR experiments (long-range correlation experiments, pure-shift methods, coupling constants measurement and prediction, residual dipolar couplings [RDCs]), and residual chemical shift anisotropies [RCSAs], evolution of density functional theory (DFT), and machine learning algorithms will have an influence on CASE systems and vice versa. This is true also for new techniques for chemical analysis (Atomic Force Microscopy [AFM], "crystalline sponge" X-ray analysis, and micro-Electron Diffraction [micro-ED]), which will be used in combination with expert systems. We foresee that CASE will be utilized widely and become a routine tool for NMR spectroscopists and analysts in academic and industrial laboratories. We believe that the "golden age" of CASE is still in the future.
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8
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Krupp A, Noll M, Reggelin M. Valine derived poly (acetylenes) as versatile chiral lyotropic liquid crystalline alignment media for RDC-based structure elucidations. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2021; 59:577-586. [PMID: 32012341 DOI: 10.1002/mrc.5003] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Revised: 01/22/2020] [Accepted: 01/27/2020] [Indexed: 06/10/2023]
Abstract
Anisotropic samples of lyotropic liquid crystalline (LLC) phases of valine derived polyaryl acetylenes were employed as chiral alignment media for the measurement of residual dipolar couplings (RDCs) of 12 small, chiral, organic molecules. The quadrupolar splitting of the deuterium signal of CDCl3 can be adjusted by temperature and concentration changes from 0 to 350 Hz. The LLC phases showed excellent orienting properties for all analytes bearing various functional groups. The precise extraction of RDCs in the range of up to ±30 Hz from F2-coupled HSQC spectra was possible. Additionally, the chiral environment led to diastereomorphous interactions with the enantiomers of chiral analytes leading to two different sets of RDCs. This differential order effect was particularly pronounced with H-bond donors like alcohols and 2° amines.
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Affiliation(s)
- Alexis Krupp
- Clemens Schöpf Institut for Organic Chemistry and Biochemistry, Technical University of Darmstadt, Darmstadt, Germany
- Nitrochemie Aschau GmbH, Aschau am Inn, Germany
| | - Markus Noll
- Clemens Schöpf Institut for Organic Chemistry and Biochemistry, Technical University of Darmstadt, Darmstadt, Germany
| | - Michael Reggelin
- Clemens Schöpf Institut for Organic Chemistry and Biochemistry, Technical University of Darmstadt, Darmstadt, Germany
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9
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de Melo Sousa CM, Giordani RB, de Almeida WAM, Griesinger C, Gil RR, Navarro-Vázquez A, Hallwass F. Effect of the solvent on the conformation of monocrotaline as determined by isotropic and anisotropic NMR parameters. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2021; 59:561-568. [PMID: 31715029 DOI: 10.1002/mrc.4968] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Revised: 10/25/2019] [Accepted: 11/04/2019] [Indexed: 06/10/2023]
Abstract
The conformation in solution of monocrotaline, a pyrrolizidine alkaloid presenting an eleven-membered macrocyclic diester ring, has been investigated using a combination of isotropic and anisotropic nuclear magnetic resonance parameters measured in four solvents of different polarity (D2 O, DMSO-d6 , CDCl3 , and C6 D6 ). Anisotropic nuclear magnetic resonance parameters were measured in different alignment media, based on their compatibility with the solvent of interest: cromoglycate liquid crystal solution was used for D2 O, whereas a poly (methyl methacrylate) polymer gel was chosen for CDCl3 and C6 D6 , and a poly (hydroxyethyl methacrylate) gel for DMSO-d6 . Whereas the pyrrolizidine ring shows an E6 exo-puckered conformation in all of the solvents, the macrocyclic eleven-membered ring adopts different populations of syn-parallel and anti-parallel relative orientation of the carbonyl groups according to the polarity of the solvent.
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Affiliation(s)
- Cleyton Marcos de Melo Sousa
- Departamento de Química Fundamental, Universidade Federal de Pernambuco, Recife, Pernambuco, Brazil
- Instituto Federal de Pernambuco, Caruaru, Pernambuco, Brazil
| | - Raquel Brandt Giordani
- Laboratório de Farmacognosia, Departamento de Farmácia, Universidade Federal do Rio Grande do Norte, Natal, Rio Grande do Norte, Brazil
| | | | - Christian Griesinger
- Abteilung für NMR-basierte Strukturbiologie, Max-Planck-Institut für Biophysikalische Chemie, Göttingen, Germany
| | - Roberto R Gil
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania
| | - Armando Navarro-Vázquez
- Departamento de Química Fundamental, Universidade Federal de Pernambuco, Recife, Pernambuco, Brazil
| | - Fernando Hallwass
- Departamento de Química Fundamental, Universidade Federal de Pernambuco, Recife, Pernambuco, Brazil
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10
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Das A, Nath N. Elucidating natural product structures using a robust measurement of carbon residual chemical shift anisotropy combined with DFT. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2021; 59:569-576. [PMID: 31758720 DOI: 10.1002/mrc.4975] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Revised: 08/20/2019] [Accepted: 08/31/2019] [Indexed: 06/10/2023]
Abstract
Determination of configurations and conformations is an important step in the structural characterization of small molecules. Apart from utilizing isotropic J-couplings and nuclear overhauser effect (NOEs) measured in isotropic solution, anisotropic Nuclear Magnetic resonance (NMR) data such as residual dipolar couplings and residual chemical shift anisotropies (RCSAs) were also used to elucidate complex small molecule structures. Measuring RCSA has always been historically difficult due to the isotropic shift effect accompanied by molecular alignment and therefore only occasionally applied in a few examples. Here, we present a robust measurement of carbon RCSAs using a smaller gel-stretching device to determine the structures of a few small molecules. A systematic study on how different density functional theory computed anisotropies of the chemical shift anisotropy tensors impact RCSA data interpretation has also been discussed. We also discuss the effect of utilizing various carbons as reference nuclei for RCSA data extraction as well as the orientation behavior of estrone in orthogonal alignment media.
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Affiliation(s)
- Akhi Das
- Department of Chemistry, Gauhati University, Guwahati, India
| | - Nilamoni Nath
- Department of Chemistry, Gauhati University, Guwahati, India
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11
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Ibáñez de Opakua A, Zweckstetter M. Extending the applicability of P3D for structure determination of small molecules. MAGNETIC RESONANCE (GOTTINGEN, GERMANY) 2021; 2:105-116. [PMID: 37904779 PMCID: PMC10539764 DOI: 10.5194/mr-2-105-2021] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Accepted: 03/15/2021] [Indexed: 11/01/2023]
Abstract
The application of anisotropic nuclear magnetic resonance (NMR) parameters for the correct structural assignment of small molecules requires the use of partially ordered media. Previously we demonstrated that the use of P3D simulations using poly(γ -benzyl-L-glutamate) (PBLG) as an alignment medium allows for the determination of the correct diastereomer from extremely sparse NMR data. Through the analysis of the structural characteristics of small molecules in different alignment media, here we show that when steric or electrostatic factors dominate the alignment, P3D-PBLG retains its diastereomer discrimination power. We also demonstrate that P3D simulations can define the different conformations of a flexible small molecule from sparse NMR data.
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Affiliation(s)
- Alain Ibáñez de Opakua
- German Center for Neurodegenerative Diseases (DZNE), Von-Siebold-Str. 3a, 37075 Göttingen, Germany
| | - Markus Zweckstetter
- German Center for Neurodegenerative Diseases (DZNE), Von-Siebold-Str. 3a, 37075 Göttingen, Germany
- Department for NMR-based Structural Biology, Max Planck Institute for Biophysical Chemistry, Am Faßberg 11, 37077 Göttingen, Germany
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12
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da Silva DGB, Hallwass F, Navarro-Vázquez A. Single experiment measurement of residual dipolar couplings in aqueous solution using a biphasic bisperylene imide chromonic liquid crystal. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2021; 59:408-413. [PMID: 33295034 DOI: 10.1002/mrc.5120] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 12/01/2020] [Accepted: 12/06/2020] [Indexed: 06/12/2023]
Abstract
The use of the biphasic isotropic/nematic region in a bisperylene imide-based lyotropic liquid crystal system allows the extraction of proton-carbon 1 DCH residual dipolar couplings in aqueous solution from a single F1-coupled HSQC experiment. The method was successfully applied to the RDC-based conformational analysis of sucrose.
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Affiliation(s)
- Danilo G B da Silva
- Departamento de Química Fundamental, CCEN, Universidade Federal de Pernambuco, Recife, Pernambuco, Brazil
| | - Fernando Hallwass
- Departamento de Química Fundamental, CCEN, Universidade Federal de Pernambuco, Recife, Pernambuco, Brazil
| | - Armando Navarro-Vázquez
- Departamento de Química Fundamental, CCEN, Universidade Federal de Pernambuco, Recife, Pernambuco, Brazil
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13
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Recchia MJJ, Cohen RD, Liu Y, Sherer EC, Harper JK, Martin GE, Williamson RT. "One-Shot" Measurement of Residual Chemical Shift Anisotropy Using Poly-γ-benzyl-l-glutamate as an Alignment Medium. Org Lett 2020; 22:8850-8854. [PMID: 33140974 DOI: 10.1021/acs.orglett.0c03225] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
A method for the measurement of residual chemical shift anisotropy in one experiment using a biphasic isotropic/anisotropic lyotropic liquid crystalline medium based on poly-γ-benzyl-l-glutamate as the alignment medium is presented. This approach is demonstrated on the model compound strychnine and neotricone, a depsidone natural product with a questionable structural assignment based on comparison with the closely related excelsione and in-depth density functional theory calculations.
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Affiliation(s)
- Michael J J Recchia
- Department of Chemistry & Biochemistry, University of North Carolina Wilmington, Wilmington, North Carolina 28409, United States
| | - Ryan D Cohen
- Analytical Research & Development, Merck & Company Inc., Rahway, New Jersey 07065, United States
| | - Yizhou Liu
- Analytical Research & Development, Pfizer Worldwide Research and Development, Groton, Connecticut 06340, United States
| | - Edward C Sherer
- Analytical Research & Development, Merck & Company Inc., Rahway, New Jersey 07065, United States
| | - James K Harper
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah 84602, United States
| | - Gary E Martin
- Department of Chemistry, Seton Hall University, South Orange, New Jersey 07079, United States
| | - R Thomas Williamson
- Department of Chemistry & Biochemistry, University of North Carolina Wilmington, Wilmington, North Carolina 28409, United States
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14
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Lesot P, Gil RR, Berdagué P, Navarro-Vázquez A. Deuterium Residual Quadrupolar Couplings: Crossing the Current Frontiers in the Relative Configuration Analysis of Natural Products. JOURNAL OF NATURAL PRODUCTS 2020; 83:3141-3148. [PMID: 32970418 DOI: 10.1021/acs.jnatprod.0c00745] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The determination of the 3D structure (configuration and preferred conformation) of complex natural and synthetic organic molecules is a long-standing but still challenging task for chemists, with various implications in pharmaceutical sciences whether or not these substances have specific bioactivities. Nuclear magnetic resonance (NMR) in aligning media, either lyotropic liquid crystals (LLCs) or polymer gels, in combination with molecular modeling is a unique framework for solving complex structural problems whose analytical wealth lies in the establishment of nonlocal structural correlations. As an alternative to the already well-established anisotropic NMR parameters, such as RDCs (residual dipolar couplings) and RCSAs (residual chemical shift anisotropies), it is shown here that deuterium residual quadrupolar couplings (2H-RQCs) can be extracted from 2H 2D-NMR spectra recorded at the natural abundance level in samples oriented in a homopolypeptide LLCs (poly-γ-benzyl-l-glutamate (PBLG)). These 2H-RQCs were successfully used to address nontrivial structural problems in organic molecules. The performance and scope of this new tool is examined for two natural chiral compounds of pharmaceutical interest (strychnine and artemisinin). This is the first report in which the 3D structure/relative configuration of complex bioactive molecules is unambiguously determined using only 2H-RQCs, which, in this case, are at 2H natural abundance.
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Affiliation(s)
- Philippe Lesot
- Université Paris-Saclay, UFR d'Orsay, RMN en Milieu Orienté, ICMMO, UMR CNRS 8182, Bât. 410, 15 rue du Doyen, Georges Poitou, F-91405 Orsay, France
- Centre National de la Recherche Scientifique (CNRS), 3 rue Michel Ange, F-75016 Paris, France
| | - Roberto R Gil
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Philippe Berdagué
- Université Paris-Saclay, UFR d'Orsay, RMN en Milieu Orienté, ICMMO, UMR CNRS 8182, Bât. 410, 15 rue du Doyen, Georges Poitou, F-91405 Orsay, France
| | - Armando Navarro-Vázquez
- Departamento de Química Fundamental, Universidade Federal de Pernambuco, Cidade Universitária, CEP 50.740-540 Recife, Pernambuco, Brazil
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15
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Ndukwe IE, Lam YH, Pandey SK, Haug BE, Bayer A, Sherer EC, Blinov KA, Williamson RT, Isaksson J, Reibarkh M, Liu Y, Martin GE. Unequivocal structure confirmation of a breitfussin analog by anisotropic NMR measurements. Chem Sci 2020; 11:12081-12088. [PMID: 34094423 PMCID: PMC8162999 DOI: 10.1039/d0sc03664a] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Structural features of proton-deficient heteroaromatic natural products, such as the breitfussins, can severely complicate their characterization by NMR spectroscopy. For the breitfussins in particular, the constitution of the five-membered oxazole central ring cannot be unequivocally established via conventional NMR methods when the 4′-position is halogenated. The level of difficulty is exacerbated by 4′-iodination, as the accuracy with which theoretical NMR parameters are determined relies extensively on computational treatment of the relativistic effects of the iodine atom. It is demonstrated in the present study, that the structure of a 4′-iodo breitfussin analog can be unequivocally established by anisotropic NMR methods, by adopting a reduced singular value decomposition (SVD) protocol that leverages the planar structures exhibited by its conformers. Structural features of proton-deficient heteroaromatic natural products, such as the breitfussins, can severely complicate their characterization by NMR spectroscopy.![]()
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Affiliation(s)
- Ikenna E Ndukwe
- Analytical Research & Development, (Rahway), Merck & Co. Inc. Kenilworth NJ USA
| | - Yu-Hong Lam
- Computational and Structural Chemistry, Merck & Co., Inc. Rahway NJ 07065 USA
| | - Sunil K Pandey
- Department of Chemistry and Centre for Pharmacy, University of Bergen Allégaten 41 NO-5020 Bergen Norway
| | - Bengt E Haug
- Department of Chemistry and Centre for Pharmacy, University of Bergen Allégaten 41 NO-5020 Bergen Norway
| | - Annette Bayer
- Department of Chemistry, UiT the Arctic University of Tromsø NO-9037 Tromsø Norway
| | - Edward C Sherer
- Analytical Research & Development, (Rahway), Merck & Co. Inc. Kenilworth NJ USA
| | - Kirill A Blinov
- MestReLab Research S. L. Santiago de Compostela A Coruna 15706 Spain
| | - R Thomas Williamson
- Analytical Research & Development, (Rahway), Merck & Co. Inc. Kenilworth NJ USA
| | - Johan Isaksson
- Department of Chemistry, UiT the Arctic University of Tromsø NO-9037 Tromsø Norway
| | - Mikhail Reibarkh
- Analytical Research & Development, (Rahway), Merck & Co. Inc. Kenilworth NJ USA
| | - Yizhou Liu
- Analytical Research & Development, (Rahway), Merck & Co. Inc. Kenilworth NJ USA
| | - Gary E Martin
- Analytical Research & Development, (Rahway), Merck & Co. Inc. Kenilworth NJ USA
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16
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Relative configuration of micrograms of natural compounds using proton residual chemical shift anisotropy. Nat Commun 2020; 11:4372. [PMID: 32873801 PMCID: PMC7463026 DOI: 10.1038/s41467-020-18093-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Accepted: 07/28/2020] [Indexed: 01/12/2023] Open
Abstract
3D molecular structure determination is a challenge for organic compounds or natural products available in minute amounts. Proton/proton and proton/carbon correlations yield the constitution. J couplings and NOEs oftentimes supported by one-bond 1H,13C residual dipolar couplings (RDCs) or by 13C residual chemical shift anisotropies (RCSAs) provide the relative configuration. However, these RDCs or carbon RCSAs rely on 1% natural abundance of 13C preventing their use for compounds available only in quantities of a few 10’s of µgs. By contrast, 1H RCSAs provide similar information on spatial orientation of structural moieties within a molecule, while using the abundant 1H spin. Herein, 1H RCSAs are accurately measured using constrained aligning gels or liquid crystals and applied to the 3D structural determination of molecules with varying complexities. Even more, deuterated alignment media allow the elucidation of the relative configuration of around 35 µg of a briarane compound isolated from Briareum asbestinum. Determination of 3D molecular structures remains challenging for natural products or organic compounds available in minute amounts. Here, the authors determine the structure of complex molecules, including few micrograms of briarane B-3 isolated from Briareum asbestinums, through measurement of 1H residual chemical shift anisotropy.
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17
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Ndukwe IE, Wang X, Lam NYS, Ermanis K, Alexander KL, Bertin MJ, Martin GE, Muir G, Paterson I, Britton R, Goodman JM, Helfrich EJN, Piel J, Gerwick WH, Williamson RT. Synergism of anisotropic and computational NMR methods reveals the likely configuration of phormidolide A. Chem Commun (Camb) 2020; 56:7565-7568. [PMID: 32520016 PMCID: PMC7436192 DOI: 10.1039/d0cc03055d] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Characterization of the complex molecular scaffold of the marine polyketide natural product phormidolide A represents a challenge that has persisted for nearly two decades. In light of discordant results arising from recent synthetic and biosynthetic reports, a rigorous study of the configuration of phormidolide A was necessary. This report outlines a synergistic effort employing computational and anisotropic NMR investigation, that provided orthogonal confirmation of the reassigned side chain, as well as supporting a further correction of the C7 stereocenter.
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Affiliation(s)
- Ikenna E Ndukwe
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA, USA
| | - Xiao Wang
- Analytical Research & Development, Merck & Co. Inc, Rahway, NJ, USA
| | - Nelson Y S Lam
- University Chemical Laboratory, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Kristaps Ermanis
- University Chemical Laboratory, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Kelsey L Alexander
- Scripps Institution of Oceanography and Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, CA, USA and Department of Chemistry, University of California, San Diego, CA, USA
| | - Matthew J Bertin
- Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, RI, USA
| | - Gary E Martin
- Department of Chemistry, Seton Hall University, South Orange, NJ, USA
| | - Garrett Muir
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada
| | - Ian Paterson
- University Chemical Laboratory, Lensfield Road, Cambridge, CB2 1EW, UK
| | - Robert Britton
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada
| | | | - Eric J N Helfrich
- Institute of Microbiology, Eidgenössische Technische Hochschule (ETH) Zürich, Zurich, Switzerland
| | - Jörn Piel
- Institute of Microbiology, Eidgenössische Technische Hochschule (ETH) Zürich, Zurich, Switzerland
| | - William H Gerwick
- Scripps Institution of Oceanography and Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, CA, USA
| | - R Thomas Williamson
- Department of Chemistry & Biochemistry, University of North Carolina Wilmington, Wilmington, NC, USA.
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18
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Köck M, Reggelin M, Immel S. The Advanced Floating Chirality Distance Geometry Approach-How Anisotropic NMR Parameters Can Support the Determination of the Relative Configuration of Natural Products. Mar Drugs 2020; 18:md18060330. [PMID: 32599876 PMCID: PMC7344786 DOI: 10.3390/md18060330] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 06/16/2020] [Accepted: 06/18/2020] [Indexed: 11/16/2022] Open
Abstract
The configurational analysis of complex natural products by NMR spectroscopy is still a challenging task. The assignment of the relative configuration is usually carried out by analysis of interproton distances from NOESY or ROESY spectra (qualitative or quantitative) and scalar (J) couplings. About 15 years ago, residual dipolar couplings (RDCs) were introduced as a tool for the configurational determination of small organic molecules. In contrast to NOEs/ROEs which are local parameters (distances up to 400 pm can be detected for small organic molecules), RDCs are global parameters which allow to obtain structural information also from long-range relationships. RDCs have the disadvantage that the sample needs a setup in an alignment medium in order to obtain the required anisotropic environment. Here, we will discuss the configurational analysis of five complex natural products: axinellamine A (1), tetrabromostyloguanidine (2), 3,7-epi-massadine chloride (3), tubocurarine (4), and vincristine (5). Compounds 1-3 are marine natural products whereas 4 and 5 are from terrestrial sources. The chosen examples will carefully work out the limitations of NOEs/ROEs in the configurational analysis of natural products and will also provide an outlook on the information obtained from RDCs.
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Affiliation(s)
- Matthias Köck
- Alfred-Wegener-Institut für Polar-und Meeresforschung in der Helmholtz-Gemeinschaft, Am Handelshafen 12, 27570 Bremerhaven, Germany
| | - Michael Reggelin
- Clemens-Schöpf-Institut für Organische Chemie und Biochemie, Technische Universität Darmstadt, Alarich-Weiss-Straße 4, 64287 Darmstadt, Germany
| | - Stefan Immel
- Clemens-Schöpf-Institut für Organische Chemie und Biochemie, Technische Universität Darmstadt, Alarich-Weiss-Straße 4, 64287 Darmstadt, Germany
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19
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Ibáñez de Opakua A, Klama F, Ndukwe IE, Martin GE, Williamson RT, Zweckstetter M. Determination of Complex Small-Molecule Structures Using Molecular Alignment Simulation. Angew Chem Int Ed Engl 2020; 59:6172-6176. [PMID: 31971323 PMCID: PMC7187346 DOI: 10.1002/anie.202000311] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Revised: 01/23/2020] [Indexed: 11/12/2022]
Abstract
Correct structural assignment of small molecules and natural products is critical for drug discovery and organic chemistry. Anisotropy-based NMR spectroscopy is a powerful tool for the structural assignment of organic molecules, but it relies on the utilization of a medium that disrupts the isotropic motion of molecules in organic solvents. Here, we establish a quantitative correlation between the atomic structure of the alignment medium, the molecular structure of the small molecule, and molecule-specific anisotropic NMR parameters. The quantitative correlation uses an accurate three-dimensional molecular alignment model that predicts residual dipolar couplings of small molecules aligned by poly(γ-benzyl-l-glutamate). The technique facilitates reliable determination of the correct stereoisomer and enables unequivocal, rapid determination of complex molecular structures from extremely sparse NMR data.
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Affiliation(s)
- Alain Ibáñez de Opakua
- Structural Biology in DementiaGerman Center for Neurodegenerative Diseases (DZNE)Von-Siebold-Strasse 3a37075GöttingenGermany
| | - Frederik Klama
- Department for NMR-based Structural BiologyMax Planck Institute for Biophysical ChemistryAm Fassberg 1137077GöttingenGermany
| | - Ikenna E. Ndukwe
- Analytical Research & Development (Rahway)Merck & Co. Inc.KenilworthNJUSA
- Complex Carbohydrate Research CenterUniversity of GeorgiaAthensGA30602USA
| | - Gary E. Martin
- Analytical Research & Development (Rahway)Merck & Co. Inc.KenilworthNJUSA
- Department of Chemistry and BiochemistrySeton Hall UniversitySouth OrangeNJ07079USA
| | - R. Thomas Williamson
- Analytical Research & Development (Rahway)Merck & Co. Inc.KenilworthNJUSA
- Department of Chemistry & BiochemistryUniversity of North Carolina WilmingtonWilmingtonNC28409USA
| | - Markus Zweckstetter
- Structural Biology in DementiaGerman Center for Neurodegenerative Diseases (DZNE)Von-Siebold-Strasse 3a37075GöttingenGermany
- Department for NMR-based Structural BiologyMax Planck Institute for Biophysical ChemistryAm Fassberg 1137077GöttingenGermany
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20
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A Novel pH-Tunable Secondary Conformation Containing Mixed Micellar System in Anticancer Treatment. Cancers (Basel) 2020; 12:cancers12020503. [PMID: 32098177 PMCID: PMC7072654 DOI: 10.3390/cancers12020503] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 02/17/2020] [Accepted: 02/18/2020] [Indexed: 12/12/2022] Open
Abstract
In this study, for the first time, we precisely assembled the poly-γ-benzyl-l-glutamate and an amphiphilic copolymer d-α-tocopherol polyethylene glycol succinate into a mixed micellar system for the embedment of the anticancer drug doxorubicin. Importantly, the intracellular drug-releasing behaviors could be controlled by changing the secondary structures of poly-γ-benzyl-l-glutamate via the precise regulation of the buffer’s pH value. Under neutral conditions, the micellar architectures were stabilized by both α-helix secondary structures and the microcrystalline structures. Under acidic conditions (pH 4.0), the interior structures transformed into a coil state with a disordered alignment, inducing the release of the loaded drug. A remarkable cytotoxicity of the Dox-loaded mixed micelles was exhibited toward human lung cancer cells in vitro. The internalizing capability into the cancer cells, as well as the intracellular drug-releasing behaviors, were also identified and observed. The secondary structures containing Dox-loaded mixed micelles had an outstanding antitumor efficacy in human lung cancer A549 cells-bearing nude mice, while little toxicities occurred or interfered with the hepatic or renal functions after the treatments. Thus, these pH-tunable α-helix-containing mixed micelles are innovative and promising for controlled intracellular anticancer drug delivery.
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21
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Ibáñez de Opakua A, Klama F, Ndukwe IE, Martin GE, Williamson RT, Zweckstetter M. Bestimmung komplexer kleiner Molekülstrukturen mittels molekularer Ausrichtungssimulation. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202000311] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Alain Ibáñez de Opakua
- Translationale Strukturelle Biologie der DemenzDeutsches Zentrum für Neurodegenerative Erkrankungen (DZNE) Von-Siebold-Str. 3a 37075 Göttingen Deutschland
| | - Frederik Klama
- Abteilung für NMR-basierte StrukturbiologieMax-Planck-Institut für Biophysikalische Chemie Am Fassberg 11 37077 Göttingen Deutschland
| | - Ikenna E. Ndukwe
- Analytical Research & Development (Rahway), Merck & Co. Inc. Kenilworth NJ USA
- Complex Carbohydrate Research CenterUniversity of Georgia Athens GA 30602 USA
| | - Gary E. Martin
- Analytical Research & Development (Rahway), Merck & Co. Inc. Kenilworth NJ USA
- Department of Chemistry and BiochemistrySeton Hall University South Orange NJ 07079 USA
| | - R. Thomas Williamson
- Analytical Research & Development (Rahway), Merck & Co. Inc. Kenilworth NJ USA
- Department of Chemistry & BiochemistryUniversity of North Carolina Wilmington Wilmington NC 28409 USA
| | - Markus Zweckstetter
- Translationale Strukturelle Biologie der DemenzDeutsches Zentrum für Neurodegenerative Erkrankungen (DZNE) Von-Siebold-Str. 3a 37075 Göttingen Deutschland
- Abteilung für NMR-basierte StrukturbiologieMax-Planck-Institut für Biophysikalische Chemie Am Fassberg 11 37077 Göttingen Deutschland
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22
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Li XL, Chi LP, Navarro-Vázquez A, Hwang S, Schmieder P, Li XM, Li X, Yang SQ, Lei X, Wang BG, Sun H. Stereochemical Elucidation of Natural Products from Residual Chemical Shift Anisotropies in a Liquid Crystalline Phase. J Am Chem Soc 2020; 142:2301-2309. [PMID: 31889437 DOI: 10.1021/jacs.9b10961] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Determination of the stereochemistry of organic molecules still represents one of the major obstacles in the structure elucidation procedure in drug discovery. Although the application of residual dipolar couplings (RDCs) has revolutionized this field, residual chemical shift anisotropies (RCSAs) which contain valuable structural information for nonprotonated carbons have only been scarcely employed so far. In this study, we present a simple but highly effective solution to extract RCSAs of the analytes in a liquid crystalline phase formed by AAKLVFF oligopeptides. This method does not require any special instruments, devices, or correction during postacquisition data analysis and thus can be easily applied in any chemistry laboratory. To illustrate the potential of this method, the relative configurations of four known natural products (1-4) belonging to different structural classes were confirmed. Moreover, we unambiguously elucidated the stereochemistry of spiroepicoccin A (5), a rare thiodiketopiperazine marine natural product whose configuration could not be assigned based on conventional NMR methods.
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Affiliation(s)
- Xiao-Lu Li
- Section of Structural Biology , Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP) , Berlin 13125 , Germany
| | - Lu-Ping Chi
- Laboratory of Marine Biology and Biotechnology , Qingdao National Laboratory for Marine Science and Technology , Qingdao 266071 , People's Republic of China.,University of Chinese Academy of Sciences , Yuquan Road 19A , Beijing 100049 , People's Republic of China
| | - Armando Navarro-Vázquez
- Departamento de Química Fundamental , Universidade Federal de Pernambuco , Recife , Pernambuco 50670-901 , Brazil
| | - Songhwan Hwang
- Section of Structural Biology , Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP) , Berlin 13125 , Germany
| | - Peter Schmieder
- Section of Structural Biology , Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP) , Berlin 13125 , Germany
| | - Xiao-Ming Li
- Laboratory of Marine Biology and Biotechnology , Qingdao National Laboratory for Marine Science and Technology , Qingdao 266071 , People's Republic of China
| | - Xin Li
- Laboratory of Marine Biology and Biotechnology , Qingdao National Laboratory for Marine Science and Technology , Qingdao 266071 , People's Republic of China
| | - Sui-Qun Yang
- Laboratory of Marine Biology and Biotechnology , Qingdao National Laboratory for Marine Science and Technology , Qingdao 266071 , People's Republic of China
| | - Xinxiang Lei
- School of Pharmaceutical Sciences , South Central University for Nationalities , Wuhan 430074 , People's Republic of China
| | - Bin-Gui Wang
- Laboratory of Marine Biology and Biotechnology , Qingdao National Laboratory for Marine Science and Technology , Qingdao 266071 , People's Republic of China
| | - Han Sun
- Section of Structural Biology , Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP) , Berlin 13125 , Germany
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23
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Ndukwe IE, Brunskill A, Gauthier DR, Zhong YL, Martin GE, Williamson RT, Reibarkh M, Liu Y. 13C NMR-Based Approaches for Solving Challenging Stereochemical Problems. Org Lett 2019; 21:4072-4076. [PMID: 31117703 DOI: 10.1021/acs.orglett.9b01248] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Determining the configuration of proton-deficient molecules is challenging using conventional NMR methods including nuclear Overhauser effect (NOE) and the proton-dependent J-based configuration analysis (JBCA). The problem is exacerbated when only one stereoisomer is available. Alternative methods based on the utilization of 13C NMR chemical shifts, 13C-13C homonuclear couplings measured at natural abundance, and residual chemical shift anisotropy measurements in conjunction with density functional theory calculations are illustrated with a proton-deficient model compound.
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Affiliation(s)
- Ikenna E Ndukwe
- Analytical Research & Development , Merck & Co. Inc. , Rahway , New Jersey 07065 , United States
| | - Andrew Brunskill
- Analytical Research & Development , Merck & Co. Inc. , Rahway , New Jersey 07065 , United States
| | - Donald R Gauthier
- Analytical Research & Development , Merck & Co. Inc. , Rahway , New Jersey 07065 , United States
| | - Yong-Li Zhong
- Analytical Research & Development , Merck & Co. Inc. , Rahway , New Jersey 07065 , United States
| | - Gary E Martin
- Analytical Research & Development , Merck & Co. Inc. , Rahway , New Jersey 07065 , United States
| | - R Thomas Williamson
- Analytical Research & Development , Merck & Co. Inc. , Rahway , New Jersey 07065 , United States
| | - Mikhail Reibarkh
- Analytical Research & Development , Merck & Co. Inc. , Rahway , New Jersey 07065 , United States
| | - Yizhou Liu
- Analytical Research & Development , Merck & Co. Inc. , Rahway , New Jersey 07065 , United States
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