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Immel S, Köck M, Reggelin M. NMR-Based Configurational Assignments of Natural Products: How Floating Chirality Distance Geometry Calculations Simplify Gambling with 2 N-1 Diastereomers. J Nat Prod 2022; 85:1837-1849. [PMID: 35820115 DOI: 10.1021/acs.jnatprod.2c00427] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Using NMR data, the assignment of the correct 3D configuration and conformation to unknown natural products is of pivotal importance in pharmaceutical and medicinal chemistry. In this report, we quantify the probability of configurational assignments to judge the quality of structural elucidations using Bayesian inference in combination with floating-chirality distance geometry simulations. Based on reference-free NOE/ROE data, residual dipolar couplings (RDCs), and residual quadrupolar couplings (RQCs) in various combinations, we demonstrate how the relative configurations of three natural compounds, namely, jatrohemiketal (1), artemisinin (2), and Taxol (3), can be unambiguously established without the necessity to carry out time-consuming DFT-based configurational and conformational analyses. Our results quantitatively describe how reliably molecular geometries can be inferred from experimental NMR data, thereby unequivocally unveiling remaining assignment ambiguities. The methodology presented here will dramatically reduce the risk of incorrect structural assignments based on the overinterpretation of incomplete data and DFT-based structure models in chemistry.
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Affiliation(s)
- Stefan Immel
- Clemens-Schöpf-Institut für Organische Chemie und Biochemie, Technische Universität Darmstadt, Alarich-Weiss-Straße 4, 64287 Darmstadt, Germany
| | - 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
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2
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Immel S, Köck M, Reggelin M. Bayesian Inference Applied to NMR-Based Configurational Assignments by Floating Chirality Distance Geometry Calculations. J Am Chem Soc 2022; 144:6830-6838. [PMID: 35412312 DOI: 10.1021/jacs.2c00813] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Using NMR data, the assignment of the correct 3D configuration and conformation to unknown natural products is of pivotal importance in pharmaceutical and medicinal chemistry. In this report, we quantify the quality and probability of structural elucidations using Bayesian inference in combination with floating chirality distance geometry simulations. Here, we will discuss the configurational analysis of three complex natural products including isopinocampheol (1), plakilactone H (2), and iodocallophycoic acid A (3) using NMR restraints of various types and in different combinations (residual dipolar couplings (RDCs) and NOE-derived distances). Our results quantitatively demonstrate how reliably molecular geometries can be inferred from experimental NMR data, unequivocally unveiling remaining assignment ambiguities. The methodology presented here can dramatically reduce the risk of incorrect structural assignments based on the overinterpretation of incomplete data in chemistry.
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Affiliation(s)
- Stefan Immel
- Clemens Schöpf Institut für Organische Chemie und Biochemie, Technische Universität Darmstadt, Alarich-Weiss-Straße 4, 64287 Darmstadt, Germany
| | - Matthias Köck
- Alfred-Wegener-Institut für Polar- and 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
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3
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Pulver B, Schönberger T, Weigel D, Köck M, Eschenlohr Y, Lucas T, Podlesnik N, Opatz T, Dreiseitel W, Pütz M, Schäper J, Jacobsen-Bauer A, Auwärter V, Westphal F. Structure elucidation of the novel synthetic cannabinoid Cumyl-tosyl-indazole-3-carboxamide (Cumyl-TsINACA) found in illicit products in Germany. Drug Test Anal 2022; 14:1387-1406. [PMID: 35338591 DOI: 10.1002/dta.3261] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 03/21/2022] [Accepted: 03/22/2022] [Indexed: 11/11/2022]
Abstract
New chemical moieties continue to appear in synthetic cannabimimetics (SC), the largest group of new psychoactive substances in the EU. We describe the first comprehensive characterisation of the novel SC Cumyl-TsINACA (N-(2-phenylpropan-2-yl)-1-tosyl-1H-indazole-3-carboxamide) from seized case samples. Structure elucidation was performed within the EU-project ADEBAR plus to facilitate confident identification by other researchers and practitioners worldwide. Characteristic MS fragmentations include the cleavage of the sulfonamide bond (S-N), the aryl sulfone bond (C-S) and the elimination rearrangement of SO2 in the side chain. Cumyl-TsINACA is a full receptor agonist at hCB1 (Emax = 228%) with very weak binding affinity (Ki = 292 nm) and low functional activity (EC50 = 31 μm). Thermal degradation of Cumyl-TsINACA was observed under GC conditions. The degree to which the tosyl side chain is cleaved due to pyrolysis primarily depends on solvent, the use of glass wool in the liner, and injector temperature. The determination of the constitution by NMR spectroscopy was ambiguous due to the high number of neighbouring, non-proton-bearing atoms. Therefore, other possible structures compatible with the NMR correlations were generated using the WebCocon software. The unambiguous structural evidence was finally obtained by spectra comparison after the synthesis of Cumyl-TsINACA. The low thermal stability, as well as the low affinity and potency, render this compound unfavourable for the use as a psychoactive substance. Thus, we do not expect widespread adoption of this SC.
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Affiliation(s)
- Benedikt Pulver
- Institute of Forensic Medicine, Forensic Toxicology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Hermann Staudinger Graduate School, University of Freiburg, Freiburg, Germany.,State Bureau of Criminal Investigation Schleswig-Holstein, Forensic Science Institute, Kiel, Germany
| | - Torsten Schönberger
- Federal Criminal Police Office, Forensic Science Institute, Wiesbaden, Germany
| | - Diana Weigel
- Federal Criminal Police Office, Forensic Science Institute, Wiesbaden, Germany
| | - Matthias Köck
- Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
| | - Yvonne Eschenlohr
- Bavarian State Criminal Police Office, Forensic Science Institute, München, Germany
| | - Tobias Lucas
- Department of Chemistry, Johannes Gutenberg University, Mainz, Germany
| | - Nika Podlesnik
- Department of Chemistry, Johannes Gutenberg University, Mainz, Germany
| | - Till Opatz
- Department of Chemistry, Johannes Gutenberg University, Mainz, Germany
| | - Wolfgang Dreiseitel
- Hessian State Criminal Police Office, Forensic Science Institute, Wiesbaden, Germany
| | - Michael Pütz
- Federal Criminal Police Office, Forensic Science Institute, Wiesbaden, Germany
| | - Jan Schäper
- Department of Chemistry, Johannes Gutenberg University, Mainz, Germany
| | | | - Volker Auwärter
- Institute of Forensic Medicine, Forensic Toxicology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Folker Westphal
- State Bureau of Criminal Investigation Schleswig-Holstein, Forensic Science Institute, Kiel, Germany
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Immel S, Köck M, Reggelin M. NMR-Based Configurational Assignments of Natural Products: Gibbs Sampling and Bayesian Inference Using Floating Chirality Distance Geometry Calculations. Mar Drugs 2021; 20:14. [PMID: 35049868 PMCID: PMC8781118 DOI: 10.3390/md20010014] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 12/12/2021] [Accepted: 12/20/2021] [Indexed: 02/07/2023] Open
Abstract
Floating chirality restrained distance geometry (fc-rDG) calculations are used to directly evolve structures from NMR data such as NOE-derived intramolecular distances or anisotropic residual dipolar couplings (RDCs). In contrast to evaluating pre-calculated structures against NMR restraints, multiple configurations (diastereomers) and conformations are generated automatically within the experimental limits. In this report, we show that the "unphysical" rDG pseudo energies defined from NMR violations bear statistical significance, which allows assigning probabilities to configurational assignments made that are fully compatible with the method of Bayesian inference. These "diastereomeric differentiabilities" then even become almost independent of the actual values of the force constants used to model the restraints originating from NOE or RDC data.
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Affiliation(s)
- Stefan Immel
- Clemens-Schöpf-Institut für Organische Chemie und Biochemie, Technische Universität Darmstadt, Alarich-Weiss-Straße 4, 64287 Darmstadt, Germany
| | - 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
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5
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Faisal MR, Kellermann MY, Rohde S, Putra MY, Murniasih T, Risdian C, Mohr KI, Wink J, Praditya DF, Steinmann E, Köck M, Schupp PJ. Ecological and Pharmacological Activities of Polybrominated Diphenyl Ethers (PBDEs) from the Indonesian Marine Sponge Lamellodysidea herbacea. Mar Drugs 2021; 19:md19110611. [PMID: 34822482 PMCID: PMC8621810 DOI: 10.3390/md19110611] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 10/14/2021] [Accepted: 10/15/2021] [Indexed: 11/27/2022] Open
Abstract
Two known Polybrominated Diphenyl Ethers (PBDEs), 3,4,5-tribromo-2-(2′,4′-dibromophenoxy)phenol (1d) and 3,4,5,6-tetrabromo-2-(2′,4′-dibromophenoxy)phenol (2b), were isolated from the Indonesian marine sponge Lamellodysidea herbacea. The structure was confirmed using 13C chemical shift average deviation and was compared to the predicted structures and recorded chemical shifts in previous studies. We found a wide range of bioactivities from the organic crude extract, such as (1) a strong deterrence against the generalist pufferfish Canthigaster solandri, (2) potent inhibition against environmental and human pathogenic bacterial and fungal strains, and (3) the inhibition of the Hepatitis C Virus (HCV). The addition of a bromine atom into the A-ring of compound 2b resulted in higher fish feeding deterrence compared to compound 1d. On the contrary, compound 2b showed only more potent inhibition against the Gram-negative bacteria Rhodotorula glutinis (MIC 2.1 μg/mL), while compound 1d showed more powerful inhibition against the other human pathogenic bacteria and fungi. The first report of a chemical defense by compounds 1d and 2b against fish feeding and environmental relevant bacteria, especially pathogenic bacteria, might be one reason for the widespread occurrence of the shallow water sponge Lamellodysidea herbacea in Indonesia and the Indo-Pacific.
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Affiliation(s)
- Muhammad R. Faisal
- Environmental Biochemistry, Institute of Chemistry and Biology of the Marine Environment (ICBM), Carl-von-Ossietzky University of Oldenburg, Schleusenstr. 1, 26382 Wilhelmshaven, Germany; (M.R.F.); (M.Y.K.); (S.R.)
| | - Matthias Y. Kellermann
- Environmental Biochemistry, Institute of Chemistry and Biology of the Marine Environment (ICBM), Carl-von-Ossietzky University of Oldenburg, Schleusenstr. 1, 26382 Wilhelmshaven, Germany; (M.R.F.); (M.Y.K.); (S.R.)
| | - Sven Rohde
- Environmental Biochemistry, Institute of Chemistry and Biology of the Marine Environment (ICBM), Carl-von-Ossietzky University of Oldenburg, Schleusenstr. 1, 26382 Wilhelmshaven, Germany; (M.R.F.); (M.Y.K.); (S.R.)
| | - Masteria Y. Putra
- Research Center for Biotechnology, Research Organization for Life Science, National Research and Innovation Agency (BRIN), Cibinong 16911, Indonesia; (M.Y.P.); (T.M.); (D.F.P.)
| | - Tutik Murniasih
- Research Center for Biotechnology, Research Organization for Life Science, National Research and Innovation Agency (BRIN), Cibinong 16911, Indonesia; (M.Y.P.); (T.M.); (D.F.P.)
| | - Chandra Risdian
- Microbial Strain Collection (MISG), Helmholtz Centre for Infection Research, Inhoffenstraße 7, 38124 Braunschweig, Germany; (C.R.); (K.I.M.); (J.W.)
- Research Unit for Clean Technology, Indonesian Institute of Sciences (LIPI), Bandung 40135, Indonesia
| | - Kathrin I. Mohr
- Microbial Strain Collection (MISG), Helmholtz Centre for Infection Research, Inhoffenstraße 7, 38124 Braunschweig, Germany; (C.R.); (K.I.M.); (J.W.)
| | - Joachim Wink
- Microbial Strain Collection (MISG), Helmholtz Centre for Infection Research, Inhoffenstraße 7, 38124 Braunschweig, Germany; (C.R.); (K.I.M.); (J.W.)
| | - Dimas F. Praditya
- Research Center for Biotechnology, Research Organization for Life Science, National Research and Innovation Agency (BRIN), Cibinong 16911, Indonesia; (M.Y.P.); (T.M.); (D.F.P.)
- TWINCORE-Centre for Experimental and Clinical Infection Research, Institute of Experimental Virology, Feodor-Lynen-Str. 7–9, 30625 Hannover, Germany;
- Department of Molecular and Medical Virology, Ruhr-University Bochum, 44801 Bochum, Germany
| | - Eike Steinmann
- TWINCORE-Centre for Experimental and Clinical Infection Research, Institute of Experimental Virology, Feodor-Lynen-Str. 7–9, 30625 Hannover, Germany;
- Department of Molecular and Medical Virology, Ruhr-University Bochum, 44801 Bochum, Germany
| | - Matthias Köck
- Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany;
| | - Peter J. Schupp
- Environmental Biochemistry, Institute of Chemistry and Biology of the Marine Environment (ICBM), Carl-von-Ossietzky University of Oldenburg, Schleusenstr. 1, 26382 Wilhelmshaven, Germany; (M.R.F.); (M.Y.K.); (S.R.)
- Helmholtz Institute for Functional Marine Biodiversity (HIFMB), University of Oldenburg, Ammerländer Heerstraße 231, 26129 Oldenburg, Germany
- Correspondence: ; Tel.: +49-4421-944-100
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6
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Köck M, Lindel T, Junker J. Incorporation of 4J-HMBC and NOE Data into Computer-Assisted Structure Elucidation with WebCocon. Molecules 2021; 26:molecules26164846. [PMID: 34443433 PMCID: PMC8398166 DOI: 10.3390/molecules26164846] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2021] [Revised: 06/24/2021] [Accepted: 06/25/2021] [Indexed: 01/13/2023] Open
Abstract
Over the past decades, different software programs have been developed for the Computer-Assisted Structure Elucidation (CASE) with NMR data using with various approaches. WebCocon is one of them that has been continuously improved over the past 20 years. Here, we present the inclusion of 4JCH correlations (4J-HMBC) in the HMBC interpretation of Cocon and NOE data in WebCocon. The 4J-HMBC data is used during the structure generation process, while the NOE data is used in post-processing of the results. The marine natural product oxocyclostylidol was selected to demonstrate WebCocon’s enhanced HMBC data processing capabilities. A systematic study of the 4JCH correlations of oxocyclostylidol was performed. The application of NOEs in CASE is demonstrated using the NOE correlations of the diterpene pyrone asperginol A known from the literature. As a result, we obtained a conformation that corresponds very well to the existing X-ray structure.
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Affiliation(s)
- Matthias Köck
- Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, 27570 Bremerhaven, Germany
- Correspondence: (M.K.); (J.J.)
| | - Thomas Lindel
- Institute of Organic Chemistry, Technical University of Braunschweig, 38106 Braunschweig, Germany;
| | - Jochen Junker
- Oswaldo Cruz Foundation–CDTS, Rio de Janeiro 21040-900, Brazil
- Correspondence: (M.K.); (J.J.)
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Köck M, Reggelin M, Immel S. Model-Free Approach for the Configurational Analysis of Marine Natural Products. Mar Drugs 2021; 19:md19060283. [PMID: 34063741 PMCID: PMC8223791 DOI: 10.3390/md19060283] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 05/09/2021] [Accepted: 05/11/2021] [Indexed: 12/17/2022] Open
Abstract
The NMR-based configurational analysis of complex marine natural products is still not a routine task. Different NMR parameters are used for the assignment of the relative configuration: NOE/ROE, homo- and heteronuclear J couplings as well as anisotropic parameters. The combined distance geometry (DG) and distance bounds driven dynamics (DDD) method allows a model-free approach for the determination of the relative configuration that is invariant to the choice of an initial starting structure and does not rely on comparisons with (DFT) calculated structures. Here, we will discuss the configurational analysis of five complex marine natural products or synthetic derivatives thereof: the cis-palau’amine derivatives 1a and 1b, tetrabromostyloguanidine (1c), plakilactone H (2), and manzamine A (3). The certainty of configurational assignments is evaluated in view of the accuracy of the NOE/ROE data available. These case studies will show the prospective breadth of application of the DG/DDD method.
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Affiliation(s)
- Matthias Köck
- Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany
- Correspondence: (M.K.); (S.I.)
| | - Michael Reggelin
- Clemens-Schöpf-Institute for Organic Chemistry and Biochemistry, Technical University of Darmstadt, Alarich-Weiss-Straße 4, 64287 Darmstadt, Germany;
| | - Stefan Immel
- Clemens-Schöpf-Institute for Organic Chemistry and Biochemistry, Technical University of Darmstadt, Alarich-Weiss-Straße 4, 64287 Darmstadt, Germany;
- Correspondence: (M.K.); (S.I.)
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8
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Wibowo JT, Kellermann MY, Köck M, Putra MY, Murniasih T, Mohr KI, Wink J, Praditya DF, Steinmann E, Schupp PJ. Anti-Infective and Antiviral Activity of Valinomycin and Its Analogues from a Sea Cucumber-Associated Bacterium, Streptomyces sp. SV 21. Mar Drugs 2021; 19:md19020081. [PMID: 33540548 PMCID: PMC7912928 DOI: 10.3390/md19020081] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 01/22/2021] [Accepted: 01/28/2021] [Indexed: 12/15/2022] Open
Abstract
The manuscript investigated the isolation, characterization and anti-infective potential of valinomycin (3), streptodepsipeptide P11A (2), streptodepsipeptide P11B (1), and one novel valinomycin analogue, streptodepsipeptide SV21 (4), which were all produced by the Gram-positive strain Streptomycescavourensis SV 21. Although the exact molecular weight and major molecular fragments were recently reported for compound 4, its structure elucidation was not based on compound isolation and spectroscopic techniques. We successfully isolated and elucidated the structure based on the MS2 fragmentation pathways as well as 1H and 13C NMR spectra and found that the previously reported structure of compound 4 differs from our analysis. Our findings showed the importance of isolation and structure elucidation of bacterial compounds in the era of fast omics technologies. The here performed anti-infective assays showed moderate to potent activity against fungi, multi drug resistant (MDR) bacteria and infectivity of the Hepatitis C Virus (HCV). While compounds 2, 3 and 4 revealed potent antiviral activity, the observed minor cytotoxicity needs further investigation. Furthermore, the here performed anti-infective assays disclosed that the symmetry of the valinomycin molecule is most important for its bioactivity, a fact that has not been reported so far.
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Affiliation(s)
- Joko T. Wibowo
- Institute for Chemistry and Biology of the Marine Environment (ICBM), Carl-von-Ossietzky University Oldenburg, Schleusenstraße 1, D-26382 Wilhelmshaven, Germany;
- Research Center for Biotechnology, Indonesian Institute of Science, Jl. Raya Bogor KM 46, Cibinong 16911, Indonesia; (M.Y.P.); (T.M.); (D.F.P.)
- Correspondence: (J.T.W.); (P.J.S.); Tel.: +49-4421-944-100 (P.J.S.)
| | - Matthias Y. Kellermann
- Institute for Chemistry and Biology of the Marine Environment (ICBM), Carl-von-Ossietzky University Oldenburg, Schleusenstraße 1, D-26382 Wilhelmshaven, Germany;
| | - Matthias Köck
- Alfred-Wegener-Institut für Polar- und Meeresforschung in der Helmholtz-Gemeinschaft, Am Handelshafen 12, 27570 Bremerhaven, Germany;
| | - Masteria Y. Putra
- Research Center for Biotechnology, Indonesian Institute of Science, Jl. Raya Bogor KM 46, Cibinong 16911, Indonesia; (M.Y.P.); (T.M.); (D.F.P.)
| | - Tutik Murniasih
- Research Center for Biotechnology, Indonesian Institute of Science, Jl. Raya Bogor KM 46, Cibinong 16911, Indonesia; (M.Y.P.); (T.M.); (D.F.P.)
| | - Kathrin I. Mohr
- Helmholtz Centre for Infection Research, Inhoffenstraße 7, 38124 Braunschweig, Germany; (K.I.M.); (J.W.)
| | - Joachim Wink
- Helmholtz Centre for Infection Research, Inhoffenstraße 7, 38124 Braunschweig, Germany; (K.I.M.); (J.W.)
| | - Dimas F. Praditya
- Research Center for Biotechnology, Indonesian Institute of Science, Jl. Raya Bogor KM 46, Cibinong 16911, Indonesia; (M.Y.P.); (T.M.); (D.F.P.)
- TWINCORE-Centre for Experimental and Clinical Infection Research (Institute of Experimental Virology) Hannover, Feodor-Lynen-Str. 7-9, 30625 Hannover, Germany;
- Department of Molecular and Medical Virology, Ruhr-University Bochum, 44801 Bochum, Germany
| | - Eike Steinmann
- TWINCORE-Centre for Experimental and Clinical Infection Research (Institute of Experimental Virology) Hannover, Feodor-Lynen-Str. 7-9, 30625 Hannover, Germany;
- Department of Molecular and Medical Virology, Ruhr-University Bochum, 44801 Bochum, Germany
| | - Peter J. Schupp
- Institute for Chemistry and Biology of the Marine Environment (ICBM), Carl-von-Ossietzky University Oldenburg, Schleusenstraße 1, D-26382 Wilhelmshaven, Germany;
- Helmholtz Institute for Functional Marine Biodiversity at the University of Oldenburg (HIFMB), Ammerländer Heerstrasse 231, D-26129 Oldenburg, Germany
- Correspondence: (J.T.W.); (P.J.S.); Tel.: +49-4421-944-100 (P.J.S.)
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Mancini F, Unver MY, Elgaher WAM, Jumde VR, Alhayek A, Lukat P, Herrmann J, Witte MD, Köck M, Blankenfeldt W, Müller R, Hirsch AKH. Frontispiece: Protein‐Templated Hit Identification through an Ugi Four‐Component Reaction. Chemistry 2020. [DOI: 10.1002/chem.202086462] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Federica Mancini
- Department for Drug Design and Optimization Helmholtz Institute for Pharmaceutical Research Saarland (HIPS)–, Helmholtz Centre for Infection Research (HZI) Campus Building E8.1 66123 Saarbrücken Germany
- Department of Pharmacy Saarland University Campus Building E8.1 66123 Saarbrücken Germany
| | - M. Yagiz Unver
- Department for Drug Design and Optimization Helmholtz Institute for Pharmaceutical Research Saarland (HIPS)–, Helmholtz Centre for Infection Research (HZI) Campus Building E8.1 66123 Saarbrücken Germany
- Stratingh Institute for Chemistry University of Groningen Nijenborgh 7 9747 AG Groningen The Netherlands
| | - Walid A. M. Elgaher
- Department for Drug Design and Optimization Helmholtz Institute for Pharmaceutical Research Saarland (HIPS)–, Helmholtz Centre for Infection Research (HZI) Campus Building E8.1 66123 Saarbrücken Germany
| | - Varsha R. Jumde
- Department for Drug Design and Optimization Helmholtz Institute for Pharmaceutical Research Saarland (HIPS)–, Helmholtz Centre for Infection Research (HZI) Campus Building E8.1 66123 Saarbrücken Germany
| | - Alaa Alhayek
- Department for Drug Design and Optimization Helmholtz Institute for Pharmaceutical Research Saarland (HIPS)–, Helmholtz Centre for Infection Research (HZI) Campus Building E8.1 66123 Saarbrücken Germany
- Department of Pharmacy Saarland University Campus Building E8.1 66123 Saarbrücken Germany
| | - Peer Lukat
- Department of Structure and Function of Proteins HZI 38124 Braunschweig Germany
| | - Jennifer Herrmann
- Department of Microbial Natural Products HIPS–HZI 66123 Saarbrücken Germany
| | - Martin D. Witte
- Stratingh Institute for Chemistry University of Groningen Nijenborgh 7 9747 AG Groningen The Netherlands
| | - Matthias Köck
- Department of Microbial Natural Products HIPS–HZI 66123 Saarbrücken Germany
| | - Wulf Blankenfeldt
- Department of Structure and Function of Proteins HZI 38124 Braunschweig Germany
- Institute for Biochemistry, Biotechnology and Bioinformatics Technische Universität Braunschweig Spielmannstr. 7 38106 Braunschweig Germany
| | - Rolf Müller
- Department of Pharmacy Saarland University Campus Building E8.1 66123 Saarbrücken Germany
- Department of Microbial Natural Products HIPS–HZI 66123 Saarbrücken Germany
| | - Anna K. H. Hirsch
- Department for Drug Design and Optimization Helmholtz Institute for Pharmaceutical Research Saarland (HIPS)–, Helmholtz Centre for Infection Research (HZI) Campus Building E8.1 66123 Saarbrücken Germany
- Department of Pharmacy Saarland University Campus Building E8.1 66123 Saarbrücken Germany
- Stratingh Institute for Chemistry University of Groningen Nijenborgh 7 9747 AG Groningen The Netherlands
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Mancini F, Unver MY, Elgaher WAM, Jumde VR, Alhayek A, Lukat P, Herrmann J, Witte MD, Köck M, Blankenfeldt W, Müller R, Hirsch AKH. Protein-Templated Hit Identification through an Ugi Four-Component Reaction*. Chemistry 2020; 26:14585-14593. [PMID: 32428268 PMCID: PMC7756422 DOI: 10.1002/chem.202002250] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Indexed: 12/21/2022]
Abstract
Kinetic target-guided synthesis represents an efficient hit-identification strategy, in which the protein assembles its own inhibitors from a pool of complementary building blocks via an irreversible reaction. Herein, we pioneered an in situ Ugi reaction for the identification of novel inhibitors of a model enzyme and binders for an important drug target, namely, the aspartic protease endothiapepsin and the bacterial β-sliding clamp DnaN, respectively. Highly sensitive mass-spectrometry methods enabled monitoring of the protein-templated reaction of four complementary reaction partners, which occurred in a background-free manner for endothiapepsin or with a clear amplification of two binders in the presence of DnaN. The Ugi products we identified show low micromolar activity on endothiapepsin or moderate affinity for the β-sliding clamp. We succeeded in expanding the portfolio of chemical reactions and biological targets and demonstrated the efficiency and sensitivity of this approach, which can find application on any drug target.
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Affiliation(s)
- Federica Mancini
- Department for Drug Design and OptimizationHelmholtz Institute for Pharmaceutical Research Saarland (HIPS)–, Helmholtz Centre for Infection Research (HZI)Campus Building E8.166123SaarbrückenGermany
- Department of PharmacySaarland UniversityCampus Building E8.166123SaarbrückenGermany
| | - M. Yagiz Unver
- Department for Drug Design and OptimizationHelmholtz Institute for Pharmaceutical Research Saarland (HIPS)–, Helmholtz Centre for Infection Research (HZI)Campus Building E8.166123SaarbrückenGermany
- Stratingh Institute for ChemistryUniversity of GroningenNijenborgh 79747AGGroningenThe Netherlands
| | - Walid A. M. Elgaher
- Department for Drug Design and OptimizationHelmholtz Institute for Pharmaceutical Research Saarland (HIPS)–, Helmholtz Centre for Infection Research (HZI)Campus Building E8.166123SaarbrückenGermany
| | - Varsha R. Jumde
- Department for Drug Design and OptimizationHelmholtz Institute for Pharmaceutical Research Saarland (HIPS)–, Helmholtz Centre for Infection Research (HZI)Campus Building E8.166123SaarbrückenGermany
| | - Alaa Alhayek
- Department for Drug Design and OptimizationHelmholtz Institute for Pharmaceutical Research Saarland (HIPS)–, Helmholtz Centre for Infection Research (HZI)Campus Building E8.166123SaarbrückenGermany
- Department of PharmacySaarland UniversityCampus Building E8.166123SaarbrückenGermany
| | - Peer Lukat
- Department of Structure and Function of ProteinsHZI38124BraunschweigGermany
| | - Jennifer Herrmann
- Department of Microbial Natural ProductsHIPS–HZI66123SaarbrückenGermany
| | - Martin D. Witte
- Stratingh Institute for ChemistryUniversity of GroningenNijenborgh 79747AGGroningenThe Netherlands
| | - Matthias Köck
- Department of Microbial Natural ProductsHIPS–HZI66123SaarbrückenGermany
| | - Wulf Blankenfeldt
- Department of Structure and Function of ProteinsHZI38124BraunschweigGermany
- Institute for Biochemistry, Biotechnology and BioinformaticsTechnische Universität BraunschweigSpielmannstr. 738106BraunschweigGermany
| | - Rolf Müller
- Department of PharmacySaarland UniversityCampus Building E8.166123SaarbrückenGermany
- Department of Microbial Natural ProductsHIPS–HZI66123SaarbrückenGermany
| | - Anna K. H. Hirsch
- Department for Drug Design and OptimizationHelmholtz Institute for Pharmaceutical Research Saarland (HIPS)–, Helmholtz Centre for Infection Research (HZI)Campus Building E8.166123SaarbrückenGermany
- Department of PharmacySaarland UniversityCampus Building E8.166123SaarbrückenGermany
- Stratingh Institute for ChemistryUniversity of GroningenNijenborgh 79747AGGroningenThe Netherlands
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11
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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: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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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12
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Primahana G, Risdian C, Mozef T, Sudarman E, Köck M, Wink J, Stadler M. Nonocarbolines A-E, β-Carboline Antibiotics Produced by the Rare Actinobacterium Nonomuraea sp. from Indonesia. Antibiotics (Basel) 2020; 9:E126. [PMID: 32192170 PMCID: PMC7148486 DOI: 10.3390/antibiotics9030126] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 03/12/2020] [Accepted: 03/14/2020] [Indexed: 12/12/2022] Open
Abstract
During the course of our ongoing screening for novel biologically active secondary metabolites, the rare Actinobacterium, Nonomuraea sp. 1808210CR was found to produce five unprecedented β-carboline derivatives, nonocarbolines A-E (1-5). Their structures were elucidated from high-resolution mass spectrometry, 1D and 2D nuclear magnetic resonance spectroscopy, and the absolute configuration of 4 was determined by using the modified Mosher method. Nonocarboline B (2) displayed moderate antifungal activity against Mucor hiemalis, while nonocarboline D (4) exhibited significant cytotoxic activity against the human lung carcinoma cell line A-549 with the IC50 value of 1.7 µM.
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Affiliation(s)
- Gian Primahana
- Department Microbial Drugs, Helmholtz Centre for Infection Research GmbH (HZI), Inhoffenstrasse 7, 38124 Braunschweig, Germany; (G.P.); (E.S.)
- Research Center for Chemistry, Indonesian Institute of Sciences (LIPI), Kawasan Puspiptek, Serpong, 15314 Tangerang Selatan, Indonesia;
| | - Chandra Risdian
- Working group Microbial Strain Collection, Helmholtz Centre for Infection Research GmbH (HZI), Inhoffenstrasse 7, 38124 Braunschweig, Germany; (C.R.); (J.W.)
- Research Unit for Clean Technology, Indonesian Institute of Sciences (LIPI), Bandung 40135, Indonesia
| | - Tjandrawati Mozef
- Research Center for Chemistry, Indonesian Institute of Sciences (LIPI), Kawasan Puspiptek, Serpong, 15314 Tangerang Selatan, Indonesia;
| | - Enge Sudarman
- Department Microbial Drugs, Helmholtz Centre for Infection Research GmbH (HZI), Inhoffenstrasse 7, 38124 Braunschweig, Germany; (G.P.); (E.S.)
| | - Matthias Köck
- Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung (AWI), Am Handelshafen 12, 27570 Bremerhaven, Germany;
| | - Joachim Wink
- Working group Microbial Strain Collection, Helmholtz Centre for Infection Research GmbH (HZI), Inhoffenstrasse 7, 38124 Braunschweig, Germany; (C.R.); (J.W.)
| | - Marc Stadler
- Department Microbial Drugs, Helmholtz Centre for Infection Research GmbH (HZI), Inhoffenstrasse 7, 38124 Braunschweig, Germany; (G.P.); (E.S.)
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13
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Immel S, Köck M, Reggelin M. Cover Image, Volume 31, Issue 5. Chirality 2019. [DOI: 10.1002/chir.23073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Immel S, Köck M, Reggelin M. Configurational analysis by residual dipolar couplings: A critical assessment of diastereomeric differentiabilities. Chirality 2019; 31:384-400. [PMID: 30916829 DOI: 10.1002/chir.23065] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Revised: 02/20/2019] [Accepted: 02/21/2019] [Indexed: 11/06/2022]
Abstract
Two independent statistical models for evaluating the certainties of configurational assignments of compounds based on nuclear magnetic resonance (NMR) data are evaluated and compared. Both methods yield weights or probabilities with which two or more structure models (constitutional or configurational isomers or even conformers) could be differentiated based on experimental parameters. Although this paper focusses on the use of residual dipolar couplings (RDCs) for the differentiation of diastereomers, the concept can be expanded to any set of experimental NMR-derived parameters. It is demonstrated that highly reliable configurational assignments crucially must depend on thorough statistical analysis, which is frequently neglected in the literature.
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Affiliation(s)
- Stefan Immel
- Clemens Schöpf Institut für Organische Chemie und Biochemie, Technische Universität Darmstadt, Darmstadt, Germany
| | - Matthias Köck
- Alfred-Wegener-Institut (AWI), Helmholtz-Zentrum für Polar- und Meeresforschung, Sektion Ökologische Chemie, Bremerhaven, Germany.,Helmholtz-Zentrum für Infektionsforschung (HZI), Abteilung Chemische Biologie, Braunschweig, Germany
| | - Michael Reggelin
- Clemens Schöpf Institut für Organische Chemie und Biochemie, Technische Universität Darmstadt, Darmstadt, Germany
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Immel S, Köck M, Reggelin M. Configurational Analysis by Residual Dipolar Coupling Driven Floating Chirality Distance Geometry Calculations. Chemistry 2018; 24:13918-13930. [PMID: 29999551 DOI: 10.1002/chem.201802800] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Indexed: 11/06/2022]
Abstract
A new method implemented into a computer program (ConArch+ ) has been developed and applied to demonstrate the successful implementation of residual dipolar couplings (RDCs) in distance geometry (DG) calculations for the configurational assignment of chiral compounds. Unlike established protocols, the new approach combines floating chirality (fc) in 4D- and 3D-distance bounds driven dynamics (DDD) calculations with structural information from RDCs. Thus, relative configurations of chiral compounds were generated only by observables (e.g., NOEs, RDCs) rendering tedious evaluations of calculated structures against RDCs obsolete. We demonstrate the potential of this novel procedure by the simultaneous determination of the configuration and the conformation of three natural products, (-)-isopinocampheol (1), tubocurarine (2), and vincristine (3), as well as for diisopropylidene-β-d-fructopyranose (4).
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Affiliation(s)
- Stefan Immel
- Technische Universität Darmstadt, Clemens Schöpf Institut für Organische Chemie und Biochemie, Alarich-Weiss-Strasse 4, 64287, Darmstadt, Germany
| | - Matthias Köck
- Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung, Am Handelshafen 12, 27570, Bremerhaven, Germany.,Helmholtz-Institut für Pharmazeutische Forschung Saarland (HIPS), Abteilung Mikrobielle Naturstoffe, Universität des Saarlandes, Universitätscampus E8.1, 66123, Saarbrücken, Germany
| | - Michael Reggelin
- Technische Universität Darmstadt, Clemens Schöpf Institut für Organische Chemie und Biochemie, Alarich-Weiss-Strasse 4, 64287, Darmstadt, Germany
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16
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Einarsdottir E, Magnusdottir M, Astarita G, Köck M, Ögmundsdottir HM, Thorsteinsdottir M, Rapp HT, Omarsdottir S, Paglia G. Metabolic Profiling as a Screening Tool for Cytotoxic Compounds: Identification of 3-Alkyl Pyridine Alkaloids from Sponges Collected at a Shallow Water Hydrothermal Vent Site North of Iceland. Mar Drugs 2017; 15:md15020052. [PMID: 28241423 PMCID: PMC5334632 DOI: 10.3390/md15020052] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Revised: 02/10/2017] [Accepted: 02/16/2017] [Indexed: 01/15/2023] Open
Abstract
Twenty-eight sponge specimens were collected at a shallow water hydrothermal vent site north of Iceland. Extracts were prepared and tested in vitro for cytotoxic activity, and eight of them were shown to be cytotoxic. A mass spectrometry (MS)-based metabolomics approach was used to determine the chemical composition of the extracts. This analysis highlighted clear differences in the metabolomes of three sponge specimens, and all of them were identified as Haliclona (Rhizoniera) rosea (Bowerbank, 1866). Therefore, these specimens were selected for further investigation. Haliclona rosea metabolomes contained a class of potential key compounds, the 3-alkyl pyridine alkaloids (3-APA) responsible for the cytotoxic activity of the fractions. Several 3-APA compounds were tentatively identified including haliclamines, cyclostellettamines, viscosalines and viscosamines. Among these compounds, cyclostellettamine P was tentatively identified for the first time by using ion mobility MS in time-aligned parallel (TAP) fragmentation mode. In this work, we show the potential of applying metabolomics strategies and in particular the utility of coupling ion mobility with MS for the molecular characterization of sponge specimens.
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Affiliation(s)
- Eydis Einarsdottir
- Faculty of Pharmaceutical Sciences, University of Iceland, Reykjavík 107, Iceland.
| | | | - Giuseppe Astarita
- Denali Therapeutics, South San Francisco, CA 94080, USA.
- Department of Biochemistry and Molecular & Cellular Biology, Georgetown University, Washington, DC 20057, USA.
| | - Matthias Köck
- Helmholtz Center for Polar and Marine Research, Alfred-Wegener-Institute, Bremerhaven D-27570, Germany.
| | | | | | - Hans Tore Rapp
- Department of Biology and KG Jebsen Centre for Deep Sea Research, University of Bergen, Bergen 5020, Norway.
| | - Sesselja Omarsdottir
- Faculty of Pharmaceutical Sciences, University of Iceland, Reykjavík 107, Iceland.
| | - Giuseppe Paglia
- Center for Biomedicine, European Academy of Bolzano/Bozen, Bolzano 39100, Italy.
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Abstract
A chemical investigation of the tropical sponge Agelas sceptrum from Plana Cays (Bahamas) led to the isolation of two hybrid pyrrole-imidazole alkaloids (PIAs), 15'-oxoadenosceptrin (1) and decarboxyagelamadin C (2). Herein, we report their challenging structure elucidation established by NMR and ECD spectroscopy. 15'-Oxoadenosceptrin (1) shows sceptrin merged with an adenine moiety, not yet encountered in the PIA family, whereas decarboxyagelamadin C (2) is a close derivative of agelamadins C to E recently isolated from an Agelas sp. from Okinawa.
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Affiliation(s)
- Julie Muñoz
- Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung Am Handelshafen 12, 27570 Bremerhaven, Germany
| | - Matthias Köck
- Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung Am Handelshafen 12, 27570 Bremerhaven, Germany
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18
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Göthel Q, Sirirak T, Köck M. Bromotyrosine-derived alkaloids from the Caribbean sponge Aplysina lacunosa. Beilstein J Org Chem 2015; 11:2334-42. [PMID: 26734082 PMCID: PMC4685874 DOI: 10.3762/bjoc.11.254] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Accepted: 09/01/2015] [Indexed: 11/24/2022] Open
Abstract
Three new bromotyrosine-derived alkaloids 14-debromo-11-deoxyfistularin-3 (1), aplysinin A (2), and aplysinin B (3), together with 15 known compounds (4-18) were isolated from the sponge Aplysina lacunosa collected from Stirrup Cay, Bahamas. The structures of the isolated compounds were identified on the basis of MS and NMR data analysis. The (13)C NMR assignment of spirocyclohexadienylisoxazoline moieties of 1 and 2 were confirmed by an 1,1-ADEQUATE experiment. Compounds 1 and 2 showed a mild to moderate cytotoxic activities against KB-31 and FS4-LTM cell lines. Only aplysinin A (2) exhibited cytotoxicity against MCF-7 cells.
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Affiliation(s)
- Qun Göthel
- Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung, Am Handelshafen 12, 27570 Bremerhaven, Germany
| | - Thanchanok Sirirak
- Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung, Am Handelshafen 12, 27570 Bremerhaven, Germany
| | - Matthias Köck
- Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung, Am Handelshafen 12, 27570 Bremerhaven, Germany
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Cychon C, Lichte E, Köck M. The marine sponge Agelas citrina as a source of the new pyrrole-imidazole alkaloids citrinamines A-D and N-methylagelongine. Beilstein J Org Chem 2015; 11:2029-37. [PMID: 26664624 PMCID: PMC4660978 DOI: 10.3762/bjoc.11.220] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Accepted: 07/22/2015] [Indexed: 11/23/2022] Open
Abstract
The chemical investigation of the Caribbean sponge Agelas citrina revealed four new pyrrole-imidazole alkaloids (PIAs), the citrinamines A-D (1-4) and the bromopyrrole alkaloid N-methylagelongine (5). All citrinamines are dimers of hymenidin (6) which was also isolated from this sponge as the major metabolite. Citrinamines A (1) and B (2) are derivatives of the PIA dimer mauritiamine (7), whereas citrinamine C (3) is derived from the PIA dimer nagelamide B (8). Citrinamine D (4) shows an uncommon linkage between the imidazole rings of both monomeric units as it is only observed in the benzocyclobutane ring moiety of benzosceptrins A-C (9-11). Compound 5 is the N-methyl derivative of agelongine (12) which consist of a pyridinium ring and an ester linkage instead of the aminoimidazole moiety and the common amide bond in PIAs.
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Affiliation(s)
- Christine Cychon
- Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung, Am Handelshafen 12, 27570 Bremerhaven, Germany
| | - Ellen Lichte
- Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung, Am Handelshafen 12, 27570 Bremerhaven, Germany
| | - Matthias Köck
- Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung, Am Handelshafen 12, 27570 Bremerhaven, Germany
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20
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Cychon C, Schmidt G, Mordhorst T, Köck M. Structure Elucidation of Submilligram Quantities of Natural Products - Application to Haliclamines G and H from the Arctic Marine Sponge Haliclona viscosa. ACTA ACUST UNITED AC 2014. [DOI: 10.5560/znb.2012-0039] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Two new haliclamines were identified directly from the crude extract of the Arctic sponge Haliclona viscosa using improved chromatographic conditions and a detailed knowledge about the fragmentation pattern of haliclamines. These are haliclamine G (1) with two alkyl chains of equal length (10 methylene groups) and haliclamine H (2) with alkyl chains of 10 and 12 methylene groups. Due to the limited amount of sponge material available, the haliclamines were not isolated, and the structure elucidation relied on the chromatographic and mass spectrometric comparison with synthetic compounds
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Affiliation(s)
- Christine Cychon
- Alfred-Wegener-Institut für Polar- und Meeresforschung in der Helmholtz-Gemeinschaft, Am Handelshafen 12, 27570 Bremerhaven, Germany
| | - Gesine Schmidt
- Alfred-Wegener-Institut für Polar- und Meeresforschung in der Helmholtz-Gemeinschaft, Am Handelshafen 12, 27570 Bremerhaven, Germany
| | - Thorsten Mordhorst
- Alfred-Wegener-Institut für Polar- und Meeresforschung in der Helmholtz-Gemeinschaft, Am Handelshafen 12, 27570 Bremerhaven, Germany
| | - Matthias Köck
- Alfred-Wegener-Institut für Polar- und Meeresforschung in der Helmholtz-Gemeinschaft, Am Handelshafen 12, 27570 Bremerhaven, Germany
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Schmidt G, Timm C, Köck M. Haliclocyclin C, a New Monomeric 3-Alkyl Pyridinium Alkaloid from the Arctic Marine Sponge Haliclona viscosa. ACTA ACUST UNITED AC 2014. [DOI: 10.1515/znb-2011-0717] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
For the first time, the macrocyclic monomeric 3-alkyl pyridinium alkaloid with an alkyl chain of 13 methylene groups, haliclocyclin C (1), could be identified from a natural source in the crude extract of the Arctic sponge Haliclona viscosa. Structure elucidation was carried out by comparison of the natural product with the corresponding synthetic compound.
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Affiliation(s)
- Gesine Schmidt
- Alfred-Wegener-Institut für Polar- und Meeresforschung, Am Handelshafen 12, 27570 Bremerhaven, Germany
| | - Christoph Timm
- Alfred-Wegener-Institut für Polar- und Meeresforschung, Am Handelshafen 12, 27570 Bremerhaven, Germany
| | - Matthias Köck
- Alfred-Wegener-Institut für Polar- und Meeresforschung, Am Handelshafen 12, 27570 Bremerhaven, Germany
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Göthel Q, Köck M. New sesquiterpene hydroquinones from the Caribbean sponge Aka coralliphagum. Beilstein J Org Chem 2014; 10:613-21. [PMID: 24778711 PMCID: PMC3999825 DOI: 10.3762/bjoc.10.52] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Accepted: 12/23/2013] [Indexed: 11/23/2022] Open
Abstract
Four new sulfated sesquiterpene hydroquinones siphonodictyals E1-E4 (1-4) and cyclosiphonodictyol A (5) were isolated from a sample of the Caribbean sponge Aka coralliphagum collected off the coast of San Salvador in the Bahamas. The structures of the new compounds were elucidated on the basis of mass spectrometric and NMR spectroscopic analysis. Compounds 1-4 are derivatives of siphonodictyal E (9). Siphonodictyal E4 (4) exhibited mild antiproliferation activity against L929 mouse fibroblast, KB-31 epidermoid carcinoma, and MCF-7 breast cancer cell lines, while siphondictyal E3 (3) and cyclosiphonodictyol A (5) showed moderate activity against Gram-positive bacteria.
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Affiliation(s)
- Qun Göthel
- Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung, Am Handelshafen 12, 27570 Bremerhaven, Germany
| | - Matthias Köck
- Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung, Am Handelshafen 12, 27570 Bremerhaven, Germany
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23
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Berger R, Courtieu J, Gil RR, Griesinger C, Köck M, Lesot P, Luy B, Merlet D, Navarro-Vázquez A, Reggelin M, Reinscheid UM, Thiele CM, Zweckstetter M. Is Enantiomer Assignment Possible by NMR Spectroscopy Using Residual Dipolar Couplings from Chiral Nonracemic Alignment Media?-A Critical Assessment. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201107626] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Berger R, Courtieu J, Gil RR, Griesinger C, Köck M, Lesot P, Luy B, Merlet D, Navarro-Vázquez A, Reggelin M, Reinscheid UM, Thiele CM, Zweckstetter M. Is Enantiomer Assignment Possible by NMR Spectroscopy Using Residual Dipolar Couplings from Chiral Nonracemic Alignment Media?-A Critical Assessment. Angew Chem Int Ed Engl 2012; 51:8388-91. [DOI: 10.1002/anie.201107626] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2011] [Revised: 06/08/2012] [Indexed: 11/09/2022]
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Schmidt G, Timm C, Grube A, Volk CA, Köck M. Viscosalines B1,2 and E1,2: Challenging New 3-Alkyl Pyridinium Alkaloids from the Marine Sponge Haliclona viscosa. Chemistry 2012; 18:8180-9. [DOI: 10.1002/chem.201101362] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2011] [Revised: 12/14/2011] [Indexed: 11/10/2022]
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Köck M, Schmidt G, Seiple IB, Baran PS. Configurational analysis of tetracyclic dimeric pyrrole-imidazole alkaloids using a floating chirality approach. J Nat Prod 2012; 75:127-130. [PMID: 22332969 PMCID: PMC3315375 DOI: 10.1021/np200514g] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The structure elucidation of the palau'amine congener tetrabromostyloguanidine (1), which used interproton distances from ROESY spectra as restraints in a computational approach, the so-called fc-rDG/DDD method, led to a revision of the relative configuration of palau'amine (2) and its congeners in 2007. The recent total synthesis of (±)-palau'amine (2) subsequently confirmed the computed structural revision of the relative configuration. In order to test a broader application range of the fc-rDG/DDD method, the present study investigated two additional dimeric pyrrole-imidazole alkaloids, axinellamine A (3) and 3,7-epi-massadine chloride (4). These calculations allowed the simultaneous assignment of the relative configuration for all eight stereogenic centers of compounds 3 and 4 without using any information from the reported configurations. In contrast to the palau'amine congeners, the fc-rDG/DDD method confirmed the relative configuration originally described for axinellamine A (3) and 3,7-epi-massadine chloride (4).
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Affiliation(s)
- Matthias Köck
- Alfred-Wegener-Institut für Polar- und Meeresforschung in der Helmholtz-Gemeinschaft, Am Handelshafen 12, D-27570 Bremerhaven, Germany.
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Seiple IB, Su S, Young IS, Nakamura A, Yamaguchi J, Jørgensen L, Rodriguez RA, O’Malley DP, Gaich T, Köck M, Baran PS. Enantioselective total syntheses of (-)-palau'amine, (-)-axinellamines, and (-)-massadines. J Am Chem Soc 2011; 133:14710-26. [PMID: 21861522 PMCID: PMC3173569 DOI: 10.1021/ja2047232] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Dimeric pyrrole-imidazole alkaloids represent a rich and topologically unique class of marine natural products. This full account will follow the progression of efforts that culminated in the enantioselective total syntheses of the most structurally ornate members of this family: the axinellamines, the massadines, and palau'amine. A bio-inspired approach capitalizing on the pseudo-symmetry of the members of this class is recounted, delivering a deschloro derivative of the natural product core. Next, the enantioselective synthesis of the chlorocyclopentane core featuring a scalable, catalytic, enantioselective Diels-Alder reaction of a 1-siloxydiene is outlined in detail. Finally, the successful divergent conversion of this core to each of the aforementioned natural products, and the ensuing methodological developments, are described.
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Affiliation(s)
- Ian B. Seiple
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California, 92037
| | | | | | - Akifumi Nakamura
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California, 92037
| | - Junichiro Yamaguchi
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California, 92037
| | - Lars Jørgensen
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California, 92037
| | - Rodrigo A. Rodriguez
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California, 92037
| | - Daniel P. O’Malley
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California, 92037
| | - Tanja Gaich
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California, 92037
| | - Matthias Köck
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California, 92037
| | - Phil S. Baran
- Department of Chemistry, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California, 92037
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Schmidt G, Timm C, Köck M. Haliclocyclin C, a New Monomeric 3-Alkyl Pyridinium Alkaloid from the Arctic Marine Sponge Haliclona viscosa. Z Naturforsch B 2011. [DOI: 10.5560/znb.2011.66b0745] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Bickmeyer U, Heine M, Podbielski I, Münd D, Köck M, Karuso P. Tracking of fast moving neuronal vesicles with ageladine A. Biochem Biophys Res Commun 2010; 402:489-94. [DOI: 10.1016/j.bbrc.2010.10.055] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2010] [Accepted: 10/13/2010] [Indexed: 10/18/2022]
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Bickmeyer U, Grube A, Klings KW, Pawlik JR, Köck M. Siphonodictyal B1 from a marine sponge increases intracellular calcium levels comparable to the Ca2+-ATPase (SERCA) inhibitor thapsigargin. Mar Biotechnol (NY) 2010; 12:267-272. [PMID: 19609614 DOI: 10.1007/s10126-009-9206-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2008] [Accepted: 06/13/2009] [Indexed: 05/28/2023]
Abstract
Siphonodictyal B1 is a sesquiterpene-hydroquinone isolated from the Caribbean coral reef bioeroding sponge Siphonodictyon coralliphagum. Siphonodictyal B1 increased intracellular calcium levels in neuroendocrine cells (PC12) in the presence and absence of extracellular calcium using Fura-2 as a calcium-sensitive dye. The calcium rise was comparable in amplitude and timing to the application of the sarco-endoplasmic reticulum calcium-ATPase (SERCA) inhibitor thapsigargin from the terrestrial plant Thapsia garganica. The effects of thapsigargin and siphonodictyal B1 on intracellular calcium levels were not distinguishable in pharmacological experiments conducted with caffeine, ryanodine, muscarine, and thapsigargin in calcium-free and calcium-containing buffer, although thapsigargin was effective at lower concentrations. Thapsigargin is a sesquiterpene-lactone and has no structural similarities to siphonodictyal B1. We conclude that thapsigargin and siphonodictyal B1 share SERCAs as cellular targets. Siphonodictyal B1 may be involved in the process of bioeroding the calcium carbonate endoskeleton of the scleractinian corals attacked by S. coralliphagum.
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Affiliation(s)
- Ulf Bickmeyer
- Alfred-Wegener-Institut für Polar- und Meeresforschung in der Helmholtz-Gemeinschaft, Biologische Anstalt Helgoland, Kurpromenade 201, 27498 Helgoland, Germany.
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Meyer SW, Mordhorst TF, Lee C, Jensen PR, Fenical W, Köck M. Penilumamide, a novel lumazine peptide isolated from the marine-derived fungus, Penicillium sp. CNL-338. Org Biomol Chem 2010; 8:2158-63. [PMID: 20401392 PMCID: PMC3779348 DOI: 10.1039/b910629d] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A novel lumazine peptide, penilumamide (1), was isolated from the fermentation broth of a marine-derived fungal strain, identified as Penicillium sp. (strain CNL-338) and the structure of the new metabolite was determined by analysis of ESI-TOF MS data combined with 1D and 2D NMR experiments.
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Affiliation(s)
- Sven W Meyer
- Alfred-Wegener-Institut für Polar- und Meeresforschung in der Helmholtz-Gemeinschaft, Am Handelshafen 12, D-27570 Bremerhaven, Germany
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Abstract
In addition to the four known stylissamides, A (1), B (2), C, and D, two new cyclic heptapeptides, stylissamides E (3) and F (4), were isolated from the Caribbean sponge Stylissa caribica. The structures of 3 and 4 were elucidated from a combination of mass spectrometric and NMR spectroscopic data as cyclo-(cis-Pro(1)-Tyr(2)-trans-Pro(3)-Ala(4)-Ile(5)-Gln(6)-Ile(7)) for stylissamide E (3) and cyclo-(trans-Pro(1)-cis-Pro(2)-Phe(3)-Asp(4)-trans-Pro(5)-Arg(6)-Phe(7)) for stylissamide F (4).
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Affiliation(s)
- Christine Cychon
- Alfred-Wegener-Institut für Polar- und Meeresforschung in der Helmholtz-Gemeinschaft, Am Handelshafen 12, 27570 Bremerhaven, Germany
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Abstract
Phakellins 3 and 4 and isophakellins 5 and 6 are tetracyclic pyrrole-imidazole alkaloids. Their structure elucidation is herein reviewed using state-of-the-art NMR methods. Special emphasis has been given to the application of ADEQUATE NMR pulse sequences. Furthermore, (15)N NMR chemical shifts, proton T1 relaxation times, and (1)J(CH) coupling constants were determined.
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Affiliation(s)
- Sven W Meyer
- Alfred-Wegener-Institut für Polar- and Meeresforschung in der Helmholtz-Gemeinschaft, Am Handelshafen 12, D-27570 Bremerhaven, Germany
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Timm C, Volk C, Sasse F, Köck M. The first cyclic monomeric 3-alkylpyridinium alkaloid from natural sources: identification, synthesis, and biological activity. Org Biomol Chem 2008; 6:4036-40. [DOI: 10.1039/b808647h] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Bats JW, Gerlach M, Reggelin M, Köck M. 2-Hydroxy-4,6-dimethoxy-3-(3-methylbutanoyl)benzaldehyde. Acta Crystallogr C 2007; 63:o664-6. [DOI: 10.1107/s0108270107048044] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2007] [Accepted: 10/01/2007] [Indexed: 11/10/2022] Open
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Grube A, Immel S, Baran P, Köck M. Massadinchlorid: eine Vorstufe in der Biosynthese von Massadin und Stylissadin. Angew Chem Int Ed Engl 2007. [DOI: 10.1002/ange.200790221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Grube A, Immel S, Baran P, Köck M. Inside Cover: Massadine Chloride: A Biosynthetic Precursor of Massadine and Stylissadine (Angew. Chem. Int. Ed. 35/2007). Angew Chem Int Ed Engl 2007. [DOI: 10.1002/anie.200790172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Grube A, Immel S, Baran P, Köck M. Innentitelbild: Massadinchlorid: eine Vorstufe in der Biosynthese von Massadin und Stylissadin (Angew. Chem. 35/2007). Angew Chem Int Ed Engl 2007. [DOI: 10.1002/ange.200790172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Affiliation(s)
- Achim Grube
- Alfred-Wegener-Institut für Polar- und Meeresforschung in der Helmholtz-Gemeinschaft, Am Handelshafen 12, 27570 Bremerhaven, Deutschland
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Abstract
Since its discovery in 1993, the marine natural product palau'amine has intrigued natural product chemists. Its exotic molecular architecture and purported bioactivity made it an ideal target for synthesis. However, as the years went by and related marine alkaloids were isolated, a skeptical eye was cast on the structure of palau'amine; recently these suspicions were confirmed and the structure of palau'amine revised. This Minireview gives a careful overview of the structural revision and its ramifications to both its biogenesis and total synthesis.
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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.
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Schmidt G, Grube A, Köck M. Stylissamides A–D – New Proline-Containing Cyclic Heptapeptides from the Marine SpongeStylissa caribica. European J Org Chem 2007. [DOI: 10.1002/ejoc.200700013] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Affiliation(s)
- Markus Nett
- Institute for Pharmaceutical Biology, University of Bonn, Nussallee 6, 53115 Bonn, Germany
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Köck M, Lindel T. Chemistry Unprotected. Angew Chem Int Ed Engl 2007; 46:5268-71. [PMID: 17604380 DOI: 10.1002/anie.200702455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Matthias Köck
- Alfred-Wegener-Institut, Am Handelshafen 12, 27570 Bremerhaven, Germany.
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Köck M, Lindel T. Chemistry Unprotected. Angew Chem Int Ed Engl 2007. [DOI: 10.1002/ange.200702455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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