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Zeng Z, Qasem AMA, Blagbrough IS, Woodman TJ. Intramolecular through-space NMR spectroscopic effect of steric compression on 1H NMR spectroscopy. Org Biomol Chem 2024; 22:7915-7935. [PMID: 39248501 DOI: 10.1039/d4ob01108b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/10/2024]
Abstract
The intramolecular through-space NMR spectroscopic effect of steric compression is related to intramolecular through-space van der Waals repulsion. The electron cloud of a proton can be pushed away by the electron cloud of a nearby proton or functional group. As the electron population of the sterically compressed proton is decreased (therefore deshielded), the chemical shift sharply moves downfield, which may result in ambiguity for the proton signal assignment. Also, the conformation of the local area of the sterically compressed proton can be altered by the steric repulsion, therefore, the coupling constant/coupling pattern of a sterically compressed proton could be influenced. This review summarizes and presents the impacts on the chemical shift and coupling constant by the 1H NMR spectroscopic effect of steric compression extracted from the reported examples from the 1950s to 2021.
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Affiliation(s)
- Ziyu Zeng
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 501 Haike Road, Zhang Jiang Hi-Tech Park, Pudong, Shanghai 201203, P. R. China
| | - Ashraf M A Qasem
- Department of Pharmaceutical Sciences, Faculty of Pharmacy, Zarqa University, Jordan.
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Qasem AA, Rowan MG, Blagbrough IS. Effect of Position 1 Substituent and Configuration on APCI-MS Fragmentation of Norditerpenoid Alkaloids Including 1- epi-Condelphine. ACS OMEGA 2022; 7:40493-40501. [PMID: 36385853 PMCID: PMC9647891 DOI: 10.1021/acsomega.2c05697] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Accepted: 10/11/2022] [Indexed: 06/16/2023]
Abstract
Norditerpenoid alkaloids (NDA) are hexacyclic highly oxygenated compounds, and the analysis of their 3D configuration is important as it helps to interpret their bioactive conformations. High-performance liquid chromatography/atmospheric pressure chemical ionization mass spectrometry (LC/MS-APCI) is a promising technique to investigate NDA stereochemistry. The effect of the alpha (α)-substituent at carbon 1 and its configuration on the stability of NDA in the mass spectrometer was studied. It was observed that 1-OH NDA are more stable compared to 1-OMe NDA due to the intramolecular H-bonding that exists in 1-OH NDA. In addition, 1-epi-condelphine 9 was found to be less stable in the mass spectrometer compared to condelphine 7 as the nitrogen is no longer hydrogen-bonded to the β-hydroxyl at position 1, which highlights the importance of the substituent configuration at carbon 1.
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Qasem AMA, Rowan MG, Blagbrough IS. Poisonous Piperidine Plants and the Biodiversity of Norditerpenoid Alkaloids for Leads in Drug Discovery: Experimental Aspects. Int J Mol Sci 2022; 23:12128. [PMID: 36292987 PMCID: PMC9603787 DOI: 10.3390/ijms232012128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 10/04/2022] [Accepted: 10/07/2022] [Indexed: 11/16/2022] Open
Abstract
There are famous examples of simple (e.g., hemlock, Conium maculatum L.) and complex (e.g., opium poppy, Papaver somniferum L., Papaveraceae) piperidine-alkaloid-containing plants. Many of these are highly poisonous, whilst pepper is well-known gastronomically, and several substituted piperidine alkaloids are therapeutically beneficial as a function of dose and mode of action. This review covers the taxonomy of the genera Aconitum, Delphinium, and the controversial Consolida. As part of studying the biodiversity of norditerpenoid alkaloids (NDAS), the majority of which possess an N-ethyl group, we also quantified the fragment occurrence count in the SciFinder database for NDA skeletons. The wide range of NDA biodiversity is also captured in a review of over 100 recently reported isolated alkaloids. Ring A substitution at position 1 is important to determine the NDA skeleton conformation. In this overview of naturally occurring highly oxygenated NDAs from traditional Aconitum and Delphinium plants, consideration is given to functional effect and to real functional evidence. Their high potential biological activity makes them useful candidate molecules for further investigation as lead compounds in the development of selective drugs.
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Wang L, Marner M, Mettal U, Liu Y, Schäberle TF. Seven New Alkaloids Isolated from Marine Flavobacterium Tenacibaculum discolor sv11. Mar Drugs 2022; 20:md20100620. [PMID: 36286444 PMCID: PMC9605681 DOI: 10.3390/md20100620] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2022] [Revised: 09/27/2022] [Accepted: 09/28/2022] [Indexed: 11/16/2022] Open
Abstract
Marine flavobacterium Tenacibaculum discolor sv11 has been proven to be a promising producer of bioactive nitrogen-containing heterocycles. A chemical investigation of T. discolor sv11 revealed seven new heterocycles, including the six new imidazolium-containing alkaloids discolins C-H (1−6) and one pyridinium-containing alkaloid dispyridine A (7). The molecular structure of each compound was elucidated by analysis of NMR and HR-ESI-MS data. Furthermore, enzymatic decarboxylation of tryptophan and tyrosine to tryptamine and tyramine catalyzed by the decarboxylase DisA was investigated using in vivo and in vitro experiments. The antimicrobial activity of the isolated compounds (1−7) was evaluated. Discolin C and E (1 and 3) exhibited moderate activity against Gram-positive Bacillus subtilis DSM10, Mycobacterium smegmatis ATCC607, Listeria monocytogenes DSM20600 and Staphylococcus aureus ATCC25923, with MIC values ranging from 4 μg/mL to 32 μg/mL.
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Affiliation(s)
- Lei Wang
- Institute for Insect Biotechnology, Justus-Liebig-University Giessen, 35392 Giessen, Germany
- Fraunhofer Institute for Molecular Biology and Applied Ecology (IME), Branch for Bioresources, 35392 Giessen, Germany
| | - Michael Marner
- Fraunhofer Institute for Molecular Biology and Applied Ecology (IME), Branch for Bioresources, 35392 Giessen, Germany
| | - Ute Mettal
- Institute for Insect Biotechnology, Justus-Liebig-University Giessen, 35392 Giessen, Germany
- Fraunhofer Institute for Molecular Biology and Applied Ecology (IME), Branch for Bioresources, 35392 Giessen, Germany
| | - Yang Liu
- Institute for Insect Biotechnology, Justus-Liebig-University Giessen, 35392 Giessen, Germany
- Fraunhofer Institute for Molecular Biology and Applied Ecology (IME), Branch for Bioresources, 35392 Giessen, Germany
- Correspondence: (Y.L.); (T.F.S.); Tel.: +49-(0)641-97219-140 (T.F.S.)
| | - Till F. Schäberle
- Institute for Insect Biotechnology, Justus-Liebig-University Giessen, 35392 Giessen, Germany
- Fraunhofer Institute for Molecular Biology and Applied Ecology (IME), Branch for Bioresources, 35392 Giessen, Germany
- German Center for Infection Research (DZIF), Partner Site Giessen-Marburg-Langen, 35392 Giessen, Germany
- Correspondence: (Y.L.); (T.F.S.); Tel.: +49-(0)641-97219-140 (T.F.S.)
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Liu XY, Ke BW, Qin Y, Wang FP. The diterpenoid alkaloids. THE ALKALOIDS. CHEMISTRY AND BIOLOGY 2022; 87:1-360. [PMID: 35168778 DOI: 10.1016/bs.alkal.2021.08.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The diterpenoid alkaloids are a family of extremely important natural products that have long been a research hotspot due to their myriad of intricate structures and diverse biological properties. This chapter systematically summarizes the past 11 years (2009-2019) of studies on the diterpenoid alkaloids, including the "so-called" atypical ones, covering the classification and biogenetic relationships, phytochemistry together with 444 new alkaloids covering 32 novel skeletons and the corrected structures, chemical reactions including conversion toward toxoids, synthetic studies, as well as biological activities. It should be noted that the synthetic studies, especially the total syntheses of various diterpenoid alkaloids, are for the first time reviewed in this treatise. This chapter, in combination with our four previous reviews in volumes 42, 59, 67, and 69, will present to the readers a more completed and updated profile of the diterpenoid alkaloids.
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Affiliation(s)
- Xiao-Yu Liu
- Department of Chemistry of Medicinal Natural Products, West China School of Pharmacy, Sichuan University, Chengdu, China; Key Laboratory of Drug-Targeting and Drug Delivery System of the Education Ministry and Sichuan Province, Sichuan Engineering Laboratory for Plant-Sourced Drug and Sichuan Research Center for Drug Precision Industrial Technology, West China School of Pharmacy, Sichuan University, Chengdu, China
| | - Bo-Wen Ke
- West China Hospital, Sichuan University, Chengdu, China
| | - Yong Qin
- Department of Chemistry of Medicinal Natural Products, West China School of Pharmacy, Sichuan University, Chengdu, China; Key Laboratory of Drug-Targeting and Drug Delivery System of the Education Ministry and Sichuan Province, Sichuan Engineering Laboratory for Plant-Sourced Drug and Sichuan Research Center for Drug Precision Industrial Technology, West China School of Pharmacy, Sichuan University, Chengdu, China.
| | - Feng-Peng Wang
- Department of Chemistry of Medicinal Natural Products, West China School of Pharmacy, Sichuan University, Chengdu, China.
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Qasem AMA, Zeng Z, Rowan MG, Blagbrough IS. Norditerpenoid alkaloids from Aconitum and Delphinium: structural relevance in medicine, toxicology, and metabolism. Nat Prod Rep 2021; 39:460-473. [PMID: 34636385 DOI: 10.1039/d1np00029b] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Covering: 77 A.D. up to 2020Norditerpenoid alkaloids (NDA), typically N-ethylpiperidine containing C19 or C18 natural product diterpenes, are hexacycles with several contiguous often oxygenated stereocentres. As a function of their structural complexity, they display important pharmacological activities. The processed plants are used as important folk drugs and four NDAs have now been clinically approved. Many metabolism studies on Aconitum alkaloids have been reported as the understanding of their biotransformation in living systems and in cell-free systems is important for the development of these alkaloids as drugs. This Highlight sets out the missing links in NDA biosynthesis, their biological applications, SAR, toxicity, metabolism, and analytical studies.
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Affiliation(s)
- Ashraf M A Qasem
- Department of Pharmacy and Pharmacology, University of Bath, Bath BA2 7AY, UK.
| | - Ziyu Zeng
- Department of Pharmacy and Pharmacology, University of Bath, Bath BA2 7AY, UK.
| | - Michael G Rowan
- Department of Pharmacy and Pharmacology, University of Bath, Bath BA2 7AY, UK.
| | - Ian S Blagbrough
- Department of Pharmacy and Pharmacology, University of Bath, Bath BA2 7AY, UK.
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Zeng Z, Kociok-Köhn G, Woodman TJ, Rowan MG, Blagbrough IS. The 1H NMR Spectroscopic Effect of Steric Compression Is Found in [3.3.1]Oxa- and Azabicycles and Their Analogues. ACS OMEGA 2021; 6:12769-12786. [PMID: 34056428 PMCID: PMC8154237 DOI: 10.1021/acsomega.1c01093] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Accepted: 04/20/2021] [Indexed: 06/12/2023]
Abstract
The through-space 1H NMR effect of steric compression by the lone-pair electrons of O- and N-atoms is shown in synthetic [3.3.1]oxa- and azabicycles. The electrons of the compressed proton bond are pushed away by the repulsive force generated by the lone-pair electrons of the heteroatom. There is a corresponding significant increase in the chemical shift of the compressed proton. The intensity of this deshielding effect is related to the proximity and overlap of the lone-pair or compressing atom. The steric compression decreases when the lone-pair electrons of the heteroatom and the compressed proton are not directly overlapped, for example, in [4.3.1]- and [3.2.1]azabicycles. Steric compression is also caused by a proton, deuterium, or an ethyl group close in space to the compressed proton. The protonated [3.3.1]azabicycle adopts a true-boat/true-chair conformation in its crystal lattice, but in solution the conformation is true-chair/true-chair.
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Affiliation(s)
- Ziyu Zeng
- Department
of Pharmacy and Pharmacology, University
of Bath, Bath BA2 7AY, U.K.
| | - Gabriele Kociok-Köhn
- Material
and Chemical Characterisation Facility, University of Bath, Bath BA2 7AY, U.K.
| | - Timothy J. Woodman
- Department
of Pharmacy and Pharmacology, University
of Bath, Bath BA2 7AY, U.K.
| | - Michael G. Rowan
- Department
of Pharmacy and Pharmacology, University
of Bath, Bath BA2 7AY, U.K.
| | - Ian S. Blagbrough
- Department
of Pharmacy and Pharmacology, University
of Bath, Bath BA2 7AY, U.K.
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Zeng Z, Kociok‐Köhn G, Woodman TJ, Rowan MG, Blagbrough IS. Structural Studies of Norditerpenoid Alkaloids: Conformation Analysis in Crystal and in Solution States. European J Org Chem 2021. [DOI: 10.1002/ejoc.202100179] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Ziyu Zeng
- Department of Pharmacy and Pharmacology University of Bath Bath BA2 7AY UK
| | - Gabriele Kociok‐Köhn
- Material and Chemical Characterisation Facility University of Bath Bath BA2 7AY UK
| | - Timothy J. Woodman
- Department of Pharmacy and Pharmacology University of Bath Bath BA2 7AY UK
| | - Michael G. Rowan
- Department of Pharmacy and Pharmacology University of Bath Bath BA2 7AY UK
| | - Ian S. Blagbrough
- Department of Pharmacy and Pharmacology University of Bath Bath BA2 7AY UK
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Alkhzem A, Woodman TJ, Blagbrough IS. Individual p K a Values of Tobramycin, Kanamycin B, Amikacin, Sisomicin, and Netilmicin Determined by Multinuclear NMR Spectroscopy. ACS OMEGA 2020; 5:21094-21103. [PMID: 32875246 PMCID: PMC7450637 DOI: 10.1021/acsomega.0c02744] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Accepted: 07/23/2020] [Indexed: 05/13/2023]
Abstract
NMR spectroscopy is a powerful technique for separating and measuring each distinct pK a value of the amino groups around aminoglycoside antibiotics. Unambiguous assignments were made for each individual amine substituent on 2-deoxystreptamine, tobramycin, kanamycin B, amikacin, sisomicin, and netilmicin using variations in the NMR spectroscopic chemical shift (δ) with 1H, 13C, and 15N HMBC; the individual pK a values of netilmicin are reported for the first time.
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Affiliation(s)
| | - Timothy J. Woodman
- Department of Pharmacy and
Pharmacology, University of Bath, Bath BA2 7AY, U.K.
| | - Ian S. Blagbrough
- Department of Pharmacy and
Pharmacology, University of Bath, Bath BA2 7AY, U.K.
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