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Grossert JS, Crowell AMJ, Boschi D, Lolli ML, White RL. Tandem mass spectrometry of homologous 3-hydroxyfurazan and nitrile amino acids: Analysis of cooperative interactions and fragmentation processes. JOURNAL OF MASS SPECTROMETRY : JMS 2024; 59:e5043. [PMID: 38789127 DOI: 10.1002/jms.5043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2024] [Revised: 04/23/2024] [Accepted: 05/06/2024] [Indexed: 05/26/2024]
Abstract
The assignment of structure by tandem mass spectrometry (MS/MS) relies on the interpretation of the fragmentation behavior of gas-phase ions. Mass spectra were acquired for a series of heterocyclic mimetics of acidic amino acids and a related series of nitrile amino acids. All amino acids were readily protonated or deprotonated by electrospray ionization (ESI), and distinctive fragmentation processes were observed when the ions were subjected to collision-induced dissociation (CID). The deprotonated heterocycles showed bond cleavages of the 3-hydroxyfurazan ring with formation of oxoisocyanate and the complementary deprotonated nitrile amino acid. Further fragmentation of the deprotonated nitrile amino acids was greatly dependent on the length of the alkyl nitrile side chain. Competing losses of CO2 versus HCN occurred from α-cyanoglycinate (shortest chain), whereas water was lost from 2-amino-5-cyanopentanoate (longest chain). Interestingly, loss of acrylonitrile by a McLafferty-type fragmentation process was detected for 2-amino-4-cyanobutanoate, and several competing processes were observed for β-cyanoalanate. In one process, cyanide ion was formed either by consecutive losses of ammonia, carbon dioxide, and acetylene or by a one-step decarboxylative elimination. In another, complementary ions were obtained from β-cyanoalanate by loss of acetonitrile or HN=CHCO2H. Fragmentation of the protonated 3-hydroxyfurazan and nitrile amino acids resulted in the cumulative loss (H2O + CO), a loss that is commonly observed for protonated aliphatic α-amino acids. Overall, the distinct fragmentation behavior of the multifunctional 3-hydroxyfurazan amino acids correlated with the charged site, whereas fragmentations of the deprotonated nitrile amino acids showed cooperative interactions between the nitrile and the carboxylate groups.
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Affiliation(s)
- J Stuart Grossert
- Department of Chemistry, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Andrew M J Crowell
- Department of Chemistry, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Donatella Boschi
- Dipartimento di Scienza e Tecnologia del Farmaco (DSTF), Università degli Studi di Torino, Torino, Italy
| | - Marco L Lolli
- Dipartimento di Scienza e Tecnologia del Farmaco (DSTF), Università degli Studi di Torino, Torino, Italy
| | - Robert L White
- Department of Chemistry, Dalhousie University, Halifax, Nova Scotia, Canada
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Liu S, Lai C, Long Y, Yang W, Ren Q, Huang L, Chen J. The global profiling of alkaloids in Aconitum stapfianum and analysis of detoxification material basis against Fuzi. J Chromatogr A 2021; 1652:462362. [PMID: 34261022 DOI: 10.1016/j.chroma.2021.462362] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 05/25/2021] [Accepted: 06/22/2021] [Indexed: 11/16/2022]
Abstract
Aconitum alkaloids are versatile in chemical structures and are well known for their bioactivity and toxicity. Cases of analogs with closely similar structures or positional isomers are widespread in herbs of the Aconitum genus. It is still challenging to rapidly identify unknown compounds via mass spectrometry, especially positional isomers. Herein, to profile the alkaloids of Aconitum stapfianum that possess bioactivity against intoxication by the lateral root of Aconitum carmichaelii (Fuzi), a strategy was developed by carefully determining the fragmentation pathways of authentic standards. A series of rules was summarized and involved charge site effects, hydrogen bonding effects, competitive channels between charge-remote reactions and charge migration reactions, and fragment patterns exhibiting a "diamond shape". Accordingly, a total of 124 alkaloids in A. stapfianum were tentatively characterized, including 85 potential new compounds and 24 sets of isomers. On the other hand, to explore the material basis of detoxification, a chemical constituent comparison was made between A. stapfianum and Fuzi, and principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) were performed to identify markers that were different between the two . In total, 25 characteristic markers were identified to discriminate between these two herbal medicines, of which 14 compounds were specific for A. stapfianum and most of them were characteristic for a para-substituted benzoic acid ester at C-14.
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Affiliation(s)
- Sisi Liu
- School of Resources Environmental & Chemical Engineering, Nanchang University, Nanchang 330031, China
| | - Changjiangsheng Lai
- State Key Laboratory Breeding Base of Dao-di Herbs, National Resource Center for Chinese Materia Medica, Academy of Chinese Medical Sciences, Beijng 100700, China
| | - Yihong Long
- School of Resources Environmental & Chemical Engineering, Nanchang University, Nanchang 330031, China
| | - Weiran Yang
- School of Resources Environmental & Chemical Engineering, Nanchang University, Nanchang 330031, China.
| | - Qi Ren
- Jiangxi Institute for Drug Control, NMPA Key Laboratory of Quality Evaluation of Traditional Chinese Patent Medicine, Jiangxi Province Engineering Research Center of Drug and Medical Device Quality, Nanchang 330029, China
| | - Luqi Huang
- State Key Laboratory Breeding Base of Dao-di Herbs, National Resource Center for Chinese Materia Medica, Academy of Chinese Medical Sciences, Beijng 100700, China.
| | - Jinlong Chen
- School of Resources Environmental & Chemical Engineering, Nanchang University, Nanchang 330031, China; Center for Post-doctoral research, China Academy of Chinese Medical Sciences, Beijng 100700, China.
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Nestorowicz K, Jaoui M, Rudzinski KJ, Lewandowski M, Kleindienst TE, Spólnik G, Danikiewicz W, Szmigielski R. Chemical composition of isoprene SOA under acidic and non-acidic conditions: effect of relative humidity. ATMOSPHERIC CHEMISTRY AND PHYSICS 2018; 18:18101-18121. [PMID: 32158471 PMCID: PMC7063744 DOI: 10.5194/acp-18-18101-2018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The effect of acidity and relative humidity on bulk isoprene aerosol parameters has been investigated in several studies; however, few measurements have been conducted on individual aerosol compounds. The focus of this study has been the examination of the effect of acidity and relative humidity on secondary organic aerosol (SOA) chemical composition from isoprene photooxidation in the presence of nitrogen oxide (NO x ). A detailed characterization of SOA at the molecular level was also investigated. Experiments were conducted in a 14.5 m3 smog chamber operated in flow mode. Based on a detailed analysis of mass spectra obtained from gas chromatography-mass spectrometry of silylated derivatives in electron impact and chemical ionization modes, ultra-high performance liquid chromatography/electrospray ionization/time-of-flight high-resolution mass spectrometry, and collision-induced dissociation in the negative ionization modes, we characterized not only typical isoprene products but also new oxygenated compounds. A series of nitroxy-organosulfates (NOSs) were tentatively identified on the basis of high-resolution mass spectra. Under acidic conditions, the major identified compounds include 2-methyltetrols (2MT), 2-methylglyceric acid (2mGA), and 2MT-OS. Other products identified include epoxydiols, mono- and dicarboxylic acids, other organic sulfates, and nitroxy- and nitrosoxy-OS. The contribution of SOA products from isoprene oxidation to PM2.5 was investigated by analyzing ambient aerosol collected at rural sites in Poland. Methyltetrols, 2mGA, and several organosulfates and nitroxy-OS were detected in both the field and laboratory samples. The influence of relative humidity on SOA formation was modest in non-acidic-seed experiments and stronger under acidic seed aerosol. Total secondary organic carbon decreased with increasing relative humidity under both acidic and non-acidic conditions. While the yields of some of the specific organic compounds decreased with increasing relative humidity, others varied in an indeterminate manner from changes in the relative humidity.
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Affiliation(s)
- Klara Nestorowicz
- Environmental Chemistry Group, Institute of Physical Chemistry Polish Academy of Sciences, 01-224 Warsaw, Poland
| | - Mohammed Jaoui
- US Environmental Protection Agency, 109 T.W. Alexander Drive, RTP, NC 27711, USA
| | - Krzysztof Jan Rudzinski
- Environmental Chemistry Group, Institute of Physical Chemistry Polish Academy of Sciences, 01-224 Warsaw, Poland
| | - Michael Lewandowski
- US Environmental Protection Agency, 109 T.W. Alexander Drive, RTP, NC 27711, USA
| | | | - Grzegorz Spólnik
- Mass Spectrometry Group, Institute of Organic Chemistry, Polish Academy of Science, 01-224 Warsaw, Poland
| | - Witold Danikiewicz
- Mass Spectrometry Group, Institute of Organic Chemistry, Polish Academy of Science, 01-224 Warsaw, Poland
| | - Rafal Szmigielski
- Environmental Chemistry Group, Institute of Physical Chemistry Polish Academy of Sciences, 01-224 Warsaw, Poland
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LeBlanc LM, Powers SW, Grossert JS, White RL. Competing fragmentation processes of β-substituted propanoate ions upon collision-induced dissociation. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2016; 30:2133-2144. [PMID: 27476993 DOI: 10.1002/rcm.7699] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Revised: 07/22/2016] [Accepted: 07/22/2016] [Indexed: 06/06/2023]
Abstract
RATIONALE When subjected to collisional activation, gas-phase carboxylate ions typically undergo decarboxylation. However, alternative fragmentation processes dominate when the carboxylate group is located within certain structural motifs. In this work, the fragmentation processes of β-substituted carboxylate ions are characterized to improve correlations between reactivity and structure. METHODS Mass spectra were collected using both ion trap and triple quadrupole mass spectrometers operating in the negative ion mode; collision-induced dissociation (CID) of ions was used to study the relationship between product ions and the structures of their precursor ions. Quantum mechanical computations were performed on a full range of reaction geometries at the MP2/6-311++G(2d,p)//B3LYP/6-31++G(2d,p) level of theory. RESULTS For a series of β-substituted carboxylate ions, a product ion corresponding to the anion of the β-substituent was obtained upon CID. Detailed computations indicated that decarboxylative elimination and at least one other fragmentation mechanism had feasible energetics for the formation of substituent anions differing in their gas-phase basicities. Predicted energetics for anti- and synperiplanar alignments in the transition structures for decarboxylative elimination correlated with the positions of crossover points in breakdown curves acquired for conformationally constrained ions. CONCLUSIONS The feasibility of more than one mechanism was established for the fragmentation of β-substituted propanoates. The contribution of each mechanistic pathway to the formation of the substituent anion was influenced by structural variations and conformational constraints, but mostly depended on the nature of the substituent. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Luc M LeBlanc
- Department of Chemistry, Dalhousie University, 6274 Coburg Road, PO Box 15000, Halifax, Nova Scotia, Canada, B3H 4R2
| | - Sean W Powers
- Department of Chemistry, Dalhousie University, 6274 Coburg Road, PO Box 15000, Halifax, Nova Scotia, Canada, B3H 4R2
| | - J Stuart Grossert
- Department of Chemistry, Dalhousie University, 6274 Coburg Road, PO Box 15000, Halifax, Nova Scotia, Canada, B3H 4R2
| | - Robert L White
- Department of Chemistry, Dalhousie University, 6274 Coburg Road, PO Box 15000, Halifax, Nova Scotia, Canada, B3H 4R2.
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LeBlanc LM, Crowell AMJ, Grossert JS, White RL. Phenyl group participation in rearrangements during collision-induced dissociation of deprotonated phenoxyacetic acid. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2015; 29:2293-2301. [PMID: 26522323 DOI: 10.1002/rcm.7395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Revised: 08/11/2015] [Accepted: 09/10/2015] [Indexed: 06/05/2023]
Abstract
RATIONALE The identification of trace constituents in biological and environmental samples is frequently based on the fragmentation patterns resulting from the collision-induced dissociation (CID) of gas-phase ions. Credible mechanistic characterization of fragmentation processes, including rearrangements, is required to make reliable assignments for structures of precursor and product ions. METHODS Mass spectra were collected using both ion trap and triple quadrupole mass spectrometers operating in the negative ion mode. Precursor ion scans and CID of ions generated in-source were used to establish precursor-product ion relationships. Density functional theory (DFT) computations were performed at the MP2/6-311++G(2d,p)//B3LYP/6-31++G(2d,p) level of theory. RESULTS Product ions at m/z 93 and 107 obtained upon CID of phenoxyacetate were attributed to phenoxide and o-methylphenoxide, respectively. An isotopic labeling experiment and computations showed that the phenoxide ion was formed by intramolecular displacement with formation of an α-lactone and also by a Smiles rearrangement. Rearrangement of phenoxyacetate via the ion-neutral complex formed in the α-lactone displacement pathway gave the isomeric o-hydroxyphenylacetate ion which yielded o-methylphenoxide upon decarboxylation. Computations provided feasible energetics for these pathways. CONCLUSIONS Previously unrecognized and energetically favorable rearrangements during the collision-induced fragmentation of phenoxyacetate have been characterized using isotopic labeling and DFT computations. Notably, the phenyl substituent plays an indispensable role in each rearrangement process resulting in multiple pathways for the fragmentation of phenoxyacetate.
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Affiliation(s)
- Luc M LeBlanc
- Department of Chemistry, Dalhousie University, 6274 Coburg Road, PO Box 15000, Halifax, Nova Scotia, B3H 4R2, Canada
| | - Andrew M J Crowell
- Department of Chemistry, Dalhousie University, 6274 Coburg Road, PO Box 15000, Halifax, Nova Scotia, B3H 4R2, Canada
| | - J Stuart Grossert
- Department of Chemistry, Dalhousie University, 6274 Coburg Road, PO Box 15000, Halifax, Nova Scotia, B3H 4R2, Canada
| | - Robert L White
- Department of Chemistry, Dalhousie University, 6274 Coburg Road, PO Box 15000, Halifax, Nova Scotia, B3H 4R2, Canada
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