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Mane SS, Ghaste M, Dearden DV. Mass spectrometry-based gas phase intramolecular benzyl migration in sparsentan, a novel endothelin and angiotensin II receptor antagonist. JOURNAL OF MASS SPECTROMETRY : JMS 2023; 58:e4980. [PMID: 37903508 DOI: 10.1002/jms.4980] [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: 07/21/2023] [Revised: 09/19/2023] [Accepted: 10/05/2023] [Indexed: 11/01/2023]
Abstract
We report a collision-induced dissociation (CID) based gas phase rearrangement study using quadrupole time-of-flight mass spectrometry coupled with liquid chromatography on a novel endothelin and angiotensin II receptor antagonist, sparsentan. We performed tandem mass spectrometry to identify precursor and fragment ion relationships and assigned structures for major fragment ions. We propose a benzyl migration mechanism based on bond length measurements in density functional theory (B3LYP/6-31+G*) optimized geometries of protonated sparsentan and its m/z 547 fragment. Protonated sparsentan undergoes loss of ethanol, which yields a resonance-stabilized benzylic cation with m/z 547, which further fragments into m/z 353 via benzyl migration, where the benzylic cation migrates to one of the nucleophilic nitrogen atoms followed by proton transfer from the sulfonamide nitrogen to a carbonyl oxygen, resulting in a neutral loss of mass 194. Further fragmentation of m/z 353 results in m/z 258, which undergoes radical and neutral loss to yield m/z 193 and 194, respectively. The proposed mechanism of generation of m/z 353 was confirmed by CID of deuterated sparsentan. Considering the importance of gas phase rearrangements of organic molecules in structural identifications as well as the novelty of the molecule, these findings will be helpful for future studies to predict gas phase benzyl migration in sparsentan analogs and for degradation product and metabolite identification of sparsentan and its analogs using LC-MS.
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Affiliation(s)
- Sudam S Mane
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah, 84602-1030, USA
| | - Manoj Ghaste
- Analytical Chemistry Department, Nelson Laboratories, 6280 S. Redwood Road, Salt Lake City, Utah, 84123, USA
| | - David V Dearden
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah, 84602-1030, USA
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Baira SM, Ragampeta S, Talluri MVNK. A comprehensive study on rearrangement reactions in collision-induced dissociation mass spectrometric fragmentation of protonated diphenyl and phenyl pyridyl ethers. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2019; 33:1440-1448. [PMID: 31115092 DOI: 10.1002/rcm.8488] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Revised: 05/01/2019] [Accepted: 05/13/2019] [Indexed: 06/09/2023]
Abstract
RATIONALE Recently, we have reported a forced degradation study of a pharmaceutical drug regorafenib which contains a phenyl pyridyl ether derivative as building block. We observed interesting rearrangements in two of its degradation products in tandem mass spectrometry (MS/MS) experiments. As diphenyl ether derivatives are also molecular building blocks of biological importance and used as herbicides and flame retardants, we decided to investigate specifically the fragmentation behavior of these compounds along with phenyl pyridyl derivatives in detail using high-resolution electrospray ionization (ESI) MS/MS. METHODS To understand the fragmentation reactions of protonated substituted diphenyl ethers and phenyl pyridyl ethers, ESI-MS/MS experiments were performed using a quadrupole time-of-flight (QTOF) mass spectrometer. RESULTS In contrast to radical cations of diphenyl ether derivatives which do not eliminate CO, the [M + H]+ ions of substituted diphenyl ethers undergo rearrangement reactions after loss of neutral molecules (H2 O, HCl, etc.) to form a bicyclic structure containing a keto group and do eliminate CO. Similar rearrangement followed by fragmentation was observed for protonated phenyl pyridyl ethers and the degradation products formed from regorafenib and sorafenib. CONCLUSIONS The protonated ions of substituted diphenyl ethers and phenyl pyridyl ethers on collision-induced dissociation have exhibited interesting rearrangement reactions, despite the nature of the substituent on both the aryl moieties. The proposed fragmentation patterns of these compounds give an insight into the understanding of gas-phase reactions in mass spectrometric studies of diphenyl ether and phenyl pyridyl ether derivatives.
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Affiliation(s)
- Shandilya Mahamuni Baira
- Department of Pharmaceutical Analysis, National Institute of Pharmaceutical Education & Research, Balanagar, Hyderabad, Telangana, India
| | - Srinivas Ragampeta
- Department of Pharmaceutical Analysis, National Institute of Pharmaceutical Education & Research, Balanagar, Hyderabad, Telangana, India
- Analytical Department, CSIR - Indian Institute of Chemical Technology, Hyderabad, Telangana, India
| | - M V N Kumar Talluri
- Department of Pharmaceutical Analysis, National Institute of Pharmaceutical Education & Research, Balanagar, Hyderabad, Telangana, India
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Smith IR, Charlier AHR, Pritzlaff AM, Shishlov A, Barnes B, Bentz KC, Easterling CP, Sumerlin BS, Fanucci GE, Savin DA. Probing Membrane Hydration at the Interface of Self-Assembled Peptide Amphiphiles Using Electron Paramagnetic Resonance. ACS Macro Lett 2018; 7:1261-1266. [PMID: 35651263 DOI: 10.1021/acsmacrolett.8b00728] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The relative hydrophilicity at the interface of a nanoparticle was measured utilizing electron paramagnetic resonance (EPR) spectroscopy. The supramolecular structure was assembled from spin-labeled peptide amphiphiles (PA) derived from N-carboxy anhydrides (NCA). Cyanuric chloride, or 2,4,6-trichloro-1,3,5-triazine (TCT), was used as a modular platform to synthesize the spin-labeled, lipid-mimetic macroinitiator used for the ring-opening polymerization of γ-benzyl-l-glutamic acid NCA to produce polyglutamate-b-dodecanethiol2. Through static and dynamic light scattering, as well as transmission electron microscopy, PAs with DP of 50 and 17 were shown to assemble into stable nanoparticles with an average hydrodynamic radius of 117 and 84 nm, respectively. Continuous wave EPR spectroscopy revealed that the mobility parameter (h-1/h0) and 2Aiso of the nitroxide radical increased with increasing pH, in concert with the deprotonation of the PE side chains and associated helix-coil transition. These results are consistent with an increase in the relative hydration and polarity at the nanoparticle interface, which would be dependent on the secondary structure of the polypeptide. This research suggests that a pH stimulus could be used to facilitate water diffusion through the membrane.
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Affiliation(s)
- Ian R. Smith
- George & Josephine Butler Polymer Research Laboratory, Center for Macromolecular Science & Engineering, Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, Florida 32611-7200, United States
| | - Alban H. R. Charlier
- George & Josephine Butler Polymer Research Laboratory, Center for Macromolecular Science & Engineering, Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, Florida 32611-7200, United States
| | - Amanda M. Pritzlaff
- George & Josephine Butler Polymer Research Laboratory, Center for Macromolecular Science & Engineering, Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, Florida 32611-7200, United States
| | - Alexander Shishlov
- George & Josephine Butler Polymer Research Laboratory, Center for Macromolecular Science & Engineering, Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, Florida 32611-7200, United States
| | - Brooke Barnes
- George & Josephine Butler Polymer Research Laboratory, Center for Macromolecular Science & Engineering, Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, Florida 32611-7200, United States
| | - Kyle C. Bentz
- George & Josephine Butler Polymer Research Laboratory, Center for Macromolecular Science & Engineering, Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, Florida 32611-7200, United States
| | - Charles P. Easterling
- George & Josephine Butler Polymer Research Laboratory, Center for Macromolecular Science & Engineering, Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, Florida 32611-7200, United States
| | - Brent S. Sumerlin
- George & Josephine Butler Polymer Research Laboratory, Center for Macromolecular Science & Engineering, Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, Florida 32611-7200, United States
| | - Gail E. Fanucci
- George & Josephine Butler Polymer Research Laboratory, Center for Macromolecular Science & Engineering, Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, Florida 32611-7200, United States
| | - Daniel A. Savin
- George & Josephine Butler Polymer Research Laboratory, Center for Macromolecular Science & Engineering, Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, Florida 32611-7200, United States
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Chai Y, Wang L, Wang L. How does a CC double bond cleave in the gas phase? Fragmentation of protonated ketotifen in mass spectrometry. JOURNAL OF MASS SPECTROMETRY : JMS 2016; 51:1105-1110. [PMID: 27591732 DOI: 10.1002/jms.3843] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Revised: 08/28/2016] [Accepted: 08/30/2016] [Indexed: 06/06/2023]
Abstract
In the literature, it is reported that the protonated ketotifen mainly undergoes CC double bond cleavage in electrospray ionization tandem mass spectrometry (ESI-MS/MS); however, there is no explanation on the mechanism of this fragmentation reaction. Therefore, we carried out a combined experimental and theoretical study on this interesting fragmentation reaction. The fragmentation of protonated ketotifen (m/z 310) always generated a dominant fragment ion at m/z 96 in different electrospray ionization mass spectrometers (ion trap, triple quadrupole and linear trap quadrupole (LTQ)-orbitrap). The mechanism of the generation of this product ion (m/z 96) through the CC double bond cleavage was proposed to be a sequential hydrogen migration process (including proton transfer, continuous two-step 1,2-hydride transfer and ion-neutral complex-mediated hydride transfer). This mechanism was supported by density functional theory (DFT) calculations and a deuterium labeling experiment. DFT calculations also showed that the formation of the product ion m/z 96 was most favorable in terms of energy. This study provides a reasonable explanation for the fragmentation of protonated ketotifen in ESI-MS/MS, and the fragmentation mechanism is suitable to explain other CC double bond cleavage reactions in mass spectrometry. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Yunfeng Chai
- Tea Research Institute, Chinese Academy of Agricultural Sciences, 9 South Meiling Road, Hangzhou, 310008, PR China
- College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, 310058, PR China
| | - Lu Wang
- College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, 310058, PR China
| | - Lin Wang
- Beijing Key Laboratory for Green Catalysis and Separation, Department of Chemistry and Chemical Engineering, Beijing University of Technology, Beijing, 100124, PR China
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Chiguru V, Lingesh A, R. S, N. S. Forced degradation study of racecadotril: Effect of co-solvent, characterization of degradation products by UHPLC-Q-TOF-MS/MS, NMR and cytotoxicity assay. J Pharm Biomed Anal 2016; 128:9-17. [DOI: 10.1016/j.jpba.2016.05.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Revised: 05/04/2016] [Accepted: 05/05/2016] [Indexed: 10/21/2022]
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Cautereels J, Claeys M, Geldof D, Blockhuys F. Quantum chemical mass spectrometry: ab initio prediction of electron ionization mass spectra and identification of new fragmentation pathways. JOURNAL OF MASS SPECTROMETRY : JMS 2016; 51:602-614. [PMID: 28239969 DOI: 10.1002/jms.3791] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Revised: 05/11/2016] [Accepted: 05/24/2016] [Indexed: 06/06/2023]
Abstract
The electron ionization mass spectra of four organic compounds are predicted based on the results of quantum chemical calculations at the DFT/B3LYP/6-311 + G* level of theory. This prediction is performed 'ab initio', i.e. without any prior knowledge of the thermodynamics or kinetics of the reactions under consideration. Using a set of rules determining which routes will be followed, the fragmentation of the molecules' bonds and the complete resulting fragmentation pathways are studied. The most likely fragmentation pathways are identified based on calculated reaction energies ΔE when bond cleavage is considered and on activation energies ΔE‡ when rearrangements are taken into account; the final intensities of the peaks in the spectrum are estimated from these values. The main features observed in the experimental mass spectra are correctly predicted, as well as a number of minor peaks. In addition, the results of the calculations allow us to propose fragmentation pathways new to empirical mass spectrometry, which have been experimentally verified using tandem mass spectrometry measurements. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Julie Cautereels
- Department of Chemistry, University of Antwerp, Groenenborgerlaan 171, B-2020, Antwerp, Belgium
| | - Magda Claeys
- Department of Pharmaceutical Sciences, University of Antwerp, Universiteitsplein 1, B-2610, Antwerp, Belgium
| | - Davy Geldof
- Department of Chemistry, University of Antwerp, Groenenborgerlaan 171, B-2020, Antwerp, Belgium
| | - Frank Blockhuys
- Department of Chemistry, University of Antwerp, Groenenborgerlaan 171, B-2020, Antwerp, Belgium
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Chai Y, Xiong X, Yue L, Jiang Y, Pan Y, Fang X. Intramolecular Halogen Transfer via Halonium Ion Intermediates in the Gas Phase. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2016; 27:161-167. [PMID: 26383734 DOI: 10.1007/s13361-015-1261-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2015] [Revised: 08/31/2015] [Accepted: 09/01/2015] [Indexed: 06/05/2023]
Abstract
The fragmentation of halogen-substituted protonated amines and quaternary ammonium ions (R(1)R(2)R(3)N(+)CH2(CH2)nX, where X = F, Cl, Br, I, n = 1, 2, 3, 4) was studied by electrospray ionization tandem mass spectrometry. A characteristic fragment ion (R(1)R(2)R(3)N(+)X) resulting from halogen transfer was observed in collision-induced dissociation. A new mechanism for the intramolecular halogen transfer was proposed that involves a reactive intermediate, [amine/halonium ion]. A potential energy surface scan using DFT calculation for CH2-N bond cleavage process of protonated 2-bromo-N,N-dimethylethanamine supports the formation of this intermediate. The bromonium ion intermediate-involved halogen transfer mechanism is supported by an examination of the ion/molecule reaction between isolated ethylenebromonium ion and triethylamine, which generates the N-bromo-N,N,N-triethylammonium cation. For other halogens, Cl and I also can be involved in similar intramolecular halogen transfer, but F cannot be involved. With the elongation of the carbon chain between the halogen (bromine as a representative example) and amine, the migration ability of halogen decreases. When the carbon chain contains two or three CH2 units (n = 1, 2), formal bromine cation transfer can take place, and the transfer is easier when n = 1. When the carbon chain contains four or five CH2 units (n = 3, 4), formal bromine cation transfer does not occur, probably because the five- and six-membered cyclic bromonium ions are very stable and do not donate the bromine to the amine.
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Affiliation(s)
- Yunfeng Chai
- Department of Chemistry, Zhejiang University, Hangzhou, 310027, China
- College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, 310058, China
| | | | - Lei Yue
- Department of Chemistry, Zhejiang University, Hangzhou, 310027, China
| | - You Jiang
- National Institute of Metrology, Beijing, 100013, China
| | - Yuanjiang Pan
- Department of Chemistry, Zhejiang University, Hangzhou, 310027, China.
| | - Xiang Fang
- National Institute of Metrology, Beijing, 100013, China.
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Paulose J, Achuthan RP, Linsha MPL, Mathai G, Prasanth B, Kumar Talluri MVN, Srinivas R. Protonated N-benzyl- and N-(1-phenylethyl)tyrosine amides dissociate via ion/neutral complexes. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2015; 29:1577-1584. [PMID: 28339153 DOI: 10.1002/rcm.7256] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Revised: 06/08/2015] [Accepted: 06/15/2015] [Indexed: 06/06/2023]
Abstract
RATIONALE The collisional-induced dissociations (CID) of the [M+H]+ ions of molecules having benzyl groups attached to N-atoms have been proposed to involve migration of the benzyl group through the intermediacy of ion/neutral complexes (INCs). We report the investigation of the mechanism of dissociation of protonated N-benzyl- and N-(1-phenylethyl)tyrosine amides by electrospray ionization (ESI) tandem mass spectrometry (MS/MS) and density functional theory (DFT) calculations. METHODS The amides were synthesized from the corresponding amino acids and amines. The ESI-MS/MS spectra were recorded using an Agilent QTOF 6540 mass spectrometer. The DFT calculations were performed by using Gaussian 09 software. The structures of the [M+H]+ ions, intermediates, products and transition states (TS) were optimized at the B3LYP/6-31G(d,p) level of theory. RESULTS CID of the [M+H]+ ions of N-benzyltyrosine amide yields two product ions due to rearrangements: (i) the [M+H-74]+ ion (m/z 197) due to benzyl migration to the hydroxyphenyl ring and (ii) the [M+H-45]+ ion (m/z 226) due to benzyl migration to the NH2 group. DFT calculations suggest that the rearrangements occur through an INC in which the benzyl cation is the cation partner. The [M+H]+ ion of N-(1-phenylethyl)tyrosine amide rearranges to an INC of the 1-phenylethyl cation. Subsequent elimination of styrene occurs by transfer of a proton from the 1-phenylethyl cation to the neutral partner. CONCLUSIONS The [M+H]+ ions of both N-benzyl (1) and N-(1-phenylethyl) (2) tyrosine amide rearrange into INCs. The dissociation of [M+H]+ ion of 1 yields the benzyl cation and [M+H-74]+ and [M+H-45]+ due to benzyl migration to the hydroxyphenyl ring and NH2 group, respectively. However, the formation of the [M+H-74]+ ion is not observed when the aromatic ring is deactivated. The [M+H]+ ion of 2 either dissociates to form the 1-phenylethyl cation or [M+H-styrene]+ . Copyright © 2015 John Wiley & Sons, Ltd.
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Affiliation(s)
- Justin Paulose
- Department of Chemistry, Sacred Heart College, Thevara, Kochi, India
- Bharathiyar University, Coimbatore, Tamilnadu, India
| | - Revi P Achuthan
- Department of Chemistry, Sacred Heart College, Thevara, Kochi, India
- Bharathiyar University, Coimbatore, Tamilnadu, India
| | - Maria P L Linsha
- Department of Chemistry, Sacred Heart College, Thevara, Kochi, India
- Bharathiyar University, Coimbatore, Tamilnadu, India
| | - George Mathai
- Department of Chemistry, Sacred Heart College, Thevara, Kochi, India
- Bharathiyar University, Coimbatore, Tamilnadu, India
| | - B Prasanth
- National Institute of Pharmaceutical Education and Research, Hyderabad, India
| | - M V N Kumar Talluri
- National Institute of Pharmaceutical Education and Research, Hyderabad, India
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Li F, Zhang X, Zhang H, Jiang K. Gas-phase fragmentation of the protonated benzyl ester of proline: intramolecular electrophilic substitution versus hydride transfer. JOURNAL OF MASS SPECTROMETRY : JMS 2013; 48:423-429. [PMID: 23584935 DOI: 10.1002/jms.3162] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Revised: 12/11/2012] [Accepted: 12/19/2012] [Indexed: 06/02/2023]
Abstract
In this study, the gas phase chemistry of the protonated benzyl esters of proline has been investigated by electrospray ionization mass spectrometry and theoretical calculation. Upon collisional activation, the protonated molecules undergo fragmentation reactions via three primary channels: (1) direct decomposition to the benzyl cation (m/z 91), (2) formation of an ion-neutral complex of [benzyl cation + proline](+), followed by a hydride transfer to generate the protonated 4,5-dihydro-3H-pyrrole-2-carboxylic acid (m/z 114), and (3) electrophilic attack at the amino by the transferring benzyl cation, and the subsequent migration of the activated amino proton leading to the simultaneous loss of (H2O + CO). Interestingly, no hydrogen/deuterium exchange for the fragment ion m/z 114 occurs in the d-labeling experiments, indicating that the transferring hydride in path-b comes from the methenyl hydrogen rather than the amino hydrogen. For para-substituted benzyl esters, the presence of electron-donating substituents significantly promotes the direct decomposition (path-a), whereas the presence of electron-withdrawing ones distinctively inhibits that channel. For the competing channels of path-b and path-c, the presence of electron-donating substituents favors path-b rather than path-c, whereas the presence of electron-withdrawing ones favors path-c rather than path-b.
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Affiliation(s)
- Fei Li
- Key Laboratory of Organosilicon Chemistry and Material Technology, Hangzhou Normal University, Hangzhou, 310012, China
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