ESI‐MS/MS analysis of protonated <i>N</i>‐methyl amino acids and their immonium ions

Pallerla, Pavankumar; Bhumireddy, Sudarshana Reddy; Lingampally, Sai Sachin; Ragi, Nagarjuna Chary; Prabhakar, S.

doi:10.1002/jms.4426

Cited by 8 publications

(8 citation statements)

References 26 publications

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“…The MS 2 fragment showed fragment ions at m / z 188 [M + H-NHCH 3 ] + , corresponding to the loss of the methyl amine group, and at 173 [M + H-COOH] + , due to the loss of the carboxyl group. In addition, the fragment ion at m / z 101 was due to the side chain C 4 H 7 O 2 N, while the fragment at m / z 118 was due to C 8 H 7 N. The mass data are in good agreement with the literature [ 52 ].…”

Section: Resultssupporting

confidence: 84%

“…7.19 min) exhibited ESI-MS in negative mode at m / z 309 [M] − , in addition to a prominent fragment ion at m / z 219 [M + H-R] − , corresponding to the molecular weight of N -methyl tryptophan. From these data and with the help of the available literature, compound 19 was tentatively identified as an N- methyl tryptophan derivative [ 52 ].…”

Section: Resultsmentioning

confidence: 99%

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Metabolites Profiling and In Vitro Biological Characterization of Different Fractions of Cliona sp. Marine Sponge from the Red Sea Egypt

et al. 2023

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Red Sea marine sponges are an important source of biologically active natural products. Therefore, the present study aimed to investigate, for the first time, the components of n-hexane, dichloromethane, and ethyl acetate fractions of Cliona sp. marine sponge collected from the Red Sea, Egypt using UPLC-ESI-MS/MS (Ultra-performance liquid chromatography electrospray ionization tandem mass spectrometry) analysis. The analysis revealed the tentative identification of 23, 16, and 24 compounds from the n-hexane, dichloromethane, and ethyl acetate fractions of Cliona sp., respectively. In addition, the examination of these fractions resulted in the isolation and identification of three sterols and one amino acid. The identification of the isolated compounds was confirmed by 1D and 2D NMR (Nuclear Magnetic Resonance), and MS (Mass spectrometry), and IR (Infrared) spectroscopy. The in vitro cytotoxic, antioxidant, and antimicrobial activities of the total ethanolic extract and its sub-fractions were also evaluated. Interestingly, the ethyl acetate fraction showed potent cytotoxic activity against colon (HCT-116) and human larynx carcinoma (HEP-2) cell lines with IC50 (Half-maximal Inhibitory Concentration) 6.11 ± 0.2 and 12.6 ± 0.9 µg/mL, respectively. However, the dichloromethane fraction showed strong antioxidant activity, with IC50 75.53 ± 3.41 µg/mL. Notably, the total ethanolic extract showed the strongest antibacterial activity against Staphylococcus aureus and Escherichia coli, with MIC (Minimum Inhibitory Concentration) 62.5 ± 0.82 and 125 ± 0.62 µg/mL, respectively, compared to other fractions. In conclusion, this is the first report on the secondary metabolites content and biological activities of Cliona sp. from the Red Sea, Egypt. It also highlights the need for further research on the most active fractions against various cancer cell lines and resistant bacterial and fungal strains. Cliona sp. extract and its fractions could be a potential source of novel and safe natural drugs with a wide range of medicinal and pharmaceutical applications.

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Section: Resultssupporting

confidence: 84%

Section: Resultsmentioning

confidence: 99%

Metabolites Profiling and In Vitro Biological Characterization of Different Fractions of Cliona sp. Marine Sponge from the Red Sea Egypt

et al. 2023

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“…Although primary loss of the α‐amino group of LysH + as NH 3 has been suggested, 27 earlier work had shown the retention of 15 N label from [α‐ 15 N]LysH + and the loss of 15 NH 3 from [ε‐ 15 N]LysH + (Scheme 1), 7,17 which was consistent with the prevalent loss of the side‐chain amino group as NH 3 . Moreover, the loss of the corresponding amine from the carboxymethyl, ethyl, methyl, dimethyl, and trimethyl side‐chain derivatives of lysine 28,33–36 further supported the predominant side‐chain regiochemistry of this fundamental fragmentation process. The structures of the resulting product ions from LysH + ( 4a ) and OrnH + ( 3a ) are consistent with those of protonated pipecolic acid (PipH + , 4b ) 7,19,21,28,34 and proline (ProH + , 3b ), 13,21 respectively, indicating cyclization upon nucleophilic displacement of the protonated side‐chain amino group by the α‐amino group 7,11 .…”

Section: Introductionmentioning

confidence: 78%

Fragmentation reactions of protonated α,ω‐diamino carboxylic acids: The importance of functional group interactions

Grossert

White

2021

J Mass Spectrom

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Protonated members of a homologous series of biologically significant α,ω‐diamino carboxylic acids were subjected to collision induced dissociation (CID). The resulting fragmentation patterns were studied using isotopic labeling, quantum mechanical computations, and pseudo MS3 experiments conducted primarily on an ion trap mass spectrometer. Each protonated α,ω‐diamino acid showed a primary neutral loss of either ammonia or water; a clear explanation was developed for the observed variation of the two losses within the series. Protonated 2,3‐diaminopropanoic acid, 2,4‐diaminobutanoic acid, and 2,7‐diaminoheptanoic acid gave secondary losses of water, carbon monoxide, and a loss of water plus carbon monoxide, respectively. In the parallel pathways characterized for the fragmentations of protonated ornithine and lysine, the α‐nitrogen of the diamino acid was maintained in the cyclic iminium product formed by successive losses of NH3 and (H2O + CO), whereas the side‐chain nitrogen was retained by consecutive losses of H2O and (CO, NH3). The 1‐piperideine ion from protonated lysine was fragmented further, losing ethylene from carbons 4 and 5. Protonated 2,6‐diaminopimelic acid fragmented by analogous reactions. Detailed mechanistic schemes for the fragmentation of both protonated 2,3‐diaminopropanoic and ornithine were generated from MP2/DFT computations. This work highlights the participation of the side‐chain amino group, which distinguishes the gas‐phase chemistry of protonated α,ω‐diamino acids from the well‐documented fragmentation reactions of protonated α‐amino acids bearing a hydrogen atom or an alkyl side chain. In general, the results further illustrate the importance of intramolecular separations affecting the specific interactions between functional groups leading to the fragmentation of multifunctional ions.

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“…For structural characterization of N α -acetyl amino acids (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20), the [M + H] + ions product-ion MS/MS spectra were acquired at different collision energies (CEs). The MS/MS spectra at a particular CE that displayed more structure indicative product ions were considered for the study (Table 1).…”

Section: Lc-esi-ms/ms Of [Mmentioning

confidence: 99%

“…As the acetylation could be either on alpha -NH 2 and/or side chain function groups, it is essential to characterize all possible acetylated products of amino acids for future untargeted metabolomics studies. In this study, a total of 20 N α -acetyl amino acids(1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20), six side-chain acetyl amino acids(21)(22)(23)(24)(25)(26), and six diacetyl amino acids(27)(28)(29)(30)(31)(32) were studied by LC/MS and LC-ESI-MS/MS (HRMS), where the isomeric compounds were well separated.The HRMS data of selected ions and their product ions provided valuable information in understanding the actual fragmentation patterns.Most of the acetyl amino acids specifically showed [MH À H 2 O] + ion and [MH À C 2 H 2 O] + (ketene loss) ion. The acetyl amino acids also showed expected ketene losses from the different product ions anticipated from free amino acids.…”

mentioning

confidence: 99%

Characterization of isomeric acetyl amino acids and di‐acetyl amino acids by LC/MS/MS

Ramunaidu,

Pavankumar,

Ragi

et al. 2023

J Mass Spectrom

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Acetylation of amino acids is important in the molecular biology and biochemistry because they are part of several metabolic pathways. N‐acetyl amino acids can form through degradation of N‐acetyl proteins or direct acetylation of amino acids by specific enzymes. Acetylation of α‐amino acids can be either on the alpha –NH2 or on the side‐chain functional group, where both the acetyl products are isomeric and can show different biological roles. Theoretically, all proteinogenic α‐amino acids are expected to undergo acetylation and they can be a part of metabolome. Thus, it is essential to detect and identify all the possible acetylated products of α‐amino acids for untargeted metabolomics studies. In this study, it is aimed to synthesize and characterize all acetylated products of natural α‐amino acids. A total of 20 Nα‐acetyl amino acids (1–20), six side‐chain acetyl amino acids (21–26), and six diacetyl amino acids (27–32) were synthesized and characterized by liquid chromatography‐electrospray ionizationtandem mass spectrometry (LC–ESI–MS/MS). The [M + H]+ ions of all the acetyl amino acids were subjected to MS/MS experiments to obtain their structural information. Apart from the expected loss of (H2O + CO) (immonium ions), most of the acetyl amino acids specifically showed loss of H2O and loss of a ketene (C2H2O) from [M+H]+ ions. The side‐chain acetyl amino acids showed a clear‐cut structure specific fragment ions that enabled easy differentiation from their isomeric Nα‐acetyl amino acids. The other isomeric/isobaric acetyl amino acids could also be easily distinguished by their MS/MS spectra. The MS/MS of immonium ions of the acetyl amino acids were also studied, and they included characteristic products reflecting the structures of parent Nα‐acetyl and side‐chain acetyl amino acids.

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ESI‐MS/MS analysis of protonated N‐methyl amino acids and their immonium ions

Cited by 8 publications

References 26 publications

Metabolites Profiling and In Vitro Biological Characterization of Different Fractions of Cliona sp. Marine Sponge from the Red Sea Egypt

Metabolites Profiling and In Vitro Biological Characterization of Different Fractions of Cliona sp. Marine Sponge from the Red Sea Egypt

Fragmentation reactions of protonated α,ω‐diamino carboxylic acids: The importance of functional group interactions

Characterization of isomeric acetyl amino acids and di‐acetyl amino acids by LC/MS/MS

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