Electrospray ionization tandem mass spectrometry of labdane‐type acid diterpenes

Aguiar, Gabriela P.; Crevelin, Eduardo José; Dias, Herbert Júnior; Ambrósio, Sérgio Ricardo; Bastos, Jairo K.; Heleno, Vladimir Constantino Gomes; Vessecchi, Ricardo; Crotti, Antônio Eduardo Miller

doi:10.1002/jms.4284

Cited by 18 publications

(19 citation statements)

References 25 publications

(52 reference statements)

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“…The identification of casearin‐like compounds is usually performed by high‐performance liquid chromatography with diode‐array detection (HPLC‐DAD) because of the chromophore diene moiety in their side chains ( Z or E , that absorbs in the range of 220 to 235 nm), often assisted by comparison with the retention times of authentic standards, although these are not commercially available 3,21,22 . Similarly, liquid chromatography combined with high‐resolution mass spectrometry (HPLC/HRMS) has assisted the annotation of some diterpenes 23–25 due to its high sensitivity and short analysis times although it is limited for the differentiation of positional isomers 26,27 . Nuclear magnetic resonance (NMR) spectroscopy is a highly effective method for the complete structural elucidation of clerodane‐type diterpenes and differentiation of isomers.…”

Section: Introductionmentioning

confidence: 99%

Fragmentation study of clerodane diterpenes from Casearia species by tandem mass spectrometry (quadrupole time‐of‐flight and ion trap)

Danuello

Castro

Pilon

et al. 2020

Rapid Comm Mass Spectrometry

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Rationale Clerodane‐type diterpenes from Casearia species show important pharmacological activites such as antitumor, antimicrobial and anti‐inflamatory. There are several mass spectrometry (MS)‐based methods for identification of diterpenes; however, there is still a lack of MS procedures capable of providing characteristic fragmentation pathways for a rapid and unambiguous elucidation of casearin‐like compounds. Methods Casearin‐like compounds were investigated by electrospray ionization tandem mass spectrometry (ESI‐MS/MS). The fragmentation studies were carried out by tandem mass spectrometry in space (quadrupole time‐of‐flight (QTOF)) using different collision energies and also by tandem mass spectrometry in time (QIT) by selective isolation of product ions. Results Casearin‐like compounds presented a predominance of sodium‐ and potassium‐cationized precursor ions. Both QIT and QTOF techniques provided sequential neutral losses of esters related to the R1 to R5 substituents linked to the nucleus of the clerodane diterpenes. The fragmentation pathway is initiated with a cleavage of the ester moieties R2 followed by the elimination of the ester groups R3, both losing neutral carboxylic acids. Using QIT, it was also possible to observe the cleavage of the ester groups R1 or R5 by MS4 experiments. Conclusions Through a rational analysis of the fragmentation mechanisms of Casearia diterpenes it was possible to suggest an annotation strategy based on the sequential cleavages of the ester groups related to the R2, R3 and R5 substituents. These results will assist studies of the dereplication and metabolomics involving casearin‐like compounds present in complex extracts of Casearia species.

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Section: Introductionmentioning

confidence: 99%

Fragmentation study of clerodane diterpenes from Casearia species by tandem mass spectrometry (quadrupole time‐of‐flight and ion trap)

Danuello

Castro

Pilon

et al. 2020

Rapid Comm Mass Spectrometry

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“…As part of our ongoing project on the gas‐phase fragmentation reactions of biologically active synthetic and natural compounds, and given the scarcity of ESI‐MS/MS data of MKCs, here we investigate the gas‐phase fragmentation pathways of selected curcuminoids by ESI‐MS/MS combined with thermochemical data obtained at the B3LYP/6‐31+G(d) level of theory.…”

Section: Introductionmentioning

confidence: 99%

Electrospray ionization tandem mass spectrometry of monoketone curcuminoids

Vieira

Orenha

Crevelin

et al. 2020

Rapid Comm Mass Spectrometry

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Rationale Although monoketone curcuminoids (MKCs) have been largely investigated due to their biological activities, data on the gas‐phase fragmentation reactions of protonated MKCs under collision‐induced dissociation (CID) conditions are still scarce. Here, we combined electrospray ionization tandem mass spectrometry (ESI‐MS/MS) data, multiple‐stage mass spectrometry (MSn), deuterium exchange experiments, accurate‐mass data, and thermochemical data estimated by computational chemistry to elucidate and to rationalize the fragmentation pathways of eleven synthetic MKCs. Methods The MKCs were synthesized by Claisen‐Schmidt condensation under basic (1–9) or acidic (10–11) conditions. ESI‐CID‐MS/MS analyses and deuterium‐exchange experiments were carried out on a triple quadrupole mass spectrometer. MSn analyses on an ion trap mass spectrometer helped to elucidate the fragmentation pathways. Accurate‐mass data and thermochemical data, obtained at the B3LYP/6–31+G(d,p) level of theory, were used to support the ion structures. Results The most intense product ions were the benzyl ions ([C7H2R1R2R3R4R5]+) and the acylium ions ([M + H − C8H3R1R2R3R4R5]+), which originated directly from the precursor ion as a result of two competitive hydrogen rearrangements. Product ions [M + H – H2O]+ and [M + H − C6HR1R2R3R4R5]+, which are formed after Nazarov cyclization, were also common to all the analyzed compounds. In addition, •Br and •Cl eliminations were diagnostic for the presence of these halogen atoms at the aromatic ring, whereas •CH3 eliminations were useful to identify the methyl and methoxy groups attached to this same ring. Nazarov cyclization in the gas phase occurred for all the investigated MKCs and did not depend on the presence of the hydroxyl group at the aromatic ring. However, the presence and the position of a hydroxyl group at the aromatic rings played a key role in the Nazarov cyclization mechanism. Conclusions Our results reinforce some aspects of the fragmentation pathways previously published for 1,5‐bis‐(2‐methoxyphenyl)‐1,4‐pentadien‐3‐one and 1,5‐bis‐(2‐hydroxyphenyl)‐1,4‐pentadien‐3‐one. The alternative fragmentation mechanism proposed herein can explain the fragmentation of a wider diversity of monoketone curcuminoids.

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“…As part of our ongoing project on the fragmentation reactions of natural products and synthetic compounds, we investigate the fragmentation pathways of a series of synthetic DBNs and BNs by ESI accurate‐mass MS/MS and MS n combined with thermochemical data estimated by Computational Chemistry.…”

Section: Introductionmentioning

confidence: 99%

“…17 Similarly, Boldizsár and coworkers reported that water elimination from the Cirsium vulgare fruit benzofuran NL balanophonin also involves benzofuran ring opening, with aromatic chain loss followed by aliphatic chain elimination. 18 As part of our ongoing project on the fragmentation reactions of natural products [19][20][21][22][23] and synthetic compounds, 24,25 we investigate the fragmentation pathways of a series of synthetic DBNs and BNs by ESI accurate-mass MS/MS and MS n combined with thermochemical data estimated by Computational Chemistry.…”

mentioning

confidence: 99%

Gas‐phase fragmentation reactions of protonated benzofuran‐ and dihydrobenzofuran‐type neolignans investigated by accurate‐mass electrospray ionization tandem mass spectrometry

et al. 2018

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We have investigated gas‐phase fragmentation reactions of protonated benzofuran neolignans (BNs) and dihydrobenzofuran neolignans (DBNs) by accurate‐mass electrospray ionization tandem and multiple‐stage (MSn) mass spectrometry combined with thermochemical data estimated by Computational Chemistry. Most of the protonated compounds fragment into product ions B ([M + H–MeOH]+), C ([B–MeOH]+), D ([C–CO]+), and E ([D–CO]+) upon collision‐induced dissociation (CID). However, we identified a series of diagnostic ions and associated them with specific structural features. In the case of compounds displaying an acetoxy group at C‐4, product ion C produces diagnostic ions K ([C–C2H2O]+), L ([K–CO]+), and P ([L–CO]+). Formation of product ions H ([D–H2O]+) and M ([H–CO]+) is associated with the hydroxyl group at C‐3 and C‐3′, whereas product ions N ([D–MeOH]+) and O ([N–MeOH]+) indicate a methoxyl group at the same positions. Finally, product ions F ([A–C2H2O]+), Q ([A–C3H6O2]+), I ([A–C6H6O]+), and J ([I–MeOH]+) for DBNs and product ion G ([B–C2H2O]+) for BNs diagnose a saturated bond between C‐7′ and C‐8′. We used these structure‐fragmentation relationships in combination with deuterium exchange experiments, MSn data, and Computational Chemistry to elucidate the gas‐phase fragmentation pathways of these compounds. These results could help to elucidate DBN and BN metabolites in in vivo and in vitro studies on the basis of electrospray ionization ESI‐CID‐MS/MS data only.

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Electrospray ionization tandem mass spectrometry of labdane‐type acid diterpenes

Cited by 18 publications

References 25 publications

Fragmentation study of clerodane diterpenes from Casearia species by tandem mass spectrometry (quadrupole time‐of‐flight and ion trap)

Fragmentation study of clerodane diterpenes from Casearia species by tandem mass spectrometry (quadrupole time‐of‐flight and ion trap)

Electrospray ionization tandem mass spectrometry of monoketone curcuminoids

Gas‐phase fragmentation reactions of protonated benzofuran‐ and dihydrobenzofuran‐type neolignans investigated by accurate‐mass electrospray ionization tandem mass spectrometry

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