Electrospray ionization tandem mass spectrometry of labdane-type acid diterpenes

Autor(es)

Aguiar, Gabriela P. ^[1] ; Crevelin, Eduardo J. ^[2] ; Dias, Herbert J. ^[2] ; Ambrosio, Sergio R. ^[1] ; Bastos, Jairo K. ^[3] ; Heleno, Vladimir C. G. ^[1] ; Vessecchi, Ricardo ^[2] ; Crotti, Antonio E. M. ^[2]

Afiliação do(s) autor(es)

^[1] Univ Franca, Nucleo Pesquisas Ciencias Exatas & Tecnol, Franca - Brazil

^[2] Univ Sao Paulo, Fac Filosofia Ciencias & Letras Ribeirao Preto, Dept Quim, Ribeirao Preto, SP - Brazil

^[3] Univ Sao Paulo, Sch Pharmaceut Sci Ribeirao Preto, Ribeirao Preto - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Journal of Mass Spectrometry; v. 53, n. 11, p. 1086-1096, NOV 2018.
• Citações Web of Science: 1

Resumo

Copaifera (Leguminoseae) species produce a commercially interesting oleoresin that displays several biological activities, including antimicrobial and anti-inflammatory properties. Labdane-type diterpenes are the main chemical constituents of these oleoresins, and copalic acid is the only compound that has been detected in all Copaifera oleoresins. In this study, we investigate some aspects of the gas-phase fragmentation reactions involved in the formation of the product ions from the deprotonated compounds (-)-ent-copalic acid (1), (-)-ent-3 beta-hydroxy-copalic acid (2), (-)-ent-3 beta-acetoxy-copalic acid (3), and (-)-ent-agathic acid (4) by electrospray ionization tandem mass spectrometry (ESI-MS/MS) and multiple stage mass spectrometry (MSn). Our results reveal that the product ion with m/z 99 is common to all the analyzed compounds, whereas the product ion with m/z 217 is diagnostic for compounds 2 and 3. Moreover, only compound 4 undergoes CO2 (44 u) and acetic acid (60 u) elimination from the precursor ion. Thermochemical data obtained by computational chemistry at the B3LYP/6-31G(d) level of theory support the proposed ion structures. These data helped us to identify these compounds in a crude commercial Copaifera langsdorffii oleoresin by selective multiple reaction monitoring (MRM). Finally, a precursor ion scan (PIS) strategy aided screening of labdane-type acid diterpenes other than 1 to 4 in the same Copaifera oleoresin sample and led us to propose the structures of 8,17-dihydro-ent-agathic acid (5) and 3-keto-ent-copalic acid (6), which have not been previously reported in Copaifera oleoresins. (AU)

• Processo FAPESP: 13/20094-0 - Avaliação da atividade antiparasitária e inseticida de compostos benzofurânicos e estudo de suas reações de fragmentação em fase gasosa empregando espectrometria de massas sequencial
• Beneficiário: Antônio Eduardo Miller Crotti
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 11/13630-7 - Validação química e farmacológica de extratos e princípios ativos de espécies de Copaifera
• Beneficiário: Jairo Kenupp Bastos
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 12/22832-5 - Estudo da fragmentação de diterpenos do tipo labdano isolados do óleo-resina de Copaifera langsdorffii empregando espectrometria de massas sequencial
• Beneficiário: Gabriela de Paula Aguiar
• Modalidade de apoio: Bolsas no Brasil - Mestrado
• Processo FAPESP: 14/23604-1 - Química computacional: uma ferramenta para estudos envolvendo espectrometria de massas, reatividade e mecanismos de reação/fragmentação de compostos orgânicos
• Beneficiário: Ricardo Vessecchi Lourenço
• Modalidade de apoio: Auxílio à Pesquisa - Regular