resumo
The phenolic composition of Eucalyptus grandis, Eucalyptus urograndis (E. grandis x E. urophylla) and Eucalyptus maidenii bark is reported for the first time. High performance liquid chromatography-electrospray ionization mass spectrometry (HPLC-ESI-MS) and tandem mass spectrometry (MSn) analysis of the methanol:water (50:50) extracts allowed to identify thirteen, twelve and twenty-four phenolic compounds in E. grand's, E. urograndis and E. maidenii bark extracts, respectively. Furthermore, ellagic acid-rhamnoside, dihydroxy-isopropylchromone-hexoside and dihydroxy-(methylpropyl)isopropylchromone-hexoside are referenced for the first time as constituents of Eucalyptus species. Epicatechin and quercetin-glucuronide are the major phenolic compounds in E. grandis and E. urograndis bark, followed by ellagic acid-rhamnoside and ellagic acid in E. grand's and by galloyl-bis-hexahydroxydiphenoyl (HHDP)-glucose and gallic acid in E. urograndis. Catechin, chlorogenic acid and methyl-ellagic acid-pentose are the major compounds in E. maidenii bark. The phenolic content of the three extracts shows a positive correlation with their antioxidant activities, evaluated by 2,2-diphenyl-2-picrylhydrazyl hydrate (DPPH) radical scavenging, showing activity values between those of two commercial antioxidants, ascorbic acid and butylated hydroxytoluene (BHT). These results, together with the phenolic composition, confirm the high potential of these species as source of biologically active phenolic compounds. (C) 2012 Elsevier B.V. All rights reserved.
palavras-chave
PERFORMANCE LIQUID-CHROMATOGRAPHY; MOLECULAR-WEIGHT POLYPHENOLS; MASS-SPECTROMETRY; OUTER BARKS; E-RUDIS; GLOBULUS; CAMALDULENSIS; WOOD
categoria
Agriculture
autores
Santos, SAO; Villaverde, JJ; Freire, CSR; Domingues, MRM; Neto, CP; Silvestre, AJD
nossos autores
Armando Jorge Domingues Silvestre
Professor Catedrático
Carlos Pascoal Neto
Diretor do Raiz
Carmen Sofia da Rocha Freire Barros
Investigador Coordenador
Sónia Andreia Oliveira Santos
Investigador Auxiliaragradecimentos
The authors wish to thank to 7th Framework Programme FP7/2007-2013, for funding project AFORE: Forest biorefineries: Added-value from chemicals and polymers by new integrated separation, fractionation and upgrading technologies (CP-IP 228589-2) and to Fundacao para a Ciencia e Tecnologia for the awarding of a Ph.D. grant (SFRH/BD/42021/2007) to Sonia A.O. Santos and a post-doctoral grant to Juan Jose Villaverde (BPD/UI89/4520/2009). The authors thank the financial support provided to QOPNA (project PEst-C/QUI/UI0062/2011), CICECO (Pest-C/CTM/LA0011/2011) and RNEM (REDE/1504/REM/2005 - that concerns the Portuguese Mass Spectrometry Network) by FCT. The authors are also grateful to RAIZ - Institut de Investigacao da Floresta e Papel for providing the Eucalyptus bark samples.