resumo
Eucalyptus globulus bark contains four significant families of compounds, namely triterpenic (TT) acids (betulinic, betulonic, oleanolic and ursolic acids, and the acetylated forms of the latter two), long chain aliphatic alcohols, fatty acids, and sterols. The first group is the most abundant and possesses demonstrated bioactivity, which raises the importance of this biomass. The supercritical fluid extraction (SFE) of E. globulus bark was carried out in this work with carbon dioxide at 100, 140 and 200 bar, and 40, 50 and 60 degrees C, and the extracts were analyzed by GC-MS. The results are compared with those obtained by Soxhlet with dichloromethane, and the influence of the operating conditions upon the global yield and the individual yields of the triterpenic acids is discussed in detail. The acetylated TT acids imparted a large effect on the extraction yields, as they appeared in large concentrations on the extracts independently of their absolute loadings in the bark. The polarity of the free acids, higher than that of their acetyl derivatives, justifies this behavior. Modeling calculations were also performed for interpreting the SFE results. The experimental observations are in agreement with predictions accomplished for the solubilities and mass transfer fluxes of ursolic acid and 3-acetylursolic acid that were chosen as key IT acids in the process. (C) 2012 Elsevier B.V. All rights reserved.
palavras-chave
EQUATION-OF-STATE; CARBON-DIOXIDE; URSOLIC ACID; GAS CHROMATOGRAPHY; INDOLE ALKALOIDS; CO2 EXTRACT; SUPPRESSION; POMACE; OIL
categoria
Chemistry; Engineering
autores
de Melo, MMR; Oliveira, ELG; Silvestre, AJD; Silva, CM
nossos autores
Armando Jorge Domingues Silvestre
Professor Catedrático
Carlos Manuel Silva
Professor associado
Marcelo Morais Rodrigues de Melo
Bolseiro de pós-Doutoramentoagradecimentos
Authors acknowledge the 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 Associate Laboratory CICECO (Pest-C/CTM/LA0011/2011).