abstract
The bark of Eucalyptus globulus is a promising source of polyphenolic compounds that could be extracted employing polar solvents. Extraction experiments were planned according to the Box-Behnken design to evaluate the effect of temperature and time of extraction and the ethanol/water ratio on the dependent variables total phenolic content (TPC; as gallic acid equivalents, GAE), antioxidant activity (AA; as millimoles of ascorbic acid equivalents, AAE), proanthocyanidins (Pac; as mimosa extract equivalents, MEE), Stiasny number (SN), and coextracted total carbohydrates (TC). Response surface models were developed, and statistical analysis of variance was performed. A maximum of TPC of 32% (W-GAE/W-extract) was achieved for 264 min, 82.5 degrees C, and 52% ethanol corresponding to about 2% of the bark weight. These conditions are close to those leading to maximum values of compounds with AA (2.1 mmol(AAE)/g(extract)) and Pac 14% (w(MEE)/w(extract)). TC in the extract and the SN predicted were 22.7% (w(TC)/w(extract)) and 37, respectively. Preliminary studies concerning the biological activity of some extracts have demonstrated their differential capacity to reduce human breast cancer cell proliferation.
keywords
RESPONSE-SURFACE METHODOLOGY; CASTANEA-SATIVA SHELL; ANTIOXIDANT ACTIVITY; NATURAL ANTIOXIDANTS; CHEMICAL-COMPOSITION; PHENOLIC-COMPOUNDS; MASS-SPECTROMETRY; STEM BARK; E-RUDIS; WOOD
subject category
Engineering
authors
Mota, I; Pinto, PCR; Novo, C; Sousa, G; Guerreiro, O; Guerra, AR; Duarte, MF; Rodrigues, AE
our authors
Ângela Guerra
PhD Student
Maria de Fátima Pereira Duarte
Principal ResearcherGroups
acknowledgements
This work was carried out under Project BIIPP No. 11551, Integrated Biorefinery Industry Pulp and Paper, funded by the European Regional Development Fund (ERDF) through the Operational Programme for Competitiveness Factors (POFC) of the National Strategic Reference Framework (NSRF). This work was partially supported by Projects PEst-C/EQB/LA0020/2011 and PEst-C/CTM/LA0011/2011 funded by the ERDF through the POFC and by the Foundation for Science and Technology (FCT). We thank Mr. Nigel Dunning and Mimosa Extract Co. (Pty) Ltd. (South Africa) for kindly providing the mimosa extract.