Original scientific paper
Effect of the extraction solvent on the oleuropein content and antioxidant properties of olive leaf (cv. Oblica, Lastovka and Levantinka) extracts
Ivana Generalić Mekinić
orcid.org/0000-0003-1701-871X
; Department of Food Technology and Biotechnology, Faculty of Chemistry and Technology, University of Split, Teslina 10, HR-21000 Split, Croatia
M. Gotovac
; Department of Food Technology and Biotechnology, Faculty of Chemistry and Technology, University of Split, Teslina 10, HR-21000 Split, Croatia
Danijela Skroza
; Department of Food Technology and Biotechnology, Faculty of Chemistry and Technology, University of Split, Teslina 10, HR-21000 Split, Croatia
I. Ljubenkov
orcid.org/0000-0002-8947-3255
; Department of Chemistry, Faculty of Science, University of Split, Teslina 12, HR-21000 Split, Croatia
F. Burčul
orcid.org/0000-0002-6932-6098
; Department of Biochemistry, Faculty of Chemistry and Technology,University of Split, Teslina 10, HR-21000 Split, Croatia
Višnja Katalinić
; Department of Food Technology and Biotechnology, Faculty of Chemistry and Technology, University of Split, Teslina 10, HR-21000 Split, Croatia
Abstract
In the last few decades numerous studies have proved that an olive leaf is a rich source of bioactive phenolic compounds, mainly oleuropein and its derivatives. The aim of this study was to investigate the influence of the extraction solvent on the phenolic and oleuropein content in the leaf extracts of Dalmatian autochthonic olive cultivars: Oblica, Lastovka and Levantinka. The antioxidant activity of leaf extracts was determined using FRAP method and by metal chelating activity evaluation. The recovery obtained using methanol and ethanol (50:50, v/v) was higher than by use of water solvents. The highest share of total phenols and oleuropein was detected in ethanolic extract of Lastovka, while almost two-fold lower amounts were obtained using water extracts, both hot water and room temperature water. The extremely significant correlation between the FRAP and oleuropein/phenolic content points out the importance of these compounds in the total reducing activity of the extracts. All tested extracts provided good chelating activity probably due to the high concentrations of oleuropein but also the presence of other compounds with catechol structure, which is the most important structural feature of strong chelating activity. According to the obtained results it can be concluded that the extraction of polyphenols from olive leaves, especially from Lastovka cultivar, could present an interesting means of increasing the value of this cheap plant material that often remains unused after the harvest.
Keywords
olive leaf; oleuropein; HPLC; reducing ability; chelating activity
Hrčak ID:
125416
URI
Publication date:
15.7.2014.
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