Antioxidant and Cytotoxic Activity of Essential Oils and Their Principal Components: Spectrophotometric, Voltammetric, and Theoretical Investigation of the Chelating Effect of Eugenol and Carvacrol

The antioxidant and chelating properties of essential oils of Syzygium aromaticum L. and Origanum vulgare L. and their principal eugenol and carvacrol constituents were evaluated by the thiobarbituric acid reactive substance (TBARS) assay and in the presence of iron(II) ions by cyclic voltammetry. In the TBARS assay, carvacrol and eugenol were more efficient than the butylated hydroxytoluene (BHT) standard. The anodic current of iron(II) decreased by 99.7% in the presence of S. aromaticum oil, 99.8% for eugenol, 89.3% for O. vulgare, and 99.4% for carvacrol. The UV spectra contained a band at 390 nm for the interaction between Fe(II) and ligands. Thermodynamically stable complexes are formed in the ratios of 1:3 Fe(II)/eugenol and 1:2 Fe(II)/carvacrol. The essential oils and their principal constituents eugenol and carvacrol can be used in food preservation because they have a low cytotoxicity and act as antioxidants through chelation of metal ions.