Antioxidant Activity of Canolol

Koski et al. (2003) showed that canolol is attributed to the better stability of the crude rapeseed oils and the polar fraction containing vinylsyringol showed lipid 

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To assess the antioxidant activity of canolol, it is necessary to isolate canolol from canola oil by extraction from roasted seeds. For the extraction, about 50 g of oil was diluted with 200 mL mixture composed of ethylacetate/cyclohexane (1 1). From this solution, 7 mL was used for purification by gel permeation chromatography (GPC). The purity of the extract was established by HPLC with recalculation of the nsed amount of extract. From 1.5 g oil, 3 mg purified extract was obtained. 

For the assessment of the antioxidant activity of canolol, the 3-carotene-linoleic acid assay as well as the DPPH method was used. Using the 3-carotene-linoleic acid assay model system, rapid discolouration was observed in the absence of an antioxidant. The free linoleic acid radical, formed by abstraction of a hydrogen atom from one of its methylene gronps, attacks the P-carotene molecnles resnlting in the loss of double bonds and its characteristic orange colour. The rate of bleaching of the P-carotene solution was determined by measuring the difference between the initial... 

Also the measurement of the free radical DPPH showed that canolol has an antioxidant activity capable of reducing the concentration of DPPH free radicals in the test tube. However, the antioxidant activity of canolol was only about half of the activity of Trolox or sinapic acid in this test. 

The mechanism of the antioxidant activity of canolol was critically analysed by Galano et al. (2011). Three possible pathways are... 

Kuwahara H., Kanazawa A., Wakamatu D., Morimura S., Kida K., Akaike T., Maeda H. Antioxidative and antimutagenic activities of 4-vinyl-2,6-dimethoxyphenol (canolol) isolated from canola oH. Journal of Agricultural and Food Chemistry, 52 4380-4387 (2004). 

More recently, another derivative of sinapic acid has been identified because of its highly potent antioxidant activity and the antimutagenic and anticarcino-genic properties (Kuwahara et al., 2004 Vuorela et al., 2005 Cao et al., 2008). This derivative, 2,6-dimethoxy-4-vinylphenol (vinylsyringol) or canolol, was first identified in two independent studies by Koski et al. (2003) and Wakamatsu et al. (2005) in crude canola oil. Kuwahara et al. (2004) described the antimutagenic potency of this compound as higher than a-tocopherol, P-carotene, vitamin C... 

For example, the main phenol with antioxidative and antimutagenic activities that occurs in crude canola oil is 2,6-dimethoxy-4-vinylphenol known as canolol, which is produced from syringic acids. The major products of caffeic acid pyrolysis at 225 °C are pyrocatechol, 4-vinylpyrocatechol and 4-ethylpyrocatechol (see Section 8.3.4). A more complex mixture of products arises by pyrolysis of lignin, in the smoke condensates used in the meat industry, more than 150 different phenols, and dozens of aromatic alcohols, phenolic acids and hydroxylated heterocyclic compounds have been identified. 

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