Antioxidants canolol

Eid YZ. 2010. Novel antioxidant canolol reduces glucocorticoid induced oxidative stress in broiler chickens. Egyptian Poultry Science, 30(IV) 917-926. 

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. 

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). 

Recently, Harbaum-Piayda et al. (2010) demonstrated the possibility of new compounds such as cis- and tratis-diastereomers of 4-vinylsyringol dimer [cis-4,6-dimethoxy-5-hydroxy-l-methyl-3-(30,50-dimethoxy-40-hydroxyphenyl) indane and trani-4,6-dimethoxy-5-hydroxy-l-methyl-3-(30,50-dimethoxy-40-hydroxyphenyl) indane] and the vinylsyringol trimer in commercial rapeseed oils, as well as in a commercial by-product of oil refining, the deodistillate. The newly identified canolol dimer was present in the deodistillate of processed rapeseed oil in significant amounts (-3.50 g/kg). Trace amounts of phenylindane was also detected in commercial rapeseed oils. According to Harbaum-Piayda et al. (2010), this newly identified phenylindane compound had a high antioxidative potential and stressed its potential as an important phenolic compound to add value to the commercial deodistillate and rapeseed oils. 

The DNA strand breakage induced by the endogenous oxidant ONOO has been prevented by canolol and it followed in a dose-dependent manner. Antioxidative effect or terminations of oxy radical-induced strand breaks are responsible to this. The capacity of canolol to suppress ONOO-induced cell damage, killing of bacteria and mammalian cells and bacterial mutation as well as plasmid DNA strand breakage have been established with this study (Kuwahara et al., 2004). Canolol prevented oxidative stress-induced cellular apoptosis to a significant extent in SW480 cells. 

Xin D, Li Z, Wang W, Zhang W, Liu S, Zhang X. 2011. Protective effect of canolol from oxidative stress-induced cell damage in ARPE-19 cells via an ERK mediated antioxidative pathway. Molecular Vision, 17 2040-2048. 

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... 

In the literature, canolol is described as an effective antioxidant (Koski et al., 2003 Kuwahara et al., 2004 Vuorela et al., 2005 Wakamatsu et al., 2005). Figure 17.8 shows increased oxidative stability of canola oil accompanied increasing amounts of canolol. Using the Rancimat test at 120°C canolol contents below 200 itg/g in canola oil from roasted seeds resulted in slight decrease of the oxidative stability. In contrast, amounts of canolol higher than 200 g/g improved oxidative stability of the oil dramatically. Wijesundera et al. (2008) also showed an improvement in... 

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... 

The method described by Hatano et al. (1988) has a number of modifications. For each extract different concentrations were tested, an aliquot (0.5 mL) of the DPPH solution (50 mg/100 mL) was diluted in 4.5 mL methanol and 0.1 mL of a methano-lic solution of the extract added. The mixture was shaken vigorously and allowed to stand for 45 min in the dark. The decrease in absorbance was measured using a spectrophotometer at 515 nm against a blank without added extract. From a calibration curve obtained with different amounts of extract, the ED50 was calculated. The ED50 is the concentration of an antioxidant sufficient to quench 50% of the initial DPPH radicals under the experimental conditions described. Figure 17.9 compares the effect of canolol and sinapic acid with butylated hydroxytoluene (BHT)... 

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... 

Electron transfer from OOH to canolol SET was found to be endergonic as shown by Gibbs s free energy values and hence its possibility was ruled out. In both RAF and HAT, the two possible ways of reaction are H transfer from OH moiety from canolol (site 4a) and OOH addition to site C8. Compared to the other ROS, OOH has low reactivity. Therefore, it is obvious that canolol can work faster and efficiently in all ROS. It was found out that 99% of all reactions between canolol and OOH undergo through HAT pathway in all environments. Thus, it can be expected to predominantly form one product. However, it cannot be ruled out that other mechanisms are less important. Reactivity and structure of the radicals are also equally important in deciding the antioxidation mechanisms (Galano et al., 2009). 

Canolol belongs to a new class of naturally derived compounds that show the antioxidant as promising and implicates disease treatment in the near future. The future scope is supported by the current in vitro research data and there is no doubt that there is lack of data for in vivo research. The accumulated literature of vinyl phenol derivatives including vinyl syringol/canolol indicates the overwhelming role of these compounds in flavour and aroma of beer, wine and coffee (see Chapter 3). It has been already demonstrated to be effective in controlling oxidation in lipid model relevant to food. In vitro and in vivo studies conducted so far come to an agreement that. 

Given the broad spectrum and the potent which is antioxidative in nature, besides being a good antioxidant in lipids, canolol can effectively be used as a dietary supplement in combating oxidative stress in living organisms. Canolol, as a constituent of canola/rapeseed oil, has already been residual mostly in crude oils. In this context, it can be presumed well that enriching oils with canolol will benefit the value of foods. Nevertheless, to further substantiate its claim, in disease and nutrition, human clinical trials would be necessary. If human trials are in line to the in vitro and in vivo studies, canolol can be positioned as a new powerful nutraceutical and hit the market in future. 

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