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Chemical composition and antioxidant capacity of selected spice volatile aglycones in two lipid model systems

The antioxidant capacity of volatile aglycones from basil (Ocimum basilicum L.), laurel (Laurus nobilis L.) and clove (Syzygium aromaticum L. Merill et Perry) were examined. The volatile aglycones were extracted from their nonvolatile glycosidically bound compounds by enzymatic hydrolysis with β -glycosidasae enzyme. The chemical composition analyses of volatile aglycones were run on coupled system gas chromatography-mass spectrometry (GC-MS) with two different polarity columns. All volatile aglycone fractions have complex chemical compositions with identified aliphatic monoterpenic, sesquiterpenic, phenylpropanoid and norisoprenoid alcohols, ethers, acids, esters and carbonyl compounds. The major volatile aglycones are phenylpropanoid compounds. The major basil volatile aglycones are eugenol (44, 0 %) and chavicol (29, 5 %). Of laurel it is benzyl alcohol (63, 4 %), while the major clove volatile aglycone compound is eugenol (80, 5 %). The antioxidant capacity of isolated volatile aglycone fractions were tested by two lipid model systems: TBARS method (Method with Thiobarbituric Acid Reactive Species) and Rancimat method (Determination of Oxidative Stability of Fat). These methods were chosen because they are both bases on real lipid media for measurement. That is very important for real evaluation of antioxidant capacity. The results were compared with those for frequently used commercial antioxidants BHT (betahydroxytoluene) and vitamin C. The results show that the basil and laurel volatile aglycones have low antioxidant capacity or have no antioxidant capacity, tested by TBARS method. Contrary, the clove volatile aglycones antioxidant capacity was better: comparable with vitamin C capacity and lower than BHT capacity. Similarly results were obtained for basil and laurel tested by Rancimat method. Clove aglycone fraction antioxidant capacity is comparable or better than BHT capacity, but lower than vitamin C capacity. This is another confirmation of clove’ s significant role among spice plants, a guideline to its usage in dieting and replacing commercial antioxidants with natural ones.

basil (Ocimum basilicum L.); laurel (Laurus nobilis L.) and clove (Syzygium aromaticum L. Merill et Perry)

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