[Inhibition of Linseed Oil Autooxidation by Essential Oils and Extracts from Spice Plants].

Clove bud essential oil, extracts from ginger, pimento and black pepper, or ascorbyl palmytate were studied as natural antioxidants for the inhibition of autooxidation of polyunsaturated fatty acids in linseed oil. Different methods were used to estimate antioxidant efficiency. These methods are based on the following parameters: peroxide values; peroxide concentration; content of degradation products of unsaturated fatty acid peroxides, which acted with thiobarbituric acid; diene conjugate content; the content of volatile compounds that formed as products of unsaturated fatty acid peroxide degradation; and the composition of methyl esters of fatty acids in samples of oxidized linseed oil.

[Antiradical properties of essential oils and extracts from clove bud and pimento].

The antiradical properties of essential oils and extracts from the clove bud (Eugenia caryophyllata Thumb.) and berries of tree (Pimenta dioica (L.) Meriff) were studied and compared with the properties of synthetic antioxidant ionol (2,6-ditret-butyl-4-hydroxytoluene, BHT) in model reactions with the stable free 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical. The essential oils of clove bud and pimento had qualitatively close composition of the main components but differed by their quantitative content. In the studied samples, eugenol was the main compound with high antiradical activity. The reaction rates of essential oils and extracts with the DPPH radical were practically the same for essential oils and twice the reaction rate of BHT. The values of antiradical efficiency (AE) were also close for essential oils and were twice that for extracts and ionol. A synergetic action of components in the essential oil and extract of pimento on antiradical efficiency values was found.

[Effects of low doses of essential oil on the antioxidant state of the erythrocytes, liver, and the brains of mice].

We studied the effects of essential oil from oregano and clove and a mixture of lemon essential oil and a ginger extract on the antioxidant state of organs in intact and three experimental groups of Bulb mice. We found that the essential oil was an efficient in vivo bioantioxidant when mice were treated with it for 6 months even at very low doses, such as 300 ng/day. All essential oil studied inhibited lipid peroxidation (LPO) in the membranes of erythrocytes that resulted in increased membrane resistance to spontaneous hemolysis, decreased membrane microviscosity, maintenance of their structural integrity, and functional activity. The essential oil substantially decreased the LPO intensity in the liver and the brains of mice and increased the resistance of liver and brain lipids to oxidation and the activity of antioxidant enzymes in the liver. The most expressed bioantioxidant effect on erythrocytes was observed after clove oil treatment, whereas on the liver and brain, after treatment with a mixture of lemon essential oil and a ginger extract.

[Effect of oregano essential oil on the engraftment and development of Lewis carcinoma in F1 DBA C57 black hybrid mice].

The effect of a low uptake dose of oregano essential oil with drinking water for three months (Origanum vulgare L.) on the degree of Lewis carcinoma engraftment and some parameters of oxidative stress has been studied in vivo using F1 DBA C57 Black hybrid mice. Oregano essential oil has been established to possess an anticancer activity. The degree of tumor engraftment decreased by 1.8 times, its size decreased by 1.5 times, and the development of tumor was significantly suppressed in sick mice under the effect of oregano essential oil. It was found that the uptake of essential oil did not affect the intensity of lipid peroxidation in the brain of mice and resulted in a significantly (by 36%) decreased content of secondary lipid oxidation products in the liver as shown in a reaction with thiobarbituric acid as compared to control subjects. The activity of antioxidant enzymes was found to increase after three months of essential oil uptake (by 1.5-3 times) as compared to the control group. This effect of essential oil supports the presence of bioantioxidant properties in this essential oil.

[Influence of the composition of essential oils on their antioxidant and antiradical properties].

The antiradical and antioxidant properties of essential oil mixtures (EOMs) with various compositions were studied and compared in model systems of hexanal autooxidation, thermal oxidation of methyl linoleate and beta3-carotene, and in a reaction with the stable diphenylpicrylhydrazyl radical. It was found that all EOMs under investigation exhibited antiradical activity. The highest antiradical activity was observed for an EOM containing monoterpene hydrocarbons as the main components (the phenol content was low). The antioxidant activity of all EOMs was from 60 to 98% and depended on the model system composition and the method of assay. The mixture with the highest phenol content exhibits the highest antioxidant activity level in the hexanal autooxidation system. EOMs with a high content of phenols and alpha- and y-terpinenes were the most efficient antioxidants in the beta3-carotene model system. The study confirmed the possibility to vary the antioxidant and antiradical properties of essential oils by preparing their mixtures with a specific composition.

[Autooxidation of a mixture of lemon essential oils, methyl linolenoate, and methyl oleinate].

Stability of components of a mixture of methyl linolenoate and methyl oleinate with two lemon (Citrus limon L.) essential oils in hexane during their autooxidation in light was studied by gas chromatography. The essential oils differed by their quantitative ratio of components: the single-fold (1x) oil contained approximately 90% monoterpene hydrocarbons and 1.47% citral, whereas the proportions of hydrocarbons and citral in the tenfold (10x) oil were approximately 60 and 18.32%, respectively. The concentration and composition of essential oils influence the rates of fatty-acid oxidation and fatty-acid peroxide cleavage. The 1x lemon oil inhibited the oxidation of methyl linolenoate and methyl oleinate, whereas the 10x oil accelerated these processes. The distinctions in the resistance of the major components of lemon essential oil to oxidation, which are determined by their composition and antioxidant properties of unsaturated fatty acids, were revealed.