linoleic-acid and gamma-terpinene

The crude oil of Nigella sativa L. (Black cumin) has well-known nutraceutical and pharmaceutical properties. The oil is prone to rapid oxidative deterioration because of its high content of poly-unsaturated fatty acids. In the current investigation, different cold-pressed crude oils of N. sativa were examined for their composition of fatty acids and oxidative stability. The data obtained were correlated with the chemical composition and content of volatile oils, which correspond to each crude oil. Results indicated that different crude oils have the same fatty acid composition, and linoleic acid was the major constituent (60.0-61.7%). Though, the oxidative stability index of the crude oils was different ranging from 2.5 hr to 26.9 hr, as revealed by the Rancimate test at 100°C and airflow rate of 20 ml/min. The results showed that there is a straightforward correlation between the volatile oil content and the oxidative stability of the corresponding parent crude oil. In addition, high γ-terpinene content in the constitution of volatile oil can also be another contributing factor for enhancing the oxidative stability of the crude oil. The data presented here draw attention to some important factors that may guide the nutraceutical and food supplement processors in their screening for the highest quality of Nigella crude oils with maximum health benefits.

Topics: Cyclohexane Monoterpenes; Drug Stability; Linoleic Acid; Lipid Peroxidation; Monoterpenes; Nigella; Oils, Volatile; Oxidation-Reduction; Plant Oils; Seeds

This study is designed to examine the chemical composition and antioxidant activity of the essential oil and different solvent extracts of Vitexagnuscastus. GC and GC-MS analysis was resulted in the detection of 27 components, representing 94.5% of the oil. Major components of the oil were 1,8-cineole (24.98%), sabinene (13.45%), alpha-pinene (10.60%), alpha-terpinyl acetate (6.66%), and (Z)-beta-farnesene (5.40%). Antioxidant activities of the samples were determined by three different test systems, DPPH, beta-carotene/linoleic acid and reducing power assays. In all systems, water extract exhibited excellent activity potential than those of other extracts (hexane, dichloromethane, ethyl acetate and methanol) and the oil. As expected, amount of total phenolics was very high in this extract (112.46+/-1.22mugGAEs/mgextract). Dichloromethane extract has been found to be rich in flavonoids. A positive correlation was observed between the antioxidant activity potential and total phenolic and flavonoid levels of the extracts.

Topics: Antioxidants; beta Carotene; Bicyclic Monoterpenes; Cyclohexane Monoterpenes; Cyclohexanols; Eucalyptol; Gas Chromatography-Mass Spectrometry; Linoleic Acid; Monoterpenes; Oils, Volatile; Oxidation-Reduction; Plant Extracts; Plant Oils; Sesquiterpenes; Vitex

gamma-Terpinene (TH), a monoterpene hydrocarbon present in essential oils, retards the peroxidation of linoleic acid (LH). The peroxidation of TH has been shown to yield p-cymene as the only organic product in a chain reaction in which the chain carrier is the hydroperoxyl radical, HOO(.). The peroxidation of LH is well-known to be a chain reaction in which the chains are carried by linoleylperoxyl radicals, LOO., and the products are linoleyl hydroperoxides. The retardation of LH peroxidation by TH has been found to be due to rapid chain termination via a very fast cross-reaction between HOO. and LOO. radicals. This antioxidant mechanism is completely different from the mechanism of antioxidant action of vitamin E. Since vitamin E becomes a prooxidant at high concentrations, the addition of essential oils containing TH to edible lipids may provide an alternative or supplementary strategy for obtaining large increases in their oxidative stability and shelf life, something that cannot be achieved by simply adding more and more vitamin E.

Topics: Cyclohexane Monoterpenes; Fatty Acids; Free Radicals; Linoleic Acid; Lipid Peroxidation; Lipid Peroxides; Monoterpenes; Oxidation-Reduction; Terpenes