A novel method to measure both the reductive and the radical scavenging activity in a linoleic acid model system

Abstract

The aim of this study was to develop a combined method for measuring the total antioxidant activity, the reductive and the radical scavenging activity. Linoleic acid was used as the substrate for an iron-initiated lipid peroxidation to measure the total antioxidant activity. In addition, methyl esters of linoleic acid hydroperoxides were used as substrates to measure the reductive antioxidant activity. The radical scavenging antioxidant activity was calculated by subtracting the reductive antioxidative activity from the total antioxidative activity. As representative examples, the antioxidants alpha-tocopherol, ascorbic acid, trans-resveratrol and L-glutathione as well as commonly used food additives such as 2(3)-tert-butyl-4-hydroxyanisole (BHA) and 2,6-bis(1,1-dimethylethyl)-4-methylphenol (BHT) were analyzed. The results for the novel antioxidation test showed that alpha-tocopherol, BHA and BHT are primarily acting as radical scavengers, whereas ascorbic acid and L-glutathione show a strong reductive capacity. As linoleic acid as well as its hydroperoxides both are present in foods and in the organism, the test presented here can be considered representative of radical reactions occurring in food matrixes and in vivo. Further experiments are required to document the comprehensive applicability in foods and in vivo.

Margarines Fortified with α-Linolenic Acid, Eicosapentaenoic Acid, or Docosahexaenoic Acid Alter the Fatty Acid Composition of Erythrocytes but Do Not Affect the Antioxidant Status of Healthy Adults

“…The AOX of plasma samples was determined in vitro by measuring their inhibitory effect on linoleic peroxidation closely following the procedure of Bright et al (29), with some modifications as previously reported (30). The results were related to the absorption of a Trolox standard solution in water ethanol and are given as Trolox equivalents.…”

In vitro antioxidant activity of tocopherols and tocotrienols and comparison of vitamin E concentration and lipophilic antioxidant capacity in human plasma

“…Most comparisons of the antioxidant activity of fat soluble compounds, e.g. natural ones like carotenoids, lipoic acid or ubiquinones and synthetic antioxidants like 2,6-di-tertbutyl hydroxytoluene (BHT), 2-tert-butyl-hydroxy-anisol (BHA) and hydroxyltyrosol derivatives, were done only with tocopherols or exclusively with a-T [25,[27][28][29][30][31][32][33]. The aim of this study was to compare the different forms of vitamin E concerning their antioxidant activity.…”

Chemical and molecular mechanisms of antioxidants: experimental approaches and model systems

“…Many research models have been established in chemical and/or biological systems for the studies of mechanisms of action of antioxidants as well as identification of new antioxidants especially from natural substances. Generally, the antioxidant ability was measured and presented as total antioxidant activity [17,18], total antioxidant capacity [19,20], total antioxidant potentials [21], Trolox equivalent antioxidant capacity [22], total radical absorption potentials [23], ferric reducing/antioxidant power [24], and oxygen radical absorption capacity [25]. Mechanistically, these methods are based on either a single-electron transfer reaction or a hydrogen atom transfer reaction from an antioxidant or oxidant to a free radical.…”

“…The change of optical absorbance of either antioxidant or oxidant is measured for the quantitation for antioxidant capability. The chemical approaches are simple and easy to study the total antioxidant activity, which includes the radical scavenging ability and reductive activity [18]. Radicals are commonly used to measure the radical scavenging ability of antioxidant.…”

“…The antioxidant activity of these polyphenols depends significantly on the structure of the molecules, the initiation conditions and the microenvironment of the reaction medium. In vitro lipid peroxidation such as linoleic acid can be either initiated thermally by using a water soluble azo initiator 2, 2′-azobis(2-amidinopropane) hydrochloride (AAPH) [112], or initiated by metal ions Fe 2+ or Cu + with H 2 O 2 (Fenton reaction) [18,62,113]. AAPH decomposes at physiological temperature (37 °C) in aqueous solutions to generate alkyl radical (R·), which in the presence of oxygen is converted to the corresponding peroxyl radicals (ROO·).…”