2,2^|^apos;-Azobis(isobutyronitrile)-derived alkylperoxyl radical scavenging activity assay of hydrophilic antioxidants by employing EPR spin trap method

Abstract

As interest in the study of antioxidant intake from foods and other agricultural products increases, methods for performing radical scavenging activity assays based on the electron paramagnetic resonance spectroscopic method, in which there is no interference from the sample color and turbidity, are required. In this study, we have developed a rapid and simple electron paramagnetic resonance based assay to evaluate the alkylperoxyl radical scavenging activity of several antioxidants. The alkylperoxyl radical species was generated by the photolysis of azo-radical initiator 2,2'-azobis(isobutyronitrile), in which the radical generation rate and period were controlled by the illumination light. The relative alkylperoxyl radical scavenging activity was obtained by a simple formula of competing reaction of antioxidant and spin trap toward the oxygen radical. The scavenging activities toward alkylperoxyl radical and alkoxy radical species were evaluated in six antioxidants. Although quercetin showed the highest activity toward both radicals, the order of the relative activities in the other antioxidants was different mutually between the alkylperoxyl radical and the alkoxyl radical. This alkylperoxyl radical scavenging activity assay based on electron paramagnetic resonance spectroscopy is useful for evaluation of colored and turbid food samples.

Quercetin protects against acetaminophen-induced hepatorenal toxicity by reducing reactive oxygen and nitrogen species

“…Furthermore, quercetin restored the reduced activities of GSH-related enzymatic antioxidants. Quercetin is recognized to have a strong scavenging activity of oxygen radicals and protection against lipid and protein oxidation which has been primarily attributed to its flavonoid fraction [10,13,38,39].…”

Dose-Dependent Effect of Coriander (Coriandrum Sativum L.) and Fennel (Foeniculum Vulgare M.) on Lead Nephrotoxicity in Rats

“…Quercetin present in coriander and fennel seeds extracts is recognized to have a strong scavenging activity of oxygen radicals and protection against lipid and protein oxidation by reversing oxidantantioxidant imbalance and regulation of NO bioavailability in serum and kidney [51]. Flavonoids and phenolic compounds present in fennel aqueous extract possess various free radicals scavenging mechanism, e.g.…”

The ORAC Assay: Mathematical Analysis of the Rate Equations and Some Practical Considerations

“…Figure 3 shows both the numerical and analytical solutions of the ODEs of the minimal ORAC kinetic system in two "limiting" situations that we can find when the reactivity of XH is under study: one where the reactivity of PH is not very far form that of XH, k x /k p = 5, and another where the reactivity of the XH is between one and two orders of magnitude larger than that of PH, k x /k p = 50. The relative reactivity range we have chosen is in agreement with values for k x /k p experimentally determined with different types of ORAC probes and methodologies [5,13,20,22]. Absolute values of rate constants for the reaction of ROO • radicals with representative XH have been reported using flash photolysis [21].…”

“…The ratio between [XH] 0 /[PH] 0 used in the ORAC assay depends on the probe and the methodology. The concentrations of [XH] 0 and [PH] 0 are usually found in the same range if the ORAC method employs spectrophotometric or EPR probes [5,13,20,22], but certainly the [XH] 0 /[PH] 0 ratio is much higher when the ORAC methods employ a fluorometric probe [1,3,13,14,19,20].…”