Measurement of plasma hydroperoxide concentration by FOX-1 assay in conjunction with triphenylphosphine

Introduction: Hydroperoxides are well-recognized reactive oxygen species which are associated with oxidative stress, a phenomenon of current clinical interest as oxidative stress is associated with a number of disease condition. Ferrous ion oxidation xylenol orange (FOX) methods of hydroperoxide estimation has outdated other methods available for hydroperoxide estimation. Two versions FOX assays are described in the literature, FOX-1 and FOX-2, in which FOX-1 is more sensitive. Methods: we increased the sensitivity of FOX-1 assay by stabilizing the reagent pH 1.7–1.8. Analogous to FOX-2 assay, we have modified FOX-1 assay by using it in conjunction with triphenylphosphine and butylated hydroxytoluene, thus increasing the specificity of FOX-1 assay for hydroperoxide. By modified FOX-1 method, we estimated plasma hydroperoxide concentration of normal human subjects and of diabetic patients and compared with FOX-2 method. Results: The FOX-1 method showed a significant high value of plasma hydroperoxide concentration compared to FOX-2 method both in normal subjects and diabetic patients with a significant correlation. By modified FOX-1 method, the recovery percentage of cumene hydroperoxide was better in biological samples when compared to FOX-2 method. Conclusion: The modified FOX-1 method is equally specific for hydroperoxide determination when compared to FOX-2 but is more sensitive. D 2003 Elsevier B.V. All rights reserved.