Iodine mediated electrochemical detection of thiols in plant extracts using platinum screen-printed electrodes

摘要

The quantitative analysis of the ratio of reduced glutathione to total glutathione provides useful information for the evaluation of the oxidative stress levels in biological samples. We report an electro-analytical methodology for determining this ratio using cyclic voltammetry and platinum screen-printed electrodes. The method involves the use of the reaction of electro-generated iodine with biological thiols, using GSH as a model, which produces an increase in the current of the anodic peak from iodide oxidation, and allows its easy analytical quantification. Iodine reacts with thiols in its reduced state, but not with disulfides, making possible the discrimination of these two kinds of compounds in a mixture. For the total glutathione determination, sodium borohydride was added as a reducing agent. Calibration plots for the reduced and total glutathione were analyzed. It was demonstrated that this method is able to analyze these compounds in solutions spiked with reduced and oxidized glutathione. Finally, to test the effectiveness of the analytical method in real samples, plant extracts from Pisum sativum (pea) were analyzed by the developed methodology as a proof-of-concept and validated independently with a spectrophotometric method.