Fluorimetric method for the evaluation of lipoperoxidation in different membrane models

摘要

Biological and biomimetic artificial membranes generally contain significant proportions of polyunsaturated fatty acids, which make them susceptible to oxidative attack by free radicals when exposed to oxidative stress conditions. Reactive species are very difficult to detect, because they have a very short lifetime and can be counteracted by antioxidant systems in vivo. Quercetin and epigallocatechin gallate are two of the most abundant compounds in plants based diets that have well documented antioxidant effects. In the present study we aimed at evaluating the effect of these two polyphenolic compounds on lipid peroxidation susceptibility of model membranes, with a method that uses the fluorescent probe DPPP; the proposed method is cost-effective, rapid and uses very small amounts of sample. In order to test the method we used biological models (human leukemia Jurkat T cells) as well as artificial membranes (small unilamellar vesicles, SUV). For both models, we tested the effect of the polyphenols on the peroxidation of the lipid membranes induced by cumene hydroperoxide. Incubation of the cells and SUVs for 20 minutes with the polyphenols (10 uM and 20 uM) reduced the level of DPPP-peroxide generation. Quercetin proved to be more effective as antioxidant, in both models and for both tested concentrations.