Oxidation reactions in biological systems occur by free radical action that can act on some molecules such as fatty acids of cell membranes, conducting to diseases as atherosclerosis and cancer. Phenolic compounds of many natural products has been focus of researchers attention due to its functional attributes. Guarana powder (Paullinia cupana), from Amazonia, is rich in tannins (a phenolic compound), which can reach 16% in dry matter. There are few published studies in vivo about the effect of guaraná in health. The aim of this study is to investigate the inhibition of lipid peroxidation in plasma and LDL by the consumption of a beverage made with guarana powder. Volunteers (n=20) will have their blood drawn before, after one hour and after one week drinking the beverage, on a twelve-hour overnight fast. Plasma and LDL at the three moments will be submitted to oxidation by three different pathways [Copper (Cu+2), lipoxygenase and peroxynitrite] and after that will be measured the formed products of lipid peroxidation: the concentration of TBARs (Thiobarbituric acid-reactive substances) and the formation of conjugated dienes using spectrophotometric methods. The total antioxidant status of the plasma (TAS) and the levels of expression of some genes related to the antioxidant enzyme production will be determined by means of analysis of PCR real time. The data will be presented as average and standard deviation. The statistical analyses will be ANOVA (Analysis of variance) and test of Tukey will be used to verify if there is significant difference between the results before and after the consumption of each beverage and between groups. SPSS for Windows 13.0 will be used.
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