RESUMO
Erythrocytes exhibit high susceptibility to hemolysis in several pathologies due to the oxidation of cellular components. We hypothesized that annatto carotenoids improve the redox status of erythrocyte plasma membranes and promote a consequent increase in human erythrocyte resistance to hemolysis. The objective of this study was to evaluate whether food-grade annatto carotenoids can increase human erythrocyte resistance to hemolysis in vitro and ex vivo. For the in vitro experiment, erythrocytes from healthy volunteers were isolated and coincubated with bixin (BIX) or norbixin (NBIX) and 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH), glucose, or sodium nitrite (NaNO2) as hemolysis inducers. In the ex vivo study, healthy volunteers consumed a capsule containing BIX or NBIX (0.05â¯mg/kg body weight per day) or placebo for 7â¯days before blood sample collection. Their erythrocytes were isolated and incubated with AAPH, glucose, or NaNO2. In both the ex vivo and in vitro studies, erythrocytes were subjected to osmotic fragility tests. The activity of antioxidant enzymes, and reduced glutathione and lipid peroxidation levels in erythrocytes were also evaluated ex vivo. In vitro BIX and NBIX not only reduced erythrocyte membrane fragility induced by AAPH, glucose, or NaNO2 but also improved basal osmotic resistance in the micromole-per-liter range (Pâ¯<â¯.05). BIX and NBIX supplementation increased erythrocyte membrane resistance (Pâ¯<â¯.05), with BIX being more effective. Also, BIX and NBIX protected erythrocytes from lipid peroxidation and improved the cellular redox environment (Pâ¯<â¯.05). These results support the hypothesis that annatto carotenoids supplementation exerts antihemolytic properties by preventing the oxidative damage of human erythrocytes.
