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 (0.05 mg/kg
body weight per day) or placebo for 7 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 (P < .05). BIX and NBIX supplementation increased erythrocyte membrane resistance (P < .05), with BIX being more effective. Also, BIX and NBIX protected erythrocytes from lipid peroxidation and improved the cellular redox environment (P < .05). These results support the hypothesis that
annatto carotenoids supplementation exerts antihemolytic properties by preventing the oxidative damage of human erythrocytes.