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Background/Aims: Erythrocytes, continuously exposed to oxygen pressure and toxic compounds, are sensitive to oxidative stress, namely acting on integral Band 3 protein, with consequences on cell membranes deformability and anion transport efficiency. The aim of the present investigation, conducted on human erythrocytes, is to verify whether curcumin (1 or 10µM), a natural compound with proved antioxidant properties, may counteract Band 3-mediated anion transport alterations due to oxidative stress. Methods: Oxidative conditions were induced by exposure to, alternatively, either 2 mM N-ethylmaleimide (NEM) or pH-modified solutions (6.5 and 8.5). Rate constant for SO4= uptake and -SH groups estimation were measured to verify the effect of oxidative stress on anion transport efficiency and erythrocyte membranes. Results: After the exposure of erythrocytes to, alternatively, NEM or pH-modified solutions, a significant decrease in both rate constant for SO4= uptake and -SH groups was observed, which was prevented by curcumin, with a dose-dependent effect. Conclusions: Our results show that: i) the decreased efficiency of anion transport may be due to changes in Band 3 protein structure caused by cysteine -SH groups oxidation, especially after exposure to NEM and pH 6.5; ii) 10 µM Curcumin is effective in protecting erythrocytes from oxidative stress events at level of cell membrane transport. © 2015 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Background: It has been reported that biologically active compounds extracted from Cnidaria venom may induce damage by oxidative stress. Erythrocytes are constantly exposed to oxidative stresses, which can contribute to sulphydril (SH-) group oxidation and cell membrane deformability accompanied with activation of K-Cl co-transport and inhibition of anion transport. In this regard, Band 3 protein is responsible for mediating the electroneutral exchange of chloride (Cl-) for bicarbonate (HCO3-), particularly in erythrocytes, where it is the most abundant membrane protein. The aim of this study was to elucidate the effect of crude venom extracted from Pelagia noctiluca nematocysts on Band 3 -mediated anion transport in human erythrocytes. Methods: Erythrocytes were tested for SO42- uptake, K+ efflux, glutathione (GSH) levels and concentration of SH- groups. Results: The rate constant of SO42- uptake decreased progressively to 58% of control with increasing venom doses, and showed a 28% decrease after 2 mM NEM treatment. These effects can be explained by oxidative stress, which was reflected by decreased GSH levels in venom-treated erythrocytes. Hence, the decreased efficiency of anion transport may be due to changes in Band 3 structure caused by SH-group oxidation and reduced GSH concentration. In addition, an increased Cl--dependent K+ efflux was observed in venom-treated erythrocytes. Conclusion: Our results suggest that crude venom from Pelagia noctiluca alters cell membrane transport in human erythrocytes. © 2014 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]