Sulphate transport and –SH groups in human erythrocytes are protected by curcumin after oxidative stress.

The aim of the present investigation 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, in human erythrocytes. 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. 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. After the exposure 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. 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.