Studies on curcumin and curcuminoids .26. Antioxidant effects of curcumin on the red blood cell membrane

A natural polyphenol curcumin (Cur) was tested for its antioxidant effects on human red blood cell (RBC) and their membranes. Cur, at concentrations of 4-100 mu M protected RBC against H2O2-induced lysis and lipid peroxidation (LPO). Cur (100 mu M) caused significant inhibition of the LPO in normal RBC ghosts supplemented with exogenous iron and in beta-thalassemic (Th) ghosts containing endogenous iron deposits. The Cur protective effect on Th ghosts was much more pronounced when ascorbic acid was added in the system (prior to H2O2) aiming to induce partial iron reduction. Cur alone did not change the ratio of Fe2+/Fe3+ in these ghosts but significantly inhibited the rate of Fe2+ reoxidation by H2O2. The results indicate the possibility of Fe2+ complexing with Cur leading to a lower iron reactivity towards H2O2. Therefore Cur as a membrane antioxidant may protect Th RBC against iron-catalyzed oxidative damage.