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 eff ects on human red blood cell (RBC) and their membranes. Cur, at concen trations of 4-100 mu M protected RBC against H2O2-induced lysis and li pid peroxidation (LPO). Cur (100 mu M) caused significant inhibition o f 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 asco rbic acid was added in the system (prior to H2O2) aiming to induce par tial iron reduction. Cur alone did not change the ratio of Fe2+/Fe3+ i n these ghosts but significantly inhibited the rate of Fe2+ reoxidatio n by H2O2. The results indicate the possibility of Fe2+ complexing wit h Cur leading to a lower iron reactivity towards H2O2. Therefore Cur a s a membrane antioxidant may protect Th RBC against iron-catalyzed oxi dative damage.