The
antioxidant properties of
curcumin have been studied by evaluating its ability to protect RBCs from
AAPH (2,2'-azobis (2-amidinopropane) hydrochloride) induced oxidative damage. RBCs are susceptible to oxidative damage, resulting in peroxidation of the
membrane lipids, release of
hemoglobin (
hemolysis), release of intracellular K(+)
ions and depletion of
glutathione (GSH). In this paper, lipid peroxidation,
hemolysis and K(+) ion loss in RBCs were assessed respectively by formation of
thiobarbituric acid reactive substances (
TBARS), absorbance of
hemoglobin at 532nm and flame photometry. The treatment of RBCs with
curcumin showed concentration dependant decrease in level of
TBARS and
hemolysis. The IC(50) values for inhibition of lipid peroxidation and
hemolysis were estimated to be 23.2+/-2.5 and 43+/-5microM respectively. However in contrast to the above mentioned effects,
curcumin in similar concentration range, did not prevent release of intracellular K(+)
ions during the process of
hemolysis, rather
curcumin induced its release even in the absence of
hemolysis. The ability of
curcumin to prevent oxidation of intracellular GSH due to
hemolysis showed mixed results. At low concentrations of
curcumin (<10microM) it prevented GSH depletion and at higher concentrations, the GSH levels decreased gradually.
Curcumin scavenges the
peroxyl radical generated from
AAPH. Based on these results, it is concluded that
curcumin exhibits both
antioxidant/
pro-oxidant activity, in a concentration dependent manner.