Antioxidant availability of turmeric in relation to its medicinal and culinary uses.

Turmeric (Curcuma longa) has been used in Indian cooking, and in herbal remedies. Its possible mechanism of action was examined in terms of antioxidant availability during actual cooking conditions and in therapeutic applications using standardized extracts. The assays involve different levels of antioxidant action such as oxygen radical absorbance capacity (ORAC), radical scavenging abilities using 1,1-diphenyl-2-picryl hydrazyl (DPPH), 2,2'-azobis-3-ethylbenzthiazoline-6-sulfonic acid (ABTS), ferric reducing antioxidant power (FRAP) and protection of membranes examined by inhibition of lipid peroxidation besides the content of phenols and total flavonoids. The aqueous and ethanol extracts of two major preparations of turmeric, corresponding to its use in cooking and medicine, showed significant antioxidant abilities. In conclusion, the studies reveal that the ability of turmeric to scavenge radicals, reduce iron complex and inhibit peroxidation may explain the possible mechanisms by which turmeric exhibits its beneficial effects in relation to its use in cooking and medicine. Copyright 2004 John Wiley & Sons, Ltd.