Action of Curcumin as an Antioxidant against Lipid Peroxidation

Abstract

The antioxidant activity of curcumin, 1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3 , 5- dione, a natural antioxidant obtained from rhizome of Curcume longa L. , and related compounds was mea- sured against lipid peroxidation in various media. Curcumin reacted with stable radicals such as galvi- noxyl and N,N-diphenyl-1- picrylhydrazyl, indicating it to possibly serve as a potent hydrogen donor , but no curcumin radical could be observed directly by electron spin resonance spectroscopy . Neither could the radical be spin trapped with a-(4-pyridyl-1-oxide)-N-t-butylnitrone . Curcumin suppressed the oxidation of methyl linoleate in organic homogeneous solution and aqueous emulsions , soybean phosphatidylcholine liposomal membranes, and rat liver homogenate induced by free radicals. Curcum- in was a stronger antioxidant than 2,6-di-t-butyl-4-methylphenol, Comparable to isoeugenol , but weak- er than 3,4-dihydroxycinnamic acid and 2-t-butyl-4-methoxyphenol. 1