Inhibition of radiation-induced lipid peroxidation by tetrahydrocurcumin: Possible mechanisms by pulse radiolysis

The antioxidant property of tetrahydrocurcumin (THC), a reduced derivative of curcumin, was examined by its ability to inhibit radiation-induced lipid peroxidation in rat liver microsomes and compared with curcumin. The lipid peroxidation caused by irradiation of N2O-purged and aerated buffered aque ous solutions was found to be inhibited by THC in a dose- and concentration -dependent manner. In order to understand the actual reaction mechanisms in volved in the inhibition process, pulse radiolysis investigation of THC wit h radiolytically produced radicals like hydroxyl, model peroxyl radicals, a nd azide radicals were done and the transients were detected by kinetic spe ctrophotometry. The reaction of THC with hydroxyl and azide radicals gave r ise to transient absorption in the region 200-400 nm with two peaks at 310 nm and 390 nm. From the spectral properties and kinetics of these radicals, a suitable mechanism Is discussed to explain the antioxidant actions of TH C.