Inhibitory effects of phenylpropanoid metabolites on copper-induced protein oxidative modification of mice brain homogenate, in vitro.

We present the results of an in vitro investigation of the inhibitory effects of phenylpropanoid metabolites on copper-induced protein oxidative modification of mice brain homogenate. The effects of caffeic acid, 3-(3, 4-dihydroxyphenyl)-L-alanine, esculetin, ferulic acid, and scopoletin were stronger than that of mannitol as a free-radical scavenger, whereas the effects of other phenylpropanoid metabolites, cinnamic acid, coniferyl alcohol, p-coumaric acid, coumarin, phenylalanine, tyrosine, and umbelliferone, were weak. These results demonstrated that phenolic carboxylic acids with 3,4-dihydroxy or 4-hydroxy-3-methoxy substituents and benzo-alpha-pyrons with 6,7-dihydroxy or 7-hydroxy-6-methoxy substituents in phenylpropanoid metabolites inhibit metal-induced protein oxidative modification of the brain.