Hydroxycinnamic acid esters enhance peroxidase-dependent oxidation of3,4-dihydroxyphenylalanine. Differences in the enhancement among theesters

摘要

Horseradish peroxidase (HRP)-dependent oxidation of 3, 4-dihydroxyphenylalanine (dopa) was studied to elucidate the mechanism of its oxidation. The oxidation of dopa was enhanced by hydroxycinnamic acid esters and dopa suppressed HRP-dependent oxidation of the esters. These results indicate that phenoxyl radicals of hydroxycinnamic acid esters that are formed at first, can oxidize dopa. Among hydroxycinnamic acid esters used, affinity of the phenoxyl radicals for dopa was in order 4-coumaric > caffeic > ferulic acid ester radicals.