Unusually large numbers of electrons for the oxidation of polyphenolic antioxidants

Reaction mechanisms of polyphenolic antioxidants were studied using electrochemical methods (flow column electrolysis and cyclic voltammetry). In flow column electrolysis, the numbers (ns) of electrons involved in the oxidation of catechols (chlorogenic acid and caffeic acid) became larger than two (i.e. the number of –OH moieties) at pH>7; the n-values finally reached ca. 4 at pH 10. Other polyphenols including catechin, ellagic acid, and curcumin exhibited higher n-values than the numbers of –OH moieties in the whole pH range studied (4