Reactivity of trans -Resveratrol toward Electrogenerated Superoxide in N , N -Dimethylformamide.

The reactivity of 5-[( E )-2-(4-hydroxyphenyl)ethen-1-yl]benzene-1,3-diol ( trans -resveratrol) and related compounds toward electrogenerated superoxide radical anion (O 2 •- ) were investigated using electrochemistry, in situ electrolytic electron spin resonance, and in situ electrolytic ultraviolet-visible spectral measurements, in N , N -dimethylformamide (DMF) with the aid of density functional theory (DFT) calculations. The quasi-reversible cyclic voltammogram of dioxygen/O 2 •- was modified by the presence of trans -resveratrol, suggesting that the electrogenerated O 2 •- was scavenged by trans -resveratrol through proton-coupled electron transfer (PCET) via three phenolic hydroxy groups (OH) on the stilbene moiety. The reactivity of trans -resveratrol toward O 2 •- characterized by the OHs was experimentally confirmed in comparative analyses using some related compounds, pinosylvin, pterostilbene, p -coumaric acid, and so on, in DMF. The electrochemical and DFT results suggested that a concerted PCET mechanism via 4'OH of trans -resveratrol proceeds, where the coplanarity of the two phenolic rings in the stilbene moiety linked by an ethylene bridge is essential for a successful O 2 •- scavenging.