Scavenging of reactive oxygen radicals by resveratrol: antioxidant effect

Pulse radiolysis of resveratrol was carried out in aqueous solutions at pH ranging from 6.5 to 10.5. The one-electron oxidized species formed by the N-3(center dot) radicals at pH 6.5 and 10.5 were essentially the same with lambda(max) at 420 nm and rate constant varying marginally (k = (5-6.5) x 10(9) dm(3) mol(-1) s(-1)). The nature of the transients formed by NO2center dot, NOcenter dot radical reaction at pH 10.5 was the same as that with N-3(center dot), due to the similarity in decay rates and the absorption maximum. Reaction of (OH)-O-center dot radical with resveratrol at pH 7 gives an absorption maximum at 380 nm, attributed to the formation of carbon centered radical. The repair rates for the thymidine and guanosine radicals by resveratrol were approx. 1 x 10(9) dm(3) mol(-1) s(-1), while the repair rate for tryptophan was lower by nearly an order of magnitude (k = 2 x 10(8) dm(3) mol(-1) s(-1)). The superoxide radical anion was scavenged by resveratrol, as well as by the Cu-resveratrol complex with k = 2 x 10(7) and 1.5 x 10(9) dm(3) mol(-1) s(-1), respectively. Its reduction potential was also measured by cyclic voltammetry.