Portal de Periódicos da CAPES

Higher radical scavenging activities of polyphenolic antioxidants can be ascribed to chemical reactions following their oxidation

2002; Elsevier BV; Volume: 1572; Issue: 1 Linguagem: Inglês

10.1016/s0304-4165(02)00285-4

1872-8006

Hiroki Hotta, Satomi Nagano, Masashi Ueda, Yoshio Tsujino, Junko Koyama, Toshiyuki Osakai,

Antioxidant Activity and Oxidative Stress

Radical scavenging activities of 34 natural antioxidants were investigated from an electrochemical viewpoint. While the correlation of the oxidation potentials with their DPPH radical scavenging activities (represented by EC50) was not high (the correlation coefficient, r=0.73), the number of electrons n required for oxidation of an antioxidant, being obtained by continuous flow-column electrolysis with a slower flow rate (0.05 ml min−1), did show a good correlation with EC50 (1/EC50=1.67n+0.50 with r=0.94). The n values of most polyphenols were increased with a decrease in the flow rate, while those of nonpolyphenols were invariant. This suggests that a slower subsequent chemical reaction(s) should be involved in the oxidation of polyphenols, whose higher radical scavenging activities seem to be ascribed to the chemical reactions. In this study, we have proposed a possible mechanism for the oxidation of polyphenols, in which the oxidizable -OH moieties are reproduced through an oxidative dimerization (or more highly polymerization).