Chain-breaking activity of resveratrol and piceatannol in a linoleate micellar model

This study investigated the in vitro protective effects of three derivatives of resveratrol, i.e., piceatannol (trans-3,5,3′,4′-tetrahydroxystilbene), PDM2 (1,3-dichloro-5-[(1E)-2-(4-chlorophenyl)ethenyl]-benzene) and PDM11 ((E)-5-[2-(4-chlorophenyl)ethenyl]-1,3-dimethoxyphenyl-ethene), compared with resveratrol as reference compound, against oxidation of linoleate micelles (10−2 M) initiated by radiolysis-generated hydroxyl radicals. Lipid peroxidation was monitored by conjugated dienes (differential absorbance at 234 nm), and by hydroperoxides (reverse phase HPLC with chemiluminescence detection). The higher the concentration of resveratrol or piceatannol (from 10−5 M to 10−4 M), the stronger the antioxidant ability. Piceatannol, with the presence of an additional hydroxyl group, showed a better antioxidant effect than resveratrol for a given concentration (competition with the fatty acid to scavenge lipid peroxyl radicals LOO), whereas PDM2 and PDM11, without any hydroxyl group, did not exhibit any significant protective effect. A lower limit for the LOO rate constant has been estimated for piceatannol (≥1.4 × 105 M−1 s−1) and for resveratrol (≥0.3 × 105 M−1 s−1).