Antioxidant properties of trans-ε-viniferin as compared to stilbene derivatives in aqueous and nonaqueous media

trans-epsilon-Viniferin, the dimer of resveratrol, extracted from Vitis vinifera, has been evaluated for its antioxidant capacity. Its properties have been compared to those of resveratrol and synthetic stilbenic derivatives (4-hydroxystilbene, 4,4'-dihydroxystilbene, 3,5-dihydroxystilbene, and trimethylresveratrol), in regard to their liposolubility using two media with different polarity. The bleaching of beta-carotene by lipoperoxyl (LOO.) radicals in an oil/water (O/W) emulsion and the scavenging of superoxide anions (O-2(-)) in dimethyl sulfoxide (DMSO) using 5,5-dimethyl-1-pyrroline-N-oxide as a spin trap were followed using UV-visible and electron paramagnetic resonance, respectively. epsilon-Viniferin exhibits the best antioxidant capacity in the DMSO/O-2(-) polar system (IC50 = 0.14 mM) while 4,4'-dilhydroxystilbene presents the highest antioxidant capacity in the O/W/LOO. system (inhibition of beta-carotene bleaching, 82%). Partition coefficients and kinetics of partition between 1-octanol and water were measured to discuss the antioxidant efficiency of the compounds in relation with their chemical structure.