An investigation of the versatile antioxidant mechanisms of action of rosmarinate alkyl esters in oil-in-water emulsions.
The antioxidant polar paradox postulates that nonpolar antioxidants are more effective in oil-in-water emulsions than polar antioxidants. However, this trend is often not observed with antioxidants esterified with acyl chains to vary their polarity. In this study, the nonpolar eicosyl rosmarinate (20 carbons, R20) was less effective at inhibiting lipid oxidation in oil-in-water emulsions than esters with shorter fatty acyl chains such as butyl (R4), octyl (R8), and dodecyl (R12) esters. Interestingly, in the presence of surfactant micelles, the antioxidant activity of R20 was significantly increased while the antioxidant activity of R4 and R12 was slightly decreased. The presence of surfactant micelles increased the concentration of R20 at the interface of the surfactant micelles and/or emulsion droplets as determined by partitioning studies, front-face fluorescence properties, and the ability of R20 to interact with the interfacial probe, 4-hexadecylbenzenediazonium. A possible explanation for why the antioxidant activity of R20 was so dramatically increased by surfactant micelles is that a portion of the nonpolar R20 localizes in the emulsion droplet core and the surfactant micelles are able to increase the interfacial concentrations of R20 and thus its ability to scavenge free radicals produced from the decomposition of interfacial lipid hydroperoxides.
Department of Food Science, University of Massachusetts, Chenoweth Laboratory, Amherst, Massachusetts 01003, United States.
Atikorn
A
Panya
Mickaël
M
Laguerre
Christelle
C
Bayrasy
Jérôme
J
Lecomte
Pierre
P
Villeneuve
D Julian
DJ
McClements
Eric A
EA
Decker
D000975:Antioxidants / Q000737:chemistry*; D002934:Cinnamates / Q000737:chemistry*; D053630:Depsides / Q000737:chemistry*; D004655:Emulsions / Q000737:chemistry; D004952:Esters / Q000737:chemistry*; D010084:Oxidation-Reduction; D000097123:Rosmarinic Acid
D000975:Antioxidants; D002934:Cinnamates; D053630:Depsides; D004655:Emulsions; D004952:Esters; D000097123:Rosmarinic Acid