Cardanol-like co-surfactants solubilized in pegylated micelles keep theirantioxidant activity and preserve polyethylene glycol chainsfrom oxidation

Pegylated (PEG) surfactants are widely used for material and biomedical applications. Their use, however, is lim-ited by the radical-mediated oxidation of the OCH2moieties by atmospheric oxygen, that produces unwantedand toxic products such as hydroperoxides. We show herein that cardanols, natural alkylphenols byproductsof cashew nut processing, are able to form stable co-micellar systems with a model PEG-containing surfactant(Triton X-100, i.e. p-tert-octylphenoxy polyethylene-glycol ether) and display antioxidant activity toward PEGdegradation by O2. The cardanols investigated were 6-tert-butyl-3-pentadecylphenol and 4-hydroxy-6-tert-butyl-3-pentadecylphenol. The ability of cardanols to form co-micelles with Triton X-100 was investigatedby de-termining the critical micelle concentration (CMC), the microviscosity, the polarity and the aggregation number.The antioxidant activity of cardanol derivatives in dispersed systems of Triton X-100 was evaluated by studyingthe reaction with DPPH radical and the protecting activity toward the peroxidation of the polyethylene-glycoltails. The obtained activity of cardanol derivatives was similar or better than that of commercial synthetic antiox-idants BHT (2,6-di-tert-butyl-4-methylphenol) and DTBQ (2,5-di-tert-butylhydroquinone), taken as reference,under the same conditions. This study enlightens the ability of hydrogenated cardanol derivatives to act asradical-trapping agents and/or as protective co-surfactants toward the oxidative degradation PEG-coatednanoaggregates used in food and drug science.