Résumé
Lipophilized antioxidants are amphiphilic molecules constituted of a lipid moiety covalently linked to a polar group possessing antioxidant properties. They are multifunctional molecules possessing interesting physicochemical (antioxidant, surface active) and biological (antimicrobial, antiviral, antiinflammatory, anticarcinogenic, etc.) properties. They can be used to limit lipid oxidation in heterogeneous systems such as food and nonfood emulsions, liposomes, microorganisms, and cultured cells. Their activity is related to their hydrophobicity and follows a nonlinear trend named “cut-off effect,” meaning that it increases progressively with hydrophobicity until a critical point, beyond which activity collapses. The antioxidant and biological properties in heterogeneous system of lipophilized antioxidants are dictated by their reducing activity, the parent molecule toxicity, their hydrophobicity, and the position of the lipophilic group in the parent molecule. The hydrophilic/lipophilic balance of lipophilized antioxidants influences their partitioning in every phase constituting the dispersed system, and their capacity to self-aggregate, e.g., to form micelles, and/or with other molecules present, e.g., in the continuous, discontinuous, or interface in an emulsion, or in membranes in microorganisms or cells. Therefore, lipophilized antioxidants possess an interesting potential to be used as antioxidant and biological agents in food, cosmetics, and pharmaceutical products, since most of them exist as complex heterogeneous lipid dispersions.