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Kinetic and stoichiometry of the reaction of chlorogenic acid and its alkyl esters against the DPPH radical

Lopez Giraldo L.J., Laguerre M., Lecomte J., Figueroa-Espinoza M.C., Baréa B., Weiss J., Decker E.A., Villeneuve P.. 2009. Journal of Agricultural and Food Chemistry, 57 (2) : p. 863-870.

The lipophilization of polar antioxidants such as phenolics is an efficient way to enhance their solubility in apolar media. Thus, in emulsified systems, lipophilized antioxidants are supposed to locate at the lipid/aqueous phase interface and to lead to a better protection of unsaturated lipids. Herein, the antiradical activity of chlorogenic acid (5-CQA) and its corresponding esters with seven fatty alcohols (from methanol to eicosanol) have been achieved using the well-known 2,2-diphenyl-1-picrylhydrazyl (DPPH) method. Hydrophobation was shown to significantly improve the antiradical activity of 5-CQA esters which reached a maximum for butyl- and octyl-chlorogenate. In addition, for both 5-CQA and its esters, it was demonstrated that the global mechanism of DPPHo stabilization proceeded likely by electron transfer (ET), while it appeared that the pathways of DPPHo stabilization were different between 5-CQA and its esters, as confirmed by the LC-MS characterization of reaction products. Finally, strong differences were found between the tested molecules allowing the proposal of different DPPHo stabilization pathways by electron transfer for 5-CQA and its esters. (Résumé d'auteur)

Mots-clés : antioxydant; composé phénolique; radical libre; acide chlorogénique; candida; candida antarctica; lipophilisation

Thématique : Traitement et conservation des produits alimentaires; Autres thèmes

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