Effect of simple olive biophenols and analogues on the thermotropic behavior of biological model membranes

Abstract

AbstractSome foods, in particular fruits and vegetables, are known to have protective effects against cardiovascular disease and cancer. This is believed to be due to the presence of antioxidant substances such as hydroxyaromatic compounds present in these foods. We investigated the effect exerted by protochatechuic and benzoic acid, simple biophenols (BPs) present in olive oils, and their substitute analogues, veratric and xylylic acids, on the thermotropic behavior of model membranes (dimyristoylphosphatidylcholine multilamellar vesicles) by differential scanning calorimetry (DSC)DSC analysis was carried out at two different pHs (4.0 and 7.4). The acids, when dispersed in liposomes during their preparation, were found to modify the gel to liquidcrystal phase transition of the lipid vesicles at pH 4, causing a temperature shift towards lower values and a variation in enthalpy changes. The magnitude of the temperature shift and enthalpy change was a function of the concentration of BP in the lipid dispersions and their lipophilic character. The examined compounds were unable to appreciably modify the thermotropic behavior of the liposomes at pH 7.4 suggesting that the interactions and their absorption are highly influenced by the lipophilic character induced by structural factors and by the polarity of the acidic group.