Effect of n-propyl gallate on lipid peroxidation in heterogenous model membranes

Abstract

The antioxidant n-propyl gallate (nPG) is widely used in the food industry, pharmaceutics and cosmetics. Therefore, we should be well acquainted with its exact mechanism of action and its effects on the human organism, especially at the molecular level. Because of its slight solubility in water, it could be expected that, in cells, nPG would enter the membrane structures, thus altering their properties. Up to date little is known about its interaction with heterogenous lipid bilayers. That is why we focused our present study on the influence of nPG on the phase behavior of phosphatidylcholine/sphingomyelin/cholesterol (PC/SM/CHOL) ternary mixtures. Fluorescence microscopy of giant unilamellar vesicles (GUVs) was used as an experimental approach. Two phosphatidylcholine species were compared: palmitoyl-oleoyl phosphatidylcholine (POPC) and palmitoyl-docosahexaenoyl (ω-3) phosphatidylcholine (PDPC) differing in the number of double bonds at the sn-2 position (1 for POPC and 6 for PDPC). Fluorescence microscopy observations showed that the presence of docosahexaenoic acid induced the formation of micron-scale liquid-ordered (Lo) domains (model of cellular "rafts") at physiological and higher temperatures compared to the monounsaturated oleic acid. nPG decreased the liquid-ordered (Lo)/liquid-disordered (Ld) miscibility transition temperature, Tm, for both types of vesicles in a concentrationdependent manner. Its effect was more pronounced in GUVs composed of PDPC/SM/CHOL. © Biotechnol. & Biotechnol. Eq.