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Effects of saturated and polyunsaturated fatty acids on interactions with cholesterol versus 7-ketocholesterol in Langmuir monolayers and their potential biological implications

Author:
Fidalgo Rodríguez, J.L., Dynarowicz-Latka, P., Miñones Conde, J.
Source:
Colloids and surfaces 2019 v.174 pp. 189-198
ISSN:
0927-7765
Subject:
alpha-linolenic acid, atherosclerosis, blood flow, cholesterol, colloids, compressibility, geometry, lactalbumin, microscopy, omega-3 fatty acids, probability, stoichiometry
Abstract:
In this work the Langmuir monolayer technique was used to study interactions between cholesterol (chol) and 7-ketocholesterol (7-KC) with saturated (arachidic acid, AA) and polyunsaturated fatty acids (PUFAs) (ω-3 α-linolenic acid, α-LA,and ω-6 γ- linolenic, γ-LA) in order to get insight into their potential role in atherosclerosis. For this study, surface pressure (π)-area (A) isotherms, compressibility modulus (Cs−1) versus π plots, Brewster angle microscopy (BAM) images and excess functions (Aexc and ΔGexc) were analysed. Different behaviour has been observed. For cholesterol/AA mixed monolayers, components immiscibility occurs, whatever the surface pressure or the mixtures composition is, whereas for the 7-KC/AA mixed system, ideal behaviour was observed at low and high surface pressures for all the investigated compositions. However, the remaining mixed studied systems (sterol/PUFA) exhibit negative deviations from the ideality, although some differences do occurr. The magnitude of these deviations depend on the kind of a PUFA (for ω-3 PUFA greater than for ω-6) - attributed to the different geometry of their acyl chains- and the type of a sterol (for 7-KC greater than for cholesterol).The strength of attractive interactions followed the order: chol/ γ-LA <7-KC/γ-LA < chol/α-LA < 7-KC/ α-LA, postulating the formation of stable complexes of 1:2 stoichiometry for 7-KC/α-LA mixed monolayers and 1:1 stoichiometry for chol/α-LA mixed films. For 7-KC/γ-LA system, the formation of a low stability complex of 2:1 stoichiometry was suggested. The existence of these complexes can play an important role in diminishing the circulating sterols in the blood stream, thus decreasing the probability of atherosclerotic plaques formation.
Agid:
6233158