Effect of Various Dietary Fatty Acid Ethyl Esters on Plasma Cholesterol and Lipoprotein Metabolism in Rats.

Abstract

SummaryThe present study was conducted to investigate the effect of specific fatty acid esters on lipid metabolism of rats fed diets containing highly purified fatty acid ethyl esters of palmitate, stearate, palmitoleate, oleate, linoleate, and alpha linolenate. The hypocholesterolemic and hypotriglyceridemic activity of palmitoleate was comparable with that of linoleate and alpha linolenate and was significantly greater than that of palmitate, stearate, and oleate. Plasma cholesterol and LDL-cholesterol were significantly higher in rats fed the palmitate diet than those fed the stearate one. Lecithin-cholesterol acyltransferase (LCAT) activity was higher in rats fed the palmitoleate, linoleate, and alpha linolenate than in rats fed the palmitate, stearate, and oleate. There was a highly negative correlation between LCAT activity and plasma cholesterol and free cholesterol levels. These results demonstrate that palmitoleate appears to be as effective as linoleate in lowering plasma cholesterol and triglyceride levels. The stearate does not strongly increase plasma cholesterol levels as much as palmitate.

Dietary Fatty Acid Ethyl Esters and Lecithin-Cholesterol Acyltransferase Activity in Rats.

“…The LCAT activity was significantly higher in the rats fed ethyl linoleate than in those fed ethyl palmitate or ethyl oleate. These results agree with our previous report that ethyl linoleate increases the LCAT activity in a hypercholesterolemic diet [16,17]. The LCAT activity seems to depend on the quality of the substrate, particularly on the relative percentage of linoleic and oleic acid in the phospholipids, as these fatty acids characteristically are present in the lecithin 2-position.…”

“…The data demonstrate that ethyl linoleate decreases the plasma cholesterol concentration, and essentially reflects a cholesterol decrease in both the chylomicron-plus-VLDL and LDL fractions. This result is consistent with our previous report, in which we suggested that dietary ethyl linoleate decreases the plasma cholesterol concentration, especially the cholesterol concentration in the chylomicron-plus-VLDL and LDL fractions in rats fed a hypercholesterolemic diet [16,17]. As shown in Table 4, the group fed ethyl linoleate contained more linoleic acid and arachidonic acid and less palmitic acid and oleic acid in their VLDL fraction than did the other groups.…”

“…This modulation is independent of the P/S ratio, but is related to the relative composition of linoleic and oleic acids in serum phospholipids and cholesterol ester. In previous studies we reported that the LCAT activity appeared to be influenced by the kind of dietary fatty acid [16,17]. The present study was conducted to gain further information concerning the effect of dietary purified fatty acid esters on plasma LCAT activity in rats.…”

Comparison of Different Types of Dietary Oleic Acid on the Reduction of Plasma Cholesterol Levels in Rats.

“…Plasma sample (0.8 ml) was transferred to an ultracentrifuge tube and the density was adjusted with NaBr solution according to Havel et al [14] to make one of the following three densities: 1.006 (chylomicron plus VLDL), 1.063 (LDL), or 1.21 (HDL). Ultracentrifugation was carried out at 435,680x g for 4 h and 10 min at 4°C in a Beckman TL-100 equipped with a Ti-100-2 rotor [15]. Through this procedure, three lipoproteins fractions were obtained.…”

“…Plasma total cholesterol, free cholesterol, triglyceride, phospholipid, and each fraction of lipoprotein cholesterol were determined by enzymatic assays with kits purchased from wako Pure Chemical Co. [15]. Determination of LCA T activity.…”