Changes in plasma lipid composition induced by coconut oil. Effects of dipyridamole

Structural and interfacial characteristics of oil bodies in coconuts (Cocos nucifera L.)

This study investigated the structural characteristics of oil bodies from mature coconut (Cocos nucifera L.) fruit. The ultrastructure and the distribution of oil bodies in coconut endosperm were investigated using cryo-scanning electron microscopy. The interfacial characteristics of the oil bodies in suspensions isolated using two different protocols were studied using confocal laser scanning microscopy (CLSM), and the oleosins stabilizing the oil bodies were characterized using sodium dodecyl sulfate polyacrylamide electrophoresis. The oil bodies were found to be preferentially accumulated in endosperm tissues away from the inner endosperm and had a polydisperse size distribution, both intracellularly and in suspensions. The CLSM of oil bodies revealed uniform distribution of proteins and phospholipids at the interface along with glycolipids. Six different proteins were found to be associated with oil bodies some of which were disulfide-linked. This work provides new insights into the structure of coconut oil bodies and mechanisms for their stabilization.

Influence of fasting status on the effects of coconut oil on chick plasma and lipoprotein composition

For a better understanding of the hyperlipidemic function of saturated fat, we have studied the effects of diet supplementation with 10-20% coconut oil on the chick plasma and lipoprotein composition under postprandial and starvation conditions. A significant hypercholesterolemia was found in chicks fed the standard diet after 12 h of food deprivation. In these conditions, LDL-cholesterol also increased, whereas triglyceride levels were reduced in HDL, VLDL and chylomicron fractions. Coconut oil induced a significant hypercholesterolemia under both conditions, also increasing the plasma triglyceride content under postprandial conditions, but not after starvation. Coconut oil feeding increased all the chemical components of HDL, especially under postprandial conditions, but did not affect the HDL-triglycerides under food-deprivation conditions. Total cholesterol and triglyceride levels in LDL increased after coconut oil supplementation to the diet. Differences were more pronounced under postprandial conditions. Changes in VLDL and chylomicron composition were less evident.

Influence of dipyridamole on the fatty acid composition of the main lipid classes of chick serum

We have studied the effects of dipyridamole treatment on the fatty acid composition of the main lipid classes of chick serum bearing in mind the relationship between platelet aggregation and eicosanoids production from arachidonic acid. In the free fatty acids, percentages of MUFA and n-6 PUFA fell. The effects of dipyridamole appeared to be less pronounced in triglyceride fraction, but more so in serum phospholipids and cholesterol esters. The percentage of arachidonic acid was significantly reduced by dipyridamole, as well as that of different n-3 PUFA present in phospholipid fraction. The percentage of linoleic acid in serum cholesterol esters was significantly lowered by dipyridamole, whereas that of arachidonic acid did not change significantly. Our results suggest that decreased arachidonic acid in the serum phospholipids and linoleic acid in all lipid classes may be of importance in order to dipyridamole participation in several pathologies characterized by an imbalance in the production of vasodilator and vasoconstrictor prostanoids.

Effects of dietary fish oil on the fatty acid composition of the main lipid classes of chick plasma lipoproteins

We have studied the effects of diet supplementation with 10% fish oil on fatty acid composition of the main lipid classes of chick plasma lipoproteins bearing in mind the relationship between platelet aggregation and eicosanoid production from arachidonic acid. Fish oil drastically increased the percentages of 20:5 n-3 and 22:6 n-3 acids in the high density lipoprotein lipids. The 20:5/22:6 ratio increased in triacylglycerol fraction whereas in phospholipids and cholesterol esters both 20:5 and 22:6 acids increased in a similar proportion. The percentage of arachidonic acid was higher in phospholipids than in the other lipid classes from this lipoprotein fraction and was significantly reduced by fish oil feeding. Linoleic acid, which was the most abundant fatty acid in cholesterol esters, strongly decreased after fish oil consumption. Changes induced in low- and very low density lipoproteins were similar to that observed in the high density lipoproteins. However, in the very low density lipoproteins, the 20:5/22:6 ratio was not increased in triacylglycerols, in contrast to that found in the high- and low density fractions. Our results suggest that decreases observed by fish oil feeding in the percentages of arachidonic acid in phospholipids and linoleic acid in cholesterol esters in the three lipoprotein fractions may be of importance to explain some pharmacological effects of n-3 PUFA with regard to vascular diseases.