Neutral glycerides

The partition of different lipids between two immiscible solvents (countercurrent distribution) is useful for crude fractionation of lipid classes with greatly differing polarities. Repeated extractions in a carefully chosen solvent pair increase the effectiveness of the separation but in practice mixtures of lipids are still found in each fraction. A petroleum ether-ethanol-water system can be used to remove polar contaminants (into the alcoholic phase) when interest lies in the subsequent analysis of neutral glycerides, which may be recovered from the ether phase. Carbon... 

Zhang J. P. and Sun G. Y. (1995). Free fatty acids, neutral glycerides, and phosphoglycerides in transient focal cerebral ischemia. J. Neurochem. 64 1688-1695. 

The esterification of glycerol with a fatty acid produces a neutral glyceride. Esterification may occur at one, two, or all three positions, producing monoglycerides, diglycerides, or triglycerides. You will also see these referred to as mom-, di-, or triacylglycerols. 

Because there are no charges (+ or —) on these molecules, they are called neutral glycerides. These long molecules readily stack with one another and constitute the majority of the lipids stored in the bod)Ts fat cells. 

AL721 is a 7 2 1 mixture of neutral glyceride, phosphatidylcholine and phosphatidyl-ethanolamine, which is considered to be valuable in HIV therapy. In order to determine the ratio of phosphatidylcholine and phosphatidylethanolamine based on the comparison of signal intensities, a pulse sequence has to be developed which minimizes the influence of TI relaxation times and NOE differences [65]. 

I. Application of Heat or Electricity.—Up to temperatures of 150° 0. the effect of water on oils and fats is very slight, but by passing superheated steam through fatty matter heated to 200°-300° C. the neutral glycerides are completely decomposed into glycerol and fatty acids according to the equation—... 

At early incubation times PA synthesis was the higher both in toad and cattle retina however, a remarkable time-dependent increase in the incorporation of the precursor in triacylglycerol was found. After 90 min of incubation the labeling of the neutral glyceride surpassed that of all other lipid classes (Giusto Bazan,... 

The labelling of rat brain lipids >cn )Xvo with H arachidonic acid and their subsequent analysis at different times postmortem indicates that the released arachidonic acid originates from certain phospholipids. In whole brain at all time interval studies, the specific activity of the liberated arachidonate is intermediate between that of phosphatidylinositol and phosphatidylcholine but higher than that of phosphatidylethanolamine and much lower than that of the neutral glycerides. A similar situation was found in the microsomal fraction. 

When Ca " " was omitted 0.2 mM EGTA was added. Thereafter at different time intervals the retinas were removed from the incubation media and homogenized with chloroform-methanol by means of a Potter-Elvehjem homogenizer (Folch et al., 1957). Phospholipid classes were isolated by two-dimensional TLC (Rouser et al., 1970) and neutral glycerides by gradient-thickness TLC (Bazan Bazan, 1975). 

The precursor uptake was enhanced by increasing Ca " and Mg " concentration from 0.1 mM to 3 mM. The highest labeling of neutral glycerides was found at 1.15 and 1.2mM of Ca " and Mg " respectively, that is, in Ames and Hastings medium (Table 2). Phosphatidic acid phosphatidylinositol and phosphatidylcholine, on the other hand, attain highest labeling in the presence of 3 mM Mg plus 0.1 mM Ca ". Under the former condition TG radioactivity was observed to be the lowest. 

Several extracellular stimuli are known to affect the turnover of membrane lipids, particularly that of phosphatidylinositol (Michell, 1975). However, similar effects bn the neosynthesis of phospholipids and neutral glycerides are not clearly known. Nevertheless it appears that this pathway must be under metabolic control to ensure the provision of individual lipids for biogenesis, partial renewal, or repair of biomembranes. 

On the other hand, the ethiology of fatty livers caused by alcohol is still debated and manifold effects of alcohol have been reported. In man a fatty liver can result from acute or chronic ethanol ingestion. In the rat a single dose of ethanol or the chronic administration causes an increase in liver lipids (Dilxjzio 1958 Mallov 1955). Mallov (1961) demonstrated an increased mobilization of free fatty acids from the depots, caused by alcohol administration. On the other hand, ScHAPiRO et al. (1964) showed in the perfused liver, that addition of ethanol to the perfusate decreased the secretion of neutral glycerides by the liver. However, with ethanol no decrease in protein synthesis could be shown (Seakins and Robinson 1964), and normal or elevated plasma lipids were found. 

Stein, Y., and B. Shapiro The synthesis of neutral glycerides by fractions of rat liver homogenates. Biochim. biophys. Acta (Amst.) 24, 197 (1957). 

Wood, R. and Harlow, R.D. (1969) Structural studies of neutral glycerides and phospho-glycerides of rat hver. Arch. Biochem. Biophys. 131, 495-501. 

A very thorough and extensive study of the effect of various procedures of tissue preparation on the loss of triglycerides from macrophages was that of Cope and Williams (1968). Their data have shown that water-miscible methacrylates even at —20° are not suitable for the preservation of neutral glycerides. Although better retention of... 

---