Fatty acids diacylglycerol

Panetta, T., MarcheselH, V. L., Braquet, P., Spinnewyn, B. and Bazan, N. G. Effects of a platelet-activating factor antagonist (BN52021) on free fatty acids, diacylglycerols, polyphosphoinositides and blood flow in the gerbil brain Inhibition of ischemia-reperfusion induced cerebral injury. Biochem. Biophys. Res. Commun. 149 580-587,1987. 

Some palm oil processing companies in Malaysia are producing and exporting fully processed palm oil and palm olein with low free fatty acids, diacylglycerols, phosphorus, and trace metals. They guarantee the delivered quality for the oil. These oils have shown excellent frying stability. 

See also Triglycerides, Fatty Acids, Diacylglycerol Lipase, Monoacylglycerol Lipase, Diacylglycerol, Maintaining Blood Glucose Levels... 

Lipases degrade glycerides to glycerol and free fatty acids. Diacylglycerols in the free or phosphorylated form (phosphatidic acids) are precursors of groups of phospholipids that are important membrane constituents (Table 27). In the biosynthesis of these compounds the following reactions are of significance ... 

Eicosanoids, so named because they are all derived from 20-carbon fatty acids, are ubiquitous breakdown products of phospholipids. In response to appropriate stimuli, cells activate the breakdown of selected phospholipids (Figure 25.27). Phospholipase Ag (Chapter 8) selectively cleaves fatty acids from the C-2 position of phospholipids. Often these are unsaturated fatty acids, among which is arachidonic acid. Arachidonic acid may also be released from phospholipids by the combined actions of phospholipase C (which yields diacyl-glycerols) and diacylglycerol lipase (which releases fatty acids). 

Diacylglycerol is glycerol esterified to two fatty acids at the sn-1 and sn-2 positions. It is a membrane-embedded product of phospholipase C action and an activator of protein kinase C. It is also an intermediate in the biosynthesis of triacylglycerol, phosphatidyletha-nolamine and phosphatidylcholine. 

Monoacylglycerols are the monoesters of glycerol that consist of only one fatty acid attached either to the position 1(3) or 2 of the glycerol backbone. However, because both diacylglycerols and monoacylglycerols are hydrolytic products of triacylglycer-ols and phospholipids, they may be present, if any, only in negligible levels in animal and plant tissues. 

FIGURE 12.4 (A) Diagrammatic representation of the separation of major simple lipid classes on silica gel TLC — solvent system hexane diethylether formic acid (80 20 2) (CE = cholesteryl esters, WE = wax esters, HC = hydrocarbon, EEA = free fatty acids, TG = triacylglycerol, CHO = cholesterol, DG = diacylglycerol, PL = phospholipids and other complex lipids). (B) Diagrammatic representation of the separation of major phospholipids on silica gel TLC — solvent sytem chloroform methanol water (70 30 3) (PA = phosphatidic acid, PE = phosphatidylethanolamine, PS = phosphatidylserine, PC = phosphatidylcholine, SPM = sphingomyelin, LPC = Lysophosphatidylcholine). 

In positive ion mode, the characteristic peaks representative of the binding media were fatty acids from lead soaps (of palmitic acid at m/z 461 463 and of stearic acid at m/z 489 491). Other peaks corresponding to mono- and diacylglycerol cations, protonated stearic acid or its acylium ions could be found in the spectra of the reference products but not in the paint sample. The spectrum of lead white egg tempera paint exhibits peaks of phosphocholine (m/z 184) and protonated ketocholesterol (m/z 401). These peaks were not found in the spectrum from the cross-section. In negative ion mode, the spectrum of the oil... 

Free arachidonic acid, along with diacylglycerols and free docosahexaenoic acid, is a product of membrane lipid breakdown at the onset of cerebral ischemia, seizures and other forms of brain trauma. Because polyunsaturated fatty acids are the predominant FFA pool components that accumulate under these conditions, this further supports the notion that fatty acids released from the C2 position of membrane phospholipids are major contributors to the FFA pool, implicating PLA2 activation as the critical step in FFA release [1,2] (Fig. 33-6). 

It has been found that the catalytic activity of PKC is enhanced by a lipid component of the cell membrane, namely phosphatidylserine. This activity is further stimulated by sn-1,2-diacylglycerol. Oleic acid also activates the enzyme in the presence of 1,2-diacylglycerol, and thus it is presumed to mimic phosphatidylserine. In order to identify that modulating binding site for oleic acid on PKC, a photoaffinity analogue was devised. A carbene generating photophore, diazirine was placed in the apolar terminus of the unsaturated fatty acid ligand (30, Fig. 12). The synthesis and the photochemical activation properties were reported by Ruhmann and Wentrup [113]. 

Various combinations of hexane or light petroleum (40-60°C, bp) and diethyl ether, usually with a small amount of acetic acid (e.g. 90 10 1) or diisopropyl ether and acetic acid (98.5 1.5) are commonly used. The greater mobility is demonstrated by cholesterol esters followed by triacylglycerols, free fatty acids, cholestorol, diacylglycerols and monoacylglycerols, with complex polar lipids remaining unmoved. Double development in two solvents, e.g. diisopropyl... 

Wax esters have similar relative molecular masses to diacylglycerols and are eluted under comparable gas chromatographic conditions. Alternatively, the alcohol and fatty acid moieties can be released by saponification and their methyl esters subjected to gas chromatography. 

The physiological functions of carboxylesterases are still partly obscure but these enzymes are probably essential, since their genetic codes have been preserved throughout evolution [84] [96], There is some evidence that microsomal carboxylesterases play an important role in lipid metabolism in the endoplasmic reticulum. Indeed, they are able to hydrolyze acylcamitines, pal-mitoyl-CoA, and mono- and diacylglycerols [74a] [77] [97]. It has been speculated that these hydrolytic activities may facilitate the transfer of fatty acids across the endoplasmic reticulum and/or prevent the accumulation of mem-branolytic natural detergents such as carnitine esters and lysophospholipids. Plasma esterases are possibly also involved in fat absorption. In the rat, an increase in dietary fats was associated with a pronounced increase in the activity of ESI. In the mouse, the infusion of lipids into the duodenum decreased ESI levels in both lymph and serum, whereas an increase in ES2 levels was observed. In the lymph, the levels of ES2 paralleled triglyceride concentrations [92] [98],... 

Ginkgo alters lipid metabolism created by electroconvulsive shock treatments. EGb 761 reduced accumulation of free fatty acids and removal of diacylglycerol, which is more pronounced in the hippocampus than cerebral cortex (Rodriguez de Turco et al. 1993). Ginkgo also has protective effects on lipid membranes under hypoxic conditions. Bilobalide, but not ginkgolides, suppressed hydrolysis of choline induced... 

Rodriguez de Turco EB, Droy-Lefaix MT, Bazan NG. (1993). Decreased electroconvulsive shock-induced diacylglycerols and free fatty acid accumulation in the rat brain by Ginkgo biloba extract (EGb 761) selective effect in hippocampus as compared with cerebral cortex. J Neurochem. 61(4) 1438-44. 

Glycerophospholipids are used for membrane synthesis and for producing a hydrophilic surface layer on lipoproteins such as VLDL. In cell membranes, they also serve as a reservoir of second messengers such as diacylglycerol, inositol 1,4,5-triphosphate, and arachidonic acid. Their structure is similar to triglycerides, except that the last fatty acid is replaced by phosphate and a water-soluble group such as choline (phosphatidylcholine, lecithin) or inositol (phosphatidyl-inositol). 

Lingnal and gastric lipases catalyse only partial lipolysis to prodnce fatty acids and diacylglycerol. 

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