Acetal phosphatides

Although phosphohpids like acetal phosphatidic acid and lysolecithin have undoubted pharmacological activity, it is the opinion of this reviewer that, until they can be isolated by very mild conditions, their existence in the tissues examined must remain an open question. To say this is not to deny a lipid pharmacology, since prostaglandins in particular are lipids, but to reserve judgment on phospholipid pharmacology on present evidence. 

Plasmalogens ( acetal phosphatides ) Glycerol ester and enol ether Ethanolamine, choline 1 1... 

Alkenylacylethanolamine phosphatides 62 Alkenylacylglyceryl acetate 70 Alkenyidiacylethanolamine phosphatides 62... 

The lower, chloroform-rich phase is separated carefully from the protein-containing interface, and then it is washed twice with methanol-water (10 9, v/v) and the washes are discarded. The chloroform layer contains the phosphatidic acid (as a sodium salt) and can be isolated by acetone precipitation. The yields can be of the order of 90-95%. One alternative route to identification of the chloroform-soluble material is to analyze it for total phosphorus and total fatty acid ester (see procedures described earlier). In the case of diacylphosphatidylcholine as the substrate, the fatty acid ester/P molar ratio should be 2.0. Another approach is to subject the chloroform-soluble fraction to preparative thin-layer chromatography on silica gel H (calcium ion free) in a two-dimensional system with a solvent system of chloroform-methanol-28% ammonium hydroxide (65 35 6, v/v) in the first direction and a solvent system of chloroform-acetone-methanol-glacial acetic acid-water (4.5 2 1 1.3 0.5, v/v) in the second direction. The phosphatidic acid will not migrate far in the basic solvent Rf 0.10) and will show an Rf value one-half of that of any remaining starting substrate (fyO.40) in the second solvent. Of course with a simple substrate system, one can use the basic solvent in one dimension only... 

Hydrolysis of phosphatides and pigments in the crude oil miscella requires an acid pretreatment, which usually varies between 100 ppm and 500 ppm by weight of the oil, depending on the quality of the crude oil. An acid such as phosphoric or glacial acetic has been found effective in improving oil quality and reducing refining losses. Phosphoric acid is used more commonly because of its less corrosive properties and its availability. The acid is mixed with the miscella in a static mixer to provide an intimately dispersed acid phase that immediately reacts with the crude miscella. 

Besides the C20- and C22-polyenoic acids of these two types, we have found in tissue phosphatides a smaller amount of A - -C2o-trienoic acid, with a structure of the oleic acid type (3, 4). It has been knovra for some time that a C2o-tiienoic acid accumulates in liver lipids of rats on a fat-free diet. This acid has also been identified as A - -C2o-trienoic acid by Mead and Slaton (5), who have already given evidence for the synthesis of this acid, starting from acetate (6). The reasonable assumption has been made that stearic and oleic acids are intermediates in the... 

The method of Aneja and Chadha (19716) utilizes tri-isopropylbenzenesulphonyl chloride and is claimed to give products of better optical purity than other procedures. In this technique the phosphatidic acid is mixed and dried with choline acetate (in twice molar excess). The sulphonyl chloride derivative in dry pyridine is then added, and after reaction at 70 °C for 1 h, the procedure is continued at room temperature for 4 h. Excess choline acetate can then be filtered off and the product purified, after passage through a mixed-bed resin column, by chromatography on a neutral alumina column. 

Wilson and Rinne (1976) have supplied soybean cotyledons with labeled acetate and labeled glycerol. Phosphatidic acid and DG turned over rapidly, as might be expected (half-times of 6 min). Half-times of 30-60 min were calculated for PC, PE, and Pi, but inspection of the data shows relatively little change in specific activity after 60 min. Moore (1977) examined phospholipid turnover in soybean suspension cultures and found much longer half-times than Wilson and Rinne (1976). Phosphatidylcholine labeled with choline had a half-life of 36 h, and PE labeled with ethanolamine decayed in three phases with half-lives of 12, 34, and 136 h. 

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