Phospholipids. I. Studies on the thromboplastic and anticlotting activity of phospholipids

An unsaturated phosphonic acid analogue of phosphatidylethanolamine and its activity in blood-clotting systems

An unsaturated phosphonolipid analogous to phosphatidylethanolamine,rac-dioleoylglyceryl(2-aminoethyl)phosphonate, was synthesized by a general method introduced by Baer for similar saturated substances. An improvement was made in the preparation of the phthalimidoethyl-phosphonic acid precursor.The phosphonolipid was purified by DEAE cellulose and silicic acid chromatography. It was tested by comparison with synthetic phosphatidyl (dioleoyl) ethanolamine and phosphatidyl(dilinoleoyl) ethanolamine in the Hicks-Pitney test and in a test for prothrombin conversion by using purified blood coagulation factors. In both tests it had more acceleratory activity than the synthetic phosphatidylethanolamines.

The total synthesis of phosphatidyl(Dioleoyl)hydroxy-l-proline and its activity in blood-clotting systems

The phthalimidomethyl ester ofN-anisyloxycarbonyl-hydroxy-L: -proline was combined with phosphorus oxychloride andrac-1,2-diolein. The diolein was made by large-scale preparative application of the method of Krabisch and Borgström (1). The protected phosphatide, obtained by the phosphorylation reaction, was stripped of its protective groups under mild conditions. The phosphatidyl(dioleoyl)-hydroxy-L: -proline was purified by TEAE cellulose (acetate) chromatography, as developed by Rouser (6), also by silicic acid chromatography. Aqueous dispersions of the material were tested for anticoagulant activity in the antithrom-boplastin test and the Hicks-Pitney test. The new phosphatide had about one-tenth of the activity of beef brain phosphatidylserine.

Cationic antibiotics and phospholipase C as tools in the study of phospholipid structure and function. I. Inhibition of the in vitro clotting system by cationic antibiotics

The one-stage prothrombin time of human plasma was prolonged by the addition to the thromboplastic mixture of either colistin sulfate or polymyxin B. Colistimethate sodium, a derivative of colistin in which the amino groups of the cyclic polypeptide antibiotic are substituted, did not show this effect. The inhibition was greater if the antibiotics were incubated with thromboplastin in the absence of Ca++. In the Hicks–Pitney modification of the thromboplastin generation time test, the two polyamine antibiotics reduced the amount of thromboplastic activity generated. Generation, however, appeared to be initiated sooner. It is postulated that these actions by the antibiotics are the results of modifications in the zeta potentials of the thromboplastic micelles.

The total synthesis of dilinoleoylphosphatidylserine and its activity in blood clotting systems

A total synthesis ofDL: -phosphatidyl-(dilinoleoyl)-L: -serine was achieved by the acylation of the barium salt of the phthalimidomethyl ester of glycerophosphoryl-N: -anisyloxycarbonyl-L: -serine. The dilinoleoyl intermediate was treated with hydrazine to remove the phthalimidomethyl group and with hydrogen chloride to remove the anisyloxycarbonyl protecting group. The resulting phosphatidylserine was purified by Rouser's methods, solubilized, and tested for biological activity in the antithromboplastin, recalcification, and Hicks-Pitney tests. It was found to have about the same anticoagulant activity as beef brain phosphatidylserine and hence was more active than the less unsaturated phosphatidylserine synthesized earlier.