Phospholipid pharmacologically active

The effect of phenothiazine on membrane fluidity and competition between Ca2+ and phenothiazine for the anionic binding site at the phospholipid were the subject of another investigation based on DSC methodology [45]. Competition is also exhibited by other catamphiphiles and may play an important role in pharmacological activity. 

A further interesting feature of the action of drugs on phospholipids is the fact that certain materials with phospholipid structures have pharmacological activity themselves and, although it may or may not be relevant to the action of drugs, a short account has been given of current findings. 

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. 

One of the several shapes that micelles can take is laminar. Since the ends of such micelles have their lyophobic portions exposed to the surrounding solvent, they can curve upward to form spherical structures called vesicles. Vesicles comprise one or more bUayers surrounding a pocket of liquid, and are formed by molecules such as phospholipids. MultUameUar vesicles have concentric spheres of unilamellar vesicles, each separated from one another by a layer of solvent [105]. Figure 4.10 provides an illustration. Vesicles can be about the same size as living cells, but have a much simpler structure [136-139]. Vesicles can be used as drug delivery vehicles by solubilizing pharmacologically active species in the hydrocarbon core of the bilayers [140,141]. This approach has been used in the treatment of tumors and rheumatic arthritis [142]. 

This peculiar property of phosphatidylserine as pharmacological active phospholipid may be related to its capacity to induce extensive cell fusion in cell cultures in the presence of calcium (Papahadjopoulos et al., 1973). By analogy with the proposed mechanism for the phosphatidylserine-induced liberation of histamine in vitro (Goth et al., 1971 Foreman Mongar, 1975) and the role of Ca in the process of Ach (Babel-Guerin, 1974) and cathecolamine release (Blanstein et al., 1972) and of adenylate cyclase stimulation... 

Arsenocholine, formed by the substitution of arsenic for the nitrogen, has found limited use in phospholipide studies. Arsenocholine is incorporated into liver and brain lecithin of rats and mice. It is of interest to note that the pharmacological activity of the arsenic (as well as the phosphorus) analog of acetylcholine is qualitatively identical with that of acetylcholine itself. ... 

Bougis, P, Tessier, M., Van Rietschoten, J., Rochat, H., Faucon, J.F. and Dufourcq, J., 1983, Are interactions with phospholipids responsible for pharmacological activities of cardiotoxins . Mol. Cell Biochem., 55 49. 

Since predators of snakes (and humans) have to deal with snake venoms as defenses, they are included here, even though they serve in predation. Snake venoms are primarily enzymes (proteins), especially of the phospholipase A2 type, which breaks down cell membrane phospholipids hydrolytically. Other snake venoms such as cobrotoxin contain peptides with 60-70 amino acid residues. Pharmacologically, they have neurotoxic, cytotoxic, anticoagulant, and other effects. The neurotoxins, in turn, can have pre- or postsynaptic effects. Snake venoms with both neurotoxic and hemolytic effects on the heart are known as cardiotoxins. Cytotoxins attach to the cells of blood vessels and cause hemorrhage. Snake venom factors may stimulate or inhibit blood clotting. Finally, platelet-active factors can contribute to hemorrhage. 

The clotting factors are protein molecules. Activation mostly means proteolysis (cleavage of protein fragments) and, with the exception of fibrin, conversion into protein-hydrolyzing enzymes (proteases). Some activated factors require the presence of phospholipids (PL) and Ca + for their proteolytic activity. Conceivably, Ca + ions cause the adhesion of factor to a phospholipid surface, as depicted in C. Phospholipids are contained in platelet factor 3 (PF3), which is released from ag-Lullmann, Color Atlas of Pharmacology 2000 Thieme All rights reserved. Usage subject to terms and conditions of license. 

Pharmacology Pentamidine isethionate, an aromatic diamidine antiprotozoal agent, has activity against P. carinii. In vitro studies indicate that the drug interferes with nuclear metabolism and inhibits the synthesis of DNA, RNA, phospholipids, and protein synthesis. 

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