Phospholipidic compounds

Phospholipidosis, a phospholipid storage disorder, is characterized by an excessive accumulation of intracellular phospholipids. Compounds that induce phospholipidosis include a wide variety of pharmacological agents (antipsy-chotics, antidepressants, antiarrhythmics, and cholesterol-lowering agents). These compounds are of concern for the pharmaceutical industry because a candidate pharmaceutical agent can be rejected because of evidence of inducing phospholipidosis in a preclinical animal study. Phospholipidosis is widely reported in rats and is identified by the accumulation of phospholipids in the lysosomes of many cell types. 

One can place in some positions on the protein radioactive, fluorescent, or spin-labeled markers. For the same purpose one may also use antibodies and proteolytic enzymes. With these procedures one can determine those parts of the protein that are outside the membrane. Next, efforts are made to determine the position of the membrane part in the sequence. A complementary method is the hydrophobic marking of the protein by building into it hydrophobic photolabeled parts from the class of phospholipid compounds in order to determine those parts that are situated in the membrane. Another method uses proteolytic enzymes that split the protein in a specific position in the segment that is not located in the membrane. ... 

Finally, phospholipidic compounds carrying polymerizable groups such as IX and X have been shown very recently [28] to allow the preparation of stable monodisperse polystyrene latexes, with sizes in the range of 200-300 nm in diameter, carrying a phospholipid layer on their surface with yields higher than 75%. 

Aries, E., Doumenq, P., Artaud, J., Molinet, J. and Bertrand, J.C. (2001) Occurrence of fatty acids linked to non-phospholipid compounds in the polar fraction of a marine sedimentary extract from Carteau Cove, France. Organic Geochemistry 32, 193-197. 

Wissing, J. B. and Behrbohm, H. (1993) Diacylglycerol pyrophosphate, a novel phospholipid compound. FEBS Letters. 315, 95-9. 

Little is known of the chemical composition of the nuclear membrane most of our knowledge is based on indirect evidence. In a few instances, clean preparations of nuclear membranes were obtained and analyzed chemically. The nuclear membrane presumably contains lipoproteins because most nuclear lipids are phospholipids, compounds that are likely to be structural constituents moreover, few nuclear lipids are found in other nuclear structures that can be readily prepared. 

Synthesis of Glycosylated Natural Products.—The 2-araino-2-deoxy-a-D-glucosyl-m3 o-inositol phosphate (38), which was predicted to have insulin-like activity, has been synthesised, as have 3-0-(2-amino-2-deoxy-a-D-galactopyranosyl)-D-c/iiro-inositol and 6-C)-(a-D-mannopyranosyl)-D-myo-inositol which is a fragment of mycobacteria phospholipids. Compound (39), which is a key substance for the synthesis of distomycin... 

Phospholipid Biosynthesis Inhibitors. The organophosphate compounds ediphenphos [17109-49-8] (83) and iprobenphos [26087-47-8]... 

Other Reactions of Phospholipids. The unsaturated fatty acid groups in soybean lecithin can be halogenated. Acetic anhydride combined with the amino group of phosphatidylethanolamine forms acetylated compounds. PhosphoHpids form addition compounds with salts of heavy metals. Phosphatidylethanolamine and phosphatidjhnositol have affinities for calcium and magnesium ions that are related to interaction with their polar groups. 

Phosphatidic acids not only are intennediates in the biosynthesis of triacylglycerols but also are biosynthetic precursors of other members of a group of compounds called phosphoglycerides or glycerol phosphatides. Phosphorus-containing derivatives of lipids are known as phospholipids, and phosphoglycerides are one type of phospholipid. 

Phosphatidic acid, the parent compound for the glycerol-based phospholipids (Figure 8.4), consists of 5w-glycerol-3-phosphate, with fatty acids esterified at the T and 2-positions. Phosphatidic acid is found in small amounts in most natural systems and is an important intermediate in the biosynthesis of the more common glycerophospholipids (Figure 8.6). In these compounds, a... 

N. L. Vauquelin isolated the Hrst organic P compound (lethicin) from brain fat it was characterized as a phospholipid by Gobbley in 18.50. 

A 0-9% salt solution is considered to be isotonic with blood. Other electrolytes present include bicarbonate ions (HCOj ) and small amounts of potassium, calcium, magnesium, phosphate, sulphate and organic acid ions. Included among the complex compounds and present in smaller amounts are phospholipids, cholesterols, natural fats, proteins, glucose and amino acids. Under normal conditions the extracellular body fluid is slightly alkaline with a pH of 7-4. ... 

Cationic quaternary ammonium compounds such as distearyldimethylammonium-chloride (DSDMAC) used as a softener and as an antistatic, form hydrated particles in a dispersed phase having a similar structure to that of the multilayered liposomes or vesicles of phospholipids 77,79). This liposome-like structure could be made visible by electron microscopy using the freeze-fracture replica technique as shown by Okumura et al. 79). The concentric circles observed should be bimolecular lamellar layers with the sandwiched parts being the entrapped water. In addition, the longest spacings of the small angle X-ray diffraction pattern can be attributed to the inter-lamellar distances. These liposome structures are formed by the hydrated detergent not only in the gel state but also at relatively low concentrations. 

Sphingomyelins are the second major group of phospholipids. These compounds have sphingosine or a related dihydroxyamine as their backbone and are particularly abundant in brain and nerve tissue, where they are a major constituent of the coating around nerve fibers. 

No discussion of the use of biotransfarmation in lipid chemistry would be complete without some mention of chemical transformation relating to fatty adds. Fatty adds are a major component of the lipid fraction of organisms. They are mainly found as components of triglycerides and phospholipids, although they may occur in smaller quantities as free fatty adds or as esters of other moieties. Fatty adds, either as free adds or as esters, are valuable commodities in the food and cosmetics industries. They may also serve as precursors of a variety of other compounds. 

Component of the myelin sheath surrounding the axons of nerve cells. Additional compounds of the myelin sheath are phospholipids, cholesterol, cerebrosides, and specific keratins. The myelin sheath constitutes an isolating barrier during electrophysiological axonal signaling. 

Lecithin is a phospholipid, a class of compounds that make up cell membranes throughout the body. It is produced in the liver if the diet contains enough of the raw ingredients. 

A molecular variation of plasma membrane has been reported by Puccia et al. Reduction of total lipids (XL) content and significant variations of triglyceride (TG) and phospholipids (PL) fractions were observed as a consequence of exposure of C. intestinalis ovaries to TBTCl solutions. In particular, an evident TG decrease and a PL increase were observed, which probably provoked an increment in membrane fluidity, because of the high concentration of long chain fatty acids and, as a consequence, PL. This could be a cell-adaptive standing mechanism toward the pollutants, as observed in Saccharomyces cerevisiae. Also the increase in the content of the polyunsaturated fatty acids (PUPA), important in the synthesis of compounds such as prostaglandin which are present in the ovary in a stress situation, was probably a consequence of a defense mechanism to the stress provoked by the presence of TBTCl. 

The increase in Ca is initiated rapidly and begins to recover after 1 min. The order of potency correlates fairly well with the solubilities of these compounds in organic solvents (37) and their abilities to accumulate in phospholipid vesicles (38), i.e., 6>y>a>p, but not with their insecticidal activity (y 6>a p 39). At these concentrations, crystals of p-, a-, and y-HCH were evident in the cell suspensions when we made simultaneous measurements of the right-angle light scatter, indicating that the order of aqueous solubilities is 6>y>a>p. However, stimulation by 6-HCH at concentrations below its aqueous solubility limit shows a typical dose dependency of the response (Figure 10). 

Upon the spontaneous rearrangement of anhydrous phospholipids in the presence of water into a hydrated bilayer structure, a portion of the aqueous phase is entrapped within a continuous, closed bilayer structure. By this process water-soluble compounds are passively entrapped in liposomes. The efficiency of encapsulation varies and depends, for example, on the method of preparation of liposomes and the phospholipid concentration during preparation. Different parameters can be used to describe the encapsulation efficiency ... 

---