Other Lipids

Other Lipids.—Baer and his colleagues have synthesized several phosphonic acid analogues [such as (26)] of the more familiar phosphoglycerides, and the phosphinic acid derivatives (27) have also been prepared.  

Tri-isopropylbenzenesulphonyl chloride condenses alcohols and phos-phatidic acids in 60—90% yield. Phospholipids produced by this method have a higher molar rotation than previously reported, an observation which raises doubts about the purity of previous preparations. 1,2-Dipalmitoyl-jn-glycerol 3-(2-aminoethyl hydrogen phosphate) has been synthesized, labelled with H, and 57 

Methods concerning isolation and quantitative determination of lipid classes occurring in minor amounts, in certain tissues only, and in various pathological conditions are outlined in the appropriate chapters of this book. Further information may be obtained from papers and monographs by Deuel 1951/1957, Lettre, Inhoffen and Tschesche 1954, Hanahan 1960, Fieser and Fieser 1961, Stahl 1962, ZoLLNER and Eberhagen 1965. 

The importance of reliable methods is illustrated by the example of determining the concentration of cerebrosides in plasma. By measuring the increase in reducing power of a serum lipid extract before and after hydrolysis which was believed to be due to sugar released from cerebrosides Kirk (1938) found concentrations between 0 and 167 mg per 100 ml. With the use of purification procedures and specific reactions for sugars Svennerholm and Svennerholm (1958) were able to demonstrate a mean cerebroside content of 4.36 0.18 mg per 100 ml of plasma. 

At present no simple routine method is available for separation, identification and quantitation of lipoproteins. Accurate procedures are based on preparative or analytical ultracentrifugation, reviews of which were given by de Lalla and Gofman (1954), Jahnke and Scholtan (1960), Furman et al. (1961), Pezold 

Separation by precipitation fractionation (Cohn 1950) is as complicated as free and zone electrophoresis (Kunkel and Slater 1952, Dietrich 1955). More convenient methods are based upon fiocculation with sulfated polysaccharides (Bur-stein 1961, Cornwall and Kruger 1961) and immunoprecipitation (Burstein and Samaille 1958, Heiskell et al. 1961, Feldman 1964). Paper-electrophoretic separation of lipoproteins with the use of buffer containing albumin has proved valuable for differentiation of hyperlipoproteinemias (Fredrickson and Lees 

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Glyoxylate cycle A modification of the Krebs cycle, which occurs in some bacteria. Acetyl coenzyme A is generated directly from oxidation of fatty acids or other lipid compounds. 

Fig. 3-12 Lipids consist of a triglyceride, three fatty acids such as those in (a) joined to glycerol (b). Other lipids include other functional groups such as phosphate derivatives (c). (Reprinted with permission from W. K. Purves and G. H. Orians, "Life The Science of Biology," pp. 63-81, Copyright 1987 by Sinauer Associates, Inc., Simderland, MA.)...

The major lipids in the diet are triacylglycerols and, to a lesser extent, phospholipids. These are hydrophobic molecules and must be hydrolyzed and emulsified to very small droplets (micelles) before they can be absorbed. The fat-soluble vitamins— A, D, E, and K— and a variety of other lipids (including cholesterol) are absorbed dissolved in the lipid micelles. Absorption of the fat-soluble vitamins is impaired on a very low fat diet. 

Historically, the absorption of lipid-soluble nutrients has been considered to be carrier-independent, with solutes diffusing into enterocytes down concentration gradients. This is true for some lipid-soluble components of plants (e.g. the hydroxytyrosol in olive oil Manna et al., 2000). However, transporters have been reported for several lipid-soluble nutrients. For example, absorption of cholesterol is partly dependent on a carrier-mediated process that is inhibited by tea polyphenols (Dawson and Rudel, 1999) and other phytochemicals (Park et al., 2002). A portion of the decreased absorption caused by tea polyphenols may be due to precipitation of the cholesterol associated with micelles (Ikeda et al., 1992). Alternatively, plant stanols and other phytochemicals may compete with cholesterol for transporter sites (Plat and Mensink, 2002). It is likely that transporters for other lipid-soluble nutrients are also affected by phytochemicals, although this has not been adequately investigated. 

High performance liquid chromatography (HPLC) has been by far the most important method for separating chlorophylls. Open column chromatography and thin layer chromatography are still used for clean-up procedures to isolate and separate carotenoids and other lipids from chlorophylls and for preparative applications, but both are losing importance for analytical purposes due to their low resolution and have been replaced by more effective techniques like solid phase, supercritical fluid extraction and counter current chromatography. The whole analysis should be as brief as possible, since each additional step is a potential source of epimers and allomers. 

An excellent example of PLC applications in the indirect coupling version is provided by the works of Miwa et al. [12]. These researchers separated eight phospholipid standards and platelet phospholipids from the other lipids on a silica gel plate. The mobile phase was composed of methylacetate-propanol-chloro-form-methanol-0.2% (w/v) potassium chloride (25 30 20 10 10, v/v). After detection with iodine vapor (Figure 9.2), each phospholipid class was scraped off and extracted with 5 ml of methanol. The solvent was removed under a stream of nitrogen, and the fatty acids of each phospholipid class were analyzed (as their hydrazides) by HPLC. The aim of this study was to establish a standardized... 

In the BBB-PAMPA lipid formulation illustrated in Fig. 3.4, the diff values, defined as the difference log Pq-log Pi, range from 2.9 (morphine) to 4.2 (warfarin), somewhat similar to the values observed in the octanol-water system. However, it is premature to propose a pdiffi-A approximation, given the limited amount of data reported. With other lipid formulations, larger differences are usually observed. In Double-Sink PAM PA, and especially in hexadecane-PAMPA, transport of ionized drugs has not been reported [84]. 

G. A. Veldink, J. F. G. Vliegenthart and J. Boldingh. Prog. Chem. Fats Other Lipids 75 131... 

Interaction of the liposomal lipids with cellular lipid bilayers or other lipid bilayers in the body (e.g. skin lipids) depends on the nature of the lipids in the liposome. In order to... 

We have recently observed in our laboratory that water washes of undamaged leaves in a number of plants contained sterols and other lipids in sufficiently high concentration comparable with concentrations used in typical laboratory bioassays. These aqueous lipid solutions are frequently accompanied by long-chain (C-12 to C-18) fatty acids. We therefore suggest that micelle formation between the lipids and fatty acids may occur. By this mechanism the lipid solubility in the aqueous medium is significantly enhanced, thus allowing the release of otherwise water-insoluble plant constituents into the environment. Presently, experiments are in progress in our laboratory to provide further evidence for the "micelle-mechanism" of allelopathlc lipids. 

The system reported by Avdeef and co-workers [25-28,556-560] is an extension of the Roche approach, with several novel features described, including a way to assess membrane retention [25-28,556,557] and a way to quantify the effects of iso-pH [558] and gradient pH [559] conditions applied to ionizable molecules. A highly pure synthetic phospholipid, dioleoylphosphatidylcholine (DOPC), was initially used to coat the filters (2% wt/vol DOPC in dodecane). Other lipid mixtures were subsequently developed, and are described in detail in this chapter. 

A few molecules have unexpectedly low permeability in 2% DOPC, not consistent with their octanol-water partition coefficients. Notably, metoprolol has a Pe value 10 times lower in 2% DOPC, compared to 10% egg lecithin. Also, prazosin Pe appears to be significantly lower in DOPC, compared to other lipids. 

Urade, Y., el al. (2002). Iipocalin-type and hematopoietic prostaglandin D synthases as a novel example of functional convergence. Prostaglandins Other Lipid Mediators 68-9, 375 82. 

Fig. 7 Transport of hydrocarbons and other lipids by lipophorin from site of synthesis (oenocytes) to various tissues. In the case of pheromone glands specific hydrocarbons are unloaded to be used directly as a pheromone or modified with the addition of oxygen and then released as a pheromone... 

Kolattukudy PE, Walton TJ (1973) Prog Chem Fats Other Lipids 8 121... 

Investigations based on direct mass spectrometry analysis aiming at identifying waxes and other lipids in museum or archaeological items were first carried out at the end of... 

The results are consistent with the beeswax that was used in the preparation of the cosmetics preserved in the unguentaria, while the other lipids are most likely the residue of... 

B. R. T. Simoneit, Diterpenoid compounds and other lipids in deep sea sediments and their geochemical significance, Geochim. Cosmochim. Acta, 41, 463 476(1977). 

Carr et al. [2004] studied the incidence of different cleaning procedures on wool. ToF-SIMS analyses performed on the commercially scoured wool (negative ion mode) showed the presence of 18-methyleicosanoic acid thioester species (m/z 341), attributed to the presence of 18-methyleicosanoic acid (18-MEA) which is normally the predominant compound of the surface layer of wool. Other lipids are also detected. After artificial sunlight exposure, analyses show that 18-MEA disappears from the surface. 

Fullerene Cgo also functions efficiently as an antioxidant, actually being better than other lipid-soluble antioxidants at scavenging reactive oxygen species (ROS) (Wang et al., 1999). Water-soluble derivatives of C o, such as a poly-hydroxyl form, are able to function in the same respect in aqueous environments. 

Perhaps the simplest solvent dispersion method is that developed by Batzri and Korn (1973). Phospholipids and other lipids to be a part of the liposomal membrane are first dissolved in ethanol. This ethanolic solution then is rapidly injected into an aqueous solution of 0.16M KC1 using a syringe, resulting in a maximum concentration of no more than 7.5 percent ethanol. Using this method, single bilayer liposomes of about 25 nm diameter can be created that are... 

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