Lipophilic component

Dysidazirine 130 was isolated by Ireland in 1988 from a Fijian sample of the marine sponge Dysidea fragilis [194] as the major lipophilic component of the sponge and was shown to possess cytotoxic activity against L1210 cells, as well as... 

These data suggest that one of possible mechanisms of carotenoid delivery to the neural retina may involve lipoprotein uptake from the basal side of the RPE followed by its retro-endocytosis on the apical site (Lorenzi et al., 2008). Alternatively, the endocytosed lipoprotein may be degraded in the RPE followed by secretion of certain lipophilic components from the lipoprotein at the apical site. Due to low solubility of carotenoids in aqueous solutions, it may be suggested that they are secreted already bound to a protein or that an acceptor protein is available in the interphotoreceptor matrix and/or POS. 

Fig. 11 Methods for the construction of PEGylated liposomes, (a) Liposomes possessing reactive groups, such as amino and carboxyl groups, can be prepared by incorporating lipophilic components containing these functional groups into a bilayer membrane. Functionalized liposomes can be PEGylated by reaction with activated PEG derivatives, (b) Preparation of PEGylated liposomes using PEG derivatives possessing lipid moieties...

The phase behavior of systems containing pH-sensitive surfactants is another example of non-linearity of the mixing rule. If an oil phase containing an amphiphilic molecule, such as an organic acid, as in the case of naphtenic acids in crude oils, is put into contact with an alkaline water phase, the neutralization takes place at interface and results in a mixture of unneutralized acid (the lipophilic component) and its dissociated alkaline salt (the hydrophilic component). Hence, the interface contains a mixture of two surfactants whose relative proportion depends on the ionization (in the water and at interface), and thus of the pH [75]. 

To overcome the problem of DEHP leaching into parenteral infusions containing lipophilic components, a triple-layered tubing material has been used. This type of tubing is made of a PVC outer layer, while its innermost layer, which comes into contact with the drug solution, is made of inert PE. In spite of this arrangement, it has been shown that, depending on the preparation, DEHP from the PVC outer layer may be released in the infusion solution. 

Lipid A", which is the lipophilic component of bacterial lipopolysaccharide, was shown to possess many of the biological activities of lipopolysaccharide,, lethal toxicity, pyrogeni-... 

Calorimetric results for the hairless mouse stratum corneum and isolated components confirmed thermal transitions associated with increased mobility occurred in the temperature region where large increases in permeability of lipophilic components also occurred. Thermal transitions for the extracted lipids were in the 27 to 67°C range, while the protein residue sheets (primarily... 

Crystallization from the emulsified state may lead to different nucleation processes than observed for the same fat in bulk liquid form. It has been suggested that nucleation often occurs at the interface of the droplet where surface-active agents are located. The general similarity of the lipophilic components of surfactants oriented at the surface may provide some ordering and structure for the lipid molecules within the droplet and enhance nucleation, as found for example by Kaneko et al. (40) for a hydrocarbon emulsion. Walstra (11) also suggests that formation of compound crystals from emulsions of natural fats may be different than the same fat crystallized from bulk liquid. The initial polymorph formed may also be different, with more stable polymorphs more likely to form in the emulsion (38). 

O Lipophilic components Very diluted in oil phase Less protection to oil... 

The lipophilic component should be an amphiphile that promotes the formation of w/o emulsions and is capable of complex-ing with the hydrophilic surfactant at the o/w interface. Its concentration should be at least sufficient to form a close-packed... 

Soil contamination can contribute to human toxic exposure via a number of routes. These include plant uptakes of soil pollutants, including fertilizers and pesticides, that are either eaten by people directly or passed up the food chain, absorption onto the skin and subsequently into the bodies of grazing animals to be passed up through the food chain by animals, and via contaminated airborne soil particles that are ultimately inhaled by humans. Soils contain large lipophilic components that absorb lipophilic chemicals which are subsequently transferred to plants, animals, and to the air. Water distributed in soil dissolves hydrophilic chemicals and acts as a conduit for ultimate human absorption, through plants and thus up the food chain from whence they ultimately impact humans. 

The evaluation of alkamides, as an indicator for standardization, in Echinacea preparations is commonly completed using HPLC. The method of Bauer (1999b) illustrates the most common method to evaluate alkamides using reverse-phase HPLC. In this method, the lipophilic components are separated by gradient elution using water (eluent A) and acetonitrile (eluent B) linearly from 40% to 80% eluent B at 1 ml/min. The separation was completed on a C18 reverse-phase column and detection was at 254 nm. Thin-layer chromatography using silica 60 plates with... 

In detail the extraction plant has a working tank that provides the carbon dioxide necessary for the process. In the tank at about 60 bar and ambient temperature the liquefied carbon dioxide is in equilibrium with the gas phase (A). Before entering the pump the liquid gas is cooled to avoid cavitation (B). The pump then isentropically increases the pressure to the extraction value of 100 bar (C) respectively 300 bar (C ) for example. In the next step the extraction temperature is adjusted mostly to 40°C (D, D ). Then the dense CO2 is passing through the material in the extractor and takes the lipophilic components into solution. 

Without question, sodium and potassium have been the analytes receiving the most attention in conjunction with the development of new analyzers. Almost all instruments on the market utilize the potassium-selective membrane system based on the antibiotic valinomycin in a PVC membrane matrix. For blood measurements, such a membrane is quite adequate. However, in undiluted urine samples, a negative error in the measurement of potassium has been reported (KIO). Apparently, this interference comes from a negatively charged lipophilic component of the urine which can partition into the PVC membrane, reducing the membrane potential (i.e., the membrane is not permselective). Fortunately, this problem can be overcome by incorporating the valinomycin in a silicone rubber-based membrane matrix (A4) into which the unknown anionic component apparently has a less favorable partition coefficient. 

The first reports on nonaqueous microemulsions, isotropic solutions containing a hydrophilic and a lipophilic component, stabilized by a surfactant, were made by Palit and McBain in 1946 [116] and by Winsor in 1948 [117]. They both used glycols as polar solvents. The microemulsion regions were only observed visually so no structural information could be obtained. 

Bimolecular nucleophilic substitution reactions, SN2 reactions, are probably the reaction type that has been investigated the most in microemulsions. Such reactions often involve one lipophilic component that is insoluble in water and one very hydrophilic component, usually the anion of a salt with virtually no solubility in hydrocarbon. This means that the components meet and react at the interface. The area of the interface is obviously of importance. 

Microemulsions are not homogeneous at the molecular level in that they consist of microscopic domains of water and oil separated by a surfactant film. The reaction may occur in either of the two domains, as well as at the interface. However, if the solubility of the polar reactant in hydrocarbon and of the lipophilic component in water is negligible, the reaction can be assumed to be a purely interfacial reaction, i.e. no reaction occurs in the two bulk phases. 

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