Phospholipids precipitation

Producing de-oiled lecithins. De-oiled lecithin represents a special category where high phospholipid content (above 95% Al) is required. When contacted with acetone, phospholipids precipitate as a fine, free-flowing powder. After removing the acetone, de-oiled lecithins are dry powders or granules (33). 

Fatty acid patterns of the serum phospholipids (precipitated with acetone) changed considerably in response to the feeding of LEAR oil and HEAR oil (Table IV). The decrease In palmitic acid in response to LEAR and HEAR oils (day 32 vs. day 10) reflected the low level of palmitic acid in the test fats. The decrease in palmitic acid was offset by an increase in oleic acid which also reflects the fatty acid composition of the diet and the suggestion that erucic acid is metabolized to oleic acid. 

Lipids can be extracted from biological samples using a variety of organic solvents. A chloroform-methanol solvent is suitable for all lipids but it is possible to extract different classes of lipid selectively on the basis of their solubility in different organic solvents. This may be achieved by the addition of a solvent that will effect either the precipitation or the extraction of the lipids of interest. An example of the former is the precipitation of high concentrations of phospholipids with cold, dry acetone, and of the latter, the extraction of fatty acids into ether or heptane at an acid pH. However, like all solvent extraction procedures these are not entirely specific. 

The AmB/phospholipid ratio was varied between 2.5% and 50% (w/w) and, at a fixed AmB/phospholipid ratio, the phospholipid composition was varied from 100% DMPC to 100% DMPG. As a control, AmB was also precipitated alone, without lipid. 

The cholesterol excreted with the bile is poorly water-soluble. Together with phospholipids and bile acids, it forms micelles (see p. 270), which keep it in solution. If the proportions of phospholipids, bile acids and cholesterol shift, gallstones can arise. These mainly consist of precipitated cholesterol (cholesterol stones), but can also contain Ca " salts of bile acids and bile pigments (pigment stones). 

Analysis of the phospholipid fractions can also provide useful information on the quality of oilseeds as affected by stress due to environmental conditions in the field and during storage. Mounts and Nash found that the FFA content increased and the overall phospholipid content decreased as stress was applied (49). As far as individual PL classes were concerned, the content of PC and PI decreased significantly, while the PA and PE content increased, thus giving rise to an increased nonhydratable phospholipid (NHP) content in the crude oil. The NHPs refer to the phosphatides that, during degumming of crude oils with water, do not hydrate, swell, form gel, or precipitate and hence are not removed by centrifugation. 

Integral proteins are dissolved into the lipid bilayer of the membrane through interactions of the hydrophobic amino acid side chains and fatty acyl groups of phospholipids. In order to remove integral membrane proteins, the membrane must be disrupted by addition of detergents or other chaotropic reagents to solubilize the protein and to prevent aggregation and precipitation of the hydrophobic proteins upon their removal from the membrane. 

Such small particles usually are generated by air-jet micronization and less frequently by controlled precipitation or spray drying. As bulk powder, they usually tend to be very cohesive and exhibit poor flow and insufficient dispersion because of large interparticle forces such as van der Waals and electrostatic forces (Zeng et al. 2001 Podczeck 1998 Hickey et al. 1994). The control of sufficient powder flow and deaggregation (dispersion) is thus of utmost importance to ensure efficient therapy with a dry-powder aerosol. Two different formulation approaches are used currently in marketed DPI preparations to fulfill the requirements. Most often, coarse particles of a pharmacologically inactive excipient, usually a-lactose monohydrate, are added that act as a carrier and provide sufficient powder flow to the mixture. Other carbohydrates, amino acids, and phospholipids have been suggested frequently (Crowder et al. 2001). 

The detergent in the shampoo helps to dissolve the phospholipid bilayers of the cell membrane and organelles. The salt helps keep the proteins in the extract layer so they aren t precipitated with the DNA. 

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