Total lipids, extraction

Bligh, E.G. and E)yer, W.J. 1959 A rapid method of total lipid extraction and purification. Canadian Journal of Biochemical Physiology 37 911-917. 

Exposures of 10 weeks (5 days/week) to 2,500 mg/kg/day trichloroethylene in com oil by gavage resulted in altered myelin thickness in the rat mental nerve, a branch of the trigeminal nerve (Barret et al. 1991). Effects of similar exposures on the rat trigeminal nerve included decreased fiber diameter and altered fatty acid composition in total lipid extracts, indicative of demyelination (Barret et al. 1992). Stronger effects were seen with the trichloroethylene decomposition product dichloroacetylene. 

Solvent extraction of the total lipid extracts from ceramic sherds and charred surface residues Isolation of DAGs and TAGs on silica solid phase cartridges Formation of lithiated adducts from the TAG fraction by addition of 2% lithium chloride in methanol... 

Extraction is usually performed in a solvent such as dichloromethane (DCM), chloroform, methanol, or a mixture of them, to obtain the so-called total lipid extracts (TLEs). 

Figure 14.10 GC profiles of total lipid extracts of archaeological bones showing the wide spread survival of lipids, in particular cholesterol and its derivatives...

Recently, a quantitative electrospray ionization/mass spectrometry method (ESI/MS) has been developed to analyze the molecular profile, or hpidome of different lipid classes in very small samples. In this method, total lipid extracts from tissues or cultured cells can be directly analyzed. By manipulating the ionization method, the mass spectrographs of polar or even non-polar lipids can be obtained [8]. This method and the use of lipid arrays allow precise and quantitative identification of the lipid profile of a given tissue, and map functional changes that occur. 

Table 5.4. Fluorescence Parameters of DPH, DPH-PC, and TMA-DPH in Intact Sarcoplasmic Reticulum Membranes and Liposomes Made from Total Lipid Extracts of the Membranes at 37°Cab...

The maximum concentration of cholesterol retracted occurred after the passage of 2.5 kg of CO2 at 138 bar/S0°C This was 2.5 times the amount extracted at 345 bar/50°C and approximately 2.3 times the amount extracted at 241 bar/150°C. Extraction at lower pressures increased the solubility of cholesterol but decreased the weight of total lipid extracted per unit weight of CO2 used. Most of the cholesterol was removed after extracting with 20 kg CO2 at 138 bar/40°C where only 22% of the total lipid had been removed. 

The lipid collected in separator (S3) at 34.5 bar/40 C during the run was 37% of the total lipid extracted, whereas the amount of cholesterol separated at 343 bar/40°C was 70% of the cholesterol extracted. This amounts to twofold concentration of the cholesterol at the lower pressure. Use of multiple... 

Because the PL concentration in the total lipid extract is generally rather low, a preconcentration step is generally required prior to HPLC analysis crude vegetable oils e.g., contain only 0.5-2.0% of phospholipids. 

However, in a more recent paper, Caboni et al. described that the aforementioned method was not applicable for all types of food products (32). Hence, only 30% and 53% of the PL of a total lipid extract of cheese and dried egg powder, respectively, were recovered. High-performance liquid chromatography analysis revealed that the acidic phospholipids PG and PI were not... 

The fat-soluble vitamins can be extracted from the food matrix without chemical change using a solvent system that is capable of effectively penetrating the tissues and breaking lipoprotein bonds. A total lipid extraction is required for the simultaneous determination of vitamers or vitamins with a wide range of polarities, and, for this purpose, a mixture of chloroform and methanol (2 + 1) is highly efficient (82). The Rose-Gottlieb method is particularly suitable for ex-... 

The neutral lipid fraction from the DEAE-Sephadex A-50 column was combined with the lower phase obtained after Folch partition of the total lipid extract and the combined lipids dried. To the same flask, 10Q ml of 0.6 M NaOH in methanol was added. The mixture was incubated at 37°C for 5 hours. Five volumes of acetone were then added and stored overnight at 4°C. The precipitate was collected by centrifugation at 4°C and dissolved in C M (4 1, v/v). After application to the column (2.0 x 25 cm), the column was washed with chloroform. Neutral glycolipids were then eluted with tetrahydrofuran H2O (10 1). Fractions containing neutral glycosphingolipids were pooled and their glycolipid content examined by thin-layer chromatography. 

Key SA, stearic add Sph, sphingomyelin PL, total lipids extracted from the erythrocyte ghost. 

In any of the lipid isolation procedures described above, there is always the potential for inclusion of nonlipid components in the total lipid extract. These contaminants can include free amino acids, peptides, pigments, carbohydrates, inorganic salts, and other compounds. 

The most widespread and effective solvent system for this purpose is the Bligh-Dyer procedure, which was mentioned earlier in Chapter 2. A typical protocol that can be employed for total lipid extraction follows. 

The platelet preparation is mixed (depending on the volume of sample and the cell count) with sufficient methanol (usually added first) and chloroform to make a final mixture of chloroform-methanol-water (based on water in cell sample) of 1 2 0.8 (v/v). This mixture is then mixed well and allowed to stand for 25-30 min at room temperature in a dark cabinet (or shielded with aluminum foil) to allow extraction of the lipids from the cells. Then the mixture is centrifuged at 2000g for 10 min. A single-phase, clear-colored supernatant will result. This is carefully removed from the pellet and saved, because it represents the total lipid extract. Though a second extraction of the pellet with chloroform-methanol-water (1 2 0.8, v/v) can be done, it is usually not necessary. 

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