Lipids in eggs

Lizenko, E.I., Nefedova, Z.A., Titova, V.F. and Sterligova, O.P. (1983). Lipid composition and biological role of different groups of lipids in eggs and milt of freshwater fish (In Russian). In Comparative Biochemistry of Aquatic Animals (V.S. Sidorov and R.U. Vysotskaya, eds), pp. 28-42. Petrozavodsk. 

Table 11.12. Fatty acid composition of the lipids in egg yolk - Influence of feed ...

Phosphatidylcholine from other egg phospholipids Phosphatidylcholine from other egg phospholipids Isolation of total phospholipids (phosphatidylcholine, phos-phatidylethanolamine, and phosphatidylinositol) from soybean extract Isolation of phosphatides from total lipids in eggs, meat, and cheese... 

Fatty acids are synthesized by an extramitochondrial system, which is responsible for the complete synthesis of palmitate from acetyl-CoA in the cytosol. In the rat, the pathway is well represented in adipose tissue and liver, whereas in humans adipose tissue may not be an important site, and liver has only low activity. In birds, lipogenesis is confined to the liver, where it is particularly important in providing lipids for egg formation. In most mammals, glucose is the primary substrate for lipogenesis, but in ruminants it is acetate, the main fuel molecule produced by the diet. Critical diseases of the pathway have not been reported in humans. However, inhibition of lipogenesis occurs in type 1 (insulin-de-pendent) diabetes mellitus, and variations in its activity may affect the nature and extent of obesity. 

In this section, we focus on how to determine DD sites by NMR. The specification of the DD sites in bilayers can be done by utilizing the NMR signals of both drugs and membrane lipids. An example of the delivery site determination is given for the case of two benzene derivatives, propylbenezene (PrBe) and benzyl alcohol (BzOH) in egg phosphatidylcholine (EPC) bilayers [46]. Alkylbenzenes are suspected to be endocrine disruptors, and BzOH is one of the local anesthetics. 

The negative-charge lipid content in the egg lecithins is not as high as that found in BBM and especially BBB lipids (Table 7.1). Furthermore, the negative-charge content in the egg lecithin is about one-fourth that in the soy lecithin. This is clearly evident in the membrane retention parameters for the bases at the 10% lecithin levels (models 12.0 or 14.0 in Table 7.8 vs. model 16.0 in Table 7.12), as they are 20-30% lower for the lipophilic bases in egg, compared to soy. 

The permeabilities of the acid examples rise with increasing phospholipid content, up to 20% lipid, with rank ordering preserved (data not shown). Naproxen and ketoprofen show the most dramatic increases in going from 2% to 10% lipid membranes - somewhat higher in soy than in egg. Piroxicam shows less... 

The ratio between the amounts of azelaic and palmitic acids (A/P) is a parameter for differentiating drying oils from egg lipids in paint samples because the amount of dicarboxylic acid formed in the ageing of egg lipids is considerably less than it is in drying oils. Values of A/P >1 indicate a drying oil, values of A/P <0.3 are typical of egg lipids,... 

Chlordane residue data for amphibians and reptiles are extremely limited. Maximum concentrations of chlordane isomers did not exceed 70 pg/kg FW of oxychlordane in eggs of the American crocodile, Crocodylus acutus, or 250 pg/kg FW in carcass of the common garter snake, Thamnophis sirtalis (Table 13.2). However, California newts, Tarichia torosa, taken near a lake treated with 10 pg/L technical chlordane had greatly elevated chlordane residues in liver and comparatively low concentrations in carcass, stomach, and stomach contents. After 14 days, livers contained about 34 mg/kg total chlordanes lipid weight — about 19% chlordanes, 9% nonachlors, and 6% chlor-denes (Albright et al. 1980). After 2.8 years, 98% of the total chlordanes was lost. 7ra .v-nonachlor was the most persistent component in newt liver, accounting for up to 55% of the total chlordanes in specimens collected 2.8 years after application (Table 13.2) (Albright et al. 1980). 

Figure 7. Lipophilicity profile of propranolol in liposomes composed of zwitterionic and charged lipids (phosphatidyl ethanolamine (PE), oleic acid (OA), phosphatidyl inositol (PI)). Conditions of measurements are described in [113]. The dotted line indicates the partitioning profile of propranolol in the egg PC liposome system. The bars show the pH-dependent charge profile of propranolol (hatched bars positively charged propranolol) and the lipids in the membrane (black bars negatively charged lipids). Reprinted from [113] Kramer, S. (2001). Liposome/water partitioning , In Pharmacokinetic Optimization in Drug Research, eds. Testa, B. et al. Reproduced by permission of Verlag Helvetica Chimica Acta, Zurich...

In egg shells the presence of lipids has also been established and these have been characterized136, 137. ... 

Bitman, J. 1976. Status report on the alteration of fatty acid and sterol composition in lipids in meat, milk, and eggs. In Fat Content and Composition of Animal Products. National Academy of Sciences, Washington, D. C., pp. 200-237. 

The adaptation of methods for lipid extraction and quantification by colorimetric determination of either ester or cholesterol in egg yolk with some contamination of egg white is described. Results are compared with those obtained by a conventional enzymatic determination. 

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