Shark lipids

Although for the moment this model is only partially supported by experimental data it offers the opportunity to design new experiments which will help to understand the mechanisms of pardaxin insertion and pore formation in lipid bilayers and biological membranes which at a molecular level are the events leading to shark repellency and toxicity of this marine toxin. 

In the present compilation of the distribution and pharmacokinetic data of a dozen xenobiotics studied in the dogfish shark, this species yielded excellent data consistent with what we know from similar studies on terrestrial mammals. The data from the shark occasionaly provided information not available in other animals. Major transport parameters in this fish were shown to be similar to those found in mammals. This aquatic organism handles lipid-soluble pollutants by sequestering them in its fatty liver. Together with a previous summary (23) we have now studied about three dozen xenobiotics in this species. Because of its ease of handling, low cost, abundance, predictive value of transport mechanisms, and well-developed pharmacokinetics, the dogfish shark is an ideal fish species to use as a model to study aquatic pollutants. 

Bakes, M.J. Nichols, P.D. (1995) Lipid, fatty acid and squalene composition of liva oil from six species of deep-sea sharks collected in southern Australian watas. Comp. Biochem. Physiol., HOB, 267-75. 

Buteau, G. H., Jr, Simmons, J. E. Fairbaim, D. (1969). Lipid metabolism in helminth parasites. IX. Fatty acid composition of shark tapeworms and of their hosts. Experimental Parasitology, 26 209-13. 

K. Hanaoka, W. Goessler, K. Yoshida, Y. Fujittaka, T. Raise, K. Irgolic, Arsenocho-line and dimehtylated arsenic containing lipids in starspotted shark Mustelus manazo, Appl. Organomet. Chem., 13 (1999), 765-770. 

In a decade, the advanced lipid analytical technology that defines DHA as a natural fatty acid of marine oils from a deep-sea shark described around 1994 (118) has been surpassed by nondestructive NMR measurement of DHA in situ (Table 7). Thus, advanced analytical technology is supporting with new developments the benefits from marine oil omega-3 fatty acids in our daily lives. 

Lipid nutritional supplements have been in use before the term nutraceutical was coined. Products such as fish oils, shark cartilage, shark liver oil, and vitamins have been in the market since the beginning of the twentieth century. Some of the health claims of these products lacked strict scientific documentation in the past, and their curative properties were mostly anecdotal. However, today there is a better understanding of the biological properties of lipids and their application has extended to combined pharmaceutical and cosmetic fields such as disease prevention and treatment, excipients and coadjuvants, frawi-dermal carriers, and skin emolliency agents. This has led to the development of bioactive cosmetic and pharmaceutical products whose name has recently been coined as cosmeceuticals. 

Acute intoxication has been observed after ingestion of vitamin A-rich liver from the polar bear, halibut, or shark, or after the use of fish oil supplements used to lower plasma lipids. In adults, toxic doses have been in the range of one or more million units of vitamin A, but in children as low as 10 000 micrograms RE, or even in a few children under 650 micrograms RE/day (12). Symptoms occur at 6-24 hours after ingestion and include acute drowsiness, irritability, vertigo, headache, delirium and convulsions, intolerance of food, and diarrhea (SEDA-8, 344). 

Lipids constitute below 1% of the weight of fruits, vegetables, and lean fish 3.5% of milk 6% of beef 32% of egg yolk and 85% of butter. The lipids contained in the food raw materials in low quantities serve mainly as components of protein-phospholipid membranes and perform metabolic functions. In fatty commodities the majority of the lipids are stored as depot fat in the form of triacylglycerols. The lipids of numerous food fishes, such as orange roughy, mullets, codfish, and sharks,... 

One of the components in this olive oil residue that may be of interest for the industry is squalene. Squalene is used as industrial lubricant, and is widely used in several cosmetic applications as a carrier for lipid-soluble components since it is easily adsorbed by the skin (2). Squalene has also been claimed to enhance oxygenation of the blood, facilitate detoxification, strengthen immune system and protect against cancer (3). Traditionally squalene is mainly obtained from shark liver oil (4), which is an unethical use of sharks threatened by extermination and really is not acceptable. 

Lipid arsenic compounds also occur in marine animals (34,110). The compounds originally present in the lipid fraction were subjected to base and/or acid hydrolysis, and the water-soluble products identified by HPLC-ICPMS. In this way, phosphatidylarsenocholine (see Fig. 2, compound 18) and a phosphatidyl-arsenosugar (see Fig. 2, compound 5) were identified in the digestive gland of lobster (34), and evidence was presented for the presence of lipids containing arsenocholine and dimethylated arsenic moieties in shark tissues (110). 

K Hanaoka, W Goessler, K Yoshida, Y Fujitaka, T Kaise, KJ Irgolic. Arseno-choline- and dimethylated arsenic-containing lipids in starspotted shark Mustelus manazo. Appl Organomet Chem 13 765-770, 1999. 

Hydrocarbons occur in varying amounts in marine organisms. For example the liver lipids of some sharks are almost entirely hydrocarbons (Heller et aL, 1957 Lambertsen and Holman, 1963) but some other marine organisms contain only trace amounts. Squalene is the predominant hydrocarbon in marine life but small amounts of pristane and the unsaturated norphytoene are usually present (Heller et aL, 1957 Christiansen and Sorensen, 1951 Avigan and Blumer 1968 Blumer and Thomas, 1965). 

In contrast, although hydrocarbons occur in all marine organisms they generally account for 1% or less of the total lipid. Notable exceptions are the liver oils from some sharks which may contain over 30% of their lipid as squalene. 

Barley lipids, 162,163,164 Basidomycetes, 151,153,154 Basking shark, liver oils, 134 Bass, 134 Bat milk, 168 Batyl alcohol, 27 Beeftallow,51,119,124,125 Beeswax, 143... 

One can demonstrate, for example, that the fractions of a naturally occurring lipid mixture, separated by TLC, are not contaminated by one another. This is shown in Fig. 94. A small amount of hot tripal-mitin was mixed with shark liver oil and separation then carried out with adsorption TLC. An autoradiograph of the chromatogram showed that the total radioactivity was in the triglyceride fraction. The glyceryl ether diesters were not contaminated with the triglycerides despite their very similar structure. 

Fig. 94. Test of the resolution of thin-layer chromatographic separations [725]. Layer silica gel G solvent petrol ether (BP 60—70° C)-diethyl ether-acetic acid (80 + 20 + 1) time of run 1 h indicator A iodine vapour B autoradiography amounts about 200 (ig of each of the naturally occurring lipids 1 cholesteryl palmitate-l- C, tripalmitin-l- C and palmitic acid-l- C 2 human depot fat and tripalmitin-l-i C 3 dogfish shark liver oil and tripalmitin-l- C 4 lipid extract of the calcification of a human aorta and cholesteryl palmitate-l- C...

Pereira de Abreu, D.A., Paseiro Losada, P., Maroto, J. and Cruz, J.M. (2011). Natural antioxidant active packaging film and its effect on lipid damage in frozen blue shark (Prionace glauca). Innovative Food Science and Emerging Technologies, 12,50-55. 

The study of the fatty acid composition of various spedes of Mediterranean Centrophorus showed that adds 16 0, 18 ln-9 and 22 6n-3 are always the major adds, together representing 50-60% of total fatty adds (Peyronel et al, 1984). A comparative study of the fatty acid composition of several species of sharks of the far south of Australia showed that the major lipids are also diacylglycerylethers the acid moieties are predominantly 16 1, 18 1, 20 1, 22 1 and 24 1, totaling 62-84% of the total acid fraction (Bakes and Nichols, 1995 Bordier et al, 1996 Hayashi and Kishimura, 2000). 

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