The lipids of fish. 4. The lipids extracted by an ethanol:ether mixture from haddock flesh previously extracted with acetone

Abstract

Haddock flesh previously extracted with acetone was extracted with ethanol: ether (3:1, vol./vol.). The crude product, although entirely soluble in light petroleum, contained over 50% of non-lipid impurities. A large part of this impurity was readily removed by the method of Folch et al. (Jour. Biol. Chem. 191: 833, 1951) with only small accompanying loss of lipids. This loss was selective. Some additional non-lipid was removed with an ion-exchange resin. The purified extract was examined by countercurrent distr. between light petroleum and 85% ethanol. The component lipid classes found were lecithin, phosphatidylethanolamine, plasmalogens, waxes, hydrocarbons, inositol lipids and unidentified material. This last included possibly 3 different types of lipid. The plasmalogen could not be satisfactorily characterized and much of it probably did not correspond to the established formula. The inositol lipids included 2 and possibly 3 components. Certain unidentified lipids were accompanied by a nitrogenous base previously reported (Olley and Lovern, 1953) and another fraction by a different nitrogenous compound or compounds. The lecithin contained a fatty acid mixture generally similar to that of other lecithins previously isolated from haddock flesh. The unidentified lipids contained fatty acids showing certain variations from the lecithin pattern, but all similar in containing 20-30% of saturated components and having C20 acids, arachidonic acid or an isomer, as the most plentiful constituent.