The component fatty acids of the phosphatides of soya bean and rape seeds

THE fatty acids present in combination in phosphatides from the vegetable kingdom have received less notice hitherto than those from animal sources. Until Levene & Rolf, in the case of soya bean phosphatides, showed that more than one type was present, including products less soluble in alcohol than lecithin, and that the phosphatides sparingly soluble in alcohol and also the alcohol-soluble forms gave optically active barium glycerophosphate, indicating that the phosphoric acid was combined with an a-glyceryl hydroxyl group. They identified palmitic, stearic and (in the form of bromo-additive products) oleic, linoleic and linolenic acids in the mixed fatty acids; they concluded that in the alcohol-soluble phosphatides (choline compounds) the proportion of saturated acids was lower than in animal lecithin, whereas the alcohol-insoluble compounds (,3-aminoethanol derivatives) showed no marked difference in this respect from animal kephalin. Webster [1929] recorded the i.v. (Hanus) of the mixed fatty acids present in the acetone-insoluble phosphatides from wheat, maize, oats and soya beans respectively as 81*5, 65-3, 88-8 and 92-5. The only other detailed work on seed phosphatide fatty acids (again those from the soya bean) appears to be that of Suzuki and his co-workers [1930; The presence of alcohol-insoluble "kephalin" and alcohol-soluble "leci- thin" derived respectively from choline and ,B-aminoethanol was confirmed by these investigators, who also brominated the phosphatide fractions and isolated various crystalline derivatives containing mixtures of fatty acids, from which the presence of "mixed" compounds such as palmito-oleo-, or oleolinoleo-, as well as dioleoand dilinoleo-phosphatides was established. Suzuki & Yokoyama [1930] separated, by means of cadmium chloride double salts, ocand fl-"leci- thins " from soya beans, and studied the mixed fatty acids from each group by bromination. They observed the following proportions of palmitic and poly- bromostearic acids in each case: