esters of choline and of diglyceride phosphoric (phosphatidic) acids, one of the basic fractions of phosphatides. Lecithin molecules are formed from the residues of glycerol, fatty acids (primarily stearic, palmitic, oleic, and linoleic acids), phosphoric acid, and choline.

Lecithins are hygroscopic viscous substances that are readily soluble in alcohols, ethyl ether, and petroleum naptha but insoluble in acetone. They are widely distributed in animal (liver, sperm, blood, cerebral tissue, adrenal glands, egg yolk) and plant organisms (soybeans, sunflower seeds, wheat germ). The principal function of lecithins in organisms is to participate in the formation of biological membranes. A number of synthetic lecithins have also been obtained. Cerebrolecithin, extracted from the cerebrum of cattle, is used in medicine; it is prescribed for internal use in the treatment of diseases of the nervous system, general weakness, and anemia. Lecithins are also used in the food, textile, and cosmetics industries.