*2.1.1 Phosphoglycerides*

Phosphoglycerides are the mostly used phospholipids which contain three OH groups in glycerol moiety and among them two OH groups are linked to two fatty acids and phosphoric acid linked with one OH group. Phosphoglycerides are differed with their attached 'polar head alcohol group' esterified with phosphoric acid. All phosphoglycerides will have two nonpolar "tails" of fatty acid (C16 or C18) and among them one is saturated and other is unsaturated which always attaches to middle or β-hydroxyl group.

a. **Lecithins (Phosphatidyl Cholines):** Lecithin is synonym for phosphotidylcholine which is a phospholipid containing phosphate obtained either from yolk of egg or from soya beans. Lecithin contains unsaturated non polar fatty acids, glycerol and phosphoric acid attached to nitrogen base choline (See **Figure 3**).

#### *Drug Delivery through Liposomes DOI: http://dx.doi.org/10.5772/intechopen.97727*

