**2.1 Phospholipids**

Phospholipids are amphipathic [10, 11] molecules present in membrane. They contain hydrophilic head and hydrophobic tail. The hydrophilic head has phosphorus molecule as phosphoric acid group, and two hydrophobic tails have long hydrocarbon chain groups (See **Figure 2**). Phosphoglycerides, phosphoinositides and phosphosphingosides are three classes of phospholipids [12].
