Phosphatidylcholine (once given the trivial name 'lecithin') is a neutral or amphoteric phospholipid with a pH range from strongly acidic to strongly alkaline. It is usually the most abundant phospholipid in animals and plants, often amounting to almost 50% of the total complex lipids. It is the main structural component of liposomes and other phospholipid based nano assemblies which have a wide range application in the area of nucleic acid delivery.
Structure of phosphatidylcholine
The structure of a phospholipid consists of two parts: the hydrophilic "head" and the hydrophobic "tail". The variation in head and tail groups leads to the existence of a large range of phospholipids. And when the phosphate group in the hydrophilic head of phospholipids combines with an alcohol called choline, the molecule becomes phosphatidylcholine. Because it's architecture parallels that of the cell membrane, it is accepted as a building block by the cell membrane and incorporates itself into the structure of the cell.
Figure 1. General phosphatidylcholine structure; Fatty acids are linked to the glycerol backbone at the R1 and R2 positions while choline is linked to the phosphate headgroup at the X position .
Biosynthesis of phosphatidylcholine
In eukaryotes, there exist two phosphatidylcholine biosynthesis pathways: the Kennedy pathway and the methylation pathway. The Kennedy pathway begins with the direct phosphorylation of free choline into phosphocholine followed by conversion into CDP-choline and subsequently phosphatidylcholine. The methylation pathway involves a three-step methylation of phosphatidylethanolamine by at least one phospholipid N-methyltransferase to yield phosphatidylcholine.
Common phosphatidylcholine series
Phosphatidylcholine series are important excipients for nucleic acid delivery. Common phosphatidylcholine series are listed below.
1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC), a phosphatidylcholine with saturated tails, has a melting temperature of ~54 °C and a cylindrical geometry that allows DSPC molecules to form a lamellar phase, which stabilizes the structure of lipid nanoparticles . DSPC has been used to deliver mRNA-based vaccines, such as mRNA-1273 and BNT162b2covid-19.
Figure 2. The structure of DSPC.
1,2-Dimyristoyl-sn-glycero-3-phosphocholine (DMPC) belongs to the phosphatidylcholine family. It consists of saturated and symmetrical phospholipids with 14 carbon atoms. It is used in lipid bilayer studies to analyze organelle and cell membranes. In addition, studies have reported that DMPC coated on the surface of superparamagnetic iron oxide nanoparticles has advantages in drug delivery .
Figure 3. The structure of DMPC.
What we offer
Alfa Chemistry supplies a wide range of phosphatidylcholine products for companies researching vaccines. If you cannot find the product you need, please contact us. We also offer product customization according to customer's detailed requirements.
- Valente, C.; et al. Phosphatidic acid in membrane rearrangements. FEBS Letters. 2019, 593: 2428-2451.
- Koltover, I.; et al. An inverted hexagonal phase of cationic liposome-DNA complexes related to DNA release and delivery. Science. 1998, 281: 78-81.
- Han, D.; et al. 1,2-Dimyristoyl-sn-glycero-3-phosphocholine promotes the adhesion of nanoparticles to bio-membranes and transport in rat brain. RSC Adv. 2021, 11: 35455-35462.
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