Introduction to Chemistry of Lipids
Lipids comprises heterogeneous group of compounds which are insoluble in water but soluble in non-polar organic solvents such us benzene, chloroform, and ether, present in all living organisms.
The group includes fats, oils, waxes and related compounds.
General Functions of Lipids
i. They are efficient energy sources.
ii. Serve as thermal insulators.
iii. They are structural components of the cell membrane.
iv. Serve as precursors for hormones (steroid hormones).
v. They also dissolve the vitamins, which are fat-soluble and assist their digestion.
2. Classification base on composition
2.9. High density lipoprotein (HDL)
High density lipoprotein (HDL) contains apoA-I, apoC-I, apoC-II and other apolipoproteins, as well as the enzyme lecithin-cholesterol acyl transferase (LCAT), which catalyzes the formation of cholesteryl esters from lecithin (phosphatidylcholine) and cholesterol.
• It facilitates the transport of fatty acids from
extrahepatic tissues to the liver
Biological significance
Cholesterol transport
- HDL carries cholesterol from peripheral tissues to the liver, where it's excreted from the body
- HDL delivers cholesterol to the adrenals, ovaries, and testes, which are important for steroid hormone synthesis
- HDL has anti-inflammatory properties in endothelial cells and leukocytes
- HDL reduces pro-inflammatory processes in vascular smooth muscle
- HDL is anti-thrombotic through actions on endothelium and platelets