Answer to Question #100950 in Chemistry for Abhishek

Question

What prostaglandins and leucotrienes? Give their functions.

Answer 1

Prostaglandins and leukotrieans are parts of the biologically important class of fatty acids derivatives called eicosanoids. Eicosanoids are lipid inflammatory mediators primarily derived from arachidonic acid (and the Greek "eicosa" means twenty - twenty carbon fatty acid derivatives).

The main physiological effects of prostaglandins include vascular leakage, mast cell maturation, eosinophil recruitment, vascular and respiratory smooth muscle contraction - those events are essential for both normal and allergic immune responses. Other functions include production of pain and fever, relaxing of smooth muscles, neuronal function and inhibition of noradrenalin release from sympathetic nerve terminals.

Leukotriens are mainly involved in neutrophil recruitment, vascular leakage and epithelial barrier function. These inflammatory molecules are released by mast cells during an asthma attack and are primarily responsible for the bronchoconstriction. Leukotriens can also act as chemoattractants for eosinophils and attracted them into the bronchioles causing longer term hypersensitivity of the airways in chronic asthma.

Briefly, we can conclude that prostaglandins are important players in inflammation, pain, and fever and leukotriens are major mediators in asthma. When we start thinking about pain and fever the first thing to come in mind is aspirin and other nonsteroidal anti-inflammatory drugs. The mechanism of action in such drugs is quite simple. Aspirin blocks an enzyme called cyclooxygenase which catalyzes the first step in the conversion of arachidonic acid to prostaglandins.

Lipoxygenase catalyzes conversion of arachidonic acid to leukotrienes which makes it a perfect therapeutic target in asthma pacients. 5-lipoxygenase inhibitors (Zyflo) used clinically in long-term maintenance of asthma control.