37. Synthesis of Eicosanoids: Prostaglandins, Prostacyclines, Leukotrienes, Lipoxines and Tromboxanes. Regulation of Synthesis. Therapeutic Use of COX Enzyme Inhibitors. Role of ω-3 Fatty Acids.
Covers how eicosanoids are made from arachidonic acid, beginning with its release from membrane phospholipids by phospholipase A₂ and the blocking effect of cortisol. It then follows the cyclooxygenase route to prostaglandins, prostacyclin and thromboxane, and the lipoxygenase route to leukotrienes and lipoxins, with their functions. The note also covers COX-1 and COX-2 regulation, aspirin, NSAIDs and selective COX-2 inhibitors with their thrombotic risk, and the role of ω-3 fatty acids.
Topic 37 of 76 in the MU Pleven syllabus for Biochemistry (Medicine, Year 2). The free AceMed note covers it in 6 sections, about 305 words (2 min of reading), with 13 flashcards.
In this note
Synthesis of Eicosanoids: Prostaglandins, Prostacyclines, Leukotrienes, Lipoxines and Tromboxanes.
Synthesis of Eicosanoids
Pathways of Eicosanoid Synthesis
Regulation of Eicosanoid Synthesis
Therapeutic Use of COX Inhibitors
Role of ω-3 Fatty Acids (EPA & DHA)
Synthesis of Eicosanoids
1. Overview
Eicosanoids are short-lived hormone-like molecules synthesized from polyunsaturated fatty acids, mainly:
Arachidonic acid (20:4, ω-6) stored in membrane phospholipids.
They act locally (paracrine/autocrine) and have very strong biological effects on:
Inflammation
Vasodilation & vasoconstriction
Platelet aggregation
Smooth muscle contraction (bronchi, uterus, GI tract)
2. Release of Arachidonic Acid
Triggered by hormones, mechanical stress, inflammation.
Phospholipase A₂ releases arachidonic acid from membrane phospholipids.
