Biochemistry · Molecule
Arachidonic acid !
Arachidonic acid is a 20-carbon omega-6 fatty acid stored in cell membranes. Released on demand, it is the source of all eicosanoids.
Updated 2026-11-01
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Key facts
- Stored at position sn-2 of membrane phospholipids and freed by phospholipase A₂.
- COX turns it into prostaglandins and thromboxane; 5-lipoxygenase turns it into leukotrienes.
- Humans make it from linoleic acid, an essential fatty acid of the diet.
- Also called
- 20:4 ω-6
- Formula
- C₂₀H₃₂O₂
- PubChem
- CID 444899
Structure
- A 20-carbon chain with four cis double bonds (5, 8, 11, 14) and a carboxyl end.
Clinical notes
- NSAIDs and glucocorticoids act by limiting what is made from it.
- Omega-3 fatty acids compete with it and lead to less inflammatory eicosanoids.
- Essential fatty acid deficiency (scaly skin, poor growth) appears when linoleic acid is lacking.
Pathways
Related conditions
Related
- Phosphatidylcholine (lecithin)
- Prostaglandin H₂ (PGH₂)
- Thromboxane A₂ (TXA₂)
- Cyclooxygenase (COX-1 and COX-2)
- Eicosanoids: prostaglandins, thromboxanes and leukotrienes
- Phospholipids
- Lipid chemistry
Test yourself
Think of the answer, then tap the question to see it.
Which enzyme releases arachidonic acid from the membrane?
Phospholipase A₂, which cuts at position sn-2.
From which dietary fatty acid is arachidonic acid made?
Linoleic acid, an essential omega-6 fatty acid.
Which two enzyme families turn arachidonic acid into signals?
Cyclooxygenases (prostaglandins, thromboxane) and lipoxygenases (leukotrienes).
Molecules are shown in their neutral form, as the databases deposit them; in the cell the acids and phosphates are ionised.
Educational information, not medical advice. For any symptom, see a health professional.
Sources: Arachidonic Acid (CID 444899) (PubChem, NCBI, 2026) · Public domain; Cytosolic phospholipase A2 (PLA2G4A) - Homo sapiens (UniProt, 2026); Textbook of Biochemistry for Medical Students, 6th ed. (Jaypee Brothers Medical Publishers (Vasudevan DM, Sreekumari S, Vaidyanathan K), 2011).
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