Arachidonic acid (AA, sometimes ARA) is an omega-6 fatty acid 20:4(?-6). It is the counterpart to the saturated arachidic acid found in peanut oil, (L. arachis – peanut.)

Arachidonic acid is a polyunsaturated fatty acid that is present in the phospholipids of membranes of the body's cells, and is abundant in the brain.

It is also involved in cellular signaling as a second messenger.

References

^ Dorland's Medical Dictionary – 'A'. Retrieved on 2007-01-12.