γ- (gamma-) linolenic acid (GLA) is an omega-6 (omega minus six) fatty acid .
This means that it has a
double bond between carbon atoms starting at the
Ω (omega) - 6 position, which is 6 carbons back from the end opposite to
the
-COOH group
(which is normally counted as the α (alpha) carbon - number 1).
It has
3 double bonds. Each of these double bonds is in the
cis form, rather than the
trans form, so the
single hydrogen atoms are on the same side of the bond.
Alternative names for the molecule are (6Z,9Z,12Z)-octadeca-6,9,12-trienoic acid,
all-cis-6,9,12-octadecatrienoic acid
or 18:3(n-6).
It is especially common in evening primrose (
Oenothera) oil.
Alpha-linolenic acid is another isomer of this compound, with different properties.