γ- (gamma-) linolenic acid (GLA) is an omega-6 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,
It is especially common in evening primrose (Oenothera
is another isomer of this compound, with different properties.