γ-Linolenic Acid methyl ester is a weak leukotriene B4 (LTB4) receptor antagonist.

LTB 4, a potent neutrophil chemoattractant, is present at high concentrations in psoriatic lesions, bronchoalveolar lavage in asthmatics and rectal dialysates in patients with inflammatory bowel disease.

In vitro: γ-Linolenic acid methyl ester is an esterified version of the free acid which is less water soluble but more amenable for the formulation of GLA-containing diets and dietary supplements. GLA was identified as an ω-6 fatty acid which could be elongated to arachidonic acid for endogenous eicosanoid synthesis. GLA was found to be a weak leukotriene B4 (LTB4) receptor antagonist, which was able to inhibit [3H]-LTB4 binding to porcine neutrophil membranes with a Ki of 1 μM [1].

In vivo: In an in-vivo model of LTB4-induced bronchoconstriction, ricinelaidic acid andγ-Linolenic acid methyl ester at a 1 mg/kg i.v. dose could result in 46% and 53% inhibition, respectively, indicating that essential fatty acids are LTB4 receptor antagonists, which may account in part for their reported anti-inflammatory activities [1].

Clinical trial: So far, no clinical study has been conducted.

Reference:
[1] Yagaloff, K. A.,Franco, L.,Simko, B., et al. Essential fatty acids are antagonists of the leukotriene B4 receptor. Prostaglandins, Leukotrienes and Essential Fatty Acids 52, 293-297 (1995).