Description
The enzyme Δ
6 desaturase mediates the conversion of linoleic acid to γ-linolenic acid (GLA), which can then be elongated to dihomo-γ-linolenic acid (DGLA). DGLA can then be used as a substrate for Δ
5 desaturase to produce arachidonic acid (AA), the fatty acid that is used to generate eicosanoids. SC 26196 is an inhibitor of Δ
6 desaturase (IC
50 = 0.2 μM in a rat liver microsomal assay) that completely blocks the conversion of linoleic acid to arachidonic acid (AA). It is selective for Δ
6 desaturase, as IC
50 values for Δ
5 and Δ
9 desaturases exceed 200 μM and it has no effect on the conversion of dihomo-γ-linolenic acid to AA. SC 26196 is orally active
in vivo, decreasing edema in the carrageenan paw edema model in mice. It also blocks aging-related increases in AA in myocardial cardiolipin in mice, attenuating contractile dysfunction without impacting mitochondrial oxidative stress.
Biochem/physiol Actions
SC-26196 is a Delta6 fatty acid desaturase (Delta6D) inhibitor. It specifically inhibited Delta6D activity with an IC(50) value of 100 nM. The rate-limiting step in arachidonic acid synthesis is the desaturation of dietary linoleic acid by Delta6D. SC-26196 completely prevented this conversion of linoleic acid to arachidonic acid.