9(R)-HODE is one of several monohydroxylated products of linoleic acid. All known mammalian lipoxygenases appear to catalyze the oxygenation of arachidonic and linoleic acid to give products having strictly the (S) configuration at the site of oxygen insertion. However, both human umbilical vein endothelial cells and bovine aorta endothelial cells have been shown to produce 9(R)-HODE when incubated with linoleic acid. The physiological function of 9(R)-HODE and the enzyme that catalyzes its formation have not been determined.
9(R)-HODE cholesteryl ester was originally extracted from atherosclerotic lesions. It remains uncertain whether the oxidized fatty acid portion of the molecule results from enzymatic lipoxygenation or from random lipid peroxidation. 9(R)-HODE cholesteryl ester can be used as a standard for analysis of chiral HODE cholesteryl esters.
9-OxoODE, formed through the oxidation of the allylic hydroxyl group in both 9(S)-HODE and 9(R)-HODE, is present in rabbit reticulocyte plasma and mitochondrial membranes as both 9- and 13-oxoODEs, constituting approximately 2% of the total linoleate residues. The majority of these oxidized linoleate residues are esterified to membrane lipids.