Cytochrome P450 microsomal enzymes metabolize linoleic acid to a mixture of 9(S)-HpODE and 9(R)-HpODE which are subsequently reduced to their corresponding hydroxy products; these reactions produce racemic mixtures in which the R stereoisomer predominates, for instance by a R/S ratio of 80%/20% in human liver microsomes [REF].
The murine homolog of human 15(S)-lipoxygenase-2 (ALOX15B), 8(S)-lipoxygenase, while preferring arachidonic acid over linoleic acid, metabolizes linoleic acid predominantly to (9(S)-HpODE, which in tissues and cells is rapidly reduced to 9(S)-HODE [REF].