12-oxo-9(Z)-Dodecenoic acid, an ω-oxoacid metabolite derived from the ω-6 PUFA linoleic acid and the ω-3 PUFA α-linolenic acid, is synthesized in plants through the action of lipoxygenase on these PUFAs, forming 13-hydroperoxy intermediates that are subsequently processed by hydroperoxide lyase. This compound exhibits activity (at 100 µM) against the plant pathogenic oomycete P. parasitica.