Lipoxygenase-like activity was found in the crude extracts from the skin and gill of wild and cultured ayu. After incubation of arachidonic acid with the crude extract from the wild and cultured ayu skins, the major oxygenated product was estimated to be 12-hydroxyeicosa-tetraenoic acid under high-performance liquid chromatography using a Waters μ bondapak fatty acid column. On the other hand, eicosapentaenoic acid yielded 12-hydroxyeicosapentaenoic acid. This enzyme activity of wild and cultured ayu was inhibited strongly in the presence of the following reagents: BHA, esculetin, p-chloromercuribenzoate, SnCl2, CuCl2.
The C9 carbonyl compounds and alcohols specifically formed from the oxidation of poly-unsaturated fatty acids in the crude extract of wild ayu skin. In GC-MS chromatogram, a peak height of (E, Z)-2, 6-nonadienal formed from the wild ayu skin was higher than that of the cultured ayu skin, while that of 3, 6-nonadien-l-ol from the wild ayu skin was lower than that from the cultured fish skin.