An octaene fatty acid, 4,7,10,13,16,19,22,25-octacosaoctaenoic acid (28 : 8n-3), found in marine oils

We report structure determination of an octaene fatty acid, 4,7,10,13,16,19 ,22,25-octacosaoctaenoic acid (28: 8n-3), The molecular weight and double b ond locations were determined using acetonitrile chemical ionization mass s pectrometry (MS) and MS/MS and were confirmed by MS of hydrogenated and deu terogenated 28:8 and by argentation thin-layer chromatography, 28:8n-3 was 1.2 +/- 0.1%, in oil derived from the heterotrophic dinoflagellate Crypthec odinium cohnii and a commercial polyunsaturated fatty acid concentrate deri ved from fish oils (0.16 +/- 0.01%), both components of human dietary suppl ements. It was not found in whole bovine retina, cultured Y79 human retinob lastoma cells, or neonate baboon cerebral cortex, The long chain polyunsatu rates present in the C. cohnii oil suggest a possible route for 28:8n-3 bio synthesis similar to that for biosynthesis of 22:6n-3.