Arachidonic and eicosapentaenoic acids in Araucariaceae, a unique feature among seed plants

It is generally admitted that seed plants (spermaphytes) ore unable to synt hesize either arachidonic or eicosapentaenoic acids (AA and EPA), the class ic essential fatty acids in animals. We give here chromatographic and spect rometric data showing that species from the primitive family Araucariaceae (gymnosperms) are able to synthesize AA and/or EPA in their seeds and leave s. Agathis robusta, in particular, contains AA and EPA in small amounts in its seeds, with no Delta 5-unsaturated polymethylene-interrupted fatty acid s (Delta 5-UPIFA) with 18 carbon atoms, whereas Araucaria spp. contain both AA and C18 Delta 5-UPIFA. In both species, Delta 5-UPIFA with 20 carbon at oms are present as in all other Coniferophytes. All metabolic intermediates necessary for the biosynthesis of AA and/or EPA have been characterized in Araucariaceae seeds. The relevance of these observations is discussed with regard to the phylogeny of Coniferophytes.