Variability of fatty acid profiles in ferns: Relation to fern taxonomy and seasonal development.

Ferns are known to contain long chain polyunsaturated fatty acids which may provide health benefits. The objective of this study was to investigate ferns of Pacific temperate regions (Far East of Russia and New Zealand) as sources of valuable fatty acids: arachidonic (20:4n-6) and eicosapentaenoic (20:5n-3). Fatty acids were analyzed in fronds of 23 fern species from 12 families. Major fatty acids include: 18:3n-3 (6-68% of total fatty acids), 16:0 (6-33%), 18:2n-6 (5-46%), 18:1n-9 (1-60%), 20:4n-6 (1-16%). Polyunsaturated fatty acids of fern fronds belong to the omega-6 (16:2n-6, 18:2n-6, 18:3n-6, 20:2n-6, 20:3n-6, 20:4n-6) and omega-3 (16:3n-3, 18:3n-3, 18:4n-3, 20:3n-3, 20:4n-3, 20:5n-3) families. For the first time, Δ5-unsaturated polymethylene-interrupted fatty acids were reported for ferns: sciadonic (5,11,14-20:3) and juniperonic (5,11,14,17-20:4) acids (up to 1.9% and 0.4%, respectively). Fatty acid profiles in fern fronds were unrelated to fern taxonomy, but affected by spore presence: fronds with sporangia/spores contained more 18:1n-9 and/or 18:2n-6. The absolute content of 20:4n-6 was found to be relatively constant for a species in different seasons. 20:5n-3 was a minor fatty acid (traces-5%) which accumulates during the vegetation period. Young fronds of the New Zealand ferns Phymatosorus pustulatus and Pteridium esculentum were enriched in 20:4n-6, while aged fronds of Cyathea dealbata had the highest level of 20:5n-3. The mature fronds of the Far Eastern ferns Phegopteris connectilis, Dryopteris expansa, and Athyrium sinense were also enriched in 20:5n-3.