Conifer seeds: Oil content and fatty acid composition

The seed oils from twenty‐five Conifer species (from four families—Pinaceae, Cupressaceae, Taxodiaceae, and Taxaceae) have been analyzed, and their fatty acid compositions were established by capillary gas‐liquid chromatography on two columns with different polarities. The oil content of the seeds varied from less than 1% up to 50%. Conifer seed oils were characterized by the presence of several Δ5‐unsaturated polymethylene‐interrupted polyunsaturated fatty acids (Δ5‐acids) with either 18 ( cis ‐5, cis ‐9, 18∶2, cis ‐5, cis ‐9, cis ‐12 18∶3, and cis ‐5, cis ‐9, cis ‐12, cis ‐15 18∶4 acids) or 20 carbon atoms ( cis ‐5, cis ‐11 20∶2, cis ‐5, cis ‐11, cis ‐14, 20∶3, and cis ‐5, cis ‐11, cis ‐14, cis ‐17 20∶4 acids). Pinaceae seed oils contained 17–31% of Δ5‐acids, mainly with 18 carbon atoms. The 20‐carbon acids present were structurally derived from 20∶1n‐9 and 20∶2n‐6 acids. Pinaceae seed oils were practically devoid of 18∶3n‐3 acid and did not contain either Δ5‐18∶4 or Δ5‐20∶4 acids. Several Pinaceae seeds had a Δ5‐acid content higher than 50 mg/g of seed. The only Taxaceae seed oil studied ( Taxus baccata ) had a fatty acid composition related to those of Pinaceae seed oils. Cupressaceae seed oils differed from Pinaceae seed oils by the absence of Δ5‐acids with 18 carbon atoms and high concentrations in 18∶3n‐3 acid and in Δ5‐acids with 20 carbon atoms (Δ5‐20∶3 and Δ5‐20∶4 acids). Δ5‐18∶4 Acid was present in minute amounts. The highest level of Δ5‐20∶4 acid was found in Juniperus communis seed oil, but the best source of Δ5‐acids among Cupressaceae was Thuja occidentalis . Taxodiaceae seed oils had more heterogeneous fatty acid compositions, but the distribution of Δ5‐acids resembled that found in Cupressaceae seed oils. Except for Sciadopytis verticillata , other Taxodiaceae species are not interesting sources of Δ5‐acids. The distribution profile of Δ5‐acids among different Conifer families appeared to be linked to the occurrence of 18∶3n‐3 acid in the seed oils.