Δ5‐Olefinic acids in the seed lipids from four Ephedra species and their distribution between the α and β positions of triacylglycerols. Characteristics common to coniferophytes and cycadophytes

Abstract

The fatty acid compositions of the seed lipids from four Ephedra species, E. nevadensis, E. viridis, E. przewalskii, and E. gerardiana (four gymnosperm species belonging to the Cycadophytes), have been established with an emphasis on delta5-unsaturated polymethylene-interrupted fatty acids (delta5-UPIFA). Mass spectrometry of the picolinyl ester derivatives allowed characterization of 5,9- and 5,11-18:2; 5,9,12-18:3; 5,9,12,15-18:4; 5,11-20:2; 5,11,14-20:3; and 5,11,14,17-20:4 acids. Delta5-UPIFA with a delta11-ethylenic bond (mostly C20 acids) were in higher proportions than delta5-UPIFA with a delta9 double bond (exclusively C18 acids) in all species. The total delta5-UPIFA content was 17-31% of the total fatty acids, with 5,11,14-20:3 and 5,11,14,17-20:4 acids being the principal delta5-UPIFA isomers. The relatively high level of cis-vaccenic (11-18:1) acid found in Ephedra spp. seeds, the presence of its delta5-desaturation product, 5,11-18:2 acid (proposed trivial name: ephedrenic acid), and of its elongation product, 13-20:1 acid, were previously shown to occur in a single other species, Ginkgo biloba, among the approximately 170 gymnosperm species analyzed so far. Consequently, Ephedraceae and Coniferophytes (including Ginkgoatae), which have evolved separately since the Devonian period (approximately 300 million yr ago), have kept in common the ability to synthesize C18 and C20 delta5-UPIFA. We postulate the existence of two delta5-desaturases in gymnosperm seeds, one possibly specific for unsaturated acids with a delta9-ethylenic bond, and the other possibly specific for unsaturated acids with a delta11-ethylenic bond. Alternatively, the delta5-desaturases might be specific for the chain length with C18 unsaturated acids on the one hand and C20 unsaturated acids on the other hand. The resulting hypothetical pathways for the biosynthesis of delta5-UPIFA in gymnosperm seeds are only distinguished by the position of 11-18:1 acid. Moreover, 13C nuclear magnetic resonance spectroscopy of the seed oil from two Ephedra species has shown that delta5-UPIFA are essentially excluded from the internal position of triacylglycerols, a characteristic common to all of the Coniferophytes analyzed so far (more than 30 species), with the possibility of an exclusive esterification at the sn-3 position. This structural feature would also date back to the Devonian period, but might have been lost in those rare angiosperm species containing delta5-UPIFA.

Structures, practical sources (gymnosperm seeds), gas-liquid chromatographic data (equivalent chain lengths), and mass spectrometric characteristics of all-cis Δ5-olefinic acids

“…On the contrary, they are the rule. This was observed in earlier and more recent systematic studies of gymnosperm leaf [28,29] and seed lipids [30], and for the latter, extended to practically all species analysed so far (approximately 170 species analysed by author Wolff and co-workers [26,27,[31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46]). They also occur in wood [47][48][49][50][51][52] lipids, but the number of species analysed for these tissues is much more limited.…”

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

“…Article disponible sur le site http://www.ocl-journal.org ou http://dx.doi.org/10.1051/ocl.2000.0113 Arachidonic (5,8,11,[14][15][16][17][18][19][20] and eicosapentaenoic (5,8,11,14,17-20:5) acids are the classic essential fatty acids in animals that otherwise have not yet been characterized with certainty in spermaphytes (seed plants) [1]. At most, a few angiosperm species can synthesize their more immediate precursors gamma-linolenic (6,9,12-18:3) and stearidonic (6,9,12,15-18:4) acids from linoleic (9,12-18:2) and alpha-linolenic (9,12,15-18:3) acids, respectively, but they cannot further process these fatty acids.…”

“…These fatty acids occur in the seeds from all Coniferophyte families studied so far, encompassing approximately 180 species [3][4][5][6] (almost one-fourth of extant species). Known exceptions that do not contain DELTA5-UPIFA belong to the Cycadophytes [10,11]. Sciadonic acid (a C20 DELTA5-UPIFA), in particular, is a constant lipid component in the seed and leaf lipids of gymnosperms containing DELTA5-UPIFA [12], whereas the presence of other DELTA5-UPIFA (in particular C18 DELTA5-UPIFA) is much more variable.…”

The Phytochemical Constitution of Maltese Medicinal Plants – Propagation, Isolation and Pharmacological Testing

“…It was later used by the Chinese to treat asthma [196] and acute nephritis [197]. This plant contains alkaloids [198], amino acids, proteins [199], tannins and fatty acids [200]. The volatile oil of Ephedra fragilis contains (E)-phytol (10.1%), pentacosane (5.2%), 6,10,14-trimethyl-2-pentadecanone (5.3%), cis-thujopsene (3.5%), and α-terpineol (3.0%) as the major components [201].…”