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.
Chromatographic separation of a crude extract obtained from aerial parts of the Mongolian medicinal plant Scorzonera radiata yielded five new dihydrostilbenes, scorzodihydrostilbenes A-E (1-5). The structures were unambiguously elucidated on the basis of one- and two-dimensional NMR ((1)H, (13)C, COSY, HMBC, HMQC, and ROESY) and mass spectrometric data. Compounds 1-5 exhibited antioxidative activity when analyzed in the DPPH (2,2-diphenyl-1-picrylhydrazyl) assay. For 1 and 5 the antioxidant activities were stronger than that of the well-known naturally occurring stilbene antioxidant resveratrol.
A new allenic fatty acid, phlomic acid, 7,8-eicosadienoic acid or 20:2A7,8ol/ene, has been observed in several genera of the Lamiaceae, subfamily Lamioideae. The occurrence of this fatty acid seems to be correlated with the presence of an unusual 20:l acid, 20:lA9cis or 20:ln-11. Phlomic acid is apparently produced by chain-elongation of the major seed oil fatty acid, laballenic acid or 18:2A5,6a//ene. Eine neue Allen-Fettsllure im Samenbl von Phlomis (Lamiaceae). Eine neue Fettsaure mit einer Allen-Gruppierung, 7,8-Eicosadiensaure oder 20:2A7,8a//ene wurde in Samenolen verschiedener Gattungen der Lamiaceae, Unterfamilie Lamioideae, beobachtet. Das Vorkommen dieser Fettsaure, die wir der Einfachheit halber Phlomissaure genannt haben, scheint mit der Anwesenheit einer ungewohnlichen 20:l-Fettsaure korreliert zu sein, namlich 20:1A9cis oder 20:ln-11. Phlomissaure wird anscheinend durch Kettenverlangerung von Laballensaure oder 18:2A5,6o//ene hergestellt, die eine Hauptfettsaure im Samenol ist.
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