High level accumulation of gamma linolenic acid (C18:3Δ6.9,12 cis) in transgenic safflower (Carthamus tinctorius) seeds

Gamma linolenic acid (GLA; C18:3Δ6,9,12 cis), also known as γ-Linolenic acid, is an important essential fatty acid precursor for the synthesis of very long chain polyunsaturated fatty acids and important pathways involved in human health. GLA is synthesized from linoleic acid (LA; C18:2Δ9,12 cis) by endoplasmic reticulum associated Δ6-desaturase activity. Currently sources of GLA are limited to a small number of plant species with poor agronomic properties, and therefore an economical and abundant commercial source of GLA in an existing crop is highly desirable. To this end, the seed oil of a high LA cultivated species of safflower (Carthamus tinctorius) was modified by transformation with Δ6-desaturase from Saprolegnia diclina resulting in levels exceeding 70% (v/v) of GLA. Levels around 50% (v/v) of GLA in seed oil was achieved when Δ12-/Δ6-desaturases from Mortierella alpina was over-expressed in safflower cultivars with either a high LA or high oleic (OA; C18:1Δ9 cis) background. The differences in the overall levels of GLA suggest the accumulation of the novel fatty acid was not limited by a lack of incorporation into the triacylgylcerol backbone (>66% GLA achieved), or correlated with gene dosage (GLA levels independent of gene copy number), but rather reflected the differences in Δ6-desaturase activity from the two sources. To date, these represent the highest accumulation levels of a newly introduced fatty acid in a transgenic crop. Events from these studies have been propagated and recently received FDA approval for commercialization as Sonova™400.

The chemopreventive effects of Saussurea salicifolia through induction of apoptosis and phase II detoxification enzyme

The ethanol extract of the aerial part of the Mongolian medicinal plant Saussurea salicifolia induced a dose-dependent cell growth inhibition in both human gastric adenocarcinoma AGS cells and mouse hepatoma Hepa 1c1c7 cells (IC(50)=30.22 and 116.96 mug/ml), respectively. The extract induced an apoptosis in AGS cells inference from the externalization of the phosphatidylserine, the increase of the sub G0/G1 content (%) and the apoptotic morphological changes including membrane blebbing, the formation of apoptotic bodies and chromatin condensation. In order to identify active substances causing the apoptosis, we further isolated major compounds present in Saussurea salicifolia and 7 compounds were isolated including a sesquiterpene lactone, cynaropicrin, 3 lignans (trachelogenin, matairesinol and arctigenin) and 3 lignan glycosides (tracheloside, matairesinoside and arctiin). In general the lignan aglycones were more cytotoxic than their lignan glycosides in both AGS cells and Hepa 1c1c7 cells. Cynaropicrin not only showed the most potent cytotoxicity among the 7 major compounds but also it induced an apoptosis and a weak G2/M arrest in AGS cells. Arctigenin had the second-best cytotoxicity among 7 major compounds, and induced an apoptosis. In order to evaluate the induction of the phase II detoxification enzyme, we measured the induction of quinone reductase activity of the extract, fractions and compounds in Hepa 1c1c7 cells. The ethyl acetate fraction and arctigenin showed the strongest cancer chemopreventive activity (chemoprevention index=9.88 and 7.57, respectively). These data suggest that the extract as well as the lignan compounds (especially arctigenin) originated from Saussurea salicifolia may be served as potential cancer chemopreventive agents for prevention or treatment of human cancers.

Isomers of hexadecenoic and hexadecadienoic acids in Androsace septentrionalis (Primulaceae) seed oil

Seeds of Androsace septentrionalis of the genus Androsace (tribus Primuleae) from the plant family Primulaceae were studied for their oil content and FA composition. The seed oil of A. septentrionalis was found to contain two unusual FA rarely occurring in plants: 11-cis-hexadecenoic acid (16:1delta11c or 16:1n-5) and 9-cis,12-cis-hexadecadienoic acid (16:2delta9c,12c or 16:2n-4). It also contained an unusually high amount (21.4%) of 9-cis-hexadecenoic acid (palmitoleic acid; 16:1delta9c or 16:1n-7), i.e., at a level higher than that of oleic acid, in addition to common FA. Compared with most plant seed oils, at 3.8% the level of 18:1delta11c (or 18:1n-7) also was elevated. The nonidentity of the Androsace 16:2-acid with the 16:2-acid, which is very typical for Ranunculus spp., as well as its identity with the 16:2-acid typically found in Asclepiadaceae was established by co-chromatography. The structure and composition of the constituent FA of A. septentrionalis were also determined by various chromatographic methods (TLC, Ag+-TLC, capillary GLC) and spectroscopic methods (IR, GC-MS). The significant deviation of the Androsace FA pattern from that of other Primuleae, indicating a separate phylogenetic position of Androsace, is discussed.

Occurrence of a novel cis,cis,cis-octadeca-3,9,12-trienoic (Z,Z,Z-octadeca-3,9,12-trienoic) acid in Chrysanthemum (tanacetum) zawadskii herb. (Compositae) seed oil

A new octadecatrienoic acid (6.9%), found as a component of Chrysanthemum zawadskii Herb. (Asteraceae) seed oil, was shown to be the hitherto unknown cis,cis,cis-octadeca-3,9,12-trienoic acid. The oil also contained 8.6% of crepenynic acid in addition to the other common FA. The structures of the new unusual FA and other FA were confirmed by chromatographic (TLC, GC), spectroscopic (IR, UV, and NMR), and MS methods by using different chemical derivatizations (preparation of methyl ester, pyrrolidide, picolinyl esters, and dimethyloxazoline derivatives).

Occurrence of gamma-linolenic acid in compositae: a study of Youngia tenuicaulis seed oil

Seeds of Youngia tenuicaulis and other species from the plant family Compositae (Asteraceae) were studied for their oil content and fatty acid composition. The seed oil of Y. tenuicaulis growing in Mongolia was found to contain 5.6% gamma-linolenic acid (18:3delta6cis,9cis,12cis) in addition to common fatty acids. The oil was analyzed using chromatographic [capillary gas-liquid chromatography (GLC), thin-layer chromatography] and spectroscopic (infrared, gas chromatography-mass spectrometry) techniques. Seed oil fatty acids of Saussurea amara (containing gamma-linolenic acid) and of Arctium minus (containing 18:3delta3trans,9cis,12cis), as well as delta5cis- and delta5trans-18:3 were used as GLC reference substances. The evolution in this plant family of a large number of different 18:3 acids as well as the corresponding evolution of unusual desaturases should be investigated. On the other hand, the delta6cis-desaturase required for the biosynthesis of gamma-linolenic acid may have evolved independently several times in unrelated families of the plant kingdom.

Tanacetum (Chrysanthemum) corymbosum seed oil--a rich source of a novel conjugated acetylenic acid

A new conjugated trans,trans-diunsaturated acetylenic acid (17%), found for the first time in nature as a main component of the seed oil of Tanacetum (Chrysanthemum) corymbosum, was shown to be octadeca-8t,10t-dien-12-ynoic acid. Another already known naturally occurring acetylenic acid, crepenynic acid (10%), was found also in the seed oil. The structure of this new unusual fatty acid was confirmed by chromatographic (thin-layer chromatography, gas chromatography, high-performance liquid chromatography) and spectroscopic (infrared, ultraviolet, mass spectrometry) methods by using different chemical derivatizations (deuteration, preparation of picolinyl ester, dimethyloxazoline, and maleic anhydride adduct).