Population studies in Artemisia tridentata ssp. vaseyana: Chromosome numbers and sesquiterpene lactone races

The sesquiterpene lactones and chromosome numbers for three chemical races of Artemisia tridentata ssp. vaseyana have been examined from four populations in western Montana. TLC analysis of the sesquiterpene lactones in the seeds and seed producing parents demonstrated that genetic exchange does occur between sympatric sesquiterpene lactone chemical races. However, other evidence suggests that introgression between these races is restricted to zones of sympatry. There appears to be no correlation between chromosome numbers and sesquiterpene lactone races.     

Glaucolides from old world Vernonia species

The investigation of two East African and a Madagascarian Vernonia species afforded several new sesquiterpene lactones. Vernonia colorata subsp. grandis gave 19-hydroxyglaucolide A and three vernodalin derivatives, V. holstii five new cistifoliolides and V. zanzibarensis five lactones closely related to brachycalyxolide. The structures were elucidated by high field NMR techniques. The chemotaxonomic relevance is discussed briefly.     

Terpenoids from Achillea distans Waldst. & Kit. ex Willed

The flower heads of Achillea distans afforded nine new sesquiterpene lactones (one glaucolide, six guaianolides and two dimeric lactones) in addition to 18 known terpenoids. The structures and stereochemistry of the new compounds were elucidated by spectroscopic methods. The stereochemistry of 11,13-dihydroezomontanin was revised.     

Antifeedant properties and chemotaxonomic implications of sesquiterpene lactones and syringin from Rhaponticum pulchrum

From aerial parts of Rhaponticum pulchrum the guaiane-type sesquiterpene lactones aguerin B, janerin, 19-deoxyjanerin, chlorojanerin, 15-dechloro-15-hydroxychlorojanerin, cynaropicrin, cebellin G, repdiolide and repensolide were isolated, together with the phenylpropanoid glucoside syringin. In no-choice and two-choice feeding experiments aguerin B, chlorojanerin and syringin were shown to be good antifeedants against the three species of the stored product insect pests Sitophilus granarius, Trogoderma granarium and Tribolium confusum, while janerin and cynaropicrin inhibited feeding of the latter species. However, the highest antifeedant activity was recorded for the extract of the plant enriched in sesquiterpene lactones. The unexpected finding was that syringin inhibited feeding of the insects.     

Insect allelochemic effects of sesquiterpene lactones from Melampodium

The crude syrups of Melampodium americanum L. and Melampodium leucanthum Torr. and Gray and their principal sesquiterpene lactones, melampodin A and melampodinin A, significantly inhibit growth and deter feeding of the fall armyworm, Spodoptera frugiperda (J. E. Smith). Melampodin A and melampodinin A caused 2.3 × and 5.5 × greater S. frugiperda larval mortality, respectively, than glaucolide A, a sesquiterpene lactone with previously demonstrated insect allelochemic effects.     

Chemosystematic Investigation of the Annual Species of Helianthus (Asteraceae)

A total of 43 HPLC peaks tentatively considered to be sesquiterpene lactones was detected from a survey of the 18 taxa (eleven species and seven subspecies) of Helianthus sect. Helianthus using a recently developed microtechnique. All but one of the taxa showed characteristic sesquiterpene lactone patterns with between six and 15 compounds each. H. paradoxus appears to be the only species in the genus in which these compounds are not detectable. Comparison with available reference compounds allowed assignment of structures to 21 of the compounds. Known compounds can be classified into five major structural subtypes, the systematic distribution of which divides the section into three well-defined subgroups. The sesquiterpene lactone profiles of the other two annual species of the genus, H. agrestis and H. porteri, exhibit significant differences relative to any species of sect. Helianthus, which supports their exclusion from the section.     

3-oxa-guaianolides from Achillea millefolium

Aerial parts of Achillea millefolium (Mongolian origin yielded besides desacetylmatricarin two sesquiterpene lactones of a new 3-oxa-guaianolide type, 8-acetyl egelolide and 8- angeloyl egelolide.     

Guaianolides from Saussurea lappa

Two new sesquiterpene lactones with an ,β-unsaturated aldehyde group have been isolated from the roots of Saussurea lappa. Their stereostructures have been established by the combined use of spectroscopic as well as chemical methods via their synthesis from dehydrocostus lactone.     

Biosynthetic studies of lactucin derivatives in hairy root cultures of Lactuca floridana

Biosynthetic studies of the guaianolide-type sesquiterpene lactones 11βH,13-dihydrolactucin-8-O-acetate and 8-desoxylactucin were performed in Agrobacterium rhizogenes—transformed hairy root cultures of blue-flowered lettuce, Lactuca floridana. The ¹³C NMR spectra of the two guaianolides labelled by incorporation of [1-¹³C], [2-¹³C], [1,2-¹³C₂]acetate and [2-¹³C]mevalolactone showed patterns of enrichment consistent with a previously proposed biogenetic pathway for guaianolide-type sesquiterpene lactones via the acetate-mevalonate-germacradiene route.     

Systematic implications of flavonoids and sesquiterpene lactones in species of Vernonia

Systematic and evolutionary interpretations based upon the distributional data for 27 flavonoids from 39 species and 9 sesquiterpene lactones from 38 species are presented for species of Vernonia mostly from the New World.     

Intra- and interplant leaf sesquiterpene variability in Copaifera langsdorfii: relation to microlepidopteran herbivory

Oecophorid herbivory in Copaifera langsdorfii leaves along with sesquiterpene composition, concentration of most of the individual sesquiterpenes and total yield did not significantly differ between the lower and upper portions of tree canopies. Although sesquiterpene variation in leaves collected throughout individual tree canopies was less than variation among trees, leaves which were eaten by oecophorid larvae had slightly lower yields than those unattacked. Individual C. langsdorfii trees within the population were significantly different from one another in sesquiterpene yield, oecophorid herbivory and in the concentration of seven out of the 11 sesquiterpene compounds. Leaf sesquiterpenes appear to be more important in inhibiting herbivory by Stenoma aff. assignata than leaf moisture and nitrogen content and toughness.     

Inhibitory effects of Hymenaea and Copaifera leaf resins on the leaf fungus, Pestalotia subcuticularis

Leaf resins in the leguminous genera Hymenaea and Copaifera may play a role in restricting infection by the associated leaf fungus, Pestalotia. We tested this hypothesis by assessing growth of the geographically widespread Pestalotia subcuticularis presented with different compositions of resins. Leaf resins of Hymenaea and Copaifera are composed of the same suite of sesquiterpene hydrocarbons, but these vary quantitatively to form discrete compositional patterns among individuals and populations. Leaf resins may also contain sesquiterpene oxides; caryophyllene oxide, which may have been formed from the caryophyllene precursor common in these resins, inhibited fungal growth in vitro.     

Systematic implications of sesquiterpene lactones in Lactuca species

A chemosystematic study of eleven species from the genus Lactuca (Asteraceae) was performed, based on the distributional data for eight sesquiterpene lactones as diagnostic characters. The lactones were identified in leaf and root extracts by comparison of their HPLC retention times and on-line UV spectra with those of reference compounds. Our results support the status of the section Lactuca, subsection Lactuca as a recognizable group within the genus, although Lactuca aculeata is a distinct species. Moreover, sesquiterpene lactone patterns of Lactuca perennis, Lactuca tatarica, Lactuca indica and Lactuca capensis are also given. It is worth noting that the sesquiterpene lactones are absent from Lactuca tenerrima. The chemosystematic impact of lactucin-type guaianolides and the germacranolide lactuside A is discussed briefly.     

Microsampling: an alternative approach using sesquiterpene lactones for systematics

The localization of sesquiterpene lactones in glandular trichomes of numerous Asteraceae makes it possible to use a microtechnique to investigate their occurrence. General aspects of the utility and value of the method in comparison with standard procedures are discussed with special focus on the advantage of a quick, inexpensive and reproducible analytical technique in systematic and biochemical studies. Using analytical HPLC, it was possible to establish the sesquiterpene lactone profiles of all 64 known taxa of the genus Helianthus. Intraspecific variation of sesquiterpene lactones was found to be low in comparison to morphological characters. Hybrids were shown to possess the additive sesquiterpene lactone patterns of their parents. This suggests that the chemistry of these compounds could be a useful tool in taxonomy.     

Glandular trichomes and sesquiterpene lactones of Artemisia nova (Asteraceae)

The leaves of Artemisia nova Nelson are covered with a dense layer of nonglandular trichomes that obstruct the observation of glandular trichomes on the leaf surfaces. An acid-staining technique was developed that eliminates interference from the nonglandular trichomes and stains the glandular ones red, allowing them to be seen under a light microscope. Using this method it was found that these glands develop on both leaf surfaces, except over veins, and cover 21–35% of the leaf surface area at densities of 50–70 per mm². Mature glands are sac-like structure with a thin sheath or cuticle surrounding a clear transparent fluid. This fluid contains all of the sesquiterpene lactones present in the leaves, and some of the monoterpenes. These terpenoids were responsible for the red color of the glands after acid treatment.     

A chemotaxonomic survey of kaurene derivatives in the genus Alepidea (Apiaceae)

Lipophilic extracts from the roots of 16 species of Alepidea were studied by GC-MS for the presence of kaurenoic acids, dehydrokaurenoic acids, kaurenic lactones, hydroxykaurenoic acids and other kaurene derivatives. Various mixtures of these compounds are present in yields of up to 11.8% dry wt. in the rhizomes and roots. Two different isomers of kaurenoic acid occur in Alepidea, the one as a major compound in all the species, the other as a major compound only in some of them. The first isomer is clearly a useful chemical marker for the genus Alepidea, but the apparent chemical dichotomy is not obviously correlated with morphological patterns. Alepidea amatymbica, however, is part of a morphologically isolated group within the genus and also differs from other species in its chemical complexity and in the unique presence of kaurenoic lactones.     

Chemical constituents from Anthemis wiedemanniana Fisch. & Mey.

The lipophilic extract of the aerial parts of Anthemis wiedemanniana Fisch. & Mey, a Turkish endemic species, was investigated. In addition to one new natural product, namely 3,4,4-trimethyl-6-carboxy-cyclohex-2-ene-1-one, five known sesquiterpene lactones, five methylated flavonoids, one simple phenolic derivative and one nor-isoprenoid were isolated. Among the sesquiterpene lactones, canin was found to be the main compound.     

Analysis of sesquiterpene lactones in Eupatorium lindleyanum by HPLC‐PDA‐ESI‐MS/MS

Introduction – The aerial part Eupatorium lindleyanum is commonly used as an antipyretic and detoxicant clinically in traditional Chinese medicine. Our previous research showed that germacrane sesquiterpene lactones were its main active constituents, so the development of rapid and accurate methods for the identification of the sesquiterpene lactones is of great significance. Objective – To develop an HPLC‐PDA‐ESI‐MS/MS method capable for simple and rapid analysis of germacrane sesquiterpene lactones in the aerial part E. lindleyanum. Methodology – High‐performance liquid chromatography‐photodiode array detection‐electrospray ionization‐tandem mass spectrometry was used to analyze germacrane sesquiterpene lactones of Eupatorium lindleyanum. The fragmentation behavior of germacrane sesquiterpene lactones in a Micromass Q/TOF Mass Spectrometer was discussed, and 9 germacrane sesquiterpene lactones were identified by comparison of their characteristic data of HPLC and MS analyses with those obtained from reference compounds. Results – The investigated germacrane sesquiterpene lactones were identified as eupalinolides C (1), 3β‐acetoxy‐8β‐(4′‐hydroxy‐tigloyloxy)‐14‐hydroxy‐costunolide (2), eupalinolides A (3), eupalinolides B (4), eupalinolides E (5), 3β‐acetoxy‐8β‐(4′‐oxo‐tigloyloxy)‐14‐hydroxy‐heliangolide (6), 3β‐acetoxy‐8β‐(4′‐oxo‐ tigloyloxy)‐14‐hydroxy‐costunolide (7), hiyodorilactone B (8), and 3β‐acetoxy‐8β‐(4′‐hydroxy‐tigloyloxy)‐ costunolide (9). Compounds 6, 7 and 9 were reported for the first time. Conclusion – HPLC‐PDA‐ESI‐MS/MS provides a new powerful approach to identify germacrane sesquiterpene lactones in E. lindleyanum rapidly and accurately. Copyright © 2009 John Wiley & Sons, Ltd.     

Quantitative variation of the sesquiterpene lactones and chromenes of encelia farinosa

The components of the two major classes of natural products of the composite Encelia farinosa, sesquiterpene lactones and benzopyrans/benzofurans (chromenes), were resolved and quantified by high performance liquid chromatography. Geographic variation was examined over a range of mesic and xeric populations from California and Arizona (USA). The concentration of farinosin, a sesquiterpene lactone, varies significantly between individuals and seasonally within individuals. Ontogenetic comparisons revealed interpopulation variations within sesquiterpene lactones and chromenes. A geographic survey suggests the presence of two putative chemical races which vary in the amounts of sesquiterpene lactones and chromenes present. The adaptive significance of this quantitative variation is discussed.     

Diterpenes from euphorbia seguieriana

An extract of the whole plant of Euphorbia seguieriana afforded a known and three new diterpene lactones of the abietane type, seven myrsinanes and a tetracarbocyclic diterpene related to myrsinane. The structures were elucidated by means of high field NMR spectroscopy.