Allenic germacranolides,bourbonene derived lactones and other constituents from Vernonia species

An investigation of seven Vernonia species, mainly from northern Brazil, afforded in addition to known compounds three new unusual sesquiterpene lactones with an allenic group. Intensive NMR studies fully established the structures. Furthermore, two lactones derived from bourbonene, two new glaucolides, a new furansesquiterpene, a nerolidol derivative and two other sesquiterpenes derived from eudesmane were isolated. The biogenetic relationships of the sesquiterpene lactones present in Veronia species as well as the chemotaxonomic aspects are discussed.     

Guaianolides from Cichorium intybus and structure revision of Cichorium sesquiterpene lactones

The isolation and structure elucidation of a new lactucopicrin derivative from Cichorium intybus is described, together with the revised structures of several sesquiterpene lactones previously isolated from Cichorium species. The known eudesmanolide magnolialide and the known guaianolide ixerisoside D, reported for the first time from the plant material, along with the previously known chicory sesquiterpene lactones have been also isolated and identified.     

Terpenoids from Anthemis austriaca Jacq

The aerial parts of Anthemis austriaca Jacq. afforded five new sesquiterpene lactones (two of which are dimeric guaianolides) and three new guaiane type sesquiterpene acids In addition, seven known terpenoids were also found in the studied species. Their structures were elucidated by spectral methods.     

Sesquiterpene lactones from Brachylaena species

The investigation of two Brachylaena species afforded in addition to known sesquiterpene lactones and other constituents five new lactones, a germacranolide, a guaianolide and three eudesmanolides. The structures were elucidated by spectroscopic methods. The chemotaxonomy of this complex genus is discussed.     

Sesquiterpene alcohols from Artemisia pygmaea

Artemisia pygmaea Gray contains two sesquiterpene alcohols: the known cryptomeridiol (I) and pygmol (II), a new compound. No sesquiterpene lactones were found in the plant although other species of the section Tridentatae Rydb., with which A. pygmaea has been classified, are usually rich in lactones.     

Germacranolides,a guaianolide with a β-lactone ring and further constituents from Grazielia species

An investigation of three Grazielia species afforded, in addition to known compounds, several new sesquiterpene lactones, eight germacranolides, two melampolides and one guaianolide as well as three diterpenes, two geranylgeraniol derivatives and a labda-diene. Three of the sesquiterpene lactones had an additional β-lactone ring, one an acid function, and two others unusual ester functions. The structures were elucidated by spectroscopic methods and some chemical transformations. The chemotaxonomic situation is discussed briefly.     

α-Humulene derivatives including a sesquiterpene acid with a rearranged carbon skeleton from Lychophorora columnaris

An investigation of Lychnophora columnaris afforded in addition to known compounds six new α-humulene derivatives and a rearranged sesquiterpene with a new carbon skeleton. These compounds and several sesquiterpene lactones isolated from this species seem to be of chemotaxonomic importance. The structures were elucidated by spectroscopic methods and a few chemical transformations including partial synthesis.     

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.     

Caffeic acid ester derivatives and flavonoids of genus Arnaldoa (Asteraceae,Barnadesioideae)

The phytochemical composition of Arnaldoa species is barely known. In this work, the occurrence of caffeic acid ester derivatives and flavonoids in A. argentea, A. macbrideana and A. weberbaueri was established by liquid chromatography associated to high-resolution mass spectrometry analyses and comparison with data from isolated compounds. The distribution of chlorogenic acids in the genus Arnaldoa is herein described for the first time. The metabolite profile of Arnaldoa species was compared to that of Tithonia diversifolia, a known and rich source of chlorogenic acids and sesquiterpene lactones. In addition to the mono- and dicaffeoyl quinic acids present in T. diversifolia, Arnaldoa species exhibited the mono- and dicaffeoyl tartaric acids. Furthermore, mass features correspondent to that of sesquiterpene lactones present in T. diversifolia were not observed in Arnaldoa species. The chemotaxonomic implications of caffeic acid ester derivatives and flavonoid glycosides, as well as the potential absence of sesquiterpene lactones in the genus Arnaldoa and subfamily Barnadesioideae are discussed.     

Eriolanolides,eudesmanolides and a rearranged sesquiterpene from Eriophyllum species

The investigation of two Eriophyllum species afforded, in addition to numerous known compounds, eight new sesquiterpene lactones related to eriolanin, two eudesmanolides and a new type of sesquiterpene alcohol. The structures were elucidated by spectroscopic methods and a few chemical transformations. The chemotaxonomic situation of this genus, the placement of which is still in doubt, is discussed briefly.     

Anticancer sesquiterpene lactones of Michelia compressa (magnoliaceae)

Investigation of the cytotoxic active components of Michelia compressa afforded two new cytotoxic sesquiterpene lactones, michelenolide and micheliolide. Parthenolide, costunolide, santamarine, reynosin and liriodenine were also isolated and exhibited cytotoxic activity. The known sesquiterpene lactones, lanuginolide and dihydroparthenolide, were isolated but were not active. Two other new inactive sesquiterpene lactones, compressanolide and dihydroreynosin, were also obtained. The structures of michelenolide and micheliolide were confirmed by partial synthesis from parthenolide and the structure of compressanolide by partial synthesis from dihydroparthenolide.     

Neue,abgewandelte pseudoguajanolide aus Psilostrophe villosa

Investigation of the North American species Psilostrophe villosa afforded, in addition to known compounds, five new sesquiterpene lactones, which all turn out to be modified pseudoguaianolides, most of them closely related to hymenolide. However, one of the lactones is a new type of nor-pseudoguaianolide. Furthermore a new monoacetylated borneol-β-D-glucoside is present. The chemotaxonomic situation is discussed briefly.     

Germacranolides from Lychnophora species

The investigation of three further Lychnophora species and the re-investigation of one species afforded, in addition to known compounds, seven new sesquiterpene lactones all being closely related to those isolated before from the subtribe Lychnophorinae. Furthermore, a new bisabolene diketone was present in one species. The structures were elucidated by spectroscopic methods. The chemotaxonomic situation of the genus is briefly discussed.     

Neue sesquiterpenlactone und thymol-derivate aus Inula-arten

The investigation of three Inula species affords, besides known compounds, two new sesquiterpene lactones and two new thymol derivatives. The chemotaxonomic situation in this genus is still very complicated.     

Pseudoguaianolides and other sesquiterpene lactones from Gaillardia species

The aerial parts of two Gaillardia species afforded in addition to known sesquiterpene lactones 23 new pseudoguaianolides, two dugaldiolide derivatives and two seco-neopulchellin derivatives. The structures were elucidated by spectroscopic methods. Biogenetic relationships are discussed briefly.     

Glaucolides from Vernonia fulta

Four sesquiterpene lactones were isolated from the aerial parts of Vernonia fulta. Spectral characterization showed that three were new and one was known (i.e. glaucolide-B). The biogenetic relationship among these sesquiterpene lactones is discussed briefly.     

A new type of germacranolide from Vernonia species

From several South African Vernonia species, a considerable number of sesquiterpene lactones has been isolated. Together with known compounds, seven members of a new type with an enol lactone ring have been found, their structures being elucidated by spectroscopic methods and some chemical transformations. Furthermore two new derivatives of costunolide are present in two species, and three new guaianolides have been found. From some species, however, no lactones could be isolated. Together with a new bisabolene derivative, a known eremophilone has been isolated, probably for the first time, from a member of the tribe Vernonieae.     

Weitere isocedren-derivate aus Trixis paradoxa

The investigation of two further species from the tribe Mutisieae afforded in addition to known compounds three new sesquiterpene lactones and two further sesquiterpene esters, all closely related to compounds isolated before from other Trixis species. The isolation of these new substances from Trixis further establishes the chemotaxonomic situation in the subtribe Nassauviinae. From the Dinoseris species, among others, 1β-hydroxyalantolactone was isolated, indicating a relationship to the subtribe Gochnatiinae.     

11β,13-Dihydroguaianolides from Artemisia douglasiana and a thiophene acetylene from A. schmidtiana

The aerial parts of Artemisia douglasiana afforded, in addition to some known sesquiterpene lactones, 22 new closely related guaianolides. A new thiophene acetylene was isolated from the aerial parts of A. schmidtiana together with some known sesquiterpene lactones. The structures were elucidated by high field ¹H NMR spectroscopy.     

Sesquiterpene lactones from the Genus brachylaena

The investigation of four Brachylaena species afforded in addition to known sesquiterpene lactones four new guaianolide glucopyranosides and three further derivatives of salonitenolide. The chemotaxonomic relevance of these findings is discussed briefly.