Two guaianolides from cichorium pumilum

The roots of Cichorium pumilum afforded two new guaianolides, 10β-hydroxyguaia-4,13-dien-6,12-olide and the corresponding 11β,13-dihydro derivative which could be separated only after transforming the methylene lactone into the corresponding pyrazoline. The structures were elucidated by 400 MHz ¹H NMR spectroscopy. The chemotaxonomic situation is discussed briefly.     

Seven guaianolides from the tribe vernonieae

Investigation of six species, all belonging to the Vernonieae, afforded in addition to known compounds seven new guaianolides five of them related to eremanthine, one of the lactones which may be typical of the tribe. The structures were elucidated by spectroscopic methods. Chemotaxonomic aspects are discussed briefly.     

Dimeric guaianolides from Artemisia sieversiana

The aerial parts of Artemisia sieversiana afforded in addition to known compounds five new guaianolides and four dimeric guaianolides, three of them closely related to absinthin and one derived from estafiatin as a monomer. The structures were elucidated by extensive NMR studies, which allowed the assignment of the 14 chiral centres. Artemisia frigida afforded several known compounds and one new guaianolide, 8-desoxy-cumambrin B, the most likely precursor of many guaianolides.     

Six guaianolides from Stylotrichium rotundifolium

The investigation of Stylotrichium rotundifolium afforded the epoxide of β-sesquiphellandrene, a new derivative of geranylnerol and six guaianolides not isolated previously. Furthermore, two germacranolides also present in a Lasiolaena species and several known compounds were isolated. The structures were elucidated by detailed ¹H NMR investigations. The chemotaxonomic situation is discussed briefly.     

New germacranolides,guaianolides and rearranged Guaianolides from Lasiolaena santosii

The aerial parts of L. santosii afforded three new diterpenes, a phenylpropanol, three eudesmane derivatives, three germacranolides, seventeen guaianolides and four rearranged guaianolides of a, so far, unknown type. Furthermore, several known compounds were isolated. The structures of the new compounds, the separations of which caused difficulties, were elucidated by spectroscopic methods and by some chemical transformations. The chemotaxonomic situation is discussed briefly.     

Four guaianolides and other constituents from three kaunia species*

The investigation of three species of the new genus Kaunia afforded four new guaianolides and four thymol derivatives. The structures were elucidated by spectroscopic methods. The chemotaxonomic situation is discussed briefly.     

Zoapatanolides C and D,two guaianolides from Montanoa tomentosa

Further investigation of Montanoa tomentosa afforded two new guaianolides as well as the known pumilin and the previously isolated heliangolide zoapatanolide A. The structures were established on the basis of spectroscopic studies and chemical evidence.     

Three bourbonenolides and other sesquiterpene lactones from two vernonia species

A re-investigation of V. arkansana afforded several new sesquiterpene lactones, three bourbonenolides, obviously closely related to those isolated from this plant previously, a glaucolide and a methoxy derivative most probably formed by fragmentation of the corresponding bourbonenolide. From V. profuga in addition to known lactones a new guaianolide was isolated. The biogenetic relationships of the Vernonia sesquiterpene lactones are discussed briefly.     

Sesquiterpenes,guaianolides and diterpenes from Stevia myriadenia

The investigation of Stevia myriadenia afforded in addition to known compounds a new clerodane and a labdane derivative, two guaianolides, a bisabolene and a germacrene derivative. The structures were elucidated by spectroscopic methods. The chemotaxonomic situation is discussed briefly.     

Guaianolides from Centaurea kotschyi

The aerial parts of Centaurea kotschyi (var. kotschyi) afforded, besides three known sesquiterpene lactones, a new derivative of linichlorin B.     

Guaianolides from Tricholepis glaberrima

Cynaropicrin and 11,13-dihydrodesacylcynaropicrin were isolated from Tricholepis glaberrima.     

Guaianolides from Ainsliaea fragrans

Five sesquiterpene lactones were isolated from Ainsliaea fragrans, two of them being new.     

Guaianolides from Taeckholmia species

The investigation of four Taeckholmia species afforded in addition to known desacylcynaropicrin, two new guaianolides. The structures were elucidated by spectroscopic methods and chemical transformations. The chemotaxonomy is discussed briefly.     

Guaianolides from elephantopus carolinianus

The roots of Elephantopus carolinianus afforded two guaianolides as well as two known elephantopin derivatives which were the main constituents of the aerial parts.     

A guaianolide from Centaurea behen

The aerial parts of Centaurea behen afforded in addition to known lactones a new derivative of solstitialin A.     

2-Acetoxy-3α,4α-epoxy-3,4-dihydrokauniolide from grosvenoria coelocaulis

The aerial parts of Grosvenoria coelocaulis gave the known guaianolides dehydroleucodin, desacetoxymatricarin, kauniolide and a new one, 2β-acetoxy-3α,4α-epoxy-3,4-dihydrokauniolide.     

Guaianolides from the leaves of Centaurea incana

Six guaianolides have been isolated from the aerial parts of Centaurea incana from Algeria. They were identified as desoxyrepin, repin or subluteolide, repin monochlorhydrin, acroptilin, janerin and repdiolide triol.     

Germacranolides from Stilpnopappus species

The investigation of four Stilpnopappus species afforded in addition to known compounds seven new germacranolides, all related to glaucolides. The structures were elucidated by spectroscopic methods. The chemotaxonomy of the genus is discussed briefly.