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.     

New guaianolides from Pseudostifftia kingii

Pseudostifftia kingii afforded several guaianolides, two of them not isolated before.     

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.     

Highly oxygenated guaianolides from Bishopanthus soliceps

In addition to known compounds several highly oxygenated guaianolides and eudesmanolides, derived from 1β-hydroxyarbusculin A, were isolated from the aerial parts of Bishopanthus soliceps, a member of a new genus of the tribe Liabeae.     

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.     

Four guaianolides,a eudesmanolide and a germacranolide from Ursinia saxatilis

An investigation of Ursinia saxatilis afforded in addition to known compounds a new eudesmanolide derived from ursialpinolide, a germacranolide rel     

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.     

Two guaianolides from calea solidaginea

The isolation and structure elucidation of two new guaianolides, solidaginolides A(1) and B(5), from Calea solidaginea are reported. The structures of the new compounds were established by spectroscopic methods.     

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.     

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.     

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 related to arborescin from Artemisia adamsii

The aerial parts of Artemisia adamsii afforded, among several known compounds, arborescin as the main constituent. Furthermore, 11 new guaianolides, all related to arborescin, were present in minute quantities. The structures were elucidated by spectroscopic methods and the biogenetic relationships are discussed briefly.     

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.     

Guaianolides from Ainsliaea fragrans

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

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.