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.     

Dimeric guaianolides and other constituents from Gochnatia species

The roots of Gochnatia polymorpha afforded two new bisabolene derivatives and four dimeric guaianolides, two of them being isolated previously from G. paniculata. The aerial parts gave two further dimeric guaianolides. The aerial parts of G. hypoleuca afforded three new germacran-8,12-olides, a germacranolide acid and four additional dimeric guaianolides, which may be characteristic for this genus, while the presence of oxygenated germacranolides seems to be typical for the whole subtribe.     

The first sesquiterpene lactones esterified with a sesquiterpenic acid

From Hypochoeris glabra two guaianolides esterified with an unusual sesquiterpenic acid were isolated. Proton-catalysed rearrangement of the cyclopropane derivative led to a phenolic acid. The structures were elucidated by high-field ¹H NMR spectroscopy. Further guaianolides were isolated from H. uniflora and Lactuca floridana. These structures were elucidated by spectroscopic methods. The chemotaxonomic situation in the tribe is discussed briefly.     

Sesquiterpene lactones of eupatorium anomalum and eupatorium mohrii

Several new guaianolides and the previously known heliangolide eurecurvin have been isolated from Eupatorium anomalum. Eupatorium mohrii also yielded three of the new guaianolides together with eurecurvin and a new germacradienolide. The implications of these findings are discussed.     

A new guaianolide glucoside from aerial parts of Lactuca aculeata

From aerial parts of Lactuca aculeata one new and ten known sesquiterpene lactone aglycones and glycosides were isolated, including four lactucin-type guaianolides, six costus lactone-type guaianolides and one melampolide-type germacranolide. The structure of the new compound was determined as 11β-hydroxycrepidiaside B by high resolution mass spectrometry and 1D- and 2D-NMR spectroscopy.     

Dehydrocostuslactone and plant growth activity of derived guaianolides

The stereostructures of two new guaianolides, isodehydrocostuslactone and isozaluzanin C, isolated previously from Saussurea lappa, have been confirmed by their correlation with dehydrocostuslactone. Twenty new derivatives have been synthesized from these guaianolides and these have been tested as plant growth regulators. The conjugated lactones which have an exocyclic methylene group at C-4 conjugated with a C-3 ketone, show distinct enhancement in their root-forming potential, as compared with their 3-deoxy derivatives. Of further significance is the fact that these ketones display maximum activity only at lower concentrations. Other compounds show the expected structure-biological activity relationships displayed in general by guaianolides. However, the presence of an epoxide at the C-3, C-4 position does not affect the biological activity, which is indeed the case when the epoxide group occupies the C-4, C-14 position in guaianolides. The major biological parameter studied was rooting in-stem cuttings of Phaseolus aureus.     

Further guaianolides and 5-alkylcoumarins from gutenbergia and bothriocline species

From Gutenbergia marginata ten new guaianolides were isolated. Two guaianolides isolated previously from Erlangea inyangana are identical with two further lactones and their structures have been revised. From Bothriocline ripensis ethulia coumarin and two further 5-alkylcoumarin derivatives, one being a chromone, were isolated, while B. longipes and B. eupatorioides gave nine 5-alkylcoumarins and two related compounds. The structures were elucidated by highfield NMR techniques and a few chemical transformations.     

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.     

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.     

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.     

Guaianolides from Gochnatia smithii

The structure and stereochemistry of 8α-acetoxy and 8α-tigloyloxy dehydrocostus lactones, two guaianolides isolated from the aerial parts of Gochnatia smithii, were established by chemical and spectroscopic methods.     

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 Liatris squarrosa

The isolation of three new guaianolides related to spicatin from Liatris squarrosa is reported.     

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 guaianolides from Pseudostifftia kingii

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

Guaianolides from Acroptilon repens

Two new guaianolides have been isolated from the aerial parts of Acroptilon repens.     

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.     

Neue elemanolide und guajanolide aus Zinnia-arten

The investigation of three Zinnia species afforded thirteen new elemanolides. Though these compounds could be separated only in part, the spectroscopic data clearly indicate the proposed structures. Furthermore, four new guaianolides were isolated. The chemotaxonomic situation is discussed briefly.     

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.     

Eudesmanolides,guaianolides, germacranolides and elemanolides from Zinnia species

The investigation of six Zinnia species afforded in addition to already known compounds two eudesmanolides, five guaianolides, three germacranolides, five elemanolides and a dihydroxygeranylgeraniol. The structures were elucidated by spectroscopic methods and some chemical transformations. The chemotaxonomic situation is discussed briefly.