New germacranolides and other sesquiterpene lactones from Dicoma species

Two subspecies of Dicoma anomala afforded, in addition to known compounds, an eudesmanolide, a guaianolide and four germacranolides, the latter being closely related 8, 12-lactones. D. schinzii gave three new germacranolides and D. zeyheri a pair of isomeric acetylenic compounds. The structures were elucidated by highfield ¹H NMR spectroscopy. The chemotaxonomic situation of this genus is discussed briefly.     

Five germacranolides from Gochnatia discoidea

The investigation of two further Gochnatia species afforded five new germacranolides, all being 8,12-lactones. The structures were elucidated by intensive ¹H NMR studies and by some chemical transformations. The chemotaxonomic aspects are discussed briefly.     

Germacranolides from Dicoma tomentosa

An investigation of the aerial parts of Dicoma tomentosa afforded four new germacranolides and four melampolides together with urospermal A and its 11β,13-dihydroderivative. The structures were elucidated by spectroscopic methods. The chemotaxonomic situation is discussed briefly.     

Two new germacranolides from Onopordon leptolepis

The investigation of the aerial parts of O. leptolepis afforded, in addition to a known polyynaldehyde and onopordopicrin, two further germacranolides. The structures are elucidated by spectroscopic methods and by conversion to the corresponding acetates.     

New germacranolides from Inula heterolepis

The aerial parts of Inula heterolepis afforded two new germacranolides and a new eudesmanolide, all closely related to haageanolide, which was also isolated.     

Additional germacranolides from Eupatorium serotinum

The aerial parts of Eupatorium serotinum afforded in addition to compounds reported previously three new germacranolides.     

New germacranolides from Liatris species

Three closely related cis-Δ⁴-diepoxygermacranolides were isolated from two Liatris species. Structures of eleganin from L. elegans (Walt.) Michx, and liscundin and liscunditrin from L. secunda (Ell.) Small. were established by NMR spectrometry, chemical transformations and correlation with punctaliatrin previously isolated from L. punctata Hook. Reinvestigation of the latter species yielded another germacranolide liatripunctin whose structure is reported.     

Melampolides and other germacranolides from Blainvillea dichotoma

The aerial parts of Blainvillea dichotoma afforded, in addition to known compounds, seven new sesquiterpene lactones, four related to elephantin, two melampolides and a further cis,cis-germacranolide. The chemotaxonomic situation is discussed briefly.     

Seven germacranolides and four eudesmanolides from Tithonia rotundifolia

The aerial parts of Tithionia rotundifolia afforded, in addition to two known sesquiterpene lactones, eleven new ones, seven germacranolides and four eudesmanolides. The structures were determined by ¹H NMR spectroscopy.     

Further ineupatorolide-like germacranolides from Inula cuspidata

The aerial parts of Inula cuspidata afforded in addition to known compounds five germacranolides closely related to ineupatorolide A. Furthermore,     

New germacranolides and other constituents from Trichogoniopsis morii

Trichogoniopsis morii afforded, in addition to known compounds, a new toxol derivative, two diterpenes, a labdane and an ent-kaurane derivative, an eudesmanolide and five germacranolides, a furanoheliangolide and four 1-oxo-germacranolides. The structures were elucidated by spectroscopic methods and a few chemical transformations. The chemotaxonomy of the genus Trichogoniopsis is discussed briefly.     

11,13-Dehydroeriolin,schkuhrioidin and schkuhriolid,germacranolides from Schkuhria species

The isolation is reported of the new germacrolide, 11,13-dehydroeriolin, the new melampolide schkuhrioidin and schkuhriolide from Schkuhria schkuhrioides. 11,13-Dehydroeriolin is also a constituent of S. virgata. The structure and stereochemistry of the new compounds were established on chemical and spectroscopic grounds.     

Isoalantolactone derivatives and germacranolides from Blumea densiflora

The germacranolides tagitinin A and tirotundin ethyl ether and a series of new ring A-hydroxylated isoalantolactone derivatives were isolated from Blumea densiflora. Structures were established by spectroscopic methods and 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.     

Three germacranolides and other constituents from Eremanthus species

The re-investigation of Eremanthus glomerulatus afforded three new germacranolides and a guaianolide, while from E. mollis two known furanoheliangolides and a new phenylpropanol derivative were isolated. The germacranolides most probably are precursors of the widespread glaucolides. The structures were elucidated by spectroscopic methods. The chemotaxonomic situation is discussed briefly.     

Modified eudesmanolides and other sesquiterpene lactones from Wunderlichia mirabilis and Actinoseris polymorpha

Re-investigation of Wunderlichia mirabilis afforded three new modified eudesmanolides of the same type isolated previously from an Onoseris species, and minute amounts of a germacranolide for which a structure only could be proposed. Actinoseris polymorpha also contained a new germacranolide, the angetate of desacetyllaurenobiolide. Structures were elucidated by spectroscopic methods and by some chemical transformations. The significance of these findings is discussed briefly.     

New germacranolides from Isocarpha species

The investigation of two Isocarpha species has yielded eight new germacranolides most of them belonging to the heliangolides. In addition to known p-hydroxyacetophenone-derivatives, a new dihydroeuparine derivative was isolated. The chemotaxonomical aspects are discussed.     

The germacranolides of Viguiera buddleiaeformis structures of budlein-A and -B

The structure of budlein-A, the main sesquiterpene lactone of Viguiera buddleiaeformis was established as the 8 angeloyl ester of 1 keto, 8-β, 14-dihydroxy germacra-2,4,11 (13)-trien-3, (10 β) oxido-6 α, 12-olide. Its structure and stereochemistry was determined by chemical and spectroscopic means. Budlein-B, found in the same plant as a minor constituent, is 8 α, 15-dihydroxygermacra-1 (10), 4, 11 (13)-trien-6 α, 12-olide.     

New sesquiterpene lactones from Inula species

An investigation of Inula helenium, I. royleana, I. salicina and I. bifrons afforded in addition to known sesquiterpene lactones 20 new lactones, the eudesmanolides 3, 6 and 8–12, the germacranolides 14–18 and 20–22, the guaianolides 23 and 25, the pseudoguaianolide 26, the xanthanolides 28 and 32 and the cyclopropane analogue 30. Structures and configurations of these new compounds were established by extensive PMR studies and by some chemical transformations. Some of the investigated species contain besides the widely distributed pentaynene 33 several known thymol derivatives together with a new one (40).     

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.