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.     

Germacranolides in Helianthus mollis

Desacetyleupaserrin, eupaserrin and two new germacranolides, mollisorin-A and mollisorin-B, were isolated from H. mollis. ¹H NMR and ¹³C NMR data and chemical interconversions of the four germacranolides are described.     

Sesquiterpene lactones of Artemisia arbuscula and A. tridentata

Chloroform extracts of Artemisia tridentata ssp. vaseyana f. spiciformis (Osterhout) Beetle and Artemisia arbuscula Nutt. ssp. arbuscula gave identical TLC patterns and contained the known germacranolides tatridin-A (I) and tatridin-B (II), and two new germacranolides deacetyllaurenobiolide (III) and spiciformin (IV). The structures of these lactones were shown through spectral studies and chemical transformations. Deacetyllaurenobiolide was converted to the known germacranolide laurenobiolide (IIIb) and spiciformin (IV) was synthesized from deacetyllaurenobiolide along with an isomeric epoxy lactone (V).     

Millerenolides,sesquiterpene lactones from Milleria quinqueflora

The aerial parts of Milleria quinqueflora afforded 17 new germacranolides (five melampolides and 12 millerenolides), two ent-pimarene and two ent-kaurene derivatives as well as two alicyclic diterpenes and a galactoside. The structures were elucidated by NMR spectroscopy. The chemotaxonomic situation is discussed.     

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.     

Germacranolides from Mikania grazielae

Mikania grazielae afforded two new germacranolides which were identified as 2α-acetoxyeupatolide and 2α-acetoxylaurenobiolide.     

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.     

Sesquiterpene lactones from helogyne hutchisonii

The aerial parts of Helogyne hutchisonii afforded, in addition to known sesquiterpene lactones, two new heliangolides and two germacranolides. The structures were elucidated by high-field ¹H NMR spectroscopy.     

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 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.     

Further sesquiterpene lactones from Calea and Viguiera species

The aerial parts of Calea clematidea gave three new germacranolides, those of Viguiera procumbens two orizabin derivatives and those of V. linearis dihydrobudlein A. In addition to these lactones, several known ones were isolated.     

Germacranolides,calbertolides A,B and C,from Calea berteriana

The isolation and structure elucidation of two germacranolides, calbertolides A and B, and a heliangolide, calbertolide C, from Calea berteriana are reported. The structures of the new compounds were established by spectroscopic methods.     

Germacranolides and an alkyl glucoside from Tanacetum vulgare

The aerial parts of Tanacetum vulgare afforded two new germacranolides and an n-decyl glucoside. The structures have been elucidated by spectroscopic methods and chemical transformations.     

Sesquiterpene lactones from Helianthus niveus subsp. niveus

Six germacranolides, tirotundin, tagitinin A. orizabin, 8β,14-dihydroxycostunolide and its 14-isobutyrate, and 4β,5-dihydrotagitinin C, were isolated from aboveground parts of Helianthus niveus subsp. niveus. The last two compounds are new.     

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.     

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.     

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.     

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.     

Germacranolides from Piptolepis Ericoides and Vanillosmopsis species

The aerial parts of Piptolepis ericoides afforded in addition to known compounds two new germacranolides, a zexbrevanolide and piptolepolide, tentatively characterized as a germacranolide with a trans-disubstituted double bond. From the aerial parts of two Vanillosmopis species in addition to goyazensolide, a new isomer with an exocyclic double bond was isolated.