Guaianolides from Liatris squarrosa

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

Germacranolides related to chapliatrin from calea harleyi

The roots of Calea harleyi afforded four germacranolides closely related to chapliatrin and two derivatives of p-hydroxyacetophenone related to the acyloxycalefoliones.     

Two sesquiterpene lactones from Trichogonia gardneri

The structures and stereochemistries of two sesquiterpene lactones from Trichogonia gardneri were established as (6R,7S,8S,9S,IOR)-4E-9,10-dihydroxy-8-tigloxygermacr-4-en-6,12-olide) and (5R*,6R*,7S*,8S*,9R*)-14-acetoxy-3-chloro-9-hydroxy-2-oxo-8-tigloxyguia-1(10),3-dien-6,12-of olide by a combination of NMR spectrometry and X-ray diffraction. The results show that the structures of several sesquiterpene lactones which were isolated previously from related species require revision.     

Sesquiterpene lactones from Liatris acidota, L. Aspera and L. Mucronata

Examination of Liatris mucronata gave the known 15-hydroxylated heliangolides liscundin, liscunditrin, punctaliatrin and two new closely related heliangolides. Liatris acidota furnished six new similar but 15-deoxygenated heliangolides as well as euparin and 3β-acetoxytaraxaster-20-en-30-aldehyde. Liatris aspera gave a known glycosidic germacradienolide and a new germacradienolide as well as several known flavones and a known benzofuran. Structures were established by spectroscopic methods and chemical transformations.     

3-Germacren-612-olides,from an undescribed liatris taxon

A previously undescribed variant of Liatris gracilis whose taxonomic status is still uncertain furnished a series of 3-germacren-6,12-olides different from the chapliatrin analogues found in authentic L. gracilis. The stereochemistry of one of the new sesquiterpene lactones was established by X-ray diffraction. A eudesmanolide previously isolated from L. gracilis was also found in the variant.     

Three new 5,10-epoxygermacranolides from Liatris chapmanii and Liatris gracilis

Examination of Liatris chapmanii (T + G) Kuntze led to the isolation of two new germacranolides, chapliatrin (1a) and isochapliatrin (1b). Liatris gracilis Pursh gave chapliatrin and acetylchapliatrin 1c). The stereochemistry assigned to C-3, C-4 and C-10 is tentative. All three compounds possess the hitherto-unreported 5,10-oxygen linkage. L. gracilis also gave the benzofuran euparin (2) and the flavones hispidulin (dinatin, 3a and 3′,6-dimethoxy-4′,5,7-trihydroxyflavone (3b). L. chapimanii also gave 5-hydroxy-3′,4′,6,7-tetramethoxyflavone (3c).     

Sesquiterpene lactones and diterpenes from Mikania periplocifolia

The aerial parts of two collections of Mikania periplocifolia gave, in addition to mikanolide, miscandenin and several other known sesquiterpene dilactones related to them, the new dilactones 3β-hydroxy-11βH,13-dihydroisabelin, 11βH,13-dihydrodeoxymikanolide and mikaperiplocolide and three new geranylnerol derivatives.     

Deltoidin A and B,two new germacrolides from Eupatorium deltoideum

Investigation of E. deltoideum provided two new germacrolide-type sesquiterpene lactones, deltoidin A and B, besides the known guaianolide ligustrin, and diterpenes and triterpenes.     

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.     

Pseudoguaianolides related to confertin from Stevia isomeca

The aerial parts of Stevia isomeca afforded, in addition to known compounds, four new sesquiterpene lactones, three pseudoguaianolides related to stevin and a xanthanolide. The structures were elucidated by spectroscopic methods and a few chemical transformations.     

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.     

Elemanolides from Zinnia peruviana

Zinnia peruviana from Honduras afforded two new acetal-type elemanolides as well as a mixture consisting primarily of zinaflorin III.     

Germacranolides from Inula cappa

Authentic Inula cappa DC afforded a known and four unknown germacranolides related to the ineupatorolides as well as a new 2,3-dihydroxy-9-angeloxygermacra-4-en-6,12-olide. A collection previously described as Inula cappa which yielded only flavones was identified as Blumea balsamifera DC.     

Diterpenes and sesquiterpene lactones from Mikania congesta

The chloroform extract of the aerial parts of Mikania congesta, afforded four new geranylnerol derivatives, new analogs of deoxyelephantopin, a new melampolide and several known compounds. Structures were elucidated by spectroscopic methods and chemical transformations.     

New types of sesquiterpene lactones and other constituents from Trichogonia species

The investigation of five Trichogonia species afforded seven new furanoheliangolides, three dilactones of a new type, four pairs of epimeric rearra     

Guaianolides from Saussurea affinis

Cynaropicrin, 11βH-11,13-dihydrodesacylcynaropicrin, aguerins A and B, isoamberboin and the new guaianolides saussureolide and 11βH-11,13-dihydrodesacylcynaropicrin 8-β-d-glucoside were isolated from Saussurea affinis.     

Germacranolides from Melampodium americanum and Melampodium pilosum

Chemical analysis of Melampodium americanum yielded, besides the known melampodinin A, four new melampolides, melampodinin B, melampodinin C, 9-des     

Sesquiterpene lactones from Sonchus macrocarpus

Eight sesquiterpene lactones were isolated from the roots of Sonchus macrocarpus. The eudesmanolides 15-hydroxy-4β, 15-dihydroreynosin and 15-hydroxy-4β, 15, 11β, 13-tetrahydroreynosin were isolated for the first time.     

Germacranolides from Eupatoriastrum nelsonii

The aerial parts of Eupatoriastrum nelsonii afforded, in addition to known sesquiterpene lactones, four new lactones all closely related to the germacranolides isolated previously from other genera of the tribe Eupatorieae. The structures were elucidated by spectroscopic methods. Chemotaxonomic aspects are discussed briefly.     

Eudesmanolides from Pluchea dioscoridis

Reinvestigation of the aerial parts of Pluchea dioscoridis afforded, in addition to known compounds, five new eudesmanolides and a new thiophene derivative. The stereochemistry of one of the eudesmanolides isolated previously has been corrected. The structures were elucidated by spectroscopic methods.