Sesquiterpene lactols from Laserpitium halleri

Three new pairs of anomeric sesquiterpene lactols have been isolated from the roots of Leserpitium halleri. They were obtained in pure form only after methylation of the hemiacetalic hydroxyl group, which resulted in the exclusive formation of only one methyl ketal from each pair of anomers. The stereochemistry at the ketalic centre of the methyl derivatives was assessed by correlation with methylhallerin, a compound of known configuration.     

Sesquiterpene lactones from Inezia integrifolia

Inezia integrifolia afforded, in addition to known compounds, three new eudesmanolides and a guaianolide. Two of the eudesmanolides were obtained as a mixture. The relative position of the ester groups could not be determined with certainty. The chemotaxonomy is discussed briefly.     

Sesquiterpene lactones from Lactuca sativa

The aerial parts of Lactuca sativa afforded lactucin, 1 11β,13-dihydrolactucin, lactupicrin, a new melampolide and 3β,14-dihydroxy-11β,13-dihydrocostunolide.     

Sesquiterpene lactones from Calea leptocephala

Chemical analysis of Calea leptocephala yielded seven sesquiterpene lactones three of which had not been previously reported as natural products. The new compounds were represented by a furanoheliangolide, 8β-angeloyloxy-9α-acetoxycalyculatolide, the germacranolide desacetylcalein A, and a guaianolide, 8β-angeloyloxyleptocephalide. The structures of the new compounds were established by spectroscopic methods.     

Sesquiterpene lactones from Achillea micrantha

The aerial parts of Achillea micrantha afforded the eudesmanolides santamarin, reynosin, dihydrosantamarin, dihydroerynosin and the germacranolides artemorin, gallicin, dihydroparthenolide as well as a new one, dihydroparthenolide bisepoxide. The structures were elucidated by spectroscopic data.     

Sesquiterpene lactones from Carphochaete bigelovii

Five sesquiterpene lactones with C₁₀-diester side-chains have been identified as major constituents of a leaf surface extract of Carphochaete bigelovii. The structures were elucidated by spectroscopic methods and are reported for the first time. Chemosystematic implications are discussed briefly.     

Sesquiterpene lactones from Viguiera hypargyrea

The new sesquiterpene lactones 8β-[epoxyangeloyloxy]-14-hydroxytithifolin and 8-[epoxyangeloyl]-14-acetoxy-eupatolide, were isolated from Viguiera hypargyrea. The structures were established by chemical and spectroscopic means. The chemotaxonomic implications of the chemical constituents of Viguiera are briefly discussed.     

Sesquiterpene lactones from Centaurea tweediei

Aerial parts of Centaurea tweediei from Argentina afforded as the main constituent the sesquiterpene lactone onopordopicrin and minor amounts of a new heliangolide, a new guaianolide, a new eudesmanolide, a new eudesmane acid and the lignans arctigenin and matairesinol.     

Sesquiterpene lactones from leucanthemopsis pulverulenta

From Leucanthemopsis pulverulenta, two guaianolides, 8α-hydroxyestafiatin and epiligustrin, and one 4,5-cis-germacranolide, named pulverulide, have been isolated. Epiligustrin and pulverulide are new natural compounds.     

Sesquiterpene lactones from Chrysanthemum coronarium

The flower heads of Chrysanthemum coronarium afforded a new sesquiterpene lactone, dihydrocumambrin A, in addition to the known cumambrin A.     

Sesquiterpene lactones from Syncretocarpus sericeus

The aerial parts of Syncretocarpus sericeus afforded in addition to known compounds a new heliangolide. The chemistry supports the placement of thi     

Sesquiterpene lactones from pyrethrum flowers

Three new sesquiterpene lactones of the germacranolide-type [(11R)-11,13-dihydrotatridin-A, (11R)-11,13-dihydrotatridin-B and (11R)-6-O     

Sesquiterpene lactones from Tithonia rotundifolia

A chemical investigation of Tithonia rotundifolia afforded seven new sesquiterpene lactones in addition to three known ones. The structures of the new compounds 3-acetyl-15-hydroxyleptocarpin, 15-hydroxyleptocarpin and tirotundifolins A, B, C, D and E were established by spectroscopic and chemical means.     

Sesquiterpene lactones from Artemisia maritima

Two new sesquiterpene lactones have been isolated from Artemisia maritima and the structures have been assigned on the basis of their spectral properties as 1-oxo-6β,7α,11βH,14β-methylgermacra-4(5)-ene-12,6-olide and 1-oxo-6β,7α,11βH-germacra-4(5),10(14)-dien-12,6-olide.     

Sesquiterpene lactones from Perityle vaseyi

The well-known germacrolide, eupatoriopicrin, and two additional sesquiterpene lactones, were isolated from Perityle vaseyi. The latter two lactones, one a novel guaianolide and the other a known germacrolide, both contain unusual ten carbon diester side chains attached at C-8. The chemical evidence, in conjunction with morphological data, suggest that Perityle, and hence the subtribe Peritylinae, should be placed in the tribe Heliantheae.     

Sesquiterpene lactones from Artemisia argentea

The aerial parts of Artemisia argentea afforded, in addition to arborescin and argentiolides A and B, one new ketopelenolide derivative named deacetylargentiolide B and some previously unreported guaianolides.     

Sesquiterpene lactones from Vernonia marginata

A reinvestigation of the polar fraction from Vernonia marginata afforded in addition to marginatin 13 new lactones, including six glaucolides, four closely related lactones with a new carbon skeleton, named vernomargolides, two jalcaguaianolides and a pseudoelephantopide, as well as a methyl ester probably derived from a glaucolide. The structures were elucidated by NMR spectroscopy and the stereochemistry was established by NOE difference spectroscopy. Possible biogenetic relationships are discussed briefly.     

Sesquiterpene lactones from Parthenium tomentosum

Four populations of Parthenium tomentosum var. tomentosum were examinated. In addition to the known lactones, ivalbatine, acetyl ivalbatine, parthomentine, incanine and ligulatine C, three new pseudoguaianolides: 4-O-desacetyl ligulatine C; 1-dehydroperuvinine and parthoximentine were also isolated. Chemical and spectroscopic methods were used for their structural determination.