Germacrene derivatives and other sesquiterpenes from Senecio species and Lordhowea insularis

From Senecio galpinii six new highly oxygenated germacrene derivatives were isolated, while S. coronatus afforded in addition to known cacalol derivatives two new ones. This species also contained a rare tricyclic sesquiterpene angelate, so far only isolated from one species. From the aerial parts of S. pleistocephalus an angelate derived from cadinene was isolated, while Lordhowea insularis (Benth.) B. Nord. afforded farnesyl angelate, which was reported previously. The structures were elucidicated mainly by high field ¹H NMR spectroscopy.     

Homogeranyl nerol derivatives and a melampolide from Smallanthus glabratus

The investigation of the aerial parts of Smallanthus glabratus from two locations afforded the same known compounds but some additional new compounds which were not present in both collections. From the first location typical melampolides, one of them not isolated previously, and two homoditerpenes were isolated. The material from the second location gave four closely related homoditerpenes and two geranyl nerol derivatives from which the homoditerpenes were derived. The structures were elucidated by high field ¹H NMR spectroscopy. Chemotaxonomic aspects are discussed briefly.     

Eudesman-12,8β-olides and other terpenes from Artemisia species

The aerial parts of Artemisia iwayomogi afforded, in addition to already known terpenes, eleven new cudesmanolides whereas four new guaianolides were found in A. gmelinii. No sesquiterpene lactones were detected in the aerial parts of A. santolinifolia which afforded two new nerolidol derivatives besides several other already known compounds. From A. caerulescens var. cretacea six eudesmanolides were isolated, one of which has not been reported previously. The structures were elucidated by high field ¹H NMR spectroscopy and chemical transformations. The chemotaxonomic significance of sesquiterpene lactones within the section Abrotanum and the subgenus Seriphidium is briefly discussed.     

Germacranolides from anvillea garcini

The aerial parts of Anvillea garcini afforded three germacranolides, two of which had not being isolated previously. The structures were elucidated by ¹H NMR spectroscopy. The configuration of 9-acetoxy parthenolide at C-9 has been revised.     

Sesquiterpenes and acetylenes from Argyranthemum adauctum ssp. jacobaeifolium

The roots of Argyranthemum adauctum ssp. jacobaeifolium, a rare endemic from Gran Canaria, afforded two new derivatives of the aromatic acetylene frutescin and 8-isovaleryloxymyrcene, while the aerial parts gave a new bisabolol derivative. Furthermore several known compounds were isolated. The structures were elucidated by high field ¹H NMR spectroscopy and a few chemical reactions.     

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.     

Further eudesmanolides and xanthanolides from Telekia speciosa

The re-investigation of the aerial parts of Telekia speciosa afforded five new sesquiterpene lactones, two eudesmanolides and three xanthanolides, all closely related to those isolated before from this species or from related genera. The structures were elucidated by ¹H NMR spectroscopy.     

2-Oxo-labda-8(17),13-dien-15-OL from Ophryosporus chilca

The aerial parts of Ophryosporus chilca afforded several prenylated p-hydroxyacetophenones, two labdane derivatives and a cinnamyl ester. Ophryosporus peruvianus also contains prenylated p-hydroxyacetophenones. Three compounds were isolated for the first time; their structures were established by ¹H NMR spectroscopy.     

11β,13-Dihydroguaianolides from Artemisia douglasiana and a thiophene acetylene from A. schmidtiana

The aerial parts of Artemisia douglasiana afforded, in addition to some known sesquiterpene lactones, 22 new closely related guaianolides. A new thiophene acetylene was isolated from the aerial parts of A. schmidtiana together with some known sesquiterpene lactones. The structures were elucidated by high field ¹H NMR spectroscopy.     

Olefinic and acetylenic butenolides from Peucedanum alsaticum

The lipophilic root extract of Peucedanum alsaticum afforded four highly unstable butenolides which could be separated by HPLC. Whereas the stereochemistry of three olefinic derivatives, previously isolated only as their methyl ethers, were now established by ¹H NMR, the structure of a new acetylenic lactone was additionally confirmed by ¹³C NMR. The compounds are probably formed by condensation of unsaturated C₁₈-acids with pyruvate.     

Zwei neue germacranolide aus Artemisia argentea

The aerial parts of Artemisia argentea afforded, in addition to known compounds (arborescin, artemetin, sitosterol and lirioresinol-B-dimethyl ether), two new germacranolides, closely related to ketopelenolide, also isolated from an Artemisa species. The structures were elucidated by intensive ¹H NMR studies and by some chemical transformations.     

Furanosesquiterpenes from Brachymeris montana

Brachymeris montana afforded several furanosesquiterpenes two of them not being isolated previously. The structures were elucidated by highfield ¹H NMR spectroscopy. The present isolation of these characteristic sesquiterpenes from one of the woody South African genera of the Anthemideae is of chemotaxonomic interest.     

Oxygenated nerolidol derivatives from Artemisia alba

From the aerial parts of Artemisia alba of Calabrian origin, five oxygenated nerolidol derivatives were isolated, two of them bearing hydroperoxyl groups. Structures were elucidated by spectral data and chemical reactions. Acetylation of the major hydroperoxyl constituent afforded a tris-nor aldehydic derivative as a result of loss of acetone from an unstable intermediate perester. An internally consistent set of ¹³C NMR assignments for the natural products and some derivatives is presented.     

Labdane derivatives from hemizonia species

The investigation of three Hemizonia species afforded in addition to known compounds seven new labdane derivatives, all derived from labd-13-en-15-ol. The absolute configuration of these diterpenes was determined by degradation of the triol by periodate cleavage, which afforded a known norditerpene ketone. From H. fitchii two new chromene esters and the cis-isomer of a known coumarate were isolated. H. congesta afforded in addition to labdane derivatives a hydroxycubebol.     

A further steiractinolide derivative from Spilanthes leiocarpa

The aerial parts of Spilanthes leiocarpa afforded, in addition to known compounds, a new eudesmanolide as well as two elemanolides which have both been isolated previously. Careful ¹H NMR investigation showed that the configuration of one of these isomeric lactones has to be corrected.     

Characteristic lindenane sesquiterpenoid dimers and labdane diterpenoids from Chloranthus serratus

Chemical investigation on the roots of Chloranthus serratus (Chloranthaceae) afforded 11 terpenoids, including four lindenane-type sesquiterpenoid dimers (1–4), and seven labdane diterpenoids (5–11). The structures of these terpenoids were established by spectroscopic analysis (MS, ¹H, and ¹³C NMR). Compounds 4–11 were isolated from C. serratus for the first time. The chemotaxonomic significance of the isolated compounds was summarized herein.     

Sesquiterpene lactones of Neohintonia monantha

The aerial parts of Neohintonia monantha afforded a new liacylindrolide derivative, in addition to liacylindrolide itself which was previously isolated from Liatris cylindracea. The structures were elucidated by spectroscopic methods.     

Tetrahydrofuran-type terpenoids from Tanacetum vulgare

Investigation of a rare genotype of Tanacetum vulgare afforded a series of tetrahydrofuran-type terpenoids, whose pattern was different in flowers and leaves. The major constituent of the flowers was the trans Δ^3,4-hydroperoxide of davanone, whereas the leaves gave mostly a peroxyhemiketalic compound resulting from the intramolecular cyclization of the cis Δ^3,4-hydroperoxide of davanone. Structures were elucidated by spectral data and chemical reactions, including correlation with natural (+)-davanone. The peroxyhemiketalic compound upon acylation of its hydroxyl group gave an instantaneous complex reaction, resulting in the formation of a β-acyloxyenone and loss of one molecule of acetone. Among the minor constituents of the leaves, a C-10 carboxylic acid biogenetically related with davanone was isolated.     

Four new cis,cis-germacranolides from cytotoxic fractions of Melampodium cinereum

The aerial parts of Melampodium cinereum afforded an antineoplastic crude extract from which, besides the known dilactones cinerenin and melampodin B, four new cis-1(10)-cis-4,5- germacranolides, melcanthins DG, were isolated from cytotoxic fractions.     

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.