Neue sesquiterpenlactone aus Aster umbellatus

The investigation of Aster umbellatus afforded six new eudesmanolides and a new selina-triene and from Aster exilis a new tremetone derivative was isolated. The structures were elucidated by spectroscopic methods and by some chemical transformations. The chemotaxonomic situation is discussed briefly.     

Neue C10-säureamide,furanoeremophilane und andere inhaltsstoffe aus bolivianischen Senecio-arten

The investigation of seven Bolivian Senecio species afforded in addition to known compounds five new furanoeremophilanes, two C₁₀-amides, a new isoeugenol ester and the isomer of pterophorin. The structures are elucidated mainly by spectroscopic methods. While most of the new compounds are closely related to those isolated before from Senecio species, four of them are unusual. Another is a new type of a furanoeremophilane; its biogenesis however, can be explained easily from known types.     

Ein neues germacren-derivat sowie ein diterpenmalonat aus Baccharis-arten

The investigation of the aerial part of B. scandens afforded a new ketone, a germacrene derivative. The aerial parts of B. tricuneata var. lineata yielded, in addition to known ent-clerodane derivatives, a malonate of a further diterpene of this type. The structures are elucidated by spectroscopic methods.     

Eudesmane derivatives from Verbesina species

The investigation of seven Verbesina species afforded, in addition to known compounds, several new eudesmane and germacrane derivatives, all bearing a cinnamate or derivatives as residue. Furthermore, a new bisabolene aldehyde and two acetophenone derivatives were isolated. The structures were elucidated mainly by spectroscopic methods and some chemical transformations. The chemotaxonomic situation is discussed briefly.     

Neue diterpene aus Gnaphalium-arten

The investigation of Gnaphalium undulatum afforded two new labdane derivatives, one having a new carbon skeleton, and a new flavonol. Furthermore, an unknown diterpene lactose is present; its structure, however, could not be elucidated. The only American species investigated contains the trans-isomer of the precursor of the acetylenic chloroenol ether, which is widespread in Gnaphalium and in related genera. The chemotaxonomic situation is discussed briefly.     

Neue germacranolide aus Calea urticifolia

The investigation of Calea urticifolia afforded eight new germacranolides. While five are heliangolides, three are of a new type and have some unusual structural features. The structures are elucidated by extensive ¹H-NMR studies and some chemical transformations. In addition, a new isoeugenol and an unusual phloroglucinol derivative were isolated; the structure of the latter could only be established after some chemical transformations. Other Calea species contain typical C₁₇ acetylenes only, also present in other species of the subtribe Galinsoginae. So far, the results on Calea indicate that the genus is chemically heterogenous.     

Chromones and flavans from Marshallia obovata

An investigation of Marshallia obovata afforded, in addition to known thymol derivatives, one new ester. Furthermore six new chromone derivatives, all prenylated, were present together with the known spathelia chromene. The main constituent was a flavan already isolated from M. grandiflora but five new flavans were also isolated. Besides other widespread compounds a tetraester of inositol was isolated in minute amounts. All the structures were elucidated by spectroscopic methods or chemical transformations. Surprisingly, even the main 4-methoxyflavan could be split by periodic acid.     

Einige neue furanoeremophilane aus Senecio-Arten

The investigation of two varieties of the South African S. hypochoerideus affords, besides known compounds, six new furanoeremophilanes and a pimarene-derivative. By contrast, S. greyi has yielded two further new furanoeremophilanes and a new eremophilene. These structures are elucidated mainly by spectroscopic methods. Chemotaxonomic aspects are briefly discussed.     

Neue ent-atisiren- und ent-kaurensäure-derivate aus Helianthus-arten

The investigation of four Helianthus species afforded, in addition to known compounds, four new atisirenic acid derivatives, a new ent-kaurenic acid derivative, three new labdane derivatives and an unknown C₁₅-acetylenic compound. The structures of the diterpenes were elucidated by intensive NMR studies and some chemical transformations. An unusual fragmentation in the mass spectra of the atisirenes is discussed briefly.     

Ein neues clerodan-derivat sowie weitere inhaltsstoffe aus der gattung Macowania ag

The roots of M. corymbosa afford three new benzofuran derivatives very closely related to leysseralangelicate isolated from the related genus Leyssera. The aerial parts of M. glandulosa contain, besides labdanolic acid, a new cis-clerodane derivative, its structure being elucidated by spectroscopic methods and by chemical reactions. The roots of a further Macowania species closely related to M. hamata afford a new ester related to m-thymol.     

Weitere hirsutinolide aus Vernonia-arten

The investigation of two Bolivian Vernonia species afforded, in addition to known compounds, five further enollactones of the hirsutinolide type and a new hydroxyzaluzanine. The structures were elucidated by intensive ¹H NMR studies and some chemical transformations. The results show again that the hirsutinolides are probably of chemotaxonomic importance in the large genus Vernonia.     

Chemical constituents from Neopestalotiopsis clavispora culture medium with estrogenic effects in MCF-7 cells

Estrogen is a vital hormone responsible for the development of the female reproductive system. Hence, estrogen deficiency in menopause increases various symptoms. This study aimed to discover biologically active compounds from an EtOAc-extract of Neopestalotiopsis clavispora culture medium which has previously shown estrogenic activity. A new α-pyrone (1) and a new tetramic acid derivative (2), together with hymenosetin (3) and pestalotiollide B (4), were isolated from the extract. The chemical structures of the new compounds were elucidated using MS and NMR spectroscopy, and the absolute configurations were established by quantum mechanical calculations of electronic circular dichroism and gauge-including atomic orbital NMR chemical shift, followed by DP4 + analysis. The isolated compounds were initially tested for their estrogenic activities using MCF-7 estrogen responsive human breast cancer cells. Hymenosetin (3) showed estrogenic activity by increasing the proliferation of MCF-7 cells at the concentration of 2.5 μM via the phosphorylation of estrogen receptor-α.     

Neuartige sesquiterpenlactone und neue acetylenverbingen aus Athanasia-arten

The investigation of two further South African Athanasia-species afforded, in addition to known compounds, sixteen new ones, ten guaianolides, an eudesmanolide, three sesquiterpenes, a new enediynene and a phenylpropane derivative. The structures were elucidated by extensive NMR-studies. Three of the lactones are very unusual in having an endoperoxide bridge; their structures, however, were elucidated only indirectly. These further chemical results on Athanasia again add support to the idea that these species might be better placed in the genus Pentzia.     

Neue sesquiterpene aus Liabum-arten

The reinvestigation of the roots of Liabum eggersii afforded, in addition to compounds reported before, several sesquiterpene hydrocarbons with unusual carbon skeletons and the first derivative of the propellane modhephene which itself is also present. The roots of L. floribundum contain a tricyclic sesquiterpene with three five-membered rings. This ketone most probably is a derivative of the sesquiterpene silphiperfolene. The structures of the new compounds were elucidated by extensive NMR studies and by some chemical transformations. Two further species only afforded known compounds. The chemotaxonomic situation is discussed briefly.     

Neue acetylenverbindungen aus Leucanthemum-arten und revision der struktur eines germacranolids

The investigation of three Leucanthemum species afforded, in addition to known compounds, two new C₁₇-acetylenes, a new isovalerate, two phenolic acetylenes, a C₁₂-isobutylamide and a new farnesol derivative. Chrysanthemum ferulaceum contains deacetyllaurenobiolide (spiciformin) which is identical with a lactone from Inula britannica previously assumed to be a cis, cis-germacranolide.     

New labdane derivatives and further constituents of Brickellia species

The investigation of several Brickellia species and two further related species afford besides known compounds four new labdane derivatives, a new acetylenic carbinol and a new dihydrobenzofuran derivative. The structures have been elucidated by spectroscopic methods. The chemotaxonomic aspects are discussed briefly.     

Laserine oxide,an epoxide from Guillonea scabra

From the roots of Guillonea scabra several previously known compounds were isolated. In addition, a new epoxy derivative of laserine was obtained and its structure was established by chemical and spectroscopic means.     

Neue chalkon-derivate und humulon-ähnliche verbindungen aus Helichrysum-arten

The investigation of two further Helichrysum species afforded in addition to known compounds three new prenylated chalcones and two humulone-like compounds. The structures were elucidated by spectroscopic methods and some chemical transformations. The chemotaxonomic situation is discussed briefly.     

Cannabigerol-ähnliche verbindungen aus Helichrysum umbraculigerum

The investigation of a further South African Helichrysum species afforded eleven resorcinol derivatives, most of them closely related to cannabigerol and the corresponding acid, both also being present in the aerial parts of H. umbraculigerum. Furthermore a new geranyl chalcone is present. The structures are elucidated by spectroscopic methods and some chemical transformations. The occurrence of the cannabigerol-like compounds in a composite is surprising. Probably, some of these compounds are formed by the combination of three different biogenetic pathways.     

8-Oxo-α-selinen und neue scopoletin-derivate aus Conyza-arten

The investigation of three South African and a North American Conyza species afforded, in addition to known compounds, a new eudesmane ketone and five new scopoletin derivatives. The structures are elucidated by spectroscopic methods and by some chemical transformations. Two of the scopoletin enol ethers have very unusual structures. While most of the Conyza species investigated so far contain typical C₁₀-acetylenes, also present in related genera, there are some with different chemistry. The relationship of the genus to Aster and Erigeron, however, is clearly indicated.