Pradip K. Mahanta

Terpen-derivate aus Senecio-arten

Zusammenfassung Uberblickt man das jetzt vorliegende Material uber die Gattung Senecio , so bestatigt sich die schon eingangs erwahnte Festellung, das in Eine klare Differenzierung der Gattung Senecio von den Nachbargruppen von der Seite der Inhaltsstoffe her, ist nach wie vor problematisch. Wahrsche

New sesquiterpene lactones from Inula species

Abstract An investigation of Inula helenium, I. royleana, I. salicina and I. bifrons afforded in addition to known sesquiterpene lactones 20 new lactones, the eudesmanolides 3, 6 and 8–12 , the germacranolides 14–18 and 20–22 , the guaianolides 23 and 25 , the pseudoguaianolide 26 , the xanthanolides 28 and 32 and the cyclopropane analogue 30 . Structures and configurations of these new compounds were established by extensive PMR studies and by some chemical transformations. Some of the investigated species contain besides the widely distributed pentaynene 33 several known thymol derivatives together with a new one ( 40 ).

Neue furanoeremophilane und weitere inhaltsstoffe aus südafrikanischen Senecio-arten☆

Abstract The investigation of further 27 South African and a few other Senecio species afforded in addition to known compounds 18 new furanoeremophilanes, most of them being cacalol derivatives, two new lactones, a new eudesmane derivative and four acyl pyrrole derivatives. The structures are elucidated by spectroscopic methods mainly. The chemical results on more than 140 species now available indicate much of chemotaxonomic interest. Together with the chemical data on related genera, the taxonomic situation of the subtribe Senecioninae is discussed in connection with the proposed new classification. The chemical data are in good agreement with this new arrangement.

Neue sesquiterpenlactone und andere inhaltsstoffe aus vertretern der Eupatorium-gruppe☆

Abstract The investigation of twelve further species of the Eupatorium complex affords four new germacrolides and seven guaianolides together with new thymol and p-hydroxyacetophenone derivatives. The structures of these compounds have been elucidated by spectroscopic methods. Chemotaxonomic aspects of these findings are briefly discussed.

New germacranolides from Isocarpha species

Abstract 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.

Neue diterpene und sesquiterpene aus südafrikanischen Helichrysum-arten☆

Abstract The investigation of several South African Helichrysum species afforded in addition to known compounds two new kaurenic acid derivatives, three new labdane derivatives, three aromadendrene derivatives and geranylterpinene. The structures are elucidated mainly by extensive 1 H NMR-studies. The chemotaxonomic importance of these findings is discussed briefly.

Neue diterpene und germacranolide aus Mikania-Arten

Abstract From three Mikania species, three new labdanic acid and two kaurenic acid derivatives have been isolated together with known compounds and four new germacranolides, differing only in the ester moiety.

Weitere hirsutinolide aus Vernonia-arten

Abstract 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 1 H NMR studies and some chemical transformations. The results show again that the hirsutinolides are probably of chemotaxonomic importance in the large genus Vernonia .

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

Abstract 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.

Neue chalkon-derivate aus südafrikanischen Helichrysum-arten

Abstract The investigation of two South African Helichrysum species afforded in addition to known compounds two new chalcone derivatives, four related dihydrochalcones,5,7,8-trimethoxyflavone and 5-methoxy-7,8-methylenedioxyflavone. The structures are elucidated by spectroscopic methods and some chemical transformations. The chemotaxonomic situation in the large genus Helichrysum is discussed, in the light of these results.