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.     

Three eudesmanolides from Pluchea rosea

Three eudesmanolides of Pluchea rosea were found to be structurally related to the eudesmane, cuauthemone, earlier reported from plants of the same genus.     

Five eudesmanolides from Calostephane divaricata

The investigation of Calostephane divaricata afforded in addition to known compounds five new eudesmanolides, all being tri-substituted derivatives of 6-epi- α-cyclocostunolides. The structures were eluciated by highfield ¹H NMR spectroscopy. The relative positions of the oxygen functions could not be stablished with certainty. The observed shift differences agreed well with the proposed structures.     

Eudesmanolides from Dimerostemma brasilianum

The investigation of Dimerostemma brasilianum afforded, in addition to known compounds, 18 new eudesmanolides and a new diterpene lactone derived f     

Eudesmanolides and other constituents from Dimerostemma asperatum

The investigation of Dimerostemma asperatum afforded four new eudesmanolides, two unusual acetylenic esters and two diterpene lactones related to g     

Eriolanolides,eudesmanolides and a rearranged sesquiterpene from Eriophyllum species

The investigation of two Eriophyllum species afforded, in addition to numerous known compounds, eight new sesquiterpene lactones related to eriolanin, two eudesmanolides and a new type of sesquiterpene alcohol. The structures were elucidated by spectroscopic methods and a few chemical transformations. The chemotaxonomic situation of this genus, the placement of which is still in doubt, is discussed briefly.     

Modified eudesmanolides and other sesquiterpene lactones from Wunderlichia mirabilis and Actinoseris polymorpha

Re-investigation of Wunderlichia mirabilis afforded three new modified eudesmanolides of the same type isolated previously from an Onoseris species, and minute amounts of a germacranolide for which a structure only could be proposed. Actinoseris polymorpha also contained a new germacranolide, the angetate of desacetyllaurenobiolide. Structures were elucidated by spectroscopic methods and by some chemical transformations. The significance of these findings is discussed briefly.     

Four eudesmanolides from Montanoa frutescens

Chemical analysis of Montanoa frutescens afforded the known sesquiterpene lactones montafrusins A and B, as well as four new eudesmanolides which we have named montafrusins C, D, E and F. The structures of the new compounds were established by spectroscopic methods.     

Further glaucolides from south african Vernonia species

The investigation of three South African Vernonia species afforded minute amounts of five new glaucolides, two monoepoxides and three diepoxides. The structures were elucidated by ¹H NMR spectroscopy. The roots of Vernonia sutherlandii contain, in addition to vernonataloide, bergamotene and santalene, minute amounts of the corresponding acetoxy derivatives.     

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 Brachylaena species

The investigation of two Brachylaena species afforded in addition to known sesquiterpene lactones and other constituents five new lactones, a germacranolide, a guaianolide and three eudesmanolides. The structures were elucidated by spectroscopic methods. The chemotaxonomy of this complex genus is discussed.     

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.     

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.     

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.     

Sesquiterpene lactones and other constituents from Schistostephium species

From four Schistostephium species, in addition to known compounds, 43 new ones were isolated, three isocomene, two bisabolene, two eudesmane, two allo-himachalene and two nerolidol derivatives, two sesquiterpenes with a new carbon skeleton derived from isocomene, nine eudesmanolides, 20 6,12- and 8,12-germacranolides respectively, and a prostaglandin-like acid. The structures were elucidated by spectroscopic methods, especially high field ¹H NMR and some chemical transformations. The stereochemistry of some 8,12-germacranolides was established by partial synthesis which required revision of the previous assignments of the configuration of inunolide, its 4,5- and 1,10-epoxide, vernudifloride, simsiolide, 6-hydroxy-1,10-epoxyinunolide and perhaps also of tanachin. The chemotaxonomic situation is discussed briefly.     

Guaianolides from Taeckholmia species

The investigation of four Taeckholmia species afforded in addition to known desacylcynaropicrin, two new guaianolides. The structures were elucidated by spectroscopic methods and chemical transformations. The chemotaxonomy is discussed briefly.     

Ent-kauranes and 10α-methyl-eudesman-8αh,12-olides from wedelia calycina and wedelia hispida

The aerial parts of Wedelia hispida furnished small amounts of three new 10α-methyl-eudesman-8α,12-olides as well as some known ent-kauranes. Wedelia calycina yielded various ent-kaurane derivatives, several of them new.