A heliangolide from Schkuhria pinnata

Re-investigation of the aerial parts of Schkuhria pinnata afforded in addition to the heliangolides isolated previously a new one, the structure of     

Germacranolides from Schkuhria anthemoidea

The isolation of eucannabinolide and three new sesquiterpene lactones from Schkuhria anthemoidea is reported. The structures and stereochemistries of the new compounds were established by chemical and spectroscopic means. The structure of santhemoidin B was confirmed by X-ray crystallography.     

11,13-Dehydroeriolin,schkuhrioidin and schkuhriolid,germacranolides from Schkuhria species

The isolation is reported of the new germacrolide, 11,13-dehydroeriolin, the new melampolide schkuhrioidin and schkuhriolide from Schkuhria schkuhrioides. 11,13-Dehydroeriolin is also a constituent of S. virgata. The structure and stereochemistry of the new compounds were established on chemical and spectroscopic grounds.     

Heliangolides from Helianthus maximiliani

The isolation is reported of tifruticin, acetyltifruticin, deoxytifruticin, acetyldeoxytifruticin, an orizabin analog and three heliangolides from Helianthus maximiliani.     

New germacrolide- and heliangolide-type sesquiterpene lactones from Melampodium linearilobum

Chemical analysis of Melampodium linearilobum yielded, besides coumarin, seven germacrolide-type sesquiterpene lactones, linearilobin A to G and two heliangolides, linearilobin H and I. All new sesquiterpene lactones are oxygenated at C-14 and C-15 and differ by the number and types of ester moieties at C-8, C-14 and C-15. M. linearilobum represents the first species within the genus known to produce germacrolides and heliangolides instead of the more common melampolides.     

15-Hydroxy-acetylerioflorin and other constituents from Viguiera linearis

Aerial parts of Viguiera linearis afforded 16α-hydroxy-ent-kauranoic acid, viguiestenin, leptocarpin, acetylleptocarpin, budlein B, clovandiol and the new heliangolide 15-hydroxy-acetylerioflorin.     

Minor sesquiterpene lactones of Helianthus pumilus

The isolation of four known and two new germacradienolides and one known heliangolide from Helianthus pumilus, in addition to the previously report     

Heliangolides and other constituents from Bejaranoa semistriata

The investigation of Bejaranoa semistriata, a new genus in the tribe Eupatorieae, afforded in addition to known compounds a new furanoheliangolide, two epimeric 1-keto-heliangolides, two germacranolides, two nerolidol derivatives and a geranylnerol derivative. The structures were elucidated by spectroscopic methods and a few chemical transformations.     

Sesquiterpene lactones of Calea zacatechichi and C. urticifolia

Calea zacatechichi yielded the sesquiterpene lactone zexbrevin and a new analog, several analogs of neurolenin B including calein A, two analogs of budlein A and the flavones acacetin and O-methylacacetin. Calea urticifolia contained additional analogs of neurolenin B as well as a series of epoxidation products. Structures were established by spectrometric techniques. The results are contrasted with previous findings.     

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 Helianthus grosseserratus

The isolation is reported of six new sesquiterpene lactones based on the eudesmanolide, trans, trans-germacradienolide and heliangolide skeletons from Helianthus grosseserratus Martens. The diterpenes grandifloric, 17-hydroxy-ent-isokaur-15-enic and ciliaric acids and the flavones hispidulin and pectolinarigenin were also found.     

Zoapatanolide A and B,two new heliangolides from Montanoa tomentosa

The re-investigation of Montanoa tomentosa afforded, in addition to known diterpenoids of the kaurene class, two new sesquiterpene lactones, zoapatanolide A and B, of the heliangolide type.     

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     

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.     

Terpenoids and a flavan-3-ol from viguiera quinqueradiata

The isolation is reported of the new natural products from Viguiera quinqueradiata, acetylleptocarpin and (2R,3S-4′-hydroxy-3′,5,7-tri-O-methyl-flavan-3-ol. The diterpenes 15α-angeloyloxy-ent-kaur-16-en-19-oic acid, 15α-tigloyloxy-ent-kaur-16-en-19-oic acid and the sesquiterpene lactones leptocarpin and budlein A were also found.     

Three furanoheliangolides from Calea villosa

Calea villosa afforded three new sesquiterpene lactones, two furanoheliangolides and an epoxy- germacranolide, as well as several known compounds. The structures were elucidated by spectroscopic methods.     

An isomer of xanthanol from Xanthium orientale

The aerial parts of Xanthium orientale afforded an isomer of xanthanol.     

Elemanolides from Zinnia peruviana

Zinnia peruviana from Honduras afforded two new acetal-type elemanolides as well as a mixture consisting primarily of zinaflorin III.     

Tetraludins D to N,eleven new melampolides from Tetragonotheca ludoviciana

Eleven new melampolides, tetraludins D-N, were isolated from aerial parts of Tetragonotheca ludoviciana. Tetraludins D and E, F and G, J and K, and L and M represented epimeric pairs which differed only at one chiral centre of the five-carbon ester side chain at C-8. In benzene-d₆, the ¹H NMR spectra of the diastereomeric pairs of melampolides exhibited well-separated signals in particular for the absorptions due to the ester side chains that differed in chirality.