Sesquiterpene and diterpene lactones from melampodium longipilum

the aerial parts of Melampodium longipilum afforded two new diterpene lactones, 17-hydroxy- and 17-acetoxyacanthoaustralide, and a new sesquiterpene lactone, repandin E, besides the known melampolides enhydrin and fluctuanin.     

Sesquiterpene lactones from a texas population of Helianthus maximiliani

A population of Helianthus maximiliani from south-central Texas was shown to have a sesquiterpene lactone chemistry which was completely different from that reported for collections of this species from Kansas and north-central Texas. A series of five new guaianolides, two germacrolides (trans, trans-1(10),4(5)-germacradienolides), one of which is new, and a known labdane diterpene acid were isolated from a chloroform extract. Structures were determined by spectral and chemical methods. The structure of one guaianolide had been previously determined by X-ray crystallography.     

Sesquiterpene lactones from Parthenium tomentosum

Four populations of Parthenium tomentosum var. tomentosum were examinated. In addition to the known lactones, ivalbatine, acetyl ivalbatine, parthomentine, incanine and ligulatine C, three new pseudoguaianolides: 4-O-desacetyl ligulatine C; 1-dehydroperuvinine and parthoximentine were also isolated. Chemical and spectroscopic methods were used for their structural determination.     

Sesquiterpene lactones from Viguiera species

Viguiera eriophora yielded the sesquiterpene lactones erioflorin, acetylerioflorin and 17,18-dehydroviguiepinin, which was correlated with tetrahyd     

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.     

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 Centaurea solstitialis

Eight sesquiterpene lactones were isolated from Centaurea solstitialis (yellow starthistle). They are solstitialin A, repin, subluteolide, acroptilin, janerin, cynaropicrin, and the new lactones solstitiolide and episolstitiolide.     

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.     

Two oxepane-type diterpene lactones from melampodium diffusum

The isolation and structure elucidation of two new oxepane diterpene lactones, 1,10,17-trihydroxymelfusanolide and 1,10-dihydroxy-17-acetoxymelfusanolide, from Melampodium diffusum are reported. The structure determination involved chemical and spectral methods.     

Furanoheliangolides from Viguiera greggii

Three furanoheliangolide sesquiterpene lactones were isolated from Viguiera greggii, including a novel compound, 1,2-dehydrozexbrevin B, and the previously characterized zexbrevin and zexbrevin B. Structures were determined by spectral methods, chiefly ¹H and ¹³C NMR. Based on present knowledge, there appear to be no major differences between the terpenoid chemistry of Viguiera and that of Helianthus, a genus believed to be very closely related to Viguiera on morphological grounds.     

Sesquiterpene lactones of diploid and tetraploid Ambrosia camphorata

Diploid and tetraploid specimens of Ambrosia camphorata have distinct sesquiterpene lactone patterns; however, no direct correlation between chemistry and morphological patterns is detectable.     

Sesquiterpene lactones from Michelia fuscata

Two new sesquiterpene lactones, desacetyllanuginolide and michefuscalide were isolated from Michelia fuscata along with two known lactones, dehydrolanuginolide, lipiferolide and a lignan, syringaresinol. The structures of desacetyllanuginolide and michefuscalide were determined by spectral and chemical methods.     

Sesquiterpene lactones of Montanoa guatemalensis and Montanoa tomentosa subsp. Xanthiifolia

New 4,5-epoxygermacra-12,6β-olides from Montanoa guatemalensis and a Guatemalan disjunct collection of M. tomentosa subsp. xanthiifolia are reported. These compounds were unlike those from the 10 other Mexican collections of M. tomentosa previous investigated.     

Sesquiterpene lactones of Helianthus gracilentus

A series of four 2α-hydroxy-8β-acyloxygermacrolides and the heliangolide niveusin A were isolated from a dichloromethane extract of Helianthus gracilentus. The germacrolides include a new compound, 2α-hydroxy-8β-isovaleroyloxycostunolide. The terpenoid constituents of H. gracilentus are very similar to those of H. pumilus, which on morphological grounds is considered to be closely related to H. gracilentus.     

Sesquiterpene lactones and diterpenes from Mikania periplocifolia

The aerial parts of two collections of Mikania periplocifolia gave, in addition to mikanolide, miscandenin and several other known sesquiterpene dilactones related to them, the new dilactones 3β-hydroxy-11βH,13-dihydroisabelin, 11βH,13-dihydrodeoxymikanolide and mikaperiplocolide and three new geranylnerol derivatives.     

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.     

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 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.