Sesquiterpene lactones of Ambrosia chamissonis

A study of a large number of populations of Ambrosia chamissonis ranging from Southern California to British Columbia, has disclosed chemical differences within the species. Six germacranolides, in addition to chamissonin, have been found in the various populations.     

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.     

Occurrence of hysterin and dihydroisoparthenin in Parthenium hysterophorus

Two sesquiterpene lactones, hysterin and dihydroisoparthenin, have been identified in Parthenium hysterophorus from Argentina and Jamaica by TLC and NMR.     

Sesquiterpene lactones from Centaurea glomerata

The investigation of the aerial parts of Centaurea glomerata afforded four new sesquiterpene lactones of the germacradienolide type and the lignan lactone arctigenin. Their structures were elucidated by spectroscopic methods.     

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 of Ambrosia cordifolia

Extraction of Ambrosia cordifolia (Gray) Payne furnished the modified pseudoguaianolides psilostachyin C (I) and cordilin. The latter was shown to be a stereoisomer IV of psilostachyin (II). Dicorea brandegei Gray and D. canescens T. &. G. yielded no crystalline lactone components.     

Sesquiterpene lactones of Artemisia mexicana var. Angustifolia

Seven eudesmanolides were isolated and characterized from Artemisia mexicana var. angustifolia. These included arglanin, artemexifolin, ludalbin, santamarine and three new compounds named 8α-acetoxyarmexifolin, α-epoxyludalbin and armefolin. The structure of armexifolin is revised.     

Sesquiterpene lactones of Gaillardia pulchella

A Japanese cultivar of Gaillardia pulchella Foug. contained, in addition to the pseudoguaianolides, pulchellin(I) and neopulchellin(II), the guaianolide, gaillardin(III) apparently accompanied by its epimer neogaillardin(IV) and an unidentified basic principle different from pulchellidine(V) and neopulchellidine(VI). A possible biogenetic scheme for the sesquiterpene lactones including eudesmanolides, pulchellin-B, -C, -E and -F(VII) is proposed.     

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 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 Viguiera deltoidea

Three sesquiterpene lactones, 2′,3′-dihydroniveusin-A, 2′,3′-dihydroniveusin-B and 3-acetylchamissonin, were isolated from the dichloromethane extract of leaves of Viguiera deltoidea. The structures were established on the basis of physical and spectroscopic data and that of 3-acetylchamissonin was also confirmed by X-ray analysis.     

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 Ambrosia maritima (Damssissa)

Six sesquiterpene lactones were isolated from the aerial parts of Ambrosia maritima. Four pseudoguaianolides were isolated for the first time in addition to parthenin and neoambrosin.     

Sesquiterpene lactones from Helianthus niveus subsp. niveus

Six germacranolides, tirotundin, tagitinin A. orizabin, 8β,14-dihydroxycostunolide and its 14-isobutyrate, and 4β,5-dihydrotagitinin C, were isolated from aboveground parts of Helianthus niveus subsp. niveus. The last two compounds are new.     

Sesquiterpene lactones of Xanthium strumarium in a texas population and in experimental hybrids

Morphologically diverse plants in a wild population of Xanthium strumarium in eastern Texas produced widely variant combinations of sesquiterpene lactones. Some plants showed a preponderance of xanthinin and related compounds, xanthanol and xanthatin, while others a predominance of stereoisomers, xanthumin, xanthumanol and deacetoxylxanthumin. Some plants produced only one sesquiterpene lactone and other plants yielded various mixtures of xanthinin, xanthumin and related compounds, including xanthinosin and/or tomentosin. Experimental hybridization between plants containing primarily xanthinin and plants containing xanthumin, but originating in diverse parts of the world, yielded F₁ progenies with xanthanol and/or xanthumanol as the predominant sesquiterpenoid component. The F₂ generation showed segregation of the xanthinin, xanthumin and related compounds. The Texas population occurs in an area where the “italicum” (xanthinin-predominants) and “chinense” (xanthumin-predominant) morphological complexes are sympatric. The diverse patterns of sesquiterpene lactones in the Texas population probably resulted from the natural hybridization of morphological complexes that originally were spatially isolated.     

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.