Douglas A. Gage

Sesquiterpene lactone and diterpene constituents of helianthus annuus

Abstract One new furanoheliangolide derivative, 4,5-dihydroniveusin A, as well as the known compounds niveusin B and argophyllin A and B, were isolated from a Texas population of Helianthus annuus. Three previously characterized diterpene acids, grandifloric acid, ciliaric acid and 17-hydroxy-ent-isokaur-15(16)-en-19-oic acid were the principal constituents of this population.

7α-Hydroxy-sesquiterpene lactones from Decachaeta ovatifolia

Abstract In addition to the known sesquiterpene lactone pinnatifidin, and the flavones 6-methoxyacacetin and 6-methoxyapigenin, the dichloromethane extract of the aerial parts of Decachaeta ovatifolia afforded four new sesquiterpene lactones: a germacranolide 7α-hydroxycostunolide, a guaianolide 4α,15-dihydro-7α-hydroxy-3-desoxyzaluzanin C and two eudesmanolides, 7α-hydroxysantamarine and 7α-hydroxyreynosin. The structure of 7α-hydroxycostunolide was confirmed by X-ray analysis.

Sesquiterpene lactones from Vernonia marginata

Abstract A reinvestigation of the polar fraction from Vernonia marginata afforded in addition to marginatin 13 new lactones, including six glaucolides, four closely related lactones with a new carbon skeleton, named vernomargolides, two jalcaguaianolides and a pseudoelephantopide, as well as a methyl ester probably derived from a glaucolide. The structures were elucidated by NMR spectroscopy and the stereochemistry was established by NOE difference spectroscopy. Possible biogenetic relationships are discussed briefly.

Sesquiterpene lactones from Perityle vaseyi

Abstract The well-known germacrolide, eupatoriopicrin, and two additional sesquiterpene lactones, were isolated from Perityle vaseyi . The latter two lactones, one a novel guaianolide and the other a known germacrolide, both contain unusual ten carbon diester side chains attached at C-8. The chemical evidence, in conjunction with morphological data, suggest that Perityle, and hence the subtribe Peritylinae, should be placed in the tribe Heliantheae.

Quercetagetin 6,7,4′-trimethyl ether and 3-sulphate from Decachaeta haenkeana

Abstract Four 6-methoxylated flavonols, including a new quercetagetin derivative and its 3-potassium sulphate salt, were isolated from the aerial parts of Decachaeta haenkeana .

Sesquiterpene lactones of Piptothrix pubens

Abstract Eleven sesquiterpene lactones, six of which are new, were identified from Piptothrix pubens . All but one of the compounds contained a C 10 -diester attached at C-8. The taxonomic implications of these results are discussed.

Labdane diterpenes from Brickellia vernicosa

Abstract The investigation of Brickellia vernicosa afforded, in addition to the known 3α-hydroxycativic acid, three new labdane derivatives. The structures and stereochemistry have been established by spectroscopic methods and chemical transformations.

Terpenoids of Piptothrix sinaloae

Abstract In addition to three known thymol esters and five known sesquiterpene lactones, two new germacrolides and a new diterpene diester were isolated from the dichloromethane extract of the aerial parts of Piptothrix sinaloae . Structures for the new compounds were elucidated by chemical transformations and spectral methods. The current taxonomic status of P. sinaloae is discussed on the basis of both morphological and secondary metabolite data.

Sesquiterpene lactones from helogyne hutchisonii

Abstract The aerial parts of Helogyne hutchisonii afforded, in addition to known sesquiterpene lactones, two new heliangolides and two germacranolides. The structures were elucidated by high-field 1 H NMR spectroscopy.

Sesquiterpene lactones and other constituents from Piptothrix areolare

Abstract The investigation of Piptothrix areolare afforded, in addition to 7-acetoxytinifoline and cis - p -hydroxycinnamic acid, two known and two new sesquiterpene lactones sharing unusual C 10 diester side chains. These data support morphological evidence which indicates Piptothrix is closely related to the genus Ageratina . The structures and stereochemistry were determined by spectroscopic methods.