From the above ground parts of Hymenoxys turneri , three unusual 2,3-dihydroflavonol 3-acetates, two other 2,3-dihydroflavonols, two flavones and three sesquiterpene lactones were obtained. Their structures were established by spectroscopy. The dihydroflavonol acetates and dihydroflavonols were assessed for their sweetness intensity by a taste panel.

The dichloromethane extract of the leaves and flowers of Hymenoxys biennis afforded an adduct of the modified pseudoguaianolide hymenoxon and a guaianolide as well as three guaianolide glucosides, seven sesquiterpene lactone aglycones, two inositol derivatives and an aliphatic lactone. Structures of all compounds were established by spectroscopy.

The aerial parts of the Texas bitterweed Hymenoxys odorata yielded five guaianolides, four pseudoguaianolides, five modified pseudoguaianolides and one aliphatic lactone. Ten of these compounds, hymenovin B and C, hymenolane B, hymenoratin B—G and the aliphatic lactone, 3β-hydroxyicosan-1, 5β-olide were previously unreported. The known lactones are hymenoxon, hymenolane, hymenoratin, hymenograndin and florilenalin. Structures, including stereochemistries, were elucidated by NMR and NOE experiments. The structure of hymenoratin D was established by X-ray analysis.

Chemical investigation of the endangered species Hymenoxys texana afforded five inositol derivatives and two pseudoguaianolides. The structures of the compounds were elucidated by NMR and mass spectroscopy.

Six guaianolides, seven pseudoguaianolides and an aliphatic lactone were isolated from Hymenoxys scaposa var. villosa. Six of these compounds, villosin A, villosin B, 4-acetyl-chamissonolide, 2-desacetyl-2-isobutyryl- chamissonolide, 2-desoxypleniradin and 2-desoxy-14-acetoxy-pleniradin, are reported for the first time.

The leaves and flower heads of Viguiera laciniata yielded lacinolide A, a new benzoic acid ester of heliangolide, and a new chlorinated heliangolide, lacinolide B, along with six other sesquiterpene lactones, four of which were new, one known diterpene acid and two known flavanones. The structures of all compounds were elucidated by NMR and mass spectroscopy. Lacinolide A was established by X-ray crystallography.

Eight known diterpene acids, ent-12-oxokaur-9(11),16-dien-19-oic acid, ent-12β-hydroxykaur-9(11),16-dien-19-oic acid, ent-isokaur-15(16)-en-17,19-dioic acid, ent-15α,16-epoxy-17-hydroxykaura-19-oic acid, ent-kaura-17,19-dioic acid, ent-kaur-16-en-19-oic acid, grandifloric acid, angeloyloxygrandifloric acid, as well as a new sesquiterpene lactone, ladibranolide, were isolated from Viguiera ladibractate. The stereochemistry of the sesquiterpene lactone was established by NOE experiments.