William J. Crins

Flavonoid aglycones of Holocarpha obconica

Abstract Eleven flavonoid aglycones were isolated from the dichloromethane leaf-wash of the tarweed, Holocarpha obconica. Included within the extract were three novel flavanones, 7,4′-dimethoxyflavanone, 5,6,3′,4′-tetrahydroxy-7-methoxy-flavanone, and 3′,4′-dihydroxy-3,7-dimethoxyflavanone.

Carex juniperorum (Cyperaceae), a New Species from Northeastern North America, with a Key to Carex sect. Phyllostachys

Carex juniperorum, a distinctive new species of sect. Phyllostachys, is described. Carex juniperorum occurs in shallow, calcareous soil in open red-cedar woodland and associated glades in Ontario, Ohio, and Kentucky. Section Phyllostachys is lectotypified and a key is provided for the six known species. Carex juniperorum is most closely related to C. jamesii and C. willdenowii but differs from both of these species by its shorter culms 2-6.5 cm tall, shorter perigynium beaks 1.4-2.1 mm long, and pistillate scales lacking hyaline margins.

Mass spectrometry in the differentiation of flavanones and dihydroflavonols

Abstract Flavanones and dihydroflavonols exhibit characteristic fragmentation patterns that can be utilized in their differentiation. Electron-impact and high resolution mass spectrometry are used to establish the patterns and identities of the characteristic ions.

Non-polar flavonoids of Calycadenia, Lagophylla and Madia

Abstract Several combinations of flavones, flavonols, flavanones, and dihydroflavonols have been identified from five species of Calycadenia and one species each of Madia and Lagophylla . In many instances the flavones and flavonols carry extra hydroxylation at positions-6 and/or -8 and are further characterized by moderately high levels of O -methylation. These observations are consistent with earlier findings for other members of the Madiinae (Asteraceae: Heliantheae). All compounds identified are known natural products, although a few are new in the subtribe differing from compounds described earlier by virtue of one or two additional methyl ether groups.

Flavonoids of Adenothamnus validus

Abstract Twelve flavonoid aglycones and six flavonoid glycosides were isolated from the tarweed, Adenothamnus validus . 6- O -Methylation occurs in several of its constituents. Two rare glycosides, homoplantaginin and jaceoside, are among its polar flavonoids.

Non-polar phenolics of seven species of Layia (Asteraceae)

Seven species of Layia, belonging to four of the species groups recognized by Clausen, Keck and Hiesey in 1941 were examined for their external flavonoid aglycone contents. Seven flavonoid aglycones, six of which were flavones and one of which was a 3-methylated flavonol, were found in the profiles. In addition, the coumarin, scopoletin, was found in all seven species. Layia carnosa and L. chrysanthemoides lack flavonoid aglycones. Layia glandulosa and L. platyglossa have identical profiles, suggesting a phytochemical continuum between the n - 7 and n -- 8 species groups. Layia hieracioides and L paniculata produce both flavones and the methylated flavonol. Layia septentrionalis differs from the other glandular species in lacking the methylated flavonol.

Evolutionary considerations based on flavonoid aglycones in the Peritylinae

Abstract The major flavonoid aglycones of nine species of Perityle , representing its three sections ( Perityle, Pappothrix, Laphamia ), and of Pericome caudata and Amauria rotundifolia have been characterized. The array of compounds is arranged in hypothetical biosynthetic series, and these series are compared with generic and sectional limits based on morphological criteria. A process of simplification of the flavonoid aglycone profile has occurred within Perityle , with section Perityle being most primitive and section Laphamia most advanced. Correlations between chemical and other evidence suggest a close relationship between Pericome and Perityle section Perityle , while the relationship between Amauria and Perityle may not be as close as previously thought.