Marion Dörr

Externally accumulated flavonoids in three Mediterranean Ononis species.

Abstract The Mediterranean Ononis species, O. fruticosa, O. natrix subsp. ramosissima and O. tridentata, have been analyzed for their exudate flavonoids. More than 20 flavonoid aglycones were identified, some of which are rather rare natural compounds. One of them, namely hypolaetin- 8,3′,4′-trimethyl ether, had been found only once before. The results are presented in a table along with literature data, and the chemotaxonomic impact of the flavonoid patterns is discussed.

Taxonomic significance of flavonoid variation in temperate species of Nothofagus

Forty-two flavonoids and a stilbene (pinosylvin) were identified in the leaf exudates of 11 temperate species of Nothofagus from South America, Australia and New Zealand. The flavonoid profiles demonstrate significant taxonomic value at the subgeneric level. Most species of subgenus Fuscospora are characterized by the presence of pinosylvin, galangin and galangin methyl ethers. Kaempferol-type flavonols are abundant in subgenus Lophozonia while these flavonols are largely absent from species of subgenus Fuscospora. The flavonoid patterns are largely in agreement with a recent subgeneric classification of Nothofagus.

Dorema aucheri, the first umbelliferous plant found to produce exudate flavonoids

Abstract Aerial parts of Dorema aucheri exhibit a lipophilic exudate material which was shown to contain several flavone methyl esters.

Chemodiversity of Surface Flavonoids in Solanaceae

Abstract Several species of Nicotiana and Solanum and further members of the Solanaceae have been examined for their exudate flavonoids. Most of the aglycones are widespread flavonols, but rare and unusual flavonols were also found, e.g. in exudates of Physalis and Solanum species. Flavones occur throughout the family, but flavanones are rare. Our data are presented in comparison to previous results. The chemodiversity of the observed structures is discussed in relation to literature reports. Morphological and systematic aspects are briefly addressed.

Exudate Flavonoids in Asteraceae from Arizona, California and Mexico

Abstract A series of Asteraceae, belonging to the tribes Astereae, Eupatorieae, Helenieae and Heliantheae, have been analyzed for the presence of flavonoid aglycones accumulated on leaf and stem surfaces. Methyl ethers of apigenin, luteolin, kaempferol, and quercetin as well as methyl ethers of their relevant 6 -hydroxy derivatives were abundant, whereas 8 -O-substi-tuted derivatives and flavanones were encountered only occasionally; 6 ,8 -di-O-substituted flavonols were found in only one species.

EXUDATE FLAVONOIDS OF SOME SALVIA AND A TRICHOSTEMA SPECIES

Seven species of Salvia and one species of Trichostema were analyzed for their exudate flavonoids. They were found to exhibit flavonoid aglycones in various numbers and different patterns. Most of these are flavones, in which 6-methoxy-substituted compounds predominate.

On the occurrence of exudate flavonoids in the borage family (Boraginaceae).

Externally accumulated flavonoid aglycones have been found for the first time in Nonea species. They exhibit only flavones, one of thembeing the rare tricetin-4ʹ-methyl ether. Within the subfamily Boraginoideae, exudate flavonoids appear to be a rare character.

Bibenzyls from crowberry leaves

Abstract The leaf exudate of Empetrum nigrum contains, among other phenolic constituents, two novel bibenzyls. These were identified by spectroscopic methods as 3,5,3′-trihydroxy-4-methoxybibenzyl and 3,3′-dihydroxy-4,5-dimethoxybibenzyl.

Exudate Flavonoids of Eight Species of Ceanothus (Rhamnaceae)

Abstract Leaf glands of Ceanothus species excrete a lipophilic material that contains a variety of flavonoids. Most of these are aglycones, but some glycosides were also observed. Seven out of eight species exhibit flavonols, whereas flavones are excreted by only one species. Four species produce flavanones and dihydroflavonols; one excretes a remarkable quantity of flavonol glycosides. The exudate flavonoids thus form different patterns that might be characteristic for different Ceanothus species.

Flavonoids and terpenoids from the resinous exudates of Madia species (Asteraceae, Helenieae)

The resinous material accumulated on aerial parts of Madia species is shown to consist mainly of diterpenes, containing a series of flavonoid aglycones. A6- and/or 8-O-substitution is characteristic for many of these flavonoids. Three known rare diterpenes were found and the structure elucidation of a diterpene with a new carbon skeleton, named madiaol, is reported.