γ-Pyrone derivatives fromHalenia corniculata
From 500 g of the epigeal part of Halenia corniculata (L.) Cornaz., collected in the Pribaikal region of the Buryat ASSR in July 1975, by extraction with 70% ethanol followed by treatment with chloroform we have isolated 32.7 g of extractive substances. Chromatography of the chloroform extract on silica gel with elution by chloroform yielded substances (i) and (2) of xanthone nature, and chloroform-ethanol (9:1) yielded luteolin, which was identified by its UV, mass, and PMR spectra and by comparison with an authentic sample [i].
The xanthones of a Halenia species
Abstract Extracts of a Colombian species of Halenia (Gentianaceae) yielded three xanthones, 1-hydroxy-2,3,4,7-tetramethoxy-, 1-hydroxy-2,3,4,5-tetramethoxy-, and 1-hydroxy-2,3,5-tetramethoxyxanthone, which have also been found to be the major xanthones of Frasera caroliniensis
Biogenetic proposals regarding aucuparins and xanthones
Abstract The co-occurrence of aucuparins and xanthones in plants, as well as the oxygenation pattern of the natural representatives of these classes of compounds, become understandable, if their biosynthesis is considered to involve interaction of 5-dehydroshikimic acid with activated acetic acid units through Michael type addition and acylation, respectively.