F. Tomás

Flavonoids from phlomis lychnitys

Abstract The new naturally occurring acylated flavone glucoside chrysoeriol-7-β- D -(3″- E - p -coumaroyl)glucoside and other flavonoids have been isolated from the aerial parts of Phlomis lychnitys , and identified by spectral techniques. Relationships between flavonoid pattern, phylogeny and geography in Phlomis are discussed.

An HPLC study of flavones from some Spanish Sideritis species

Abstract Nine flavone aglycones were identified from the ether extracts of fifteen Sideritis species by means of HPLC techniques.

TWO FLAVONE GLYCOSIDES FROM SIDERITIS LEUCANTHA

Abstract 8-Hydroxyluteolin occurs in Sideritis leucantha as the 7-(2″-allosylglucoside) and the 8-glucoside of its 6,7-dimethyl ether has also been characterized from the same plant.

5,6,4′-trihydroxy-7,8-dimethoxyflavone from Thymus membranaceus

Abstract From the extracts of Thymus membranaceus subsp. membranaceus , the new naturally occurring 5,6,4′-trihydroxy-7,8-dimethoxyflavone (thymusin), has been isolated and identified. Its structure was elucidated by comparison with its isomeric flavone obtained on acid treatment (isothymusin); thymusin is demethylated at the 8-position during this treatment.

Thin-layer chromatographic behaviour and chemical structure of 6- and 8-methoxy-5-hydroxyflavones

Abstract Relationships have been found between the structure and the chromatographic behaviour of 5-hydroxyflavones with methoxy substituents at the 6- and/or 8-positions. Correlations involving Δ R M increments have been attempted. The important role of permethylated derivatives as a tool in flavone structure determinations is discussed.

Electron impact mass spectrometric differentiation of 5,6-dihydroxy-7,8-dimethoxy- and 5,8-dihydroxy-6,7-dimethoxyflavones

Abstract Electron Impact Mass Spectrometry provides a means of differentiating 5,6-dihydroxy-7,8-dimethoxyflavones from 5,8-dihydroxy-6,7-dimethoxyflavones. The relative abundances of [M] + , [M-H] + , [M - Me] + and [M-H 2 O] + ions vary according to the A-ring substitution pattern. The Wessely-Moser isomers were used for comparative purposes; this acidic treatment yielded novel demethylation products.

A chemotaxonomic study of flavonoids in Thymbra capitata

Abstract 5,6,4′-Trihydroxy-7,3′-dimethoxyflavone, 5,6-dihydroxy-7,3′,4′-trimethoxyflavone, luteolin, diosmetin, vicenin-2 and luteolin 7-rutinoside have been isolated and identified from Thymbra capitata . The occurrence of these compounds supports the inclusion of this plant in the genus Thymbra , rather than Thymus or Corydothymus .

Hypolaetin 8-glucoside from Sideritis leucantha

Abstract A new naturally occurring hypolaetin 8-β- D -glucoside has been isolated and identified from Sideritis leucantha. The natural compound suffered nuclear methylation during derivatization.

Free Flavone Aglycones and Flavonoid Glycosides from Satureia obovata

AbstractFrom the aerial parts of Satureia obovata, the previously known flavonoid compounds xantho microl, cirsimaritin, genkwanin, diosmetin, chrysoeriol, apigenin, luteolin, luteolin-7-0-β-D-gluco side, luteolin-7-0-β-D-rutinoside, vicenin-2 and the uncommon luteolin-3′-0-β-D-glucoside have been isolated and identified by UV, EIMS and chromatographic procedures. Previously, only xan-thomicrol has been reported from Satureia species.

Flavonoid Glycosides from Thymus membranaceus

Abstract Thymus membranaceus is an endemism of southeastern Spain, which belongs to section Pseudothymbra of genus Thymus. In this work we have achieved an investigation of the flavonoid glycosides present in the aerial parts of this plant. Among the compounds identified are the rare luteolin-7-0-β-D-xyloside, luteolin-7-0-β-D-[rhamnosyl (1→2)glucoside] and luteolin-7-0-β-D-[xylosyl (1→2)glucoside] previously not known to occur in the Labiatae.