Jean Chopin

Structural determination of C-glycosylflavones by mass spectrometry of their permethyl ethers

Abstract Permethylated C -glycosylflavones give well defined MS, including in all cases an important molecular peak. The observed fragmentations are characteristic for the nature and position of the sugar. The 6- C and 8- C glycosylated derivatives are clearly differentiated. In dissymmetrical 6,8-di- C -glycosylflavones, the natures of the sugar in both the 6- and 8- positions can be determined. The structures of several natural compounds are discussed.

Differentiation des dihydroxy-5, 7 methoxy-6 ou 8 flavones flavonols et methyl-3 flavonols par spectrometrie de masse

Abstract 5,7-Dihydroxy flavones and flavonols variously methoxylated in the 3-, 6- and/or 8-positions give characteristic fragmentation peaks. The relative abundance of M, M-1 and M-15 peaks and the presence of M-18 peak makes it possible to differentiate the 6-methoxy from the 8-methoxy isomers and three types of 6-methoxyflavones from each other.

Structural determination of C-glycosylflavones by mass spectrometry of their permethyl ethers: O-glycosyl-6-C-glycosylflavones

Abstract Permethylated O -glycosyl- C -glycosylflavones give well defined MS including an important molecular peak. Permethyl 6- C -glycosylflavones O -glycosylated on a phenolic hydroxyl group are easily distinguished from the isomeric permethyl 6- C -diholosylflavones. In both types, the position of the O -glycosidic bond can be deduced from the MS, eventually after acid hydrolysis. 2″- O -glycosyl-6- C -glycosylflavones can be differentiated from their 8- C isomers.

Structural determination of 6-C-diglycosyl-8-C-glycosyl-flavones and 6-C-glycosyl-8-C-diglycosylflavones by mass spectrometry of their permethyl ethers

Permethylated 6-C-diglycosyl-8-C-glycosylflavones and 6-C-glycosyl-8-C-diglycosylflavones gave well defined EIMS including the molecular peak and a fragmentation pattern characteristic of the 6-C-glycosyl residue. X″′-O-glycosides (8-C-disaccharides) are thus easily distinguished from X″-O-glycosides (6-C-disaccharides) and, in the latter, the position of the O-glycosidic bond should be deduced from the MS, after acid hydrolysis. Three new C-glycosylflavones have been characterized in this way from Spergularia rubra and Stellaria holostea.

Fragmentation pattern of permethyl 6-C-glycosylflavones in electron impact mass spectrometry

Abstract A mass spectral fragmentation pattern of permethyl 6- C -glycosylflavones is proposed from the MS data of permethyl derivatives mono- O -deuteriomethylated in the 2″-, 3″-, 4″- or 6″-positions. The synthesis of these compounds via O″ -glycosyl-6- C -glucosylflavones is described.

Nouvelles C-glycosylflavones extraites de Spergularia rubra

Abstract Three 6,8-di-C-glucosylflavones: 6,8-di-C-β- d -glucopyranosylapigenin, luteolin and chrysoeriol were isolated from the whole plant of Spergularia rubra. Two new compounds, 7,2″-di-O-β- d -glucopyranosyl-6-C-α- l -arabinopyranosylapigenin and 6-C-α- l -arabinopyranosylapigenin (isomollupentin), were also characterized. Structural assignments were based on 1H NMR and MS spectra and on comparison with synthetic samples. MS fragmentation patterns of the new di-O-glucosyl compound PM derivative and of its acid hydrolysis product are given.

Differentiation des hydroxy-5 dimethoxy-6,7 ou 7,8 et des triméthoxy-5,6,7 ou 5,7,8 flavones par spectrometrie de masse

Abstract The relative abundance of M and M-15 peaks in the mass spectrum allows the differentiation of 5-hydroxy-6,7-dimethoxy- and 5,7,8-trimethoxyflavones (M > M-15) from 5-hydroxy-7,8-dimethoxy and 5,6,7-trimethoxy-flavones (M

Corymboside, nouvelle di-C-glycosylflavone des racines de Carlina corymbosa

Abstract Corymboside, a new di- C -glycosylflavone from Carlina corymbosa roots, was shown to be 6- C -α- l -arabinopyranosyl-8- C -β- d -galactopyranosylapigenin by MS, CD, 1 H and 13 C NMR.

C-diholosylflavones dans les feuilles du melon (Cucumis melo)

Abstract Four C -glucosylflavones were isolated from muskmelon leaves and shown to be 6-C-diglucosylapigenin (meloside A ),6- C -diglucosyl-luteolin (meloside L ) and the respective caffeyl esters of meloside A (meloside a ) and meloside L (meloside I ).

Flavonoid glycosides of Artemisia monosperma and A. herba-alba

Abstract Ten flavonoid glycosides were isolated and identified from Artemisia monosperma : vicenin-2, lucenin-2, acacetin 7-glucoside, acacetin 7-rutinoside, the 3-glucosides and 3-rutinosides of quercetin and patuletin, and the 5-glucosides of quercetin and isorhamnetin. From Artemisia herba-alba eight flavonoid glycosides were isolated and identified: isovitexin, vicenin-2, schaftoside, isoschaftoside and the 3-glucosides and 3-rutinosides of quercetin and patuletin.