Heba H. Barakat

Tannins from the leaves of Punica granatum

Leaves of Punica granatum contain the new gallotannins, 1,2,4-tri-O-galloyl-β-glucopyranose and 1,3,4-tri-O-galloyl-β-glucopyranose together with the hitherto unknown ellagitannins, 1,4-di-O-galloyl-3,6-(R)-hexahydroxydiphenyl-β-glucopyranose and brevifolin carboxylic acid 10-monopotassium sulphate. Structures were established by conventional methods of analysis and confirmed by 1H, 13C NMR, 2D-chemical shift correlation NMR and ESI-MS (negative mode) spectrometric analysis.

Flavonol triglycosides from seeds of Nigella sativa

Abstract Three new flavonoid glycosides quercetin and kaempferol 3-glucosyl(1 → 2)galactosyl(1 → 2)glucoside and quercetin 3-(6-feruloylglucosyl)(1 → 2)galactosyl(1 → 2)glucoside were isolated and identified from seeds of Nigella sativa . The structures have been elucidated by enzymic and acid hydrolysis and spectral data (UV, MS, 1 H and 13 CNMR) and confirmed by 2-D NMR.

Flavonoid lactates from leaves of Marrubium vulgare

Abstract The new natural lactoyl (2-hydroxypropionyl) flavonoids, luteolin and apigenin 7-lactates together with their 2″- O -β-glucuronides and 2″- O -β-glucosides were isolated from the leaves of Marrubium vulgare . The known flavonoids, vicenin II, vitexin, luteolin 7-glucoside, apigenin 7-glucoside, apigenin 7-(6″- p -coumaroyl)glucoside, luteolin, chrysoeriol and apigenin were also found. The structures were established by conventional methods of analysis and confirmed by 1 H, 13 C NMR and MS analysis. 2D-chemical shift correlation NMR was applied in the case of the new flavonoids.

Polyphenolic metabolites of Epilobium hirsutum

Abstract Evaluation of the constitutive polyphenolics of the whole plant extract of Epilobium hirsutum was carried out by reverse-phase HPLC. The unique ellagitannins, 2- O -galloyl 3- O -valoneoyl dilactone-(α/β)- 4 C 1 -glucopyranose, 1′-monodecarboxyvaloneic acid dilactone and valoneic dilactone dioxine were isolated and characterized. The known polyphenolics, gallic, protocatechuic, ellagic, valoneic dilactone and p -coumaric acids, methyl gallate, p -methoxy gallic acid methyl ester, 6- O -galloylglucose, 1,6-di- O -galloylglucose, 2,3-di- O -galloylglucose, 1,2,6-tri- O -galloylglucose and the 3- O -glucuronides, 3- O -arabinosides and 3- O -rhamnosides of kaempferol, quercetin and myricetin, their free aglycones 3- O -galactoside and quercetin and myricetin were also identified. The structures were established by conventional methods of analysis and confirmed by 1 H, 13 C NMR and negative ESI-mass spectrometry. 2D-long range selective proton decoupling and chemical shift correlation NMR experiments were applied for the new polyphenolics. The HPLC phenolic profile was used for the quality assessment of the E. hirsutum extract for medicinal purposes and also as a fingerprint for the authentication of the plant material.

Niloticol, a phenolic glyceride and two phenolic aldehydes from the roots of Tamarix nilotica

Abstract From the petrol extract of the roots of Tamarix nilotica the novel glyceride, niloticol, and the hitherto unknown aldehyde, isoferulaldehyde, together with the known aldehyde, ferulaldehyde, were isolated.

Quercetin 3-glycosides from the leaves of Solanum nigrum

Abstract Two new quercetin glycosides have been identified from the leaves of Solanum nigrum, namely, quercetin 3-O-(2Gal-α-rhamnosyl)-β-glucosyl (1→6)-β-galactoside and quercetin 3-O-α-rhamnosyl(l→2)-β-galactoside. The known compounds: quercetin 3-glucosyl(l→6)galactoside, 3-gentiobioside, 3-galactoside and 3-glucoside, were also found. All structures were determined by FAB MS, 1H NMR and 13C NMR analysis.

Flavonoid galloyl glucosides from the pods of Acaciafarnesiana

Abstract Three new flavonoids: naringenin 7- O - β -(4″,6″-digalloylglucopyranoside), quercetin 7- O - β -(6″-galloylglucopyranoside) and myricetin 7- O - β -(6″-galloylglucopyranoside) were identifiedfrom the pods of Acacia farnesiana , together with naringenin and kaempferol7-(6″-galloylglucoside). The structures were determined by conventional methods of analysisand confirmed by ESI-MS (negative mode) and NMR spectroscopy.

Phenolics from the bark ofTamarix aphylla

Abstract A unique diaryloxy furanofuran lignan, together with a unique biosynthetic transformation product of the known polyphenolic, dehydrodigallic acid, and an unique isoferulylglyceryl ester, isolated from the bark ofTamarix aphylla, have been characterized on the basis of chemical and spectroscopic analysis to be (±)-2e,6e-bis-(1-oxy-2,3-dimethoxyphenyl)-3,7-dioxabicyclo-[3,3,0]-octane, decar☐ydehydrodigallic acid and 1-isoferulyl-3-pentacosanoyl-glycerol, respectively.

Flavonoids ofOchradenus baccatus

Abstract From the aerial parts of Ochradenus baccatus , the new flavonoids, quercetin 3- O -β-glucosyl(1→2)-α-rhamnoside-7- O -α-rhamnoside and quercetin 3- O - p -coumaryl(1→6)-β-glucosyl(1→6)-β-glucoside-7- O -α rhamnoside were isolated. The known quercetin glycosides, quercetin 3-gentiobioside, isoquercitrin, quercitrin, together with the known kaempferol glycosides, astragalin and afzelin, were also characterized. The structures were established by conventional methods of analysis and confirmed by spectral analysis.

Flavonoid constituents of Ephedra alata

Abstract Two new flavonol glucosides have been identified in Ephedra alata, namely, herbacetin 8-methyl ether 3-O- glucoside-7-O-rutinoside and herbacetin 7-O-(6″-quinylglucoside). The known flavonoids vicenin II, lucenin III, kaempferol 3-rhamnoside, quercetin 3-rhamnoside and herbacetin 7-glucoside were also found. The structure of the isolated compounds was determined mostly by FABMS and 1H NMR spectroscopy. The final structure of the new compounds and of herbacetin 7-glucoside was confirmed by 13C NMR spectroscopy.