Mahmoud A.M. Nawwar

NMR spectral analysis of polyphenols from Punica granatum

Abstract Brevifolin carboxylic acid, brevifolin, corilagin, 3,6-( R )-hexahydroxydiphenoyl-(α/β)- 1 C 4 -glucopyranose, 1,2,6-tri- O -galloyl-β- 4 C 1 -glucopyranose, 1,4,6-tri- O -galloyl-β- 4 C 1 -glucopyranose, ellagic acid, 3,4,8,9,10-pentahydroxydibenzo[ b,d ]pyran-6-one, granatin-B and punicafolin were isolated from the leaves of Punica granatum . 1 H and 13 C NMR spectra of brevifolin carboxylic acid and brevifolin have been recorded and assigned for the first time. A new interpretation of the NMR data or related compounds is discussed. The structure of the new natural polyphenol-1,2,3- tri- O -galloyl-β- 4 C 1 -glucopyranose has been established.

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.

Leaf phenolics of Punica granatum.

Abstract From the leaves of Punica granatum , the unique phenolic, N-(2′,5′-dihydroxyphenyl)pyridinium chloride, as well as the known flavone glycosides, apigenin 4′- O -β-glucopyranoside, luteolin 4′- O - P -glucopyranoside, luteolin 3′- O -β-glucopyranoside and luteolin 3′- O -β-xylopyranoside, were isolated and identified. Structures were established by conventional methods of analysis and confirmed by FAB-mass spectrometry and NMR 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.

Flavonoids of the flowers of tamarix nilotica

Abstract The ethyl ester of kaempferol 3-O-β- D -glucuronide, the methyl and ethyl esters of quercetin 3-O-β- D -glucuronide have been isolated from an aqueous acetone extract of the flowers of Tamarix nilotica. In addition kaempferol 3-O-sulphate-7,4′-dimethyl ether and the free aglycones were isolated. The structures were established by routine methods, by FAB-MS and by 13C NMR spectral measurements.

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.

Stachysetin, a diapigenin-7-glucoside-p,p′-dihydroxy-truxinate from Stachys aegyptiaca

Abstract Aerial parts of Stachys aegyptiaca contain the unique acylated flavonoid, diapigenin-7- O -(6″- trans ,6″- cis - p , p ′-dihydroxy- μ -truxinyl) glucoside , stachysetin, and the hitherto unknown, apigenin 7- O -(3″- p -coumaryl) glucoside . In addition, the known compounds, apigenin 7- O -(6″- p -coumaryl) glucoside and naringenin were also identified. Structures were established by conventional methods of analysis and confirmed by 1 H, 13 C NMR and mass spectral analysis. 2D-chemical shift correlation NMR was also used in the case of the new flavonoids.

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.