Sahar A.M. Hussein

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.

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.

Caffeoyl sugar esters and an ellagitannin from Rubus sanctus

The new natural caffeoyl esters, 3,6-di-O-caffeoyl-(alpha/beta)-glucose and 1-O-caffeoyl-beta-xylose, together with the hitherto unknown natural tannin, 2,3-O-hexahydroxydiphenoyl-4,6-O-sanguisorboyl-(alpha/beta)-glucose, have been isolated from the aqueous alcohol aerial part extract of Rubus sanctus. Establishment of all structures was based on the chemical and spectral evidence, including ESI-MS and 2D NMR.

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.

Flavonol triglycoside and investigation of the antioxidant and cell stimulating activities of Annona muricata Linn.

Chemical investigation on leaves of Annona muricata resulted in the isolation of the flavonol triglycoside, quercetin 3-O-α-rhamnosyl-(1″″ → 6″)-β-sophoroside, together with twelve known phenolics. The structures of these compounds were established by 1D- and 2D-nuclear magnetic resonance spectroscopic techniques and mass spectrometry data. The in vitro antioxidant studies of the investigated aqueous ethanol extract and its column fractions were accomplished using the oxygen radical absorbance capacity (ORAC) method. A stimulating effect on HaCaT human keratinocytes by the leaf extract was also assessed. Il-6 production after UV irradiation was not influenced by A. muricata leaf extract.

Gall polyphenolics of Tamarix aphylla

Abstract From an aqueous ethanolic gall extract of Tamarix aphylla the new galloyl glucoses, 2,6-digalloyl glucose and 3,6-digalloyl glucose, were isolated.

Tamarixellagic acid, an ellagitannin from the galls of Tamarix aphylla

Abstract The novel natural polyphenol, 2-O-galloyl-3-O-(3,4,5,6,7-pentahydroxybiphenyl ether-8a-carboxylic acid-1- carboxyloyl)-4,6-(S)-hexahydroxybiphenol-(α/β)-4C1-glucopyranose, tamarixellagic acid, together with the known dehydrodigallic and dehydrotrigallic acids were isolated from the galls of Tamarix aphylla. The structures were established by conventional methods of analysis and confirmed by spectral procedures.

Flavonoids from Ephedra aphylla

Abstract A new di- C -glucosylflavone, 2″2‴-di- O -β-glucopyranosyl-vicenin II and a new flavonol di- O -glycoside, herbacetin 3- O -α-rhamnopyranoside-8- O -β-glucopyranoside, were isolated from the aerial parts of Ephedra aphylla . Vicenin II, the 7-methoxy-4-quinolone 2-carboxylic acid, ephedralone, p -hydroxybenzoic, p -coumaric, protocatechuic acids and herbacetin 7-methyl ether were also isolated. The 13 C NMR spectrum of the latter compound has been assigned for the first time.