NMR spectroscopy

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1 - Thermodynamic study of Ion pairing in Aqueous solution of 〖BaF〗_2 by (_^19)F-NMR
H. Aghaie A. Aliabadi B. Sohrabi M. Aghaie M. R. Sohrabi

The ion-pair association constant values, related to the reaction + were determined by means of the NMR spectroscopy. The values of the thermodynamic functions of the ion pairing process were calculated on the basis of the NMR results. In addition, the association entro أکثر

The ion-pair association constant values, related to the reaction + were determined by means of the NMR spectroscopy. The values of the thermodynamic functions of the ion pairing process were calculated on the basis of the NMR results. In addition, the association entropy was found to be dependent on the temperature. Comparing the experimental data and the Fuoss theory it is found that ion-pair is formed in the aqueous solution. تفاصيل المقالة

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2 - Fractionation and Determination of Some Structural Properties of Persian Gum
S. Rahimi S. Abbasi

ABSTRACT: In the present study, Persian gum, an exudate gum which secrets from the mountain almond tree (Amygdalus scoparia Spach) from two different regions is evaluated by means of chemical and instrumental analysis (fractionated by solving in water and alkaline solut أکثر

ABSTRACT: In the present study, Persian gum, an exudate gum which secrets from the mountain almond tree (Amygdalus scoparia Spach) from two different regions is evaluated by means of chemical and instrumental analysis (fractionated by solving in water and alkaline solutions at 0.1, 0.5 and 1 M and also Smith degradation) using HPLC, 1HNMR and 13CNMR spectroscopy’s. The total sugar and uronic acid content of the gum are 88.70 and 10%, respectively. The results of the instrumental analyses revealed that the gum is predominantly composed of galactose and also (1→3) linked β-DGalp and rhamnose residues that exist at the backbone of polysaccharide where as the branches are composed of (1→6) linked β-DGalp and (1→) and/or (1→3) linked α-L-Araf residues. Therefore, due to the desirable structure of Persian gum (arabinogalactane) that is similar to the other hydrocolloids, it might be employed in food products. تفاصيل المقالة

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3 - Chemical constituents from the leaves and liana of Salacia nitida (Benth.) N.E.Br. (Celastraceae) and their antimicrobial activities
Brice Mba’ning Joël E. T. Ateba Angelbert F. Awantu Luciana S. Amaral Gervais M. Happi Beate Neumann Georg Stammler Bruno Lenta Silvère A. Ngouela Iran Malavazi Etienne Tsamo Norbert Sewald Edson Rodrigues-Filho

One benzophenone, 4′-hydroxy-2,4,6-trimethoxybenzophenone (1) was isolated from the liana and leaves of Salacia nitida (Benth.) N.E.Br., together with n-hexacosane (2), 29-hydroxyfriedelane (3), 3β-friedelinol (4), n-hexacosan-1-ol (5), n-octacosan-1-ol (6), أکثر

One benzophenone, 4′-hydroxy-2,4,6-trimethoxybenzophenone (1) was isolated from the liana and leaves of Salacia nitida (Benth.) N.E.Br., together with n-hexacosane (2), 29-hydroxyfriedelane (3), 3β-friedelinol (4), n-hexacosan-1-ol (5), n-octacosan-1-ol (6), mangiferin (7), β-sitosterol-3-O-β-D-glucopyranoside (8), friedelin (9), 30-hydroxyfriedelin (10), salaspermic acid (11), 22β-epi-maytenfolic acid (12), orthosphenic acid (13), maltose (14), D-mannitol (15), cangoronine (16), 7-hydroxyfriedelane-1,3-dione (17), tingenone (18), pristimerin (19), α-amyrin acetate (20), β-sitosterol (21) and stigmasterol (22), 21-hydroxyfriedelan-3-one (23), abruslactone A (24), and 2α-hydroxypopulnonic acid (25). The structures of the isolated compounds were established by means of spectroscopic analysis. In addition, the structure of (1) was confirmed by its X-ray diffraction. Compounds (1), (7), (10)-(11), (13), (16)-(19) and (25) were evaluated for their antimicrobial activities. Compound (18) showed a significant activity against Staphylococcus aureus (MIC = 23.8 µM) while compounds (11) and (19) exhibited moderate inhibiting effect against Staphylococcus aureus (MIC = 53.8 µM) and Candida glabrata (MIC = 105.9 µM), respectively. تفاصيل المقالة

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4 - Phytochemical characteristics of Galeopsis ladanum subsp. angustifolia (Ehrh. ex Hoffm.) Gaudin collected in Abruzzo region (Central Italy) with chemotaxonomic and ethnopharmacological implications
Claudio Frezza Alessandro Venditti Ilaria Serafini Alessandra Carassiti Sebastiano Foddai Armandodoriano Bianco Mauro Serafini

In this work, a phytochemical analysis on the total aerial parts of Galeopsis ladanum subsp. angustifolia (Ehrh. ex Hoffm.) Gaudin collected in Abruzzo region (Central Italy) has been reported. Nine compounds were identified belonging to five different classes of natura أکثر

In this work, a phytochemical analysis on the total aerial parts of Galeopsis ladanum subsp. angustifolia (Ehrh. ex Hoffm.) Gaudin collected in Abruzzo region (Central Italy) has been reported. Nine compounds were identified belonging to five different classes of natural compounds. Additional chemotaxonomic markers were recognized than our previous study, as well. Their presence is perfectly in accordance with the current botanical classification of the species and shows the possibility of a pronounced metabolic variability. The observed phytochemical composition may also suggest the possible use of this species in the ethnopharmacological field just like most Galeopsis species since they are endowed with several medicinal properties. Furthermore, no potential toxic component was identified in the studied accession. تفاصيل المقالة

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5 - Conformational Study of some novel Methoxy Half-Analogues of Michler’s Ketone by NMR
Naghi Saadatjou Geoffrey Hallas

One series of half-analogues of Michler’s ketone containing one or more terminal methoxysubstituents with variable tertiary amino groups have been used in this study. NMR spectralresults for the parent ketones confirm earlier findings that ortho proton shifts are أکثر

One series of half-analogues of Michler’s ketone containing one or more terminal methoxysubstituents with variable tertiary amino groups have been used in this study. NMR spectralresults for the parent ketones confirm earlier findings that ortho proton shifts are apparentlyindependent from steric effects in derivatives of Michler’s ketone because the ring current andcarbonyl-induced shifts are self-canceling. تفاصيل المقالة

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