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Proanthocyanidin glycosides from the leaves of Quercus ilex L. (Fagaceae) |
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| Authors: | Anastasia Karioti Anna Rita Bilia Luigi Messori |
| Affiliation: | a Department of Pharmacognosy and Chemistry of Natural Products, School of Pharmacy, University of Athens, Panepistimiopolis, Zografou, 157 71 Athens, Greece b Department of Pharmaceutical Sciences, University of Florence, via Ugo Schiff 6, Polo Scientifico, Sesto Fiorentino, 50019 Florence, Italy c Laboratory of Metals in Medicine, Department of Chemistry, University of Florence, Via della Lastruccia 3, 50019 Sesto Fiorentino, Firenze, Italy |
| Abstract: | From the polar extracts of the leaves of Quercus ilex L., two new proanthocyanidin glycosides, namely afzelechin-(4α→8)-catechin-3-O-β-glucopyranoside (1) and afzelechin-(4α→8)-catechin-3-O-α-rhamnopyranoside (2), were isolated in addition to catechin (3), proanthocyanidin B3 (4), prodelphinidin C (5), dehydrodicatechin A (6), quercetin (7) and six known flavonol glucosides with their acylated derivatives (8-13) and ellagic acid (14). The structures of all isolated compounds were established by spectroscopic means, mainly 1D and 2D NMR, as well as LC/MS and HR-MS spectrometric analyses. The absolute configuration of compound 1 was determined by CD measurements. The proanthocyanidin glycosides are especially interesting, as they possess the sugar in the upper unit of the dimer, which is rare for this type of compounds. |
| Keywords: | Quercus ilex Fagaceae Oak-leaves Proanthocyanidin glycosides ROESY Circular dichroism |
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