Polyphenols from Ginkgo biloba |
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Authors: | Qaâdan Fadi Nahrstedt Adolf Schmidt Mathias Mansoor Kenza |
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Institution: | 1 Faculty of Pharmacy, Petra University, Airport Street, P O Box 961343 Amman, Jordan;2 Institut fuer pharmazeutische Biologie und Phytochemie, Hittorfstrasse 56, D-48149 Muenster, Germany;3 HerbResearch, Wartbergweg 15, D-86874 Mattsies, Germany;4 School of Pharmacy, Al-Ahliyya Amman University: Amman-19328, Jordan |
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Abstract: | By Sephadex LH-20 gel chromatography of an extract from Gingko biloba leaves, polymeric proanthocyanidins were eluted after the fractions of flavonol glycosides and biflavone glycosides. A purified proanthocyanidin polymer accounted for 86.6% of the total proanthocyanidins, and for 37.7% of the total antioxidant activity of this leaf extract. For structure elucidation, the polymer was submitted to acidic depolymerization in the presence of phloroglucinol. The structures of the resulting flavan-3-ols and phloroglucinol adducts were determined on the basis of 1D-and reverse 2D-NMR (HSQC, HMBC) spectra of their peracetylated derivatives, MALDI-TOF-MS and CD-spectroscopy. The observations resulting from the degradation with phloroglucinol were confirmed by (13)C-NMR spectroscopy of the polymer. The mean molecular weight of the polymeric fraction was estimated to be 9a10 flavan-3-ol-units. |
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Keywords: | Ginkgo biloba Polymeric proanthocyanidins Anti oxidant Fremy’s salt |
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