Qaâdan Fadi, Nahrstedt Adolf, Schmidt Mathias, Mansoor Kenza
Faculty of Pharmacy, Petra University, Airport Street, P O Box 961343 Amman, Jordan.
Sci Pharm. 2010 Oct-Dec;78(4):897-907. doi: 10.3797/scipharm.1003-19. Epub 2010 Oct 28.
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 9â10 flavan-3-ol-units.
通过对银杏叶提取物进行葡聚糖凝胶LH - 20柱色谱分离，聚合原花青素在黄酮醇苷和双黄酮苷组分之后被洗脱出来。一种纯化的原花青素聚合物占总原花青素的86.6%，占该叶提取物总抗氧化活性的37.7%。为了阐明其结构，该聚合物在间苯三酚存在下进行酸性解聚。根据其全乙酰化衍生物的一维和二维核磁共振（HSQC、HMBC）谱、基质辅助激光解吸电离飞行时间质谱（MALDI - TOF - MS）和圆二色光谱（CD - 光谱）确定了所得黄烷 - 3 - 醇和间苯三酚加合物的结构。聚合物经间苯三酚降解得到的观察结果通过聚合物的碳 - 13核磁共振光谱得到证实。聚合部分的平均分子量估计为9×10个黄烷 - 3 - 醇单元。
