Faculty of Pharmacy , Al-Azhar University , Assiut 71524 , Egypt.
College of Pharmacy , Najran University , Najran 55461 , Kingdom of Saudi Arabia.
J Nat Prod. 2019 Oct 25;82(10):2682-2695. doi: 10.1021/acs.jnatprod.9b00073. Epub 2019 Sep 18.
Ellagitannin oligomers are large molecules habitually showing complex NMR spectra that are sometimes misinterpreted and lead to incorrect structures. Understanding the NMR spectroscopic features of a group of ellagitannins would overcome these inadequacies. In this study, investigation of the galls of led to the isolation of three new ellagitannin oligomers, phyllagallins T1 (), T2 (), and Q1 (), a known monomer nilotinin M4 (), four known dimers, nilotinins D7 () and D8 (), hirtellin B (), and tamarixinin A (), and a simple phenolic, dehydrotrigallic acid (). 1D and 2D NMR, HRESI-TOFMS, and ECD experiments show that compounds - are hellinoyl-type ellagitannins. The NMR spectroscopic features of this type of ellagitannins and the reasons for the abnormal upfield shifts of glucose anomeric proton and hellinoyl moiety proton signals are established considering the experimental results as well as quantum chemical calculation on a simple hellinoyl-type monomer, phyllagallin M2. Based on these results, the NMR assignments reported previously by a different research group for bracteatinin T and hirtellin T are revised. A cytotoxicity study against human oral squamous cell carcinoma cell lines (Ca9-22, HSC-2, and HSC-4) and human mesenchymal normal oral cells (HGF, HPC, and HPLF) showed cytotoxic effects with tumor-specificity higher than 5.2, 3.0, 1.6, and 2.0 for compounds , , , and , respectively.
鞣单宁低聚物是一类通常表现出复杂 NMR 谱的大分子，这些谱有时会被误解，导致结构错误。了解鞣单宁低聚物的 NMR 光谱特征将克服这些不足。在这项研究中，对 的叶瘿的研究导致了三个新的鞣单宁低聚物，叶素 T1()、T2()和 Q1()、一个已知的单体没食子素 M4()、四个已知的二聚体，没食子素 D7()和 D8()、hirtellin B()和 tamarixinin A()，以及一个简单的酚类物质，去氢三没食子酸()。1D 和 2D NMR、HRESI-TOFMS 和 ECD 实验表明，化合物 - 是 hellinoyl 型鞣单宁。考虑到实验结果以及对简单的 hellinoyl 型单体叶素 M2 的量子化学计算，确定了该类型鞣单宁的 NMR 光谱特征以及葡萄糖端基质子和 hellinoyl 部分质子信号异常向上位移的原因。基于这些结果，对不同研究小组先前报道的 bracteatinin T 和 hirtellin T 的 NMR 归属进行了修订。对人口腔鳞状细胞癌细胞系 (Ca9-22、HSC-2 和 HSC-4) 和人间充质正常口腔细胞 (HGF、HPC 和 HPLF) 的细胞毒性研究表明，化合物 - 、-、- 和 - 对肿瘤的细胞毒性作用具有肿瘤特异性，其值分别高于 5.2、3.0、1.6 和 2.0。
