Chemistry Department, Pomona College, Claremont, CA 91711, USA.
Magn Reson Chem. 2010 Jul;48(7):565-70. doi: 10.1002/mrc.2615.
Granatin B, a complex ellagitannin extracted from pomegranate fruit, has two equilibrating isomers, form a and form b. A full ensemble of proton and carbon-13 NMR methods over a wide range of temperature enabled a complete assignment of the more abundant isomer and showed it to be form b. This result is based on the NMR data for granatin alone and agrees with the previous determinations which were based on a combination of chemical methods and a partial assignment of the NMR spectra. The new NMR spectra also yield exchange rates for the hydroxyl protons as a function of temperature. A molecular model involving hydrogen bonding provides an explanation for the exchange data.
石榴果实中提取的复杂鞣花单宁格兰它宁 B 有两种平衡的同分异构体，形式 a 和形式 b。在很宽的温度范围内使用完整的质子和碳-13 NMR 方法，完成了较丰富的异构体的完全分配，并表明它是形式 b。这一结果是基于格兰它宁的 NMR 数据，与以前的基于化学方法和 NMR 谱部分分配的组合的测定结果一致。新的 NMR 谱还提供了随温度变化的羟基质子的交换速率。一个涉及氢键的分子模型为交换数据提供了一个解释。
