Zeller Wayne E, Ramsay Aina, Ropiak Honorata M, Fryganas Christos, Mueller-Harvey Irene, Brown Ronald H, Drake Chris, Grabber John H
U.S. Dairy Forage Research Center, Agricultural Research Service, U.S. Department of Agriculture , 1925 Linden Drive West, Madison, Wisconsin 53706, United States.
J Agric Food Chem. 2015 Feb 25;63(7):1967-73. doi: 10.1021/jf504743b. Epub 2015 Feb 13.
Studies with a diverse array of 22 purified condensed tannin (CT) samples from nine plant species demonstrated that procyanidin/prodelphinidin (PC/PD) and cis/trans-flavan-3-ol ratios can be appraised by (1)H-(13)C HSQC NMR spectroscopy. The method was developed from samples containing 44-∼100% CT, PC/PD ratios ranging from 0/100 to 99/1, and cis/trans ratios ranging from 58/42 to 95/5 as determined by thiolysis with benzyl mercaptan. Integration of cross-peak contours of H/C-6' signals from PC and of H/C-2',6' signals from PD yielded nuclei-adjusted estimates that were highly correlated with PC/PD ratios obtained by thiolysis (R(2) = 0.99). cis/trans-Flavan-3-ol ratios, obtained by integration of the respective H/C-4 cross-peak contours, were also related to determinations made by thiolysis (R(2) = 0.89). Overall, (1)H-(13)C HSQC NMR spectroscopy appears to be a viable alternative to thiolysis for estimating PC/PD and cis/trans ratios of CT if precautions are taken to avoid integration of cross-peak contours of contaminants.
对来自9种植物的22种纯化缩合单宁（CT）样品进行的研究表明，原花青素/原翠雀素（PC/PD）和顺式/反式黄烷-3-醇比例可通过¹H-¹³C HSQC核磁共振光谱法进行评估。该方法是从含44%至~100%CT的样品开发而来，PC/PD比例范围为0/100至99/1，顺式/反式比例范围为58/42至95/5，这些比例通过苄基硫醇硫解测定。对来自PC的H/C-6'信号和来自PD的H/C-2',6'信号的交叉峰轮廓进行积分，得到的核调整估计值与通过硫解获得的PC/PD比例高度相关（R² = 0.99）。通过对各自的H/C-4交叉峰轮廓进行积分获得的顺式/反式黄烷-3-醇比例，也与硫解测定结果相关（R² = 0.89）。总体而言，如果采取预防措施避免污染物交叉峰轮廓的积分，¹H-¹³C HSQC核磁共振光谱法似乎是硫解的可行替代方法，用于估计CT的PC/PD和顺式/反式比例。
