茶叶的1H NMR指纹图谱研究

用¹H NMR分析测定35种从福建、云南、广州、江西等地采集及购买的不同种类的茶叶.检测出约20种物质，包括多种氨基酸、茶氨酸、多种儿茶素(表没食子儿茶素(EGC)、表儿茶素(EC)、表没食子儿茶素没食子酸酯（EGCG）、表儿茶素没食子酸酯（ECG）和一些未知的儿茶素)、蔗糖、未知糖类、脂肪酸、 咖啡因等.所得谱图经主成分分析，实现了不同种类的茶叶以及铁观音产地的区分，并且发现了引起区分的化学成分：红茶和黑茶与绿茶和乌龙茶相比，部分氨基酸和一些未知成分的含量较高，而儿茶素的含量较低；安溪西坪铁观音与安溪祥华和感德铁观音相比，部分氨基酸、咖啡因、EGCG、ECG以及一些未知成分的含量较高，而EC、EGC含量相对低.另外，谱图的聚类分析也显示了与主成分分析类似的结果.

Fingerprinting Tea by 1H NMR

The chemical fingerprints of 35 tea samples collected or purchased from Fujian、Yunnan、Guangdong、Jiangxi provinces were analyzed by ¹H NMR. Upon initial signal assignment, about 20 chemical constituents in tea were identified, including amino acids, theanine, catechins (EGC, EC, EGCG, ECG and unknown catechins), sucrose, unknown sugars, fatty acids, caffeine, quinic acid and so on. The NMR data were then analyzed by the principal component analysis (PCA) technique. The results show that different kinds of tea and Tieguanyin tea from different producing areas can be differentiated based on their chemical composition. Furthermore, the chemical constituents that can be used as the fingerprints for differentiating different types of tea were found. Compared to the green tea and the oolong tea, the red tea and the black tea were found to contain higher levels of certain amino acids and some unknown substances, and lower levels of catechins. Xiping Tieguanyin, as compared to Xianghua and Gande Tieguanyin, was found to have higher levels of certain amino acids, caffeine, EGCG, ECG and some unknown substances, and lower levels of EC, EGC. Hierarchical cluster analysis (HCA) of the data shows similar results as those obtained by PCA.