Department of Food Science and Nutrition, Zhejiang University , KaiXuan Road 268, Hangzhou CN 310029, People's Republic of China.
J Agric Food Chem. 2011 Mar 9;59(5):1622-9. doi: 10.1021/jf103918v. Epub 2011 Feb 14.
Extractable and unextractable proanthocyanidins (EPAs and UEPAs) from leaves of bayberry were characterized. Both EPAs and UEPAs were analyzed by acid catalysis in the presence of excess phloroglucinol. The main cleavage product, epigallocatechin-3-O-gallate-(4β→2)-phloroglucinol, was successfully identified. The EPAs were of the prodelphinidin type. In fact, epigallocatechin-3-O-gallate (EGCG) and traces of epigallocatechin (EGC) were detected as the extension units, but only EGCG was present in the terminal units. All of the compounds exhibited a 2,3-cis configuration, and >98% of them were galloylated. The mean degree of polymerization (mDP) of bayberry leaf EPAs was 6.5, and the most abundant EPAs were the polymers, with mDP values of 9.5-26.7. The UEPAs were highly polymerized prodelphinidins consisting of EGCG and traces of EGC. In addition, EGCG, three EPA dimers, and two trimers were identified. The EPAs and UEPAs consisted mostly of EGCG, which is unusual in the plant kingdom.
从杨梅叶中提取可萃取和不可萃取原花青素（EPAs 和 UEPAs），并对其进行了表征。在过量邻苯三酚存在下，通过酸催化分析了 EPAs 和 UEPAs。成功鉴定了主要的裂解产物表儿茶素-3-O-没食子酸酯-（4β→2）-邻苯三酚。EPAs 属于原棓儿茶素型。实际上，检测到表没食子儿茶素-3-O-没食子酸酯（EGCG）和痕量表没食子儿茶素（EGC）作为延伸单元，但仅在末端单元中存在 EGCG。所有化合物均呈现 2,3-顺式构型，且 98%以上被酰化。杨梅叶 EPAs 的平均聚合度（mDP）为 6.5，最丰富的 EPAs 是具有 9.5-26.7 mDP 值的聚合物。UEPAs 是由 EGCG 和痕量 EGC 组成的高度聚合原棓儿茶素。此外，还鉴定了 EGCG、两种 EPA 二聚体和一种三聚体。EPAs 和 UEPAs 主要由 EGCG 组成，这在植物界中很不寻常。
