DeFENS-Department of Food, Environmental and Nutritional Sciences, Università degli Studi di Milano, Via Celoria 2, 20133 Milano, Italy.
Molecules. 2019 Apr 17;24(8):1504. doi: 10.3390/molecules24081504.
4-dimethylammino-cinnamaldehyde (DMAC) assays quantify total proanthocyanidins (PACs) but do not provide qualitative PAC molecular weight distribution information and cannot discriminate between A- and B-type PACs. We developed an efficient method for assessing PAC molecular weight distributions. The PACs from three commercial cranberry extracts (A1-A3) were fractionated by molecular sieves with cut-offs of 3, 10, 30, 50, and 100 kDa, and each fraction was analyzed by DMAC assays. A1, A2, and A3 contained 27%, 33%, and 15% PACs, respectively. Approximately 28 PACs, 20 flavonols, and 15 phenolic acids were identified by UHPLC-DAD-Orbitrap MS in A1 and A3, while A2 contained only flavan-3-ols. Epicatechin was the main monomer in A1 and A3, and catechin was the main in A2. Procyanidin A2 was the main dimer in A1 and A3, representing more than 85% of the total dimers, while it constituted approximately only 24% of A2. A1 and A3 contained quercetin, isorhamnetin, myricetin, and their glycosides, which were totally absent in A2. In A1 and A3 the PACs were mainly distributed in the fractions 30-3 and <3 kDa, while in A2 more than 70% were present in the fraction less than 3 kDa. Overall, obtained data strongly suggests that A2 is not cranberry-derived, or is adulterated with another source of PACs.
4-二甲氨基肉桂醛（DMAC）法测定总原花青素（PACs），但不能提供 PAC 分子量分布的定性信息，也不能区分 A 型和 B 型 PAC。我们开发了一种评估 PAC 分子量分布的有效方法。用 3、10、30、50 和 100 kDa 的分子筛对三种商业蔓越莓提取物（A1-A3）中的 PAC 进行分级，并用 DMAC 法对每个级分进行分析。A1、A2 和 A3 分别含有 27%、33%和 15%的 PAC。A1 和 A3 中通过 UHPLC-DAD-Orbitrap MS 鉴定出约 28 种 PAC、20 种类黄酮和 15 种酚酸，而 A2 仅含有黄烷-3-醇。表儿茶素是 A1 和 A3 的主要单体，儿茶素是 A2 的主要单体。原花青素 A2 是 A1 和 A3 的主要二聚体，占总二聚体的 85%以上，而在 A2 中仅占约 24%。A1 和 A3 含有槲皮素、异鼠李素、杨梅素及其糖苷，而在 A2 中完全不存在。A1 和 A3 中的 PAC 主要分布在 30-3 和<3 kDa 级分中，而 A2 中超过 70%存在于<3 kDa 级分中。总的来说，研究结果强烈表明 A2 不是蔓越莓来源的，或者与其他来源的 PAC 掺假。
