Department of Food Research, School of Chemistry, Autonomous University of Coahuila, 25280 Saltillo, Coahuila, Mexico.
Departamento de Ingenierías, Instituto Tecnológico de Ciudad Valles, Tecnológico Nacional de México, 79010 Cd. Valles, S.L.P, Mexico.
Food Chem. 2019 Sep 1;291:126-131. doi: 10.1016/j.foodchem.2019.04.020. Epub 2019 Apr 5.
Procyanidins (PCs) are polyphenols highly accumulated in litchi fruit (Litchi chinensis). Despite their bioactivity, the molecular composition of native and oxidized procyanidins is little understood. In this paper, polyphenols from litchi pericarp were extracted using two solvents (methanol and acetone). The mean degree of polymerization (mDP) of native and identification of oxidized PCs were carried out by phloroglucinolysis- and thioglycolysis-HPLC-ESI-MS/MS, respectively. About 60% of extracted polyphenols corresponded to procyanidins from litchi pericarp. Native PCs were mainly oligomeric procyanidins (mDP 4). Only (-)-epicatechin was detected as terminal and extension units in PCs. Thioglycolysis-HPLC-ESI-MS identified five oxidation markers of PCs with [M-H]m/z 575, 593, 609, 679 and 863. Intra- and intermolecular modifications of A and B-type procyanidins were identified. The method used for the characterization of PCs from litchi pericarp allowed understanding of the structural composition of its native and oxidized tannins.
原花青素（PCs）是荔枝果实（Litchi chinensis）中高度积累的多酚类物质。尽管具有生物活性，但天然和氧化原花青素的分子组成仍知之甚少。在本文中，使用两种溶剂（甲醇和丙酮）从荔枝果皮中提取多酚。采用间苯三酚裂解-和巯基乙内酯裂解-HPLC-ESI-MS/MS 分别对天然 PCs 的聚合度（mDP）和鉴定进行了研究。约 60%的提取多酚对应于荔枝果皮中原花青素。天然 PCs 主要为低聚原花青素（mDP 4）。在 PCs 中仅检测到（-）-表儿茶素作为末端和扩展单元。巯基乙内酯裂解-HPLC-ESI-MS 鉴定了 PC 中的五个氧化标记物，其[M-H]m/z 分别为 575、593、609、679 和 863。鉴定了 A 型和 B 型原花青素的分子内和分子间修饰。用于表征荔枝果皮中原花青素的方法有助于了解其天然和氧化单宁的结构组成。
