University of Illinois College of Pharmacy, 833 South Wood Street , Chicago , Illinois 60612 , United States.
Linus Pauling Institute and Department of Pharmaceutical Sciences , Oregon State University , 2900 SW Campus Way , Corvallis , Oregon 97331 , United States.
J Agric Food Chem. 2018 Oct 31;66(43):11355-11361. doi: 10.1021/acs.jafc.8b04258. Epub 2018 Oct 16.
Although procyanidins constitute a unique class of polymeric plant secondary metabolites with a variety of biological properties including potent antioxidant activity, structure determination has been challenging, and structures of many complex procyanidins remain uncertain. To expedite the characterization of procyanidins, negative ion matrix-assisted laser desorption ionization high-energy collision-induced dissociation tandem time-of-flight (MALDI-ToF/ToF) mass spectra of 20 isolated procyanidins containing catechin and epicatechin subunits with degrees of polymerization up to five were obtained and evaluated. Structurally significant fragmentation pathways of singly charged, deprotonated molecules were identified representing quinone methide, heterocyclic ring fission, and retro-Diels-Alder fragmentation. The interpretation of the tandem mass spectra for sequencing A-type, B-type, mixed-type, linear, and branched procyanidins is explained using specific examples of each.
虽然原花青素是一类具有多种生物活性的独特的植物次生代谢聚合物，包括强大的抗氧化活性，但结构测定一直具有挑战性，许多复杂原花青素的结构仍不确定。为了加速原花青素的表征，获得了 20 种含有儿茶素和表儿茶素单元、聚合度高达 5 的分离原花青素的负离子基质辅助激光解吸电离高能碰撞诱导解离串联飞行时间（ MALDI-ToF/ToF ）质谱，并对其进行了评估。鉴定了单电荷、去质子分子的结构重要的碎裂途径，包括醌甲醚、杂环环裂解和反-Diels-Alder 碎裂。使用每种类型的具体示例解释了用于测序 A 型、B 型、混合型、线性和支链原花青素的串联质谱的解释。
