Advanced analysis of oligomeric proanthocyanidins: latest approaches in liquid chromatography and mass spectrometry based analysis

Abstract

Proanthocyanidins (PAC) are an important and widely spread class of natural products with various bioactivities. The analytical evaluation of oligomeric and polymeric proanthocyanidins in complex extracts is still challenging, due to the complexity of structures. Nevertheless, in the last 20 years analytical techniques especially in the field of chromatography and mass spectrometry have been improved and offer exciting possibilities for a deeper insight into plant secondary metabolism. While classical colorimetric methods and protocols for partial hydrolysis are still valuable tools new chromatographically and mass spectrometric methods provide deep insights into the PAC fine structure, also of polymeric material. The present review focus on recent innovative LC–MS and MALDI-TOF methods, innovative strategies for advanced processing of LC-HRMS data (van Krevelen plots, Kendrick Mass Defect Analysis), MS/MS fragmentation, and newest two-dimensional LC × LC (Offline, Online, Stop-flow-2D) chromatography. Also MALDI-TOF imaging provides exciting inside in PAC distribution within biological samples and functional assays.