Novel strategy for herbal species classification based on UPLC–HRMS oligosaccharide profiling

Abstract

Oligosaccharides, which exist widely in herbs, present diverse important pharmacological activities. However, the complexity of oligosaccharides seriously challenges their profiling, quality control, and elucidation of activity. In this paper, a novel oligosaccharide analytical method based on a new derivatization pretreatment and ultra-performance liquid chromatography coupled with high resolution tandem mass spectrometry (UPLC–HRMS) procedure was developed to rapidly profile and identify the oligosaccharides of Epimedium. Oligosaccharides are easily derivatized by 2,4-bis(diethylamino)-6-hydrazino-1,3,5-triazine under convenient and mild conditions. Without any further purification steps, oligosaccharides were analyzed by an established UPLC–HRMS/MS method with high sensitivity, good separation efficiency and speed. Benefitting from the derivatization, the oligosaccharides generated a response in the MS two orders of magnitude higher than that of the free oligosaccharide. Oligosaccharides of 52 Epimedium samples were profiled and identified based on the high-resolution mass spectral data. A total of 66 oligosaccharide compounds detected in 52 Epimedium herbs were relatively quantified and statistically processed by principal component analysis (PCA). The 52 Epimedium herbs could be classified into different species based on their oligosaccharide composition and content. Thirteen oligosaccharide compounds demonstrated potential as markers for Epimedium species classification, and their structures were preliminarily identified using MS/MS spectra.