Investigation of Distinction Chemical Markers for Rhubarb Authentication Based on High-Performance Liquid Chromatography-Time-of-Flight Mass Spectrometry and Multivariate Statistical Analysis

Abstract

Rhubarb is a famous herb medicine commonly used for the treatment of purgation, anticancer, anti-inflammation, and promoting blood circulation in clinical. Recently, the situation that unofficial rhubarb is confused with official one on the market is becoming a serious threat to the efficacy of the crude drug. In this study, a comprehensive approach using principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) based on liquid chromarography coupled with electrospray ionization time-of-flight mass spectrometry and diode-array detection was established to explore novel markers for rhubarb authenticity which is important for quality assurance, pharmaceutical activity, and market protection. The method was validated based on pooled quality control samples and was found reliable and repeatable. In the procedure, metabolic fingerpringing of official and unofficial samples from different geographic regions was analyzed, and a total of 35 phenolic compounds were screened out and were tentatively characterized as authenticity markers of rhubarb based on their mass spectra and UV spectra. The content and pharmacological activity difference of these ingredients belonging to different compound classes (such as anthraquinone glycosides, catechins, stilbenes, naphthalenes, and butyrophenones) were compared by compound types on the base of extracted ion chromatograms. And anthraquinone glycosides, which have been considered as the major purgative components of rhubarb, were relatively contained more in official rhubarb. This research proved that a chemometric method based on liquid chromatography with diode-array detection and time-of-flight tandem mass spectrometry can comprehensively analyze chemical variation and provide evidence for quality control of herbal medicine.