Ultra-performance liquid chromatography-quadrupole\time-of- flight mass spectrometry with multivariate statistical analysis for exploring potential chemical markers to distinguish between raw and processed Rheum palmatum

The long term use of Rheum palmatum for the treatment of diseases associated with chronic hepatitis and renal failure can lead to liver and kidney damage. To reduce the toxicity of R. palmatum and alleviate any symptoms of decanta and celialgia, the raw material has been subjected to a specific process prior to its use for hundreds of years. Despite its extensive use in medicine, very little is currently known about the nature of the components present in this material in terms of their efficacy and overall toxicity, and the effect that processing has on the levels of these components in the processed material. The aim of this investigation was to explore potential differences in the chemical markers between batches of raw and processed R. palmatum and to develop a deeper understanding of the underlying mechanisms responsible for the enhanced efficacy and reduced toxicity of the processed material. Raw and processed R. palmatum samples were analyzed by ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF-MS) coupled with multivariate statistical analysis using principal component analysis (PCA) and orthogonal partial least square discriminant analysis (OPLS-DA). The emodin-8-O-glucoside, emodin-O-glucoside, catechin-glucopyranoside, gallic acid-3-O-glucoside, torachrysone, and chrysophanol dimethyl ether were rapidly explored as representative markers to distinguish for the first time between the raw and processed R. palmatum material. Among the potential chemical markers, Emodin-8-O-glucoside and gallic acid-3-O-glucoside were determined to be the best markers for the raw and processed R. palmatum. UPLC/Q-TOF-MS with multivariate statistical analysis represents an efficient method for exploring the chemical markers in the raw and processed R. palmatum material, as well as investigating the mechanisms associated with the processing, quality control, and safe application of R. palmatum.