Using UPLC-QTOF-MS to Analyze the Chemical Changes between Traditional and Dispensing Granule Decoctions of San-Ao-Tang

Abstract

In the present study, a chemical profiling approach based on ultra-performance liquid chromatography coupled with photodiode array detection and time-of-flight mass spectrometry (UPLC-PDA-TOF-MS) was proposed to rapidly evaluate the chemical consistency between traditional and dispensing granule decoctions of traditional medicine combinatorial formulae and validated using San-Ao-Tang (SAT) as a model combinatorial formula. SAT is an effective traditional Chinese medicine, which is usually used in treating asthma and other diseases of the respiratory system. Two decoctions were prepared: traditional decoction, which is a water extract of three mixed constituent herbs of SAT; and dispensing granule decoction, which is a mixed water extract of each individual herb of SAT. Batches of these two decoction samples were subjected to UPLC-PDA-TOF-MS analysis and the data sets of t(R)-m/z pairs, ion intensities and sample codes were processed with supervised orthogonal partial least squared discriminant analysis to holistically compare their differences. Once a clear classification trend was found in the score plot, further statistics were performed to generate points at the two ends of S, and the components that correlated to these ions were regarded as the most changed components during decoction of the combinatorial formula. The changed components were identified by comparing the mass/ultraviolet spectra and retention times with those of reference compounds and/or tentatively assigned by matching empirical molecular formulae with those of the known compounds published in the literature. Using the proposed approach, global chemical differences were found between traditional and dispensing granule decoctions, like ephedrine, pseudoephedrine, norpseudoephedrine, licorice saponine H2, licorice saponine G2 and amygdalin.