Novel software-based method to classify structurally similar compounds combined with high performance liquid chromatography–quadrupole time of flight mass spectrometry to identify complex components of herbal medicines

The components of herbal medicines (HMs) are usually extremely complex, belonging to hundreds of compound classes with diverse chemical and physical properties. Full characterization of HMs is hugely important in order to identify the individual chemical constituents and provide a first step toward determining which components are responsible for the therapeutic effects of a particular medical plant. In this study, a novel software-based approach was developed to classify structurally similar compounds, and this was combined with high performance liquid chromatography/quadrupole time-of-flight mass spectrometry (HPLC–QTOF-MS) to identify the individual components in an extract of Mentha haplocalyx. A total of 33 compounds were tentatively identified in samples of M. haplocalyx extract, including 9 new minor constituents reported for the first time. Semi-quantitative analysis of the extract sample was also carried out. Software validation and robustness tests were performed. The results of this study demonstrate the enormous potential of this strategy, using classification based on structural similarity together with HPLC–QTOF-MS, for the identification and quantification of complex components in HMs and related products.