Geographic impact evaluation of the quality of Alismatis Rhizoma by untargeted metabolomics and quantitative assay.

Abstract

The geographic impact on the quality of Alismatis Rhizoma (derived from the tuber of Alisma orientale), a reputable diuretic traditional Chinese medicine, has seldom been evaluated. Here a metabolomics-driven approach targeting the bioactive protostane triterpenes was developed, by incorporating UHPLC with quadrupole time-of-flight mass spectrometry-based untargeted metabolite profiling and multiple reaction monitoring quantitative assay, to probe the triterpene differences between Alismatis Rhizoma samples collected from Sichuan, Fujian, and Jiangxi Provinces. Following the metabolomics workflows, the samples from Sichuan and Jiangxi displayed distinct differences in their triterpene profiles, whereas those from Fujian showed remarkable intra-class variation. Twenty-three triterpenes were identified to contribute most to the differentiated clustering. A sensitive, precise, repeatable, and accurate quantitative assay method was established on a hybrid triple quadrupole-linear ion trap mass spectrometer to quantify the contents of eight triterpene compounds. Taking into account the metabolomics and quantitation results, alisol B 23-acetate and alisol A are significantly different in Alismatis Rhizoma from Sichuan and Jiangxi Provinces, and they may have the potential for geographic discrimination. These results illustrate how geographic difference impacts the triterpene chemistry of Alismatis Rhizoma. Metabolomics-driven chemical comparison is suitable for the quality evaluation of traditional Chinese medicine.