Pseudo-targeted metabolomics for differential components of Rhei Radix et Rhizoma from three plant species.

Rhei Radix et Rhizoma is common traditional Chinese medicine with multiple original plants. The content and proportion of the active components in Rhei Radix et Rhizoma from different plant species were compared to accurately evaluate the medicine qua-lity and provide a theoretical basis for precise use of this medicine in clinical practice. In this study, fresh Rhei Radix et Rhizoma samples were collected from the four-year-old plants of Rheum palmatum, R. tanguticum, and R. officinale. The relative content of 220 anthraquinones, anthrones, and tannins in the samples were determined by pseudo-targeted metabolomics, and the differential components were screened by multivariate statistical methods. The principal component analysis classified the samples into three clusters according to the original plants. The orthogonal partial least squares-discriminant analysis(OPLS-DA) screened out 117 differential components, including 8 free anthraquinones, 18 anthraquinone glycosides, 80 anthrones, and 11 tannins. Twenty-eight components had the highest content in R. tanguticum, mainly including sennosides, anthraquinone glycosides, and procyanidins. Thirty-five components showed the highest content in R. officinale, mainly including free anthraquinones and catechines. Fifty-four components showed the highest content in R. palmatum, mainly including dianthrones, while the structures of most of them cannot be determined temporarily. The content distribution of differential components in the three original plants indicates that R. tanguticum has the strongest effect of purging, while R. officinale has the strongest effect of clearing heat and purging fire, and both have stronger effects of resolvong stasis and dredging meridians than R. palmatum.