Metabolomics-based investigation of the chemical composition changes in Mongolian medicinal plant Euphorbia pekinensis before and after processing with Chebulae Fructus

Abstract

Euphorbia pekinensis (EP), known for its diuretic properties, is clinically utilized for treating conditions such as edema and malignant tumors. However, in its raw form, Euphorbia pekinensis is toxic, and oral administration of this crude medicine can lead to gastrointestinal stimulation, resulting in abdominal pain and diarrhea. In Mongolian medicine's ethnomedicinal system, a distinctive processing method called “Chebulae Fructus processing” is employed. Chebulae Fructus is used to mitigate the toxicity of EP and alleviate its purgative effects. Nevertheless, the detoxification mechanism associated with this processing method remains unexplored. It is hypothesized that processing with Chebulae Fructus may alter the chemical composition of EP, and the residual components of Chebulae Fructus within processed Chinese medicine might exhibit pharmacological antagonistic effects, thereby achieving the purpose of processing and reducing toxicity. To investigate this further, a combination of UPLC-QTOF-MS-based metabolomics technology and multivariate statistical analysis was employed to analyze and compare the chemical composition of raw and processed EP. Differential variables contributing to group separation were identified based on specific criteria, including VIP (Variable Importance in Projection) values of ≥ 1 in PLS-DA models, p-values < 0.05, and fold changes (FC) > 1.2 or < 0.8. The resulting differentially expressed features were then identified through database matching, literature review, or manual annotation. In total, 47 components were identified from the PEP samples in both positive and negative ionization modes, primarily belonging to flavonoids, terpenoids, organic acids, glycosides, and fatty acids. Among the raw EP group and PEP S4 group, 10 differential compounds were identified. Notably, one toxic terpene and one phenylpropanoid from EP were downregulated, while two bioactive components from Chebulae Fructus were upregulated in the processed group. The possible conversion reactions of these two processing Q-markers were also elucidated. The characteristic processing with Chebulae Fructus resulted in a change in the composition of this Mongolian medicine EP. Furthermore, this study provides a scientific foundation for optimizing the processing technology of EP and offers insights into the processing of other ethnomedicines with toxic properties.