Objective Utilize metabolomics techniques to analyze the changes in chemical components of raw and steamed Rhei Radix et Rhizoma and the differences in their blood-entering components, and to reveal the impact of processing on the material basis of Rhei Radix et Rhizoma. Methods UPLC-MS/MS technology was used to collect the chemical composition information of raw and steamed Rhei Radix et Rhizoma in vitro and in vivo. Identification was carried out by combining the characteristic fragment ions and fragmentation pathways of the compounds. Multivariate statistical analysis was combined to screen for differential markers. Results A total of 201 components were identified in both raw and steamed Rhei Radix et Rhizoma, including 45 anthraquinones, 43 tannins, 52 flavonoids, and 21 stilbenes, 12 phenolic acids, seven phenylpropanoids, three chromones, two aromatic aldehydes, and 16 other compounds. After steaming, 23 common components showed significant changes. Among them, seven components such as aloeemodin, gallic acid, and catechin were significantly upregulated (P < 0.05), and 16 components such as aloeemodin-1-O-β-D-glucopyranoside, sennoside A, and proanthocyanidins were significantly downregulated (P < 0.05). A total of 36 prototype components and 58 metabolites were identified in the drug-containing serum. 11 common components showed significant changes in raw and steamed Rhei Radix et Rhizoma compared with raw Rhei Radix et Rhizoma, the blood drug concentrations of some prototype and metabolite components in steamed Rhei Radix et Rhizoma increased. In particular, the blood concentration of the tannin monomer gallic acid, which is a prototype component entering the blood, and the blood concentration of prototype aglycone-type components increased. The relative content of some phase-Ⅱ metabolites of anthraquinones significantly increased. Conclusion The in-vitro and in-vivo metabolic profiles of raw and steamed Rhei Radix et Rhizoma have changed significantly. The differential components are mainly in anthraquinones, tannins, etc. Compared with raw Rhei Radix et Rhizoma, in steamed Rhei Radix et Rhizoma, most conjugated anthraquinones were converted into free anthraquinones, hydrolysable tannin polymers were decomposed into tannin monomers, and there was a dynamic transformation between condensed tannin components and flavonoid aglycone components. These conversions of components can provide a scientific basis for clarifying the material basis of the “different treatments for raw and steamed Rhei Radix et Rhizoma ”.

raw Rhei Radix et Rhizoma  /  steamed Rhei Radix et Rhizoma  /  LC-MS/MS  /  multivariate statistical analysis  /  aloeemodin  /  gallic acid  /  catechin