Investigating the Mechanisms of Astragalus mongholicus Bunge and Curcuma aromatica Salisb. in Combating Colorectal Cancer: Unraveling the Roles of Bile Acid Metabolism and Intratumoral Microbiota Regulation

Objective: To elucidate the pharmacodynamic material basis of Astragalus mongholicus Bunge and Curcuma aromatica Salisb. (AC) in the treatment of colorectal cancer (CRC) and to investigate its mechanism of action via modulation of bile acid receptors (FXR and TGR5) and the intratumoral microbiota.Methods: The chemical constituents of AC aqueous extract and their distribution in various tissues of CRC bearing mice were analyzed using UHPLC-MS/MS. An orthotopic transplant tumor model using CT26.WT cells was established to evaluate the antitumor effects and histopathological improvements mediated by major AC components, including total astragalus saponins (TAS) and zedoary turmeric oil (ZTO). Molecular docking was performed to assess the binding affinity of these components to FXR and TGR5. Western blotting was used to detect receptor protein expression levels. Fecal bile acid profiles were quantified by UPLC-QTrap-MS/MS. The structure and function of the intratumoral microbiota were analyzed using 16S rRNA sequencing, fluorescence in situ hybridization (FISH) after fecal microbiota transplantation (FMT).Results: Key components of AC, notably TAS and ZTO, were found to accumulate preferentially in intestinal tissues. Pharmacodynamic studies demonstrated that the combination of TAS and ZTO exerted stronger tumor-suppressive effects (tumor inhibition rate: 61.01%) and significantly ameliorated histopathological damage in tumor, liver, and colon tissues compared to monotherapies. Molecular docking revealed strong binding interactions (binding energy< -5.9 kcal/mol) between active constituents in TAS/ZTO and FXR/TGR5. In vivo experiments confirmed that TAS+ZTO up-regulated FXR and TGR5 protein expression in the liver and colon, and effectively reversed metabolic disorders of primary bile acids (CA, CDCA), secondary bile acids (DCA, LCA), and conjugated bile acids in model mice. Furthermore, TAS+ZOT reshaped the intratumoral microbiota structure, reducing the abundance of pro-tumor bacteria such as g_Escherichia. FMT experiments validated that the modulated microbiota derived from TAS+ZTO-treated mice inhibited tumor growth and improved bile acid metabolism.Conclusion: The primary active components of AC, TAS and ZTO, accumulate in the intestinal tract and synergistically suppress colorectal cancer progression by activating FXR/TGR5 signaling, correcting bile acid metabolic disorders, and remodeling the intratumoral microbiota microenvironment. This study reveals the multi-component, multi-target, and multi-pathway mechanism of AC, providing a scientific foundation for its clinical application.