Caffeoylquinic acids from Silphium perfoliatum L. show hepatoprotective effects on cholestatic mice by regulating enterohepatic circulation of bile acids.

ETHNOPHARMACOLOGICAL RELEVANCE

The incidence of cholestatic liver disease (CLD), which is primarily marked by abnormal bile acids (BAs) metabolism and can result in significant hepatic injury, is rising. Nevertheless, there remains a lack of effective treatments and drugs in clinical practice. Silphium perfoliatum L. (SP) is rich in various structural types of caffeoylquinic acid (CQA) compounds, and it is a traditional herb of North American Indians with hepatobiliary therapy effects. However, its therapeutic effect and mechanism of action on CLD have never been studied.

AIM OF THE STUDY

To determine if SP-8, an extract rich in CQAs from SP, protects against cholestatic liver injury induced by alpha-naphthylisothiocyanate (ANIT) and to clarify its mechanism based on the farnesoid x receptor (FXR) signaling pathway and enterohepatic circulation of BAs.

MATERIALS AND METHODS

The therapeutic efficacy of SP-8 was evaluated by assessing the serum biochemical indices, inflammatory factors, and liver histopathology. Targeted metabolomics of the BAs was studied in the feces, liver, serum, and bile using UPLC-MS/MS. Additionally, a Western blot analysis was used to examine the expression levels of the peroxisome proliferator-activated receptor γ (PPARγ), the FXR, and proteins related to the synthesis and transport of BAs. 16S rRNA gene sequencing was performed to evaluate the gut microbiota (GM). Finally, molecular docking simulations were conducted to assess the interaction between seven types of CQAs from SP-8 with FXR and PPARγ.

RESULTS

SP-8 significantly enhanced the health status of cholestatic mice induced by ANIT as evidenced by a notable reduction in the liver function indices and pro-inflammatory factors, restoration of liver pathological damage, and acceleration of BAs excretion through the feces. In addition, the levels of harmful secondary BAs in the liver and blood were significantly reduced by SP-8. Furthermore, the results of the study on the mechanism of action confirmed that SP-8 not only regulated FXR and PPARγ but also significantly ameliorated the GM structure, thereby promoting the enterohepatic circulation of BAs and achieving the homeostasis of the BAs in the blood and liver. In addition, SP-8 successfully reduced the inflammatory response by strongly suppressing the nuclear translocation of NF-κBp65. According to the molecular docking results, the extract's primary active ingredients could be the seven CQAs in SP-8, as they exhibited a strong affinity for both FXR and PPARγ. Finally, the Mantel test analysis revealed a significant correlation among cholestatic-associated parameters, the GM, and BAs.

CONCLUSION

It was confirmed for the first time that the SP-8 extract of Silphium perfoliatum L. that is rich in seven CQAs had a strong therapeutic effect on ANIT-induced CLD. Its mechanism may involve the regulation of the FXR signaling pathway and the amelioration of the GM structure to promote the homeostasis of BAs enterohepatic circulation. This study provides a potential candidate medicinal herb and its components for the development of CLD therapeutic drugs.