# Emodin and physcion alleviate cholestatic liver injury by targeting FXR: hepatoprotective components identified in processed Polygonum multiflorum Thunb. using a comprehensive two-dimensional biochromatography system

## TL;DR

This study identifies emodin and physcion as key compounds in processed Polygonum multiflorum that protect the liver by targeting the FXR pathway, reducing liver injury and inflammation.

## Contribution

A novel comprehensive 2D FXR biochromatography system was developed to identify hepatoprotective components in processed Polygonum multiflorum.

## Key findings

- Emodin and physcion were identified as FXR-binding components with increased content in processed PM.
- These compounds alleviated cholestatic liver injury in mice by upregulating FXR signaling and suppressing inflammation.
- The FXR antagonist Z-guggulsterone disrupted the hepatoprotective effects of emodin and physcion.

## Abstract

Polygonum multiflorum Thunb. (PM) is a representative traditional Chinese medicine (TCM) that exerts different effects in raw and processed forms. The hepatotoxicity of PM is markedly reduced after processing, whereas its hepatoprotective effects are enhanced.

This study aimed to establish a novel comprehensive two-dimensional (2D) biochromatography system based on farnesoid X receptor (FXR), which is an important target in cholestatic liver injury (CLI), to investigate the material basis and mechanisms underlying the enhanced hepatoprotection and reduced hepatotoxicity of processed PM (P-PM).

A comprehensive 2D FXR biochromatography system was established by immobilizing FXR on 3-mercaptopropyltrimethoxysilane (MPTS)-modified silica gel. This system was used to identify the FXR-binding components in raw PM (R-PM) and P-PM. Molecular docking, surface plasmon resonance, and frontal affinity chromatography were used to validate the interactions. The hepatoprotective effects of emodin and physcion were assessed in α-naphthylisothiocyanate (ANIT)-induced CLI mouse models, and an FXR antagonist (Z-guggulsterone) rescue experiment was performed. The expression of FXR signaling-related proteins, including FXR, small heterodimer partner (SHP), bile salt export pump (BSEP), Na+-taurocholate cotransporting polypeptide (NTCP), and inflammatory cytokines, was assessed by Western blotting, real-time quantitative reverse transcription PCR, and immunofluorescence.

The comprehensive 2D FXR biochromatography system successfully identified emodin and physcion as key FXR-binding components, with significantly increased content in P-PM. These components may contribute to the enhanced hepatoprotection and reduced hepatotoxicity of P-PM. In vivo, emodin and physcion alleviated ANIT-induced CLI, as evidenced by improved histopathological features and decreased serum levels of liver function markers. Mechanistically, both components upregulated the expression of FXR, BSEP, SHP, and NTCP while suppressing inflammatory cytokine expression. Their hepatoprotective effects and FXR-related upregulation could be disrupted by FXR antagonist Z-guggulsterone. These results suggest that emodin and physcion are key components contributing to the hepatoprotective effects of P-PM, likely through activation of the FXR signaling pathway and suppression of inflammation.

This study established a novel, efficient, rapid, and accurate comprehensive 2D FXR biochromatography system, which is suitable for screening targeted components in TCM, and can be extended to research on other TCMs.

This figure illustrates the workflow for screening FXR-binding compounds from different PM samples using a comprehensive 2D FXR biochromatography system. The diagram shows images of different PM samples, the workflow of the MPTS-functionalized chromatographic column, and the comprehensive 2D FXR biochromatography system used for compounds screening. The screening results highlight four FXR-binding components—emodin, aloe-emodin, physcion, and TSG—identified as FXR binders. The schematic also depicts how emodin and physcion activate the FXR signaling pathway to alleviate cholestatic liver injury by regulating downstream targets involved in inflammation and bile acid homeostasis.