Discovery of cis-Gnetin H from peony seed coat as a potent antifibrotic agent modulating hepatic fibro-inflammatory pathways and gut microbiota homeostasis.

BACKGROUND

Liver fibrosis is a reversible stage of chronic liver disease lacking effective therapies. The peony seed coat, a major byproduct of peony oil production, is rich in bioactive stilbenes. However, its anti-fibrotic potential and underlying mechanisms remain systematically unexplored.

PURPOSE: This study aimed to isolate stilbenes from peony seed coat, identify the potent anti-fibrotic compounds, and evaluate their anti-fibrotic activity and mechanisms of action.

METHODS

A structure-oriented separation strategy, guided by spectroscopic analysis, enabled the isolation of stilbenes. Anti-fibrotic activity was screened in TGF-β1-induced hepatic stellate cells (HSCs). In vivo efficacy was evaluated in a CCl₄-induced mouse liver fibrosis model. Mechanisms were investigated using transcriptomics, Western blotting, and 16S rRNA gene sequencing.

RESULTS

Among seven isolated stilbenes, cis-Gnetin H exhibited the most potent inhibition of HSCs activation by downregulating α-SMA, Collagen I, and Smad3. In CCl₄-treated mice, cis-Gnetin H significantly ameliorated liver injury, inflammation, and fibrosis. Mechanistically, cis-Gnetin H activated the Nrf2/HO-1 antioxidant pathway while suppressing NF-κB and TGF-β1/Smad signaling. Furthermore, cis-Gnetin H remodeled the gut microbiota by enriching beneficial genera and reducing pathogenic Staphylococcus. This microbial modulation was accompanied by increased production of SCFAs, which correlated strongly with improved hepatic parameters.

CONCLUSION

cis-Gnetin H acts as an anti-fibrotic agent through modulating hepatic inflammatory and fibrotic signaling, and regulating the gut-liver axis via microbiota restoration and metabolite enhancement. These findings highlight cis-Gnetin H as a promising therapeutic candidate and support the high-value utilization of peony agricultural byproducts.