Cynaroside Attenuates Ethinylestradiol-Induced Cholestatic Liver Injury by Modulating the FXR/BSEP/CYP7A1/SHP Axis

Abstract

Cholestatic liver diseases are characterized by disrupted bile acid homeostasis, oxidative stress, and inflammation, ultimately leading to progressive hepatic injury. Although ursodeoxycholic acid (UDCA) remains the standard pharmacological therapy, its therapeutic efficacy is limited in several cholestatic conditions. This study investigated the hepatoprotective effects of cynaroside (CYN), a naturally occurring flavonoid glycoside, against ethinylestradiol (EE)-induced cholestatic liver injury and explored its underlying molecular mechanisms. Female Wistar rats were randomly allocated into four groups (n = 7): control, EE, EE + CYN, and EE + UDCA. Liver function indices, bile acids, cholesterol, oxidative stress and inflammatory biomarkers, histopathology, immunohistochemistry, Western blotting, qRT-PCR, and molecular docking analyses were performed. EE administration induced pronounced cholestatic liver injury, as evidenced by impaired liver function, hepatic accumulation of bile acids and cholesterol, oxidative imbalance, inflammatory responses, and marked histopathological alterations. CYN significantly ameliorated these biochemical and histological abnormalities, reduced hepatic bile acid and cholesterol accumulation, restored redox homeostasis, and attenuated inflammatory responses. Mechanistically, CYN modulated the hepatic FXR/BSEP/CYP7A1/SHP regulatory network, modulated hepatic FXR and Nrf2 protein expression, suppressed NF-κB activation, and favorably regulated TNF-α, IL-1β, and BCL2 expression. Histopathological and immunohistochemical findings further confirmed substantial preservation of hepatic architecture following CYN treatment. Molecular docking revealed favorable interaction of CYN with the FXR ligand-binding domain, with a predicted binding free energy of −8.18 kcal/mol, comparable to that of UDCA (−7.95 kcal/mol). Cynaroside attenuated EE-induced cholestatic liver injury by improving bile acid homeostasis and mitigating oxidative and inflammatory responses, potentially by modulating FXR-associated signaling and its downstream regulatory network. Collectively, the results provide a rationale for continued investigation of cynaroside in the context of cholestatic liver injury.