Sinapic Acid Regulates the LXRα-ABCG5/8 Axis in the Hepatocytes: A Potential Strategy for Cholesterol Gallstone Management.

Background/Objective: Gallstone disease (cholelithiasis) is a prevalent hepatobiliary disorder with limited non-surgical therapeutic options. Sinapic acid (SINAP), a phenolic compound found in various dietary sources, has demonstrated anti-inflammatory and hepatoprotective effects. However, its role in gallstone dissolution has not been explored. This study was designed to evaluate whether sinapic acid modulates hepatic cholesterol transport and enhances gallstone dissolution using a gallstone dissolution assay in artificial bile solution. Methods: The cytotoxicity of SINAP was assessed in HepG2 cells via the MTT assay. The mRNA and protein expression of lipid transporters (ABCG5, ABCG8, and LXRα) was quantified using qRT-PCR, ELISA, and Western blotting. Additionally, molecular docking was conducted to evaluate SINAP's interaction with gallstone-related protein targets compared to that for the standard drugs (ursodeoxycholic acid and ezetimibe). Results: SINAP achieved a 53.71% gallstone weight reduction over 12 days, comparable to that with ursodiol (59.24%), and following 24 h of exposure, SINAP demonstrated minimal cytotoxicity, maintaining over 80% cell viability up to 50 µg/mL, with an IC₅₀ value of 28 µg/mL. SINAP significantly upregulated ABCG5, ABCG8, and LXRα expression (p < 0.01), suggesting enhanced bile acid secretion. Docking studies confirmed the strong binding affinities of SINAP to key cholesterol transport proteins. Conclusions: These results indicate that SINAP may serve as a promising natural candidate for non-surgical management of cholelithiasis and support further preclinical investigation.