In model of kidney disease, oleanolic acid was dissolved in 2% w/v dimethyl sulfoxide (DMSO) and then diluted with distilled water for each injection to a final DMSO concentration of 0.2% w/v. Oleanolic acid or vehicle was administered intraperitoneally (60 mg/kg i.p). one day before UUO, and was continued for 3 or 7 days after surgery.

For cell viability assay, HepG2 cells were plated at a density of 5000 per well in a 96-well plate. After culturing overnight, the cells were exposed to fresh medium containing different concentrations of OA. 24 hours later, the cell viability was determined by CellTiter-Glo Luminescence Cell Viability Assay (Promega) according to the manufacturer’s instructions. In order to determine whether OA would affect the activity of FXR-LBD, HepG2 cells were transfected with an expression vector for Gal4-DBD-FXR-LBD, a reporter plasmid pFR-Luc, an internal control Renilla luciferase vector and then treated with FXR agonist CDCA in the presence of increasing amounts of OA.