The present study investigated the improving effect of cucurbitacin B on liver fibrosis induced by concanavalin A in mice and explored its possible mechanism. AST, ALT and TB were detected by kits. ELISA was performed to detect the levels of IL 5, IL 6, IL 13 and TNF-α in serum. Haematoxylin-eosin (HE) staining and Masson's trichrome staining were used to evaluate pathological changes. Western blotting was performed to observe expression levels of sirtuin (SIRT) 1, insulin-like growth factor binding protein-related protein 1 (IGFBPrP1) and TGF β1. The activity of SIRT 2 | MATERIALS AND METHODS The study was conducted in accordance with the Basic & Clinical Pharmacology & Toxicology policy for experimental and clinical studies. 10 2.1 | Reagents Concanavalin A was purchased from Sigma-Aldrich (Merck KGaA) and dissolved in phosphate-buffered saline (PBS) (1 mg/mL). Cucurbitacin B was obtained from Sigma-Aldrich (Merck KGaA) and dissolved in dimethylsulphoxide (DMSO) (20 mg/mL), with a final concentration in 5% DMSO + 95% PBS (1 mg/mL). Selisistat (EX 527) was bought from the Selleck Chemicals. Add pure solvents of 5% DMSO + 30% PEG 300 + ddH 2 O into EX 527 from left to right before administration (5 mg/mL). Anti-sirtuin (SIRT) 1, anti-insulin like growth factor binding protein-related protein (IGFBPrP) 1, anti-transforming growth factor (TGF) β1 and anti-β-actin antibodies were acquired commercially from Abcam (Cambridge, Cambs, UK). SIRT1 activity assay kit was purchased from Abcam. ELISA kits of Interleukin (IL) 5, IL6, IL13 and tumour necrosis factor (TNF) α were obtained from ProteinTech Group, Inc. 2.2 | Animals Adult male Balb/c mice, 4-6 weeks and weight 20-25 g, were obtained from the Nanchang University Laboratory Animal Center. The animals were allowed to access food and water ad libitum and maintained under a 12-hour dark/light cycle at 22°C-25°C. Experiments were carried out according to the Guide for the Care and Use of Laboratory Animals published by the US National Institutes of Health (NIH Publication No. 85-23, revised in 1996), and approved by the Ethics Committee of Nanchang University (No. 2018-0102). Note: Data are presented as the means ± standard error in each group (n = 10). *P < .05 vs the control group; ▲ P < .05 vs the LF group; & P < .05 vs LF + 1 mg/kg Cu B or LF + 2 mg/kg Cu B; # P < .05 vs the LF + 4 mg/kg Cu B group.