OBJECTIVE The purpose of the study was to investigate the anti-fibrosis mechanism of betulinic acid (BA), an active component isolated from Bacopa monniera.METHODS In vitro HSC-T6 cells were stimulated with tumor necrosis factor (TNF-α, 10 ng·m1-1).Liver fibrosis was induced by intraperitoneal injected of thioacetamide (TAA, 200 mg·kg-1) twice per week for 6 weeks in Wister rats.BA (20 mg·kg-1 or 50 mg·kg-1) was given by gavage every day consecutively for 6 or 8 weeks to evaluate the preventive effect and the protective effect.In a TAA-induced rat liver fibrosis model, we compared the hydroxyproline content from TAA and BA administrated liver specimens on 6 and 8 weeks.We also measured histopathological and immunohistoehemieal changes in the liver specimens.RESULTS In vitro, BA effectively decreased HSC-T6 cells viability induced by TNF-α and showed little toxicity on human chang liver cells.Moreover, BA significantly attenuated the expressions of α-smooth muscle actin (α-SMA), tissue inhibitor of metalloproteinase-1 (TIMP-1) and Toll-like receptor-4 (TLR4) that increased by TNF-α stimulation and improved the levels of mstrix metallopeptidase (MMP)-13, also inhibited the activation and phosphorylation of NF-κB in a time-dependent manner.Furthermore, BA exhibited a potential effect on inducing the apoptosis of activated HSCs.Meanwhile, BA showed an excellent hepatoprotective effect both on preventing and curing hepatic fibrosis via attenuating the liver tissue hydroxyproline, immunohistochemical stain of α-SMA and hypoxia-inducible factor-1α (HIF-1 α) increased by TAA.CONCLUSION BA exerted a definite anti-fibrosis effect and that might be related to blocking TLR4/NF-κB/p65 signaling pathway.