Extract of Averrhoacarambola L. (Oxalidaceae) roots ameliorates carbon tetrachloride-induced hepatic fibrosis in rats

Ethnopharmacological relevance: The root of Averrhoa carambola L. (Oxalidaceae), a traditional Chinese medicine, was mainly used in ancient times in the treatment of urinary calculi, recurrent headache and joint pain. Aim of the study: Our aims were to explore the potential therapeutic effect of the extract of Averrhoa carambola L. (Oxalidaceae) roots (EACR) against hepatic fibrosis in CCl4-treated rats and to understand the underlying molecular mechanism. Materials and methods: Six groups of male Sprague Dawley rats were treated as follows: vehicle (olive oil), CCl4 alone, CCl4+colchicine, CCl4+EACR 1.0 g/kg, CCl4+EACR 0.5 g/kg and CCl4+EACR 0.25 g/kg. At the end of the 12th week, biomarkers of liver function, liver fibrosis, hepatic oxidative stress and antioxidant status were assayed, and histopathological and immunohistochemical evaluation of liver tissue were conducted to investigate the liver damage and fibrosis degree. Furthermore, expressions of COL-1a1, alpha-SMA, TGF-beta 1, Smad2, smad3, Smad4 and TIMP2 were examined by qPCR and/or western blot. The expressions of apoptosis-related proteins were also detected using western blot analysis. Results: EACR treatment markedly reduced the CCl4-induced elevation of serum aminotransferase activities, liver fibrosis indexes, and the extent of oxidative stress. EACR treatment also significantly reduced the accumulation of collagen and the immunostaining of alpha-SMA, TGF-beta 1 and Smad2, 4 and 7 in the liver of CCl4 treated rats. In addition, EACR treatment markedly reversed the CCl4-induced increase in mRNA expression of COL-1a1, alpha-SMA, TIMP2, TGF-beta 1, Smad2 and Smad4 and suppressed the expressions of alpha-SMA, TIMP2, TGF-beta 1, smad2, 3 and 4, BAX and cleaved caspase-3 proteins. Meanwhile, EACR treatment also significantly elevated the mRNA expression of Smad7 and the protein expression of Smad7 and Bcl-2. Conclusion: These results suggest that EACR has protective activity against liver fibrosis. The anti-fibrotic activity of EACR in vivo is associated with enhanced antioxidant, apoptosis-inhibition and increased MMP-2/TIMP-2 expression ratio, and with modulation of TGF-beta 1/Smad signaling pathway.