Hepatoprotective effect of total flavonoids of Mallotus apelta (Lour.) Muell.Arg. leaf against carbon tetrachloride-induced liver fibrosis in rats via modulation of TGF-β1/Smad and NF-κB signaling pathways.

The Mallotus apelta (Lour.) Muell.Arg. is a well-known traditional Chinese medicine (TCM) used for anti-inflammatory, hemostasis and chronic hepatitis.The purpose of this study was to explore the antifibrotic effect of total flavonoids of Mallotus apelta leaf (TFM) and its potential mechanism.

Hepatic fibrosis was induced by carbon tetrachloride (CCl₄) in rats. The CCl₄-induced rats received intragastric administration of colchicine (0.2 mg/kg per day), TFM (25, 50, 100 mg/kg per day) and the equal vehicle was given to normal rats. Pathological evaluation in hepatic tissue were examined by hematoxylin and eosin (HE) staining. And the levels of serum biochemical parameters were detected by automatic biochemical analysis. Meanwhile, the collagen deposition in liver was observed by staining with Masson's trichrome. Collagenic parameters and inflammatory factors were measured by enzyme-linked immunosorbent assay (ELISA) kits. Additionally, corresponding assay kit was used to estimate the antioxidant enzyme and lipid peroxidation. In order to explore the potential mechanism of anti-fibrotic effects in TFM, the expressions of liver fibrosis related gene and protein were analyzed by real-time quantitative reverse transcription polymerase chain reaction (RT-PCR) and Western blot.

The CCl₄-induced hepatic fibrosis were inhibited dose-dependently in rats by TFM. The results showed that the key hallmarks of liver injury including aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), albumin (ALB) and total protein (TP) in the serum were reversed in CCl₄-induced hepatic fibrosis rats which were treated by TFM. Furthermore, TFM significantly alleviates collagen accumulation and reduces the contents of hydroxyproline (Hyp), Type III precollagen (PC-III), collagen I (Col I), hyaluronic acid (HA) and laminin (LN). RT-PCR and Western blot results showed that TFM markedly inhibits liver fibrosis hallmark factor α-smooth muscle actin (α-SMA) expressions in CCl₄-induced hepatic fibrosis rats. Moreover, TFM alleviated the oxidative stress and lipid peroxidation in rats induced by CCl₄. TFM also attenuated the pro-inflammatory cytokines including interleukin-1β (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) via inhibiting nuclear factor-κB (NF-κB) activation. Meanwhile, transforming growth factor-β1 (TGF-β1)/Smad signaling pathway was inhibited by TFM treatment.

TFM can alleviate CCl₄-induced hepatic fibrosis in rats, which potential mechanism may be due to its ability of reducing ECM accumulation, improving antioxidant and regulating TGF-β1/Smad signaling pathways and NF-κB-dependent inflammatory response.