Yu-Zhe Zhao

Curcumin inhibits collagen synthesis and hepatic stellate cell activation in-vivo and in-vitro

We previously demonstrated that curcumin, a well‐known antioxidant, inhibits collagen deposition in carbon tetrachloride‐induced liver injury in rats. The major effector cells responsible for collagen synthesis in the liver are activated hepatic stellate cells. In this study, we investigated the inhibitory effects of curcumin on the collagen synthesis and activation of rat hepatic stellate cells in‐vitro, and on hepatic stellate cell activation in‐vivo. The effects of curcumin on the production of collagen and smooth muscle α‐actin proteins and of α1(I) collagen mRNA were studied in‐vivo and in‐vitro. The effect of curcumin on DNA synthesis was also determined in‐vitro. In‐vivo, treatment with curcumin reduced collagen deposition and smooth muscle α‐actin‐positive areas and lowered mRNA levels of type I collagen in the liver. In‐vitro, curcumin at a concentration of 5 μg mL−1 reduced DNA synthesis, and downregulated smooth muscle α‐actin and type I collagen expression, and α1(I) collagen mRNA expression. We concluded that curcumin inhibits collagen synthesis and hepatic stellate cell activation in‐vivo and in‐vitro, and thus may prove a valuable anti‐fibrogenic agent.

Preventive effects of a purified extract isolated from Salvia miltiorrhiza enriched with tanshinone I, tanshinone IIA and cryptotanshinone on hepatocyte injury in vitro and in vivo

Salvia miltiorrhiza is traditionally used to treat liver disease in Asia. In this study, we tested the ability of a purified extract of S. miltiorrhiza (PF2401-SF) and its constituents, tanshinone I, tanshinone IIA, and cryptotanshinone, to protect against acute and subacute liver damage induced by carbon tetrachloride by measuring serum transaminase levels, the reduced form of glutathione (GSH), antioxidant enzyme activities, and lipid peroxidation levels in the liver. We also evaluated their ability to protect primary cultured rat hepatocytes from tertiary-butylhydroperoxide (tBH) or d-galactosamine (GalN). PF2401-SF was protective at 50-200mg/kg per day in acute liver injury and 25-100mg/kg per day in subacute liver injury. Tanshinone I, tanshinone IIA, and cryptotanshinon (40 microM), inhibited lactate dehydrogenase leakage, GSH depletion, lipid peroxidation and free radical generation in vitro. PF2401-SF and its major constituents, tanshinone I, tanshinone IIA and cryptotanshinone, can protect against liver toxicity in vivo and in vitro due to its antioxidant effects.

Antioxidative and Hepatoprotective Diarylheptanoids from the Bark of Alnus japonica

The present study to evaluate the potential of constituents of the bark of Alnus japonica as a functional food with medicinal properties led to the identification of one new diarylheptanoid, named alusenone (1A), and 11 known ones (1B and 2-11). Their antioxidative and hepatoprotective activities were accessed by, respectively, a TOSC assay and a TBH-induced hepatotoxicity rat model. Mixtures 1, 2-6, 10, and 11 showed good antioxidative and hepatoprotective effects as compared with the positive controls.

Tanshinone II A Induces Apoptosis and S Phase Cell Cycle Arrest in Activated Rat Hepatic Stellate Cells

Tanshinone IIA, a major component extracted from the traditional herbal medicine, Salvia miltiorrhiza Bunge, improves blood circulation and treats chronic hepatitis and hepatic fibrosis. Activation of hepatic stellate cells (HSCs) is the predominant event in liver fibrosis. The therapeutic goal in liver fibrosis is the reversal of fibrosis and selective clearance of activated HSCs. We used rat HSCs transformed by Simian virus 40 (t-HSC/Cl-6) to overcome the limitations inherent in studying subcultures of HSCs. Treatment of t-HSC/Cl-6 cells with tanshinone IIA inhibited cell viability in a dose- and time-dependent manner. Tanshinone IIA induced apoptosis as demonstrated by DNA fragmentation, poly(ADP-ribose) polymerase and caspase-3 cleavage, increased Bax/Bcl-2 protein ratio, and depolarization of mitochondrial membranes to facilitate cytochrome c release into the cytosol. Furthermore, this compound markedly induced S phase cell cycle arrest, and down-regulated cyclins A and E, and cdk2. Thus, tanshinone IIA induces apoptosis and S phase cell cycle arrest in rat HSCs in vitro.

Butein suppresses myofibroblastic differentiation of rat hepatic stellate cells in primary culture.

Hepatic stellate cells play a key role in the pathogenesis of hepatic fibrosis. In this study, we investigate the inhibitory effect of butein on the activation and proliferation of rat primary cultured hepatic stellate cells. Possible cytotoxic effects were measured on stellate cells and hepatocytes using the 3‐(4, 5‐dimethylthiazol‐2‐yl)‐2, 5‐diphenyltetrazolium bromide (MTT) assay. The effects of butein on the production of collagen and smooth muscle α‐actin proteins were examined at the same concentration, by western blot. The effects of butein on α1(I) collagen, tissue inhibitor of metalloproteinase‐1, and metalloproteinase‐13 gene expression in activated stellate cells were investigated by measuring mRNA levels using reverse transcription polymerase chain reaction. The effect of butein on DNA synthesis was also determined. Butein, at a concentration of 1 μg mL−1, reduced DNA synthesis without affecting cell viability, and downregulated smooth muscle α‐actin and type‐I collagen expression, and α1(I) collagen and tissue inhibitor of metalloproteinase‐1 mRNA expression, while treatment with butein induced metalloproteinase‐13 mRNA expression. These findings suggest that butein is a potent inhibitor of stellate cell transformation.

1,2,3,4,6-Penta-O-galloyl-β-D-glucose from Galla Rhois Protects Primary Rat Hepatocytes from Necrosis and Apoptosis

In this study, we investigated the hepatoprotective effects of four compounds from Galla Rhois [gallic acid methyl ester, gallic acid, an equilibrium mixture of 3-galloyl-gallic acid and 4-galloyl-gallic acid isomers, and 1,2,3,4,6-penta- O-galloyl- beta- D-glucose (PGG)] in primary rat hepatocytes undergoing necrosis or apoptosis. Treatment with gallic acid methyl ester (12.5 and 50 microM) or PGG (3.125, 12.5 and 50 microM) reduced hepatocyte necrosis induced by tert-butyl hydroperoxide. PGG treatment (4 and 20 microM) also altered hepatocyte apoptosis induced by glycochenodeoxycholic acid. Based on these results, we propose that PGG warrants further evaluation as a hepatoprotective agent, because it protected primary rat hepatocytes from both necrosis and apoptosis.

Apoptotic effect of propyl gallate in activated rat hepatic stellate cells

Hepatic stellate cells (HSCs) play a central role in liver fibrosis. Inhibition of HSC growth and induction of apoptosis have been proposed as therapeutic strategies for the treatment and prevention of liver fibrosis. Propyl gallate (PG) is an antioxidant widely used in processed foods, cosmetics and medicinal preparations. However, the anti-fibrotic effect of PG in liver injury is unclear. In this study, we investigated whether PG could induce apoptosis in activated HSCs. Treatment of activated HSCs with PG inhibited cell viability in a dose- and time-dependent manner. PG induced apoptosis as demonstrated by morphological changes, poly(ADP-ribose) polymerase (PARP) cleavage, caspase-3 cleavage, increased Bad expression, and decreased Bcl-2 protein expression. Through stimulation of the activation of c-Jun NH2-terminal protein kinase (JNK) and p38 mitogen-activated protein kinases (MAPK) by PG treatment, we demonstrated that JNK and p38 MPAK are not involved in PG-induced apoptosis using their specific inhibitors. Taken together, these findings indicate that PG induces apoptosis in activated HSCs. The potential anti-fibrotic effect of PG warrants further evaluation.