Angelica sinensis aboveground part polysaccharide and its metabolite 5-MT ameliorate colitis via modulating gut microbiota and TLR4/MyD88/NF-κB pathway.

The roots of Angelica sinensis have been used in Traditional Chinese Medicine for thousands of years. However, tons of aerial parts of this herb (aboveground part) are commonly discarded during the process of root preparations. A polysaccharide (ASP-Ag-AP) in the aboveground parts of A. sinensis was isolated and preliminarily characterized as typical plant pectin. ASP-Ag-AP exhibited noticeable protective effects against dextran sodium sulfate (DSS)-induced colitis, including reduction of colonic inflammation, modulation of barrier function, and alteration of gut microbiota and serum metabolite profile. Anti-inflammatory effects of ASP-Ag-AP were observed by inhibiting TLR4/MyD88/NF-κB signaling pathway in vitro and in vivo. Additionally, the level of serum metabolite 5-methyl-dl-tryptophan (5-MT) was reduced by DSS and restored by ASP-Ag-AP, which also negatively correlated with Bacteroides, Alistipes, Staphylococcus and pro-inflammatory factors. The protection from inflammatory stress on intestinal porcine enterocytes cells (IPEC-J2) of 5-MT was observed through the inhibition of TLR4/MyD88/NF-κB pathway. Besides, 5-MT also exhibited robust anti-inflammatory effect in colitis mice with improving colitis symptoms, barrier function and gut microbiota, which was the same as presented by ASP-Ag-AP. Therefore, ASP-Ag-AP could be a promising agent for colitis prevention and 5-MT could be the signal metabolite of ASP-Ag-AP on defending against intestinal inflammatory stress.

Anti-fibrotic effect of PF2401-SF, a standardized fraction of Salvia miltiorrhiza, in thioacetamide-induced experimental rats liver fibrosis.

We previously reported the in vitro and in vivo hepatoprotective and anti-fibrotic effects of PF2401-SF, a standardized fraction of Salvia miltiorrhiza, against acute and subacute liver injury. The aim of this study was to investigate the effect of PF2401-SF on liver fibrosis induced by thioacetamide (TAA), a chronic liver injury model (12 weeks) that closely resembles fibrosis and cirrhosis in humans. Hepatoprotective activity was indicated by low serum levels of the markers aspartate amino transferase and alanine amino transferase .In addition, compared to the TAA-group livers, the PF2401-SF-treated liver tissues showed no fibrous tissue deposition in the portal areas, hepatocyte morphology more closely resembling normal tissue morphology, and significantly reduced collagen deposition. Furthermore, downregulation of collagen 1(α) and tissue inhibitor of metalloproteinase (TIMP)1 protein and mRNA expression also supports PF2401-SF's anti-fibrotic effect. We also observed reduced expression of α-smooth muscle actin (α-SMA), an important marker of hepatic stellate cells (HSCs) activation. From these results, we conclude that PF2401-SF's anti-fibrotic mechanism in the TAA model involves reduced HSC activation, and may be mediated by downregulation of central markers of fibrosis, including collagen 1(α), TIMP1, and α-SMA.

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.

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.

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.

1,2,3,4,6-penta-O-galloyl-beta-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.

PF2401-SF, standardized fraction of Salvia miltiorrhiza and its constituents, tanshinone I, tanshinone IIA, and cryptotanshinone, protect primary cultured rat hepatocytes from bile acid-induced apoptosis by inhibiting JNK phosphorylation.

Bile acid-induced hepatocyte apoptosis plays an important role in cholestatic liver disease, and the role of apoptosis may be of therapeutic interest in preventing liver disease. The dried root of Salvia miltiorrhiza Bunge (Labiatae) has been used traditionally to treat liver diseases. We investigated the antiapoptotic effects of a standardized fraction of S. miltiorrhiza (PF2401-SF) and its components, tanshinone I, tanshinone IIA, and cryptotanshinone, in primary cultured rat hepatocytes. PF2401-SF was enriched with tanshinone I (11.5%), tanshinone IIA (41.0%), and cryptotanshinone (19.1%). Glycochenodeoxycholic acid (GCDC)-induced apoptosis, as shown by DNA fragmentation, poly(ADP-ribose) polymerase cleavage, and activation of caspases-8, -9, and -3. PF2401-SF and its components, tanshinone I, tanshinone IIA, and cryptotanshinone showed antiapoptotic activity. Treatment with PF2401-SF or with its components significantly inhibited the generation of intracellular reactive oxygen species. Hydrophobic bile acids activate c-Jun-NH(2)-terminal kinase (JNK), p38 mitogen-activated protein kinases (MAPK), and extracellular signal-regulated kinase 1/2, and PF2401-SF inhibited the phosphorylation of JNK and p38. All three components of PF2401-SF inhibited JNK phosphorylation. Addition of inhibitors of MAPK showed that inhibition of JNK decreased apoptosis. These data indicate that PF2401-SF and its components protect hepatocytes from GCDC-induced apoptosis in vitro by inhibiting JNK.

Butein suppresses bile acid-induced hepatocyte apoptosis through a JNK-dependent but ERK-independent pathway.

We investigated the protective effect of butein on glycochenodeoxycholic acid (GCDC)-induced apoptosis in primary cultured rat hepatocytes. Treatment with GCDC at a concentration of 100 microM for 4 h induced apoptosis, and treatment with butein at concentrations of 30 microM inhibited the GCDC-induced apoptosis as shown by the reduced cleavage of poly(ADP-ribose) polymerase, DNA fragmentation, and activation of caspases-3, -8, and -9. c-Jun N-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK) play fundamental roles in cell survival, proliferation, and apoptosis. GCDC alone induced ERK and JNK phosphorylation. Butein alone induced ERK activation, and ERK activation was greater in hepatocytes treated with butein and GCDC than in hepatocytes exposed to GCDC alone. Butein treatment reduced JNK activation induced by GCDC. Addition of U0126, an inhibitor of ERK, did not alter the proapoptotic effect of GCDC or the antiapoptotic effect of butein. Addition of SP600125, a specific JNK inhibitor, protected hepatocytes against GCDC-induced apoptosis. These data suggest that butein has a protective effect against GCDC-induced hepatocyte apoptosis and that the protective effect of butein is JNK dependent but ERK independent.

A ginsenoside metabolite, 20-O-beta-D-glucopyranosyl-20(S)-protopanaxadiol, triggers apoptosis in activated rat hepatic stellate cells via caspase-3 activation.

We investigated the apoptotic effects of the protopanaxadiol ginsenosides, Rb (1) and Rb (2), and their intestinal bacterial metabolite, 20-O-beta-D-glucopyranosyl-20(S)-protopanaxadiol (M1), and of the protopanaxatriol ginsenoside, Rg (1), and its intestinal bacterial metabolite, 20(S)-protopanaxatriol, in activated rat hepatic stellate cells (HSCs) transformed by Simian virus 40 (T-HSC/Cl-6). As HSCs play a central role in liver fibrosis, agents that selectively induce apoptosis of HSCs could be used to treat this disease. Apoptosis was measured using cell viability tests, DNA fragmentation analysis, and immunoblot analysis of poly(ADP-ribose) polymerase cleavage. M1 (40 microM for 24 h) significantly induced apoptosis in activated rat HSCs. M1 induced apoptosis in a dose-dependent manner as shown by DNA fragmentation, an increased population of cells in the sub-G1 phase, and reduced mitochondrial transmembrane potential. M1 induced caspase-3 activity in a dose- and time-dependent manner. A specific inhibitor of caspase-3 prevented induction of apoptosis by M1 as shown by DNA fragmentation analysis. It is concluded that M1 induces apoptosis in T-HSC/Cl-6 cells via caspase-3 activation.

Polyozellin inhibits nitric oxide production by down-regulating LPS-induced activity of NF-kappaB and SAPK/JNK in RAW 264.7 cells.

Polyozellin, isolated from Polyozellus multiplex (Thelephoraceae), was investigated for its anti-inflammatory activity in the murine macrophage cell line RAW 264.7. Polyozellin inhibited both lipopolysaccharide (LPS)-induced nitric oxide (NO) production and inducible nitric oxide synthase (iNOS) gene expression in a dose-dependent manner. The effects of polyozellin on the activation of nuclear factor-kappaB (NF-kappaB) and mitogen-activated protein (MAP) kinases in these cells were studied in order to elucidate the underlying mechanism. Polyozellin suppressed the activation of both LPS-induced NF-kappaB and the stress-activated protein kinase (SAPK)/c-Jun N-terminal kinase (JNK), but had no effect on the extracellular signal-regulated kinase (ERK) or p38. These data suggest that polyozellin suppresses iNOS expression by inhibiting the activation of NF-kappaB and SAPK/JNK, leading to the inhibition of NO production.

Honokiol reduces oxidative stress, c-jun-NH2-terminal kinase phosphorylation and protects against glycochenodeoxycholic acid-induced apoptosis in primary cultured rat hepatocytes.

Hydrophobic bile acid-induced apoptosis plays an important role in cholestatic liver disease, and its prevention may be of therapeutic interest. The aim of this study was to investigate the protective effect of honokiol on glycochenodeoxycholic acid-induced apoptosis in primary cultured rat hepatocytes. Glycochenodeoxycholic acid is a hydrophobic bile salt that accumulates intrahepatically during cholestasis and induces hepatocyte apoptosis at pathophysiological concentrations. Primary rat hepatocytes were pretreated with honokiol at concentrations of 40, 20 and 10 microM 5 min before glycochenodeoxycholic acid treatment. Incubation of hepatocytes with glycochenodeoxycholic acid at a concentration of 100 microM for 4 h induced apoptosis as shown by DNA fragmentation, chromatin condensation and cleavage of poly(ADP-ribose) polymerase. Pretreatment with honokiol at concentrations of 40, 20 and 10 microM significantly inhibited the generation of intracellular reactive oxygen species and reduced activation of caspases-8, -9, and -3 and cleavage of poly-(ADP-ribose) polymerase. Glycochenodeoxycholic acid treatment up-regulated phosphorylation of stress-activated protein kinase/c-jun-NH2-terminal kinase which was inhibited by honokiol treatment. Inhibition of stress-activated protein kinase/c-jun-NH2-terminal kinase phosphorylation by SP600125 protected hepatocytes from apoptosis induced by glycochenodeoxycholic acid. These data indicate that honokiol protects hepatocytes from apoptosis induced by glycochenodeoxycholic acid in vitro and this protection may be due to reduced oxidative stress and inhibition of stress-activated protein kinase/c-jun-NH2-terminal kinase phosphorylation.

Skullcapflavone I from Scutellaria baicalensis induces apoptosis in activated rat hepatic stellate cells.

The therapeutic goal in liver fibrosis is the reversal of fibrosis and the selective clearance by apoptosis of hepatic stellate cells (HSCs), which play a central role in liver fibrogenesis. In this study, the apoptotic effect of wogonin, oroxylin A, 2',5,6',7-tetrahydroxyflavone, skullcapflavone I, and baicalein, isolated from the dried root of Scutellaria baicalensis, was investigated in activated rat HSCs, T-HSC/Cl-6 cells transformed with the Simian virus 40. Among the isolated compounds, skullcapflavone I (20 microM for 24 h) significantly induced apoptosis in activated rat HSCs while there was no change in the cell viability of hepatocytes. Skullcapflavone I increased caspase-3 and -9 activities accompanied by the proteolytic cleavage of poly(ADP-ribose) polymerase. Specific inhibitors of caspase-3 and caspase-9 prevented the apoptotic process induced by skullcapflavone I. From these results, skullcapflavone I from S. baicalensis selectively induced apoptosis in T-HSC/Cl-6 cells via caspase-3 and caspase-9 activation.

Protective effect of (S)-bakuchiol from Psoralea corylifolia on rat liver injury in vitro and in vivo.

The aim of this study was to investigate the protective effect of (S)-bakuchiol isolated from the seed of Psoralea corylifolia, on liver injury. Primary rat hepatocyte intoxication was induced by tert-butyl hydroperoxide (tBH), carbon tetrachloride (CCl4) or D-galactosamine (D-GalN). Liver injury was induced by either CCl4 or D-GalN in rats. In vitro, the cellular leakage of lactate dehydrogenase and cell viability following treatment with hepatotoxicants were significantly improved by bakuchiol treatment at a concentration range of 25-200 microM for tBH, 100-200 microM for CCl4 and 100-200 microM for D-GalN-induced hepatocyte injury. Treatment with bakuchiol significantly inhibited lipid peroxidation and intracellular glutathione depletion in hepatocytes induced by tBH, CCl4 or D-GalN. Treatment with bakuchiol (25 or 50 mg/kg, p.o.) at 1, 24 and 48 h after subcutaneous injection of CCl4 significantly reduced the levels of aspartate transaminase and alanine transaminase in serum. Histological observations revealed that fatty acid changes, hepatocyte necrosis and inflammatory cell infiltration in CCl4-injured liver was improved when treated with bakuchiol. Bakuchiol treatment (25 and 50 mg/kg, p.o.) also significantly reduced the levels of aspartate transaminase and alanine transaminase in an acute liver injury model induced by D-GalN. From these results, bakuchiol has a protective effect against tBH, CCl4 or D-GalN-induced hepatotoxicity in vitro or in vivo.

Honokiol induces apoptosis via cytochrome c release and caspase activation in activated rat hepatic stellate cells in vitro.

The therapeutic goal in liver fibrosis is the reversal of fibrosis and the selective clearance of activated hepatic stellate cells (HSCs) by inducing apoptosis. Over the past several years, we have screened for natural products that mediate apoptosis in activated HSCs. Among the candidate compounds, honokiol, isolated from Magnoliae cortex, was found to induce apoptotic death in activated rat HSCs, while there was no cell viability change in hepatocytes, at concentrations of 12.5-50 microM. Apoptosis was identified by DNA fragmentation, activation of caspase-3 and -9, and the proteolytic cleavage of poly(ADP-ribose) polymerase, down-regulation of bcl-2 and the release of mitochondrial cytochrome c into the cytoplasm.

Water-soluble polysaccharide from Eleutherococcus senticosus stems attenuates fulminant hepatic failure induced by D-galactosamine and lipopolysaccharide in mice.

The aim of this study was to investigate whether Eleutherococcus senticosus stems could attenuate D-galactosamine/lipopolysaccharide-induced fulminant hepatic failure in mice. E. senticosus, known as Siberian ginseng, is a popular folk medicine used as a tonic in Asia. Preparations of E. senticosus used in this study were as follows; (i) 70% ethanol extract (ii) water extract (iii) ethanol-soluble part of the water extract (iv) polysaccharide obtained as an 80% ethanol insoluble of the water extract. Preparations were given by intraperitoneal (300 mg/kg and 50 mg/kg) or oral (300 mg/kg) injection at 12 hr and 1 hr before a D-galactosamine/lipopolysaccharide injection. The intraperitoneal injection of water extract and polysaccharide significantly lowered serum levels of tumour necrosis factor-alpha, aspartate transaminase and alanine transaminase, improved the histologic changes in liver, inhibited hepatocyte apoptosis confirmed by the terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling method and DNA fragmentation assay, and suppressed the lethality induced by D-galactosamine/lipopolysaccharide. The oral administration of water extract and polysaccharide also reduced serum aspartate transaminase, alanine transaminase and tumour necrosis factor-alpha levels. In contrast 70% ethanol extract and ethanol-soluble part of the water extract had no protective effect when treated intraperitoneally or orally. These results indicate E. senticosus stems attenuate fulminant hepatic failure induced by D-galactosamine/lipopolysaccharide in mice and the protective effect is due to water-soluble polysaccharides in E. senticosus stems.

Tetrandrine induces apoptosis in hepatic stellate cells.

We have previously reported that tetrandrine reduced hepatic stellate cell activation and collagen accumulation in liver fibrosis induced by biliary obstruction. In the present study, we examined the apoptosis-inducing effect of tetrandrine on activated hepatic stellate cells, as the therapeutic goal in hepatic fibrosis is to eliminate the activated hepatic stellate cells by apoptosis. We used rat hepatic stellate cells transformed by Simian virus 40 (T-HSC/Cl-6) to overcome the limitations inherent in studying primary cultures of hepatic stellate cells. Tetrandrine treatment at doses of 25 and 50 microg/ml for 12 h induced apoptosis as confirmed by DNA fragmentation and increased sub-G1 DNA content as detected by flow cytometric analysis. Tetrandrine also induced the activation of caspase-3 protease and subsequent proteolytic cleavage of poly(ADP-ribose) polymerase. In conclusion, our results demonstrate that tetrandrine induces apoptosis of T-HSC/Cl-6 cells, and these results should contribute to the development of new agents for the treatment of hepatic fibrosis.

Acanthoic acid from Acanthopanax koreanum protects against liver injury induced by tert-butyl hydroperoxide or carbon tetrachloride in vitro and in vivo.

The aim of this study was to investigate the protective effect of acanthoic acid, a diterpene isolated from the root bark of Acanthopanax koreanum, on liver injury induced by either tert-butyl hydroperoxide (tBH) or carbon tetrachloride in vitro and in vivo. In vitro, the cellular leakage of lactate dehydrogenase (LDH) following treatment with 1.5 mM tBH for 1 h, was significantly inhibited by co-treatment with acanthoic acid (25 and 5 microg/mL) and the ED (50) of acanthoic acid was 2.58 microg/mL (8.5 microM). The cellular leakage of LDH following one hour of treatment with 2.5 mM CCl (4) was significantly inhibited by co-treatment with acanthoic acid (25 microg/mL) and the ED (50) of acanthoic acid was 4.25 microg/mL (14.1 microM). Co-treatment with acanthoic acid significantly inhibited the generation of intracellular reactive oxygen species (ROS) and intracellular glutathione (GSH) depletion induced by tBH or CCl (4). Acanthoic acid pretreatment (100 mg/kg per day for four consecutive days, p. o.) significantly reduced levels of aspartate transaminase and alanine transaminase in acute liver injury models induced by either tBH or carbon tetrachloride. Treatment with acanthoic acid (100 mg/kg, p. o.) at 6, 24, and 48 hours after carbon tetrachloride subcutaneous injection significantly reduced the levels of aspartate transaminase and alanine transaminase in serum. Histological observations revealed that fatty acid changes, hepatocyte necrosis and inflammatory cell infiltration in CCl (4)-injured liver were improved upon treatment with acanthoic acid. In vivo treatment with acanthoic acid was not able to modify CYP2E1 activity and protein expression in liver microsomes at the dose used, showing that the hepatoprotective effect of acanthoic acid was not mediated through inhibition of CCl (4) bioactivation. From the results above, acanthoic acid had a protective effect against tBH- or CCl (4)-induced hepatotoxicity in vitro and in vivo.

Effect of Acanthopanax koreanum Nakai (Araliaceae) on D-galactosamine and lipopolysaccharide-induced fulminant hepatitis.

The hepatoprotective effects of Acanthopanax koreanum Nakai (Araliaceae) were evaluated in D-galactosamine/lipopolysaccharide-induced fulminant hepatic failure in mouse. Preparations of Acanthopanax koreanum used were an ethanol extract, a water extract, and the ethanol-soluble and ethanol-insoluble components of the water extract of roots or stems of the plant. Mice were pretreated with various extracts by intraperitoneal injection or orally, 12 and 1 h before intraperitoneal injection of D-galactosamine and lipopolysaccharide (LPS). Intraperitoneal pretreatment with the water extract or the ethanol-insoluble component of the water extract markedly reduced the elevated levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and tumor necrosis factor-alpha (TNF-alpha), reduced the histological changes in the liver, and attenuated hepatocyte apoptosis confirmed by the terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling method and DNA fragmentation assay. Oral pretreatment with the ethanol-insoluble component of the water extract also reduced serum AST, ALT, and TNF-alpha levels. The present study shows that the ethanol-insoluble component of a water extract from Acanthopanax koreanum has a protective effect against the induction of fulminant hepatitis in mice by D-galactosamine and lipopolysaccharide.

Induction of apoptosis by tanshinone I via cytochrome c release in activated hepatic stellate cells.

Hepatic stellate cells play central roles in hepatic fibrosis. The therapeutic goal in hepatic fibrosis is to halt or reverse fibrosis. Apoptosis is suggested to eliminate activated hepatic stellate cells in fibrosis. Salvia miltiorrhiza is a traditional medicine used to improve blood circulation and treat chronic hepatitis and hepatic fibrosis. We investigated the effect of tanshinone I, an ingredient of Salvia miltiorrhiza, on the apoptotic death of rat hepatic stellate cells transformed by simian virus 40 (T-HSC/Cl-6), which retains the features of activated stellate cells. Treatment of T-HSC/Cl-6 cells with tanshinone I resulted in the induction of typical DNA fragmentation and DNA ladder formation in a concentration- and time-dependent manner. The induction of apoptosis was confirmed by flow cytometric analysis. Treatment of T-HSC/Cl-6 cells with tanshinone I caused activation of caspase-3 and subsequent proteolytic cleavage of poly(ADP-ribose) polymerase. Tanshinone I induced mitochondrial membrane dipolarization and the release of cytochrome c from mitochondria into the cytosol. In conclusion, our results demonstrate that tanshinone I induces apoptosis of T-HSC/Cl-6 cells and that tanshinone I-induced apoptosis involves caspase activation through cytochrome c release and loss of mitochondrial membrane potential.

Protective effects of honokiol and magnolol on tertiary butyl hydroperoxide- or D-galactosamine-induced toxicity in rat primary hepatocytes.

The aim of this study was to investigate the protective effect of honokiol and magnolol on hepatocyte injury induced by either tertiary butyl hydroperoxide (tBH)- or D-galactosamine (GalN). The cellular leakage of LDH and AST, and cell death by treatment with 1.5 mM tBH for 1 h, were significantly inhibited by treatment with honokiol (40 and 20 microM) or magnolol (40 microM). Treatment with honokiol or magnolol significantly inhibited lipid peroxidation in both cells and media, the generation of intracellular reactive oxygen species (ROIs), and intracellular glutathione (GSH) depletion induced by tBH. The cellular leakage of LDH and AST, and cell death, by 24-hour treatment with 30 mM GalN were significantly inhibited by treatment with honokiol (20, 5 and 1 microM) or magnolol (20, 5 and 1 microM). Treatment with honokiol (20, 5 and 1 microM) or magnolol (20 and 5 microM) significantly inhibited the intracellular GSH depletion induced by GalN. The hepatoprotective effects of honokiol and magnolol on oxidative stress induced by tBH were probably the result of their antioxidant activity. Honokiol and magnolol also had a protective effect against GalN-induced hepatotoxicity, which was used as an alternate model to oxidative stress, acting by inhibiting intracellular GSH depletion.