Schisandrin B protects against carbon tetrachloride toxicity by enhancing the mitochondrial glutathione redox status in mouse liver

Dibenzocyclooctadiene lignans from the family Schisandraceae: A review of phytochemistry, structure-activity relationship, and hepatoprotective effects

Liver injury is a common pathological process characterized by massive degeneration and abnormal death of liver cells. With increase in dead cells and necrosis, liver injury eventually leads to nonalcoholic fatty liver disease (NAFLD), hepatic fibrosis, and even hepatocellular carcinoma (HCC). Consequently, it is necessary to treat liver injury and to prevent its progression. The drug Bicylol is widely employed in China to treat chronic hepatitis B virus (HBV) and has therapeutic potential for liver injury. It is the derivative of dibenzocyclooctadiene lignans extracted from Schisandra chinensis (SC). The Schisandraceae family is a rich source of dibenzocyclooctadiene lignans, which possesses potential liver protective activity. This study aimed to comprehensively summarize the phytochemistry, structure-activity relationship and molecular mechanisms underlying the liver protective activities of dibenzocyclooctadiene lignans from the Schisandraceae family. Here, we had discussed the analysis of absorption or permeation properties of 358 compounds based on Lipinski's rule of five. So far, 358 dibenzocyclooctadiene lignans have been reported, with 37 of them exhibited hepatoprotective effects. The molecular mechanism of the active compounds mainly involves antioxidative stress, anti-inflammation and autophagy through Kelch-like ECH-associating protein 1/nuclear factor erythroid 2 related factor 2/antioxidant response element (Keap1/Nrf2/ARE), nuclear factor kappa B (NF-кB), and transforming growth factor β (TGF-β)/Smad 2/3 signaling pathways. This review is expected to provide scientific ideas for future research related to developing and utilizing the dibenzocyclooctadiene lignans from Schisandraceae family.

Study on the effect of active components of Schisandra chinensis on liver injury and its mechanisms in mice based on network pharmacology

The aim of this study was to analyze the active components of Schisandra chinensis on liver injury and its mechanism in mice by network pharmacology. The active components of S. chinensis were found through Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform (TCMSP) and their corresponding targets were predicted. The targets of liver injury were searched through Therapeutic Targets Database (TTD), DisGeNET and drugbank databases, and the Venn diagram was constructed to obtain the action targets. The "drug-active component-target" network and protein-protein interaction network (PPI) were constructed by using STRING database and Cytoscape software, and the key targets were further screened by the enrichment analysis of relevant KEGG pathways. Finally, a CCl4-induced mouse liver injury model was established to verify the efficacy and related targets of S. chinensis and clarify its mechanism. Eight active components and 56 related targets of S. chinensis were screened out based on their oral bioavailability (OB) and drug likeness (DL). Five targets of S. chinensis related to liver injury were found by using the Venn diagram. The key targets, namely Ptgs2 and Nos2 genes, were further screened out by constructing a PPI network, and Schisandrol B (SCB) was considered the key component most closely related to the liver injury in S. chinensis. The results indicate that SCB may play a role in the treatment of the CCl4-induced liver injury by down-regulating the expression of iNOS and COX-2, and regulating the expression of NF-κB and IL-17 signaling pathway to inhibit the expression of proinflammatory factors.

Antioxidant Effects of Schisandra chinensis Fruits and Their Active Constituents

Schisandra chinensis Turcz. (Baill.) fruits, their extracts, and bioactive compounds are used in alternative medicine as adaptogens and ergogens protecting against numerous neurological, cardiovascular, gastrointestinal, liver, and skin disorders. S. chinensis fruit extracts and their active compounds are potent antioxidants and mitoprotectors exerting anti-inflammatory, antiviral, anticancer, and anti-aging effects. S. chinensis polyphenolic compounds-flavonoids, phenolic acids and the major constituents dibenzocyclooctadiene lignans are responsible for the S. chinensis antioxidant activities. This review will focus on the direct and indirect antioxidant effects of S. chinensis fruit extract and its bioactive compounds in the cells during normal and pathological conditions.

Transcriptomic analyses reveal the molecular mechanisms of schisandrin B alleviates CCl4-induced liver fibrosis in rats by RNA-sequencing

Liver fibrosis is a progression of chronic liver disease with lacks effective therapies at present. Schisandrin B (Sch B), a bioactive compound extracted from the traditional Chinese medicine Schisandra chinensis, was reported to benefit liver diseases. This study aimed to investigate the therapeutic effects and molecular mechanisms of Sch B against CCl₄-induced liver fibrosis in rats. RNA sequencing and transcriptome analysis were performed collaboratively, including analysis of differential gene expression, gene ontology (GO) analysis, pathway analysis and pathway-act-network analysis. The results demonstrated that Sch B effectively alleviated CCl₄-induced liver damage and fibrosis in rats, as evidenced by improved liver function and decreased extracellular matrix deposition. Furthermore, 4440 (1878 up-regulated, 2562 down-regulated) genes in the model group versus (vs) normal group, 4243 (2584 up-regulated, 1659 down-regulated) genes in Sch B-treated group vs model group were identified as differentially expressed genes (DEGs). Subsequently, GO analysis revealed that DEGs were mainly enriched in metabolism, oxidation-reduction, endoplasmic reticulum stress and apoptosis-related biological processes. Pathway analysis suggested that Sch B up-regulated cytochrome P450 drug metabolism, PPAR signaling pathways, and down-regulated glutathione metabolism pathways. In addition, the regulatory patterns of Sch B on key genes and pathways were also confirmed. In conclusion, our study demonstrated Sch B alleviated CCl₄-induced liver fibrosis by multiple modulatory mechanisms, which provide new clues for further pharmacological study of Sch B.

Schisandrin B attenuates CCl4-induced liver fibrosis in rats by regulation of Nrf2-ARE and TGF-β/Smad signaling pathways

Liver fibrosis is a major pathological feature of chronic liver diseases and there is no effective therapy program at present. Schisandrin B (Sch B) is the major bioactive ingredient of Schisandra chinensis, with antioxidative, anti-inflammatory, antitumor, and hepatoprotective properties. This study aimed to investigate the protective effect and related molecular mechanism of Sch B against carbon tetrachloride (CCl₄)-induced liver fibrosis in rats. The in vivo therapeutic effect of Sch B on liver fibrosis induced by CCl₄ was examined in rats. In vitro, rat hepatic stellate cells (HSC-T6) were used to assess the effect of Sch B on the activation of HSCs. Sch B effectively attenuated liver damage and progression of liver fibrosis in rats, as evidenced by improved liver function and decreased collagen deposition. The effects of Sch B were associated with attenuating oxidative stress by activating nuclear factor-erythroid 2-related factor 2 (Nrf2)-mediated antioxidant signaling and suppressing HSC activation by inhibiting the transforming growth factor-β (TGF-β)/Smad signaling pathway. In an in vitro study, it was shown that Sch B inhibited TGF-β-induced HSC activation. Finally, Sch B significantly inhibited TGF-β1-stimulated phosphorylation of Smad and signaling of mitogen-activated protein kinases. This study demonstrates that Sch B prevents the progression of liver fibrosis by the regulation of Nrf2-ARE and TGF-β/Smad signaling pathways, and indicates that Sch B can be used for the treatment of liver fibrosis.

Exacerbation of N-nitrosodiethylamine Induced Hepatotoxicity and DNA Damage in Mice Exposed to Chronic Unpredictable Stress

Psychological stress contributes to increased susceptibility to a number of diseases including cancer. The present study was designed to assess the effect of chronic unpredictable stress on N-nitrosodiethylamine induced liver toxicity in terms of in vivo antioxidant status and DNA damage in Swiss albino mice. The animals used in this study were randomized into different groups based on the treatment with N-nitrosodiethylamine or chronic unpredictable stress alone and post-stress administration of N-nitrosodiethylamine. The mice were sacrificed after 12 weeks of treatment, and the status of major enzymatic and non-enzymatic antioxidants, liver function markers, lipid peroxidation and the extent of DNA damage were determined in circulation and liver tissues of all the groups. The N-nitrosodiethylamine treated group showed significantly compromised levels of the antioxidant enzymes, lipid peroxidation, and the liver function markers with enhanced DNA damage as compared to chronic unpredictable stress or control groups. A similar but less typical pattern observed in the chronic unpredictable stress treated mice. All the measured biochemical parameters were significantly altered in the group treated with the combination of chronic unpredictable stress and N-nitrosodiethylamine when compared to controls, or chronic unpredictable stress alone and/or N-nitrosodiethylamine alone treated groups. Thus, exposure to continuous, unpredictable stress conditions even in general life may significantly enhance the hepatotoxic potential of N-nitrosodiethylamine through an increase in the oxidative stress and DNA damage.

Schisandra Lignan Extract Protects against Carbon Tetrachloride-Induced Liver Injury in Mice by Inhibiting Oxidative Stress and Regulating the NF-κB and JNK Signaling Pathways

Schisandra chinensis (S. chinensis) is a traditional Chinese herbal medicine widely used for the treatment of liver disease, whose main active components are lignans. However, the action mechanisms of the lignans in S. chinensis remain unclear. This study aimed to investigate the protective effect and related molecular mechanism of Schisandra lignan extract (SLE) against carbon tetrachloride- (CCl₄-) induced acute liver injury in mice. Different doses of SLE at 50, 100, and 200 mg/kg were administered daily by gavage for 5 days before CCl₄ treatment. The results showed that SLE significantly decreased the activities of serum ALT/AST and reduced liver pathologic changes induced by CCl₄. Pretreatment with SLE not only decreased the content of MDA but increased SOD, GSH, and GSH-Px activities in the liver, suggesting that SLE attenuated CCl₄-induced oxidative stress. The expression levels of inflammatory cytokines TNF-a, IL-1β, and IL-6 were decreased after oral administration of SLE, probably because lignans inhibited the NF-κB activity. Additionally, SLE also inhibited hepatocyte apoptosis by suppressing JNK activation and regulating Bcl-2/Bax signaling pathways. In conclusion, these results suggested that SLE prevented CCl₄-induced liver injury through a combination of antioxidative stress, anti-inflammation, and antihepatocyte apoptosis and alleviated inflammation and apoptosis by regulating the NF-κB, JNK, and Bcl-2/Bax signaling pathways.

Hepatoprotective Activity of Herbal Composition SAL, a Standardize Blend Comprised of Schisandra chinensis, Artemisia capillaris, and Aloe barbadensis

Some botanicals have been reported to possess antioxidative activities acting as scavengers of free radicals rendering their usage in herbal medicine. Here we describe the potential use of “SAL,” a standardized blend comprised of three extracts from Schisandra chinensis, Artemisia capillaris, and Aloe barbadensis, in mitigating chemically induced acute liver toxicities. Acetaminophen and carbon tetrachloride induced acute liver toxicity models in mice were utilized. Hepatic functional tests from serum collected at T24 and hepatic glutathione and superoxide dismutases from liver homogenates were evaluated. Histopathology analysis and merit of blending 3 standardized extracts were also confirmed. Statistically significant and dose-correlated inhibitions in serum ALT ranging from 52.5% (p = 0.004) to 34.6% (p = 0.05) in the APAP and 46.3% (p < 0.001) to 29.9% (p = 0.02) in the CCl₄ models were observed for SAL administered at doses of 400–250 mg/kg. Moreover, SAL resulted in up to 60.6% and 80.2% reductions in serums AST and bile acid, respectively. The composition replenished depleted hepatic glutathione in association with an increase of hepatic superoxide dismutase. Unexpected synergistic protection from liver damage was also observed. Therefore, the composition SAL could be potentially utilized as an effective hepatic-detoxification agent for the protection from liver damage.

Dibenzocyclooctadiene lignans from Schisandra spp. selectively inhibit the growth of the intracellular bacteria Chlamydia pneumoniae and Chlamydia trachomatis

Lignans from Schisandra chinensis berries show various pharmacological activities, of which their antioxidative and cytoprotective properties are among the most studied ones. Here, the first report on antibacterial properties of six dibenzocyclooctadiene lignans found in Schisandra spp. is presented. The activity was shown on two related intracellular Gram-negative bacteria Chlamydia pneumoniae and Chlamydia trachomatis upon their infection in human epithelial cells. All six lignans inhibited C. pneumoniae inclusion formation and infectious progeny production. Schisandrin B inhibited C. pneumoniae inclusion formation even when administered 8 h post infection, indicating a target that occurs relatively late within the infection cycle. Upon infection, lignan-pretreated C. pneumoniae elementary bodies had impaired inclusion formation capacity. The presence and substitution pattern of methylenedioxy, methoxy and hydroxyl groups of the lignans had a profound impact on the antichlamydial activity. In addition our data suggest that the antichlamydial activity is not caused only by the antioxidative properties of the lignans. None of the compounds showed inhibition on seven other bacteria, suggesting a degree of selectivity of the antibacterial effect. Taken together, the data presented support a role of the studied lignans as interesting antichlamydial lead compounds.

Reversing effects of lignans on CCl4-induced hepatic CYP450 down regulation by attenuating oxidative stress

Oxidative stress has been proved to be a critical reason of regulating CYP450s under hepatic injury status. The study was aimed to investigate the effect of pretreatment of schisandra lignan extracts (SLE) and dimethyl diphenyl bicarboxylate (DDB) on expressions and activities of the main liver P450 isoenzymes in CCl4 induced liver injury rats and their anti-oxidative effects on both CCl4 induced liver injury rats and a CCl4 induced HepG2 cell injury model. Acute experimental liver injury induced by CCl4 caused drastically decreasing activities of the main liver P450 isoenzymes such as CYP1A2, CYP2C6, CYP2E1 and CYP3A2, as well as their protein expressions. Pretreatment of SLE (500 mg/kg) and DDB (200 mg/kg) twice a day for three days significantly decreased the losses of activities of CYP1A2, CYP2C6, CYP2E1 and CYP3A2. Similar results were observed in protein expressions. In addition, in the CCl4 induced HepG2 cells injury model and the CYP3A activity level correlated well with ROS level in several ingredients of SLE treated groups, especially in γ-schisandrin group. These results indicated that the reversion of P450 after SLE/DDB treatment were, on one hand, due to hepatoprotective effects of these lignans on livers; on the other hand, due to their regulation of P450 through anti-oxidative effect and γ-schisandrin might be the most powerful ingredient of SLE. Also, there might be potential interactions between SLE or DDB and co-administered medicines and it is necessary to adjust the dosage of co-administrated medicines in clinical medication of liver disease.

Schisandrin B exhibits anti-inflammatory activity through modulation of the redox-sensitive transcription factors Nrf2 and NF-κB

Schisandrin B (SB), a dibenzocyclooctadiene derivative isolated from Schisandra chinensis and used commonly in traditional Chinese medicine for the treatment of hepatitis and myocardial disorders, has been recently shown to modulate cellular redox balance. Since we have shown that cellular redox plays an important role in the modulation of immune responses, the present studies were undertaken to study the effects of SB on activation and effector functions of lymphocytes. SB altered the redox status of lymphocytes by enhancing the basal reactive oxygen species levels and altering the GSH/GSSG ratio in lymphocytes. It also induced nuclear translocation of redox sensitive transcription factor Nrf2 and increased the transcription of its dependent genes. SB inhibited mitogen-induced proliferation and cytokine secretion by lymphocytes. SB also significantly inhibited mitogen-induced upregulation of T cell costimulatory molecules and activation markers. It was observed that SB inhibited mitogen-induced phosphorylation of c-Raf, MEK, ERK, JNK, and p38. It suppressed IκBα degradation and nuclear translocation of NF-κB in activated lymphocytes. Anti-inflammatory effects of SB were significantly abrogated by the inhibitors of Nrf2 and HO-1, suggesting the involvement of this pathway. Similar anti-inflammatory effects of SB on lymphocyte proliferation and cytokine secretion were also observed in vivo. To our knowledge, this is the first report showing that the anti-inflammatory effects of SB are mediated via modulation of Nrf2 and NF-κB in lymphocytes.

Correlation between Antistress and Hepatoprotective Effects of Schisandra Lignans Was Related with Its Antioxidative Actions in Liver Cells

The present study was conducted to investigate the relationship between the anti-stress and hepato-protective effects of Schisandra Lignans Extract (SLE) on stress-induced liver damage. Seven weeks old male mice were fixed in a restraint tube for 18 h to induce liver damage. SLE was orally administered to animals for 5 days at dosages of 100 and 200 mg/kg/day before exposed to restraint stress. Oral administration of SLE significantly reduced restraint-induced liver damage in experimental animal. SLE was further found to significantly alleviate the provocation of corticosterone in stressed mice. SLE also significantly decreased oxidative damage and increased anti-oxidative capability of liver cells by preventing the over production and accumulation of free radicals. In conclusion, the protective effects of SLE on stress-induced liver damage were confirmed, and the correlation between hepatoprotective and anti-stress effects of schisandra lignans was possible related to its alleviation on the malignant effects of stressors for bio-homeostasis, such as balance of oxidation and reduction in cells.

In vitro antioxidation activity and genoprotective effect of selected Chinese medicinal herbs

Some traditional Chinese medicinal seeds and fruits are well known for their antioxidant properties. This research aims to investigate whether Fructus Lycii, Fructus Schisandrae Chinensis, Fructus Ligustri Lucidi and Semen Cuscutae protect DNA from oxidant challenge by hydrogen peroxide (H(2)O(2)). The standard comet assay was used to assess the genoprotective effect of these medicinal herbs. Blood was taken from three healthy adults, aged from 36 to 42. Lymphocytes were isolated and treated with different concentrations of aqueous herbal extracts, while controls were treated with phosphate buffered saline. The lymphocytes were stressed with 50 μM H(2)O(2). Treated cells were embedded in agarose and layered on slides. These sandwiched lymphocytes were lysed and afterwards subjected to an electric field in an alkaline environment. Damaged DNA was pulled out from the nucleus towards the positive electrode as a comet tail; its density was related to the degree of DNA damage. Finally, the slides were stained with fluorescence dye and tails were visually scored for 100 cells. The experiment was repeated three times and DNA damage in treated cells was compared to the controls. There was no statistical difference in DNA damage among the herb treated cells and untreated cells in the comet assay. Our data demonstrated that the selected medicinal herbs did not show in vitro DNA protection in the comet assay against oxidant challenge.

Schisandrin B prevents doxorubicin-induced chronic cardiotoxicity and enhances its anticancer activity in vivo

Background

To mitigate the cardiotoxicity of anthracycline antibiotics without compromising their anticancer activities is still an issue to be solved. We previously demonstrated that schisandrin B (Sch B) could protect against doxorubicin (Dox)-induced acute cardiotoxicity via enhancing cardiomyocytic glutathione redox cycling that could attenuate oxidative stress generated from Dox. In this study, we attempted to prove if Sch B could also protect against Dox-induced chronic cardiotoxicity, a more clinically relevant issue, without compromising its anticancer activity.

Methodology

Rat was given intragastrically either vehicle or Sch B (50 mg/kg) two hours prior to i.p. Dox (2.5 mg/kg) weekly over a 5-week period with a cumulative dose of Dox 12.5 mg/kg. At the 6th and 12th week after last dosing, rats were subjected to cardiac function measurement, and left ventricles were processed for histological and ultrastructural examination. Dox anticancer activity enhanced by Sch B was evaluated by growth inhibition of 4T1, a breast cancer cell line, and S180, a sarcoma cell line, in vitro and in vivo.

Principal Findings

Pretreatment with Sch B significantly attenuated Dox-induced loss of cardiac function and damage of cardiomyocytic structure. Sch B substantially enhanced Dox cytotoxicities toward S180 in vitro and in vivo in mice, and increased Dox cytotoxcity against 4T1 in vitro. Although we did not observe this enhancement against the implanted 4T1 primary tumor, the spontaneous metastasis to lung was significantly reduced in combined treatment group than Dox alone group.

Conclusion

Sch B is capable of protecting Dox-induced chronic cardiotoxicity and enhancing its anticancer activity. To the best of our knowledge, Sch B is the only molecule ever proved to function as a cardioprotective agent as well as a chemotherapeutic sensitizer, which is potentially applicable for cancer treatment.

Prevention and treatment of doxorubicin-induced cardiotoxicity by dexrazoxane and schisandrin B in rabbits

The cost of dexrazoxane, a drug used to provide protection from doxorubicin-induced cardiotoxicity, limits its use in low-income countries. We aimed to see whether schisandrin B, an inexpensive drug, could provide protection equivalent to that provided by dexrazoxane. New Zealand white rabbits were randomly divided into groups and treated with saline, doxorubicin, doxorubicin + dexrazoxane, or doxorubicin + schisandrin B. Doxorubicin-induced damage and the protective effects were studied by recording the echocardiographic parameters and serum levels of superoxide dismutase, malondialdehyde, cardiac troponin I, and brain natriuretic peptide and observing the histology and degree of apoptosis. Schisandrin B had dose-dependent effects in decreasing the magnitude of doxorubicin-induced indicators of cardiomyopathy to a degree that approximated the decrease produced by dexrazoxane treatment. Schisandrin B might be a useful, low-cost alternative drug for this application.

The protective effect of Schisandra lignans on stress-evoked hepatic metastases of P815 tumor cells in restraint mice

AIM OF THE STUDY

The present study was conducted to investigate the effects of schisandra lignans extract (SLE) on stress-evoked hepatic metastases of mastocytoma P815 tumor cells, which was closely related with immune function.

MATERIALS AND METHODS

The high-performance liquid chromatography (HPLC) fingerprint of SLE was recorded and the percentage composition of schisandra lignans was determined as 82.63%. The contributions of the immunomodulatory properties of SLE to the protective effects on stress-induced hepatic metastases were studied.

RESULTS

Our results found that restraint stress significantly promoted hepatic metastases of P815 tumor cells. However, oral administration of SLE (100 and 200mg/kg/d, 14d) significantly reduced the number of metastatic colonies in liver of restrained mice. SLE was further found to be significantly improving T lymphocyte proportions and increasing cytotoxic T lymphocyte (CTL) activity of immunized spleen cells in stressed mice.

CONCLUSION

These results indicated that the protective effects of SLE on hepatic metastases were related to its alleviation of the adverse effects of stressors for bio-homeostasis and immunoprotection. The obtained data provided evidences to elucidate the traditional use of Fructus schisandrae as a tonic or sedative.

Identification of liver proteins and their roles associated with carbon tetrachloride-induced hepatotoxicity

Carbon tetrachloride (CCl(4)) is a common hepatotoxin used in experimental models to elicit liver injury. To identify the proteins involved in CCl(4)-induced hepatotoxicity, two-dimensional gel electrophoresis was employed followed by mass spectrometry - mass spectrometry (MS/MS) to study the differentially expressed proteins during CCl(4) exposure in the Fischer 344 rat liver proteome for 5 weeks. Ten spots with notable changes between the Control and CCl(4) groups were successfully identified. Among them, four proteins with significant up-regulation, namely calcium-binding protein 1, protein disulfide isomerase, mitochondrial aldehyde dehydrogenase precursor, and, glutathione-S-transferase mu1 and six proteins with significant down-regulation, namely catechol-O-methyltransferase, hemoglobin-alpha-2-chain, hemopexin precursor, methionine sulfoxide reductase A, catalase and carbonic anhydrase 3, were identified. The data indicates that CCl(4) causes hepatotoxicity by depleting oxygen radical scavengers in the hepatocytes. In this rat model, we profiled hepatic proteome alterations in response to CCl(4) intoxication. The findings should facilitate understanding of the mechanism of CCl(4)-induced liver injury.

Long-term treatment with a "Yang-invigorating" Chinese herbal formula, Wu-Zi-Yan-Zong-Wan, reduces mortality and liver oxidative damage in chronic alcohol-intoxicated rats

Long-term alcohol consumption has been reported to increase oxidative stress in multiple organs and accelerate the aging process. A previous study in our laboratory has shown that Wu-Zi-Yan-Zong-Wan (WZ), a "Yang-invigorating" Chinese herbal formula, protected against ethanol-induced toxicity in HepG2 cells transfected to express human CYP2E1, presumably by enhancing mitochondrial antioxidant status and functional ability. The present study aims to investigate whether WZ extract treatment can afford protection against chronic ethanol-induced oxidative stress (a major risk factor of aging) and mortality in rats. The effect of the extract (1.8 g, 4.5 g, and 9 g raw materials/kg per day) on chronic ethanol hepatotoxicity was investigated in rats receiving steady intragastric infusion of ethanol-containing liquid diet. The results showed that long-term (42 days) herbal co-treatment protected against chronic ethanol-induced mortality and hepatotoxicity and in rats, as evidenced by decreased plasma transaminases activities. The extract also suppressed the pathological development of fatty liver, as assessed by histopathological examination and the ratio of liver weight to body weight. The hepatoprotection afforded by the extract was associated with decreases in the extents of reactive oxygen species production, lipid peroxidation, and oxidative modification of proteins, as well as the reversal of altered mitochondrial reduced glutathione level. The results suggest that the suppressive effect of WZ on chronic ethanol-induced oxidative stress and mortality may be attributed to the antioxidant action, particularly in mitochondria.

Integral pharmacokinetics of multiple lignan components in normal, CCl4-induced hepatic injury and hepatoprotective agents pretreated rats and correlations with hepatic injury biomarkers

Although pharmacokinetic alternations by hepatic injury have been extensively studied, little is known about the potential influence of hepatoprotective agent's treatment. This study was aimed to investigate the holistic pharmacokinetics of multiple lignans, CYP3A regulations, and their correlations with hepatic injury biomarkers, in hepatic injured rats pretreated with or without schisandra lignan extract (SLE) and dimethyl-diphenyl-bicarboxylate (DDB). Integral pharmacokinetics of multiple lignans based on an AUC-weighting approach was determined in normal, CCl4 induced hepatic injury rats pretreated with or without SLE and DDB. Protein expression and activities of CYP3A were determined. Pharmacokinetic parameters and CYP3A activities were correlated with serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels. CCl4 induced acute hepatic injury resulted in a nearly 8-fold enhancement of integral plasma exposures of multiple lignans, which was caused by the significant down-regulation of CYP3A. SLE and DDB pretreatment exhibited potent hepatoprotective effects, accompanied with the restored expression and activity of CYP3A, and the recovery of the respective and integral pharmacokinetics of lignans components. The integral AUC(0-tn) and CYP3A activities correlated well with ALT and AST. This study suggested that the pharmacokinetic regulating effects of hepatoprotective agent's on themselves and co-prescribed drugs should be of concern, and hepatic injury biomarkers may serve as good predictors.

Biochemical mechanism of Wu-Zi-Yan-Zong-Wan, a traditional Chinese herbal formula, against alcohol-induced oxidative damage in CYP2E1 cDNA-transfected HepG2 (E47) cells

AIM OF THE STUDY

Wu-Zi-Yan-Zong-Wan (WZ) is a traditional Chinese herbal formula which is commonly used for treating patients with "Yang deficiency". In the present study, the effect of WZ on ethanol-induced toxicity in CYP2E1 cDNA-transfected HepG2 (E47) cells was investigated.

MATERIALS AND METHODS

WZ extract was obtained by extracting the herbal powder with 50% ethanol (v/v, in water) and the effect of the extract on ethanol-induced toxicity was investigated in cultured cells.

RESULTS

The treatment with WZ extract (12.5-200 microg/mL) for 24h dose-dependently protected against ethanol-induced toxicity in E47 cells, as evidenced by the enhanced cell viability and decreased extent of lactate dehydrogeanse leakage. The cytoprotection against ethanol-induced toxicity was associated with decreases in the extents of reactive oxygen species production and lipid peroxidation, as well as increases in mitochondrial reduced glutathione and membrane potential. In addition, WZ extract treatment also suppressed the formation of DNA fragments in ethanol-intoxicated E47 cells.

CONCLUSIONS

WZ extract was found to protect against the ethanol-induced toxicity in E47 cells, possibly by virtues of its antioxidant activity.

Schisandrin B stereoisomers protect against hypoxia/reoxygenation-induced apoptosis and associated changes in the Ca(2+)-induced mitochondrial permeability transition and mitochondrial membrane potential in AML12 hepatocytes

The effects of the schisandrin B stereoisomers, (+/-)gamma-schisandrin [(+/-)gamma-Sch] and (-)schisandrin B [(-)Sch B], on hypoxia/reoxygenation-induced apoptosis were investigated in AML12 hepatocytes. Changes in cellular reduced glutathione (GSH) levels, Ca(2+)-induced mitochondrial permeability transitions (MPTs) and mitochondrial membrane potentials (Deltapsi(m) values) were also examined in (+/-)gamma-Sch- and (-)Sch B-treated cells, without or with hypoxia/reoxygenation challenge. The (+/-)gamma-Sch/(-)Sch B pretreatments (2.5-5.0 microm) protected against hypoxia/reoxygenation-induced apoptosis in AML12 cells in a concentration-dependent manner, with the (-)Sch B effect being more potent. Drug antiapoptotic effects were further evidenced by suppression of hypoxia/reoxygenation-induced mitochondrial cytochrome c release and subsequent cleavage of caspase 3 and poly-ADP-ribose polymerase by (-)Sch B pretreatment. Whereas hypoxia/reoxygenation challenge increased the extent of Ca(2+)-induced MPT pore opening, and Deltapsi(m), in AML12 hepatocytes, cytoprotection afforded by (+/-)gamma-Sch/(-)Sch B pretreatment against hypoxia/reoxygenation-induced apoptosis was associated with a decreased sensitivity to Ca(2+)-induced MPT and an increased Deltapsi(m) in both unchallenged and challenged cells, compared with the drug-free control. The results indicate that (+/-)gamma-Sch/(-)Sch B pretreatment protected against hypoxia/reoxygenation-induced apoptosis in AML12 hepatocytes and that the cytoprotection afforded by (+/-)gamma-Sch/(-)Sch B may at least in part be mediated by a decrease in sensitivity to Ca(2+)-induced MPT, which may in turn result from enhancement of cellular GSH levels by drug pretreatments.

Protective Effects of the Antioxidant 4b,5,9b,10-Tetrahydroindeno[1,2-b]indole Against TCDD Toxicity in C57BL/6J Mice

The protection against 2,3,7,8-tetrachlorodibenzo- p-dioxin (TCDD; 5 µg/kg body weight) toxicity by the antioxidant 4b,5,9b,10-tetrahydroindeno[1,2- b]indole (THII) was examined in female C57BL/6J mice. TCDD produced increases in the levels of hepatic lipid-derived aldehydes, rates of mitochondrial production of hydrogen peroxide and superoxide, and the oxidation state of cytosolic GSH. In contrast, mitochondrial GSH increased in reduction state, correlating with an increase in mitochondrial membrane potential. Systemically, TCDD lowered body weight gain, percentage body fat, and hepatic ATP levels, parameters prevented by concomitant administration of 100 µM THII in drinking water. However, TCDD-induced increases in mitochondrial respiration and decreased mitochondrial membrane fluidity were not prevented by THII. These results suggest that TCDD-mediated oxidative stress was not responsible for changes in mitochondrial respiration or membrane fluidity. Furthermore, although TCDD produced a large increase in mitochondrial oxygen consumption, this was not associated with the poor gain in weight produced by TCDD.

Asiatic Acid Derivatives Protect Primary Cultures of Rat Hepatocytes against Carbon Tetrachloride-Induced Injury via the Cellular Antioxidant System

We attempted to elucidate the hepatoprotective mechanism of two asiatic acid (AS) derivatives, 3β,23-dihydroxyurs-2-oxo-12-ene-28-oic acid (AS-10) and 3β,23-dihydroxyurs-12-ene-28-oic acid (AS-14), which exhibited significant protective activity against carbon tetrachloride (CCl4)-induced hepatotoxicity in primary cultures of rat hepatocytes. Our findings showed that AS-10 and AS-14 preserved the level of glutathione and the activities of antioxidant enzymes such as glutathione reductase, glutathione peroxidase, superoxide dismutase and catalase. In addition, these compounds ameliorated lipid peroxidation, as demonstrated by a reduction in the production of malondialdehyde. Furthermore, AS-10 and AS-14 did not restore the reduced total GSH level by BSO, indicating that the hepatoprotective activities of these compounds may be involved, in part, by regulating GSH synthesis. From these results, we suggest that both AS-10 and AS-14 exerted their hepatoprotective activities against CCl4-induced injury by preserving the cellular antioxidative defense system.

Influence of an aqueous extract of Ligustrum lucidum and an ethanol extract of Schisandra chinensis on parameters of antioxidative metabolism and spleen lymphocyte proliferation of broilers

The study was conducted to evaluate the effects of dietary supplementation with different levels of two extracts, an aqueous extract of Ligustrum lucidum (AELL), and an ethanol extract of Schisandra chinensis (EESC) on growth performance, parameters of antioxidative status and spleen lymphocyte proliferation of broilers, respectively. The results showed that neither AELL nor EESC had significant effects on growth performance of broilers. However, malondialdehyde concentration in heart and liver of the broilers were significantly decreased by feeding AELL or EESC. Superoxide dismutase activity in heart, liver, and kidney of broilers were improved by feeding different dosages of AELL or EESC. In contrast, glutathione reductase activity in serum, heart and kidney of broilers was not affected by experimental treatment. In addition, spleen lymphocyte proliferation of broilers was significantly enhanced by feeding different dosages of AELL or EESC. In conclusion, the results suggested that either AELL or EESC may improve antioxidant status and immune function of broilers.

High throughput screening and antioxidant assay of dibenzo[a,c]cyclooctadiene lignans in modified-ultrasonic and supercritical fluid extracts of Schisandra chinensis Baill by liquid chromatography--mass spectrometry and a free radical-scavenging method

Dibenzo[a,c]cyclooctadiene lignans of Schisandra chinensis Baill are well known because of their hepatoprotective activity, antioxidant activity, and anticancer effect. For the isolation of the dibenzo[a,c]cyclooctadiene lignans of Schisandra chinensis Baill two extraction methods were used: modified-ultrasonic extraction and supercritical fluid extraction. A specific and fast analytical method for structure identification is established for quality control because structure elucidation could be accomplished by means of liquid chromatography-mass spectrometry (LC-MS) technologies. The separation and identification of the compounds were completed by: (i) a water-acetonitrile gradient system using a C18 reversed-phase column; (ii) UV detection at 225 nm; (iii) MS/MS experiments with electrospray ionization interface (ESI) ion trap mass spectrometry in the positive mode. Normalized collision energy was used to obtain fragment ions of structural relevance in the LC-MS/MS. These results provided a reliable LC-MS/MS method for the determination of the dibenzo[a,c]cyclooctadiene lignans from Schisandra chinensis Baill. Finally, we also detected 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging effects (%) of the modified-ultrasonic and supercritical fluid extracts of Schisandra chinensis Baill compared with 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox). The antioxidant activities of the modified-ultrasonic and supercritical fluid extracts were lower than that of trolox.

Influence of mannan oligosaccharide,Ligustrum lucidumandSchisandra chinensison parameters of antioxidative and immunological status of broilers

The study was conducted to evaluate effects of dietary supplementation with Ligustrum lucidum (LL, 10 g/kg), Schisandra chinensis (SC, 10 g/kg), LL (10 g/kg) + mannan oligosaccharides (MOS, 50 mg/kg), or SC (10 g/kg) + MOS (50 mg/kg) on growth performance and parameters of antioxidative and immunological status of broilers. The results showed that feeding LL, SC, LL + MOS, or SC + MOS had no significant effect on growth performance of broilers relative to the control. However, compared to the control, LL, SC, LL + MOS, or SC + MOS significantly decreased malondialdehyde concentration in serum, thigh, and heart of broilers. In addition, glutathione reductase activity of heart and sera of the birds were significantly elevated by supplementation LL, SC, LK + MOS, or SC + MOS. Furthermore, LL, SC, LL + MOS, or SC + MOS significantly improved antibody titres against Newcastle disease virus and lymphocyte proliferation of broilers (p < 0.05). Whereas, no cooperating effect between LL (or SC) and MOS on antioxidant status and immunity of broilers were found.

Effects of schisandrin B enantiomers on cellular glutathione and menadione toxicity in AML12 hepatocytes

Effects of schisandrin B enantiomer ((+)Sch B and (-)Sch B) treatment on the reduced cellular glutathione (GSH) level and susceptibility to menadione-induced toxicity were investigated and compared in AML12 hepatocytes. (+)Sch B or (-)Sch B treatment at 6.25 micromol/l produced a time-dependent change in cellular GSH level, with the maximal stimulation occurring 16 h after dosing. (+)Sch B/(-)Sch B pretreatment for 16 h dose-dependently protected against menadione toxicity, with the maximum degree of protection observable at 6.25 micromol/l and the extent of protection afforded by (-)Sch B being larger than that of (+)Sch B. The cytoprotection was associated with a parallel enhancement in cellular GSH level in both non-menadione (control) and menadione-intoxicated cells. While the GSH depletion produced by buthionine sulfoximine/phorone treatment largely abrogated the cytoprotective action of (+)Sch B/(-)Sch B, it almost completely abolished the GSH-enhancing effect of (+)Sch B and (-)Sch B in both control and menadione-treated cells. Both (+)Sch B and (-)Sch B treatments increased the GSH reductase activity in control and menadione-treated cells, with the stimulatory action of (-)Sch B being more potent than that of (+)Sch B in the control condition. (+)Sch B and (-)Sch B also enhanced the gamma-glutamate cysteine ligase activity in menadione-intoxicated cells. The results indicate that (-)Sch B is more effective than (+)Sch B in enhancing cellular GSH and protecting against oxidant injury in hepatocytes.

Schisandrin B enhances doxorubicin-induced apoptosis of cancer cells but not normal cells

The dose-dependent cardiotoxicities of doxorubicin (DOX) significantly limits its anti-cancer efficacies. One of the ways to augment the efficacies of DOX at a relatively low cumulative dose is to use a chemical sensitizer. Here, we demonstrated that schisandrin B (Sch B) significantly enhanced DOX-induced apoptosis of SMMC7721, a human hepatic carcinoma cell line, and of MCF-7, a human breast cancer cell line. This enhancement was irrelevant to the action of Sch B on P-glycoprotein or other drug-transporters, but associated with the activation of caspase-9 rather than caspase-8. The loss of mitochondria membrane potential was observed when cells were treated with DOX and Sch B combined. On the other hand, at the same experimental conditions, Sch B did not enhance the DOX-induced apoptosis of primary rat cardiomyocytes and primary human fibroblasts. Therefore, it is speculative that Sch B may bring benefit to clinical chemotherapy by reducing significantly the cumulative doses of DOX and its associated cardiotoxicities.

Schisandrin B-induced increase in cellular glutathione level and protection against oxidant injury are mediated by the enhancement of glutathione synthesis and regeneration in AML12 and H9c2 cells

To define the relative role of reduced glutathione (GSH) synthesis and regeneration in schisandrin B (Sch B)-induced increase in cellular GSH level and the associated cytoprotection against oxidative challenge, the effects of L-buthionine-[S,R]-sulfoximine (BSO, a specific inhibitor of gamma-glutamate cysteine ligase (GCL)) and 1,3-bis(2-chloroethyl)-1-nitrourea (BCNU, a specific inhibitor of glutathione reductase (GR)) treatments or their combined treatment were examined in control and Sch B-treated AML12 and H9c2 cells, without and/or with menadione intoxication. Both BSO and BCNU treatments reduced cellular GSH level in AML12 and H9c2 cells, with the effect of BSO being more prominent. The GSH-enhancing effect of Sch B was also suppressed by BSO and BCNU treatments, with the effect of the combined treatment with BSO and BCNU being semi-additive. While Sch B treatment increased the GR but not GCL activity in AML12 and H9c2 cells, it increased the cellular cysteine level. BSO treatment also suppressed the Sch B-induced increase in GR activity. BSO or BCNU treatment per se did not cause any detectable cytotoxic effect, as assessed by lactate dehydrogenase leakage, but the combined treatment with BSO and BCNU was cytotoxic, particularly in H9c2 cells. The cytotoxic effect of BSO and BCNU became more apparent following the menadione challenge. The cytoprotection afforded by Sch B pretreatment was partly suppressed by BSO or BCNU treatment, or completely abrogated by the combined treatment with BSO and BCNU. In conclusion, the results indicate that the cytoprotective action of Sch B is causally related to the increase in cellular GSH level, which is likely mediated by the enhancement of GSH synthesis and regeneration.

Effect ofLigustrum lucidumandSchisandra chinensison the egg production, antioxidant status and immunity of laying hens during heat stress

The experiment was conducted to evaluate the effect of two plants belonging to Chinese herbal medicines, Ligustrum lucidum (LL) and Schisandra chinensis (SC), on the laying performance, antioxidant status and immunity of hens during heat stress. The results showed that diets supplement with 1% of either LL or SC had beneficial effects on egg production and FCR of hens during heat stress (p < 0.05), compared with the control group. Either LL or SC significantly reduced malondialdehyde (MDA) concentration of heart, liver, sera and egg yolk. In addition, glutathione reductase (GR) activity of tissues and sera of the birds was significantly elevated by supplementation LL or SC. Furthermore, LL or SC supplementation significantly elevated lymphoblastogenese of the birds and the antibody values against Newcastle disease virus (NDV). The results suggest that diets supplement with 1% of either LL or SC may enhance egg production, immune function, and antioxidant status of hens during heat stress.

Dibenzocyclooctadiene lingnans: a class of novel inhibitors of P-glycoprotein

PURPOSE

To determine if five dibenzocyclooctadiene lingnans, a class of naturally occurring compounds from Schisandra chinensis (Turcz.) Baill, have the activities to reverse P-glycoprotein (P-gp) mediated multidrug resistance (MDR).

METHODS

The IC(50)s of four MDR cell lines (K562/Adr, MCF-7/Adr, KBv200, and Bcap37/Adr) toward daunorubicin, vincristine, and paclitaxel in the presence or absence of one of the dibenzocyclooctadiene lingnans were determined by a FACscan assay. The intracellular daunorubicin accumulation in the four MDR cell lines was determined by incubation of cells with daunorubicin (2 microg/ml) in the presence or absence of one of the dibenzocyclooctadiene lingnans by a FACscan assay. The interaction of the five dibenzocyclooctadiene lingnans with P-gp was assayed by their inhibition of (3)H-azidopine photoaffinity labeling of P-gp.

RESULTS

Among the five lingnans, while schisandrin A and B, and schisantherin A demonstrated strong and comparable activities to reverse the drug resistance and the intracellular drug accumulation in four MDR cell lines, schisandrol A and B showed very limited activities. The poor activities of schisandrol A and B are possibly caused by the hydroxyl groups on the cyclooctadiene ring, because the activities of the molecules resumed when the hydroxyl group was esterified to form a benzoate. Further studies demonstrated that these compounds physically interacted with P-gp.

CONCLUSION

Schisandrin A and B, and schisantherin A are potent P-gp inhibitor and is of potential for future clinical application.

Schisandrin B—A novel inhibitor of P-glycoprotein

P-glycoprotein-mediated drug efflux is one of the major causes of the cancer multidrug resistance (MDR). Inhibition of P-glycoprotein could reverse cancer MDR. Here, we show that schisandrin B, a naturally occurring compound from Schisandra chinensis (Turcz.) Baill, bears strong potency to inhibit P-glycoprotein. Schisandrin B reversed the drug resistance of four MDR cell lines characterized with overexpression of P-glycoprotein and fully restored the intracellular drug accumulation by interacting with P-glycoprotein. Schisandrin B has a core structure of dibenzocyclooctadiene, representing a novel P-glycoprotein inhibitor. To our best knowledge, the role of schisandrin B to inhibit P-glycoprotein has not been reported.

Toxicity of hepatotoxins: new insights into mechanisms and therapy

Liver injury caused by hepatotoxins, such as carbon tetrachloride (CCl4), ethanol, and acetaminophen (APAP), is characterised by varying degrees of hepatocyte degeneration and cell death via either apoptosis or necrosis. The generation of reactive intermediate metabolites from the metabolism of hepatotoxins, and the occurrence of reactive oxygen species (ROS) during the inflammatory reaction account for a variety of pathophysiologic pathways leading to cell death, such as covalent binding, disordered cytosolic calcium homeostasis, glutathione (GSH) depletion, onset of mitochondrial permeability transition (MPT) and associated lipid peroxidation. The metabolism of hepatotoxins by cytochrome P-450 enzyme subtypes is a key step of the intoxication; therefore, enzyme inhibitors are shown to minimise the hepatotoxin-associated liver damage. Understanding the function of transcription factors, such as nuclear factor kappaB (NF-kappaB) in acute liver injury, may provide some answers as to the molecular mechanisms of toxic insults. Moreover, substantial evidence exists that MPT is involved in ROS-associated hepatocellular injury and new findings offer a novel therapeutic approach to attenuate cell damage by blocking the onset of MPT. Thus, oxidant stress and lipid peroxidation are crucial elements leading to hepatotoxin-associated liver injury. In addition to specific treatment for a given hepatotoxin, the general strategy for prevention and treatment of the damage includes reducing the production of reactive metabolites of the hepatotoxins, using anti-oxidative agents, and selectively targeting therapeutics to Kupffer cells or hepatocytes for on-going processes, which play a role in mediating a second phase of the injury.

Glutathione Redox State Regulates Mitochondrial Reactive OxygenProduction

Oxidative stress induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD; dioxin) is poorly understood. Following one dose of TCDD (5 microg/kg body weight), mitochondrial succinate-dependent production of superoxide and H2O2 in mouse liver doubled at 7-28 days, then subsided by day 56; concomitantly, levels of GSH and GSSG increased in both cytosol and mitochondria. Cytosol displayed a typical oxidative stress response, consisting of diminished GSH relative to GSSG, decreased potential to reduce protein-SSG mixed disulfide bonds (type 1 thiol redox switch) or protein-SS-protein disulfide bonds (type 2 thiol redox switch), and a +10 mV change in GSSG/2GSH reduction potential. In contrast, mitochondria showed a rise in reduction state, consisting of increased GSH relative to GSSG, increases in type 1 and type 2 thiol redox switches, and a -25 mV change in GSSG/2GSH reduction potential. Comparing Ahr(-/-) knock-out and wild-type mice, we found that TCDD-induced thiol changes in both cytosol and mitochondria were dependent on the aromatic hydrocarbon receptor (AHR). GSH was rapidly taken up by mitochondria and stimulated succinate-dependent H2O2 production. A linear dependence of H2O2 production on the reduction potential for GSSG/2GSH exists between -150 and -300 mV. The TCDD-stimulated increase in succinate-dependent and thiol-stimulated production of reactive oxygen paralleled a four-fold increase in formamidopyrimidine DNA N-glycosylase (FPG)-sensitive cleavage sites in mitochondrial DNA, compared with a two-fold increase in nuclear DNA. These results suggest that TCDD produces an AHR-dependent oxidative stress in mitochondria, with concomitant mitochondrial DNA damage mediated, at least in part, by an increase in the mitochondrial thiol reduction state.

Antioxidant parameters and lipid peroxidation in salivary glands of streptozotocin-induced diabetic rats

BACKGROUND

There is evidence suggesting an unbalance between oxidant and antioxidant status associated with diabetes. Considering that salivary function is essential for the maintenance of oral and systemic health, this study was designed to examine the levels of reduced and oxidized glutathione and the activities of the antioxidant enzymes, such as superoxide dismutase, catalase, and glutathione peroxidase, in salivary gland of streptozotocin-induced diabetic rats.

METHODS

The content of malondialdehyde was determined in the blood and in the salivary glands. The antioxidant status was investigated in the submandibular and parotid salivary glands.

RESULTS

Diabetic rats showed an increase in the content of malonaldehyde in the blood and in the submandibular salivary gland, but not in the parotid gland. Both forms, reduced and oxidized glutathione content present higher values in the diabetic submandibular gland compared with controls. No difference in the activity of superoxide dismutase between the diabetic and control glands was observed in either gland. Catalase showed higher specific activity in the parotid gland of the diabetic rats than control; however, in the submandibular gland, only when expressed as unit per gland was it higher than control. The specific activity of glutathione peroxidase was higher in the diabetic parotid gland than control; however, in the submandibular gland, its activity per gland was lower than controls.

CONCLUSION

The streptozotocin-induced diabetes in rats caused different results comparing the submandibular and parotid salivary glands.

Effects of schisandrin B pretreatment on tumor necrosis factor-alpha induced apoptosis and Hsp70 expression in mouse liver

Tumor necrosis factor-alpha (TNFalpha) could cause apoptosis in hepatic tissue of D-galactosamine sensitized mice, as evidenced by the increase in the extent of DNA fragmentation. The hepatic apoptosis induced by TNFalpha was associated with hepatocellular damage as assessed by plasma alanine aminotransferase activity. Schisandrin B (Sch B) pretreatment at daily doses ranging from 0.5 to 2 mmol/kg for 3 days caused a dose-dependent protection against TNFalpha-induced apoptosis in mice. The hepatoprotection was accompanied by a parallel reduction in the extent of hepatocellular damage. The same Sch B pretreatment regimens increased hepatic Hsp70 level in a dose-dependent manner. The relevance of Sch B-induced increase in Hsp70 expression to the prevention of TNFalpha-triggered hepatic apoptosis remains to be elucidated.

Schisandrin B protects against menadione-induced hepatotoxicity by enhancing DT-diaphorase activity

Pretreating mice with schisandrin B (Sch B), a dibenzocyclooctadiene derivative isolated from the fruit of Schisandra chinensis, at a daily dose of 1 mmol/kg for 3 days protected against menadione-induced hepatic oxidative damage in mice, as evidenced by decreases in plasma alanine aminotransferase activity (78%) and hepatic malondialdehyde level (70%), when compared with the menadione intoxicated control. In order to define the biochemical mechanism involved in the hepatoprotection afforded by Sch B pretreatment, we examined the activity of DT-diaphorase (DTD) in hepatocytes isolated from Sch B pretreated rats. Hepatocytes isolated from Sch B pretreated (a daily dose of 1 mmol/kg for 3 days) rats showed a significant increase (25%) in DTD activity. The increase in DTD activity was associated with the enhanced rate of menadione elimination in the hepatocyte culture. The ensemble of results suggests that the ability of Sch B pretreatment to enhance hepatocellular DTD activity may at least in part be attributed to the protection against menadione hepatotoxicity.

Protection of rat hepatocytes exposed to CCl4 in-vitro by cynandione A, a biacetophenone from Cynanchum wilfordii

To identify hepatoprotective agents from plant sources we use primary cultures of rat hepatocytes injured by CCl4. The hepatoprotective agents are the compounds that mitigate the injury caused by CCl4. Using this system we have investigated the biochemical mechanisms involved in the hepatoprotective activity of cynandione A, a biacetopherone, isolated from the roots of Cynanchum wilfordii Hemsley (Asclepiadaceae). Cynandione A (50 microM) significantly reduced (approximately 50%) the release into the culture medium of glutamic pyruvic transaminase and sorbitol dehydrogenase from the primary cultures of rat hepatocytes exposed to CCl4. Glutathione, superoxide dismutase, catalase and glutathione reductase play important roles in the cellular defence against oxidative stress. Cynandione A appeared to protect primary cultured rat hepatocytes exposed to CCl4 from significant drops in the levels of each of these four specific markers. Cynandione A also ameliorated lipid peroxidation by up to 50% as demonstrated by a reduction in the production of malondialdehyde. These results suggest that cynandione A protected the hepatocytes from CCl4-injury by maintaining the level of glutathione and by inhibiting the production of malondialdehyde, due to its radical scavenging properties.