Effect of diphenyl dimethyl bicarboxylate on concanavalin A-induced liver injury in mice

A Comparative Study of the Hepatoprotective Effect of Centella asiatica Extract (CA-HE50) on Lipopolysaccharide/d-galactosamine-Induced Acute Liver Injury in C57BL/6 Mice

Acute liver failure (ALF) refers to the sudden loss of liver function and is accompanied by several complications. In a previous study, we revealed the protective effect of Centella asiatica 50% ethanol extract (CA-HE50) on acetaminophen-induced liver injury. In the present study, we investigate the hepatoprotective effect of CA-HE50 in a lipopolysaccharide/galactosamine (LPS-D-Gal)-induced ALF animal model and compare it to existing therapeutic silymarin, Lentinus edodes mycelia (LEM) extracts, ursodeoxycholic acid (UDCA) and dimethyl diphenyl bicarboxylate (DDB). Serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels were decreased in the CA-HE50, silymarin, LEM, UDCA and DDB groups compared to the vehicle control group. In particular, AST and ALT levels of the 200 mg/kg CA-HE50 group were significantly decreased compared to positive control groups. Lactate dehydrogenase (LDH) levels were significantly decreased in the CA-HE50, silymarin, LEM, UDCA and DDB groups compared to the vehicle control group and LDH levels of the 200 mg/kg CA-HE50 group were similar to those of the positive control groups. Superoxide dismutase (SOD) activity was significantly increased in the 100 mg/kg CA-HE50, LEM and UDCA groups compared to the vehicle control group and, in particular, the 100 mg/kg CA-HE50 group increased significantly compared to positive control groups. In addition, the histopathological lesion score was significantly decreased in the CA-HE50 and positive control groups compared with the vehicle control group and the histopathological lesion score of the 200 mg/kg CA-HE50 group was similar to that of the positive control groups. These results show that CA-HE50 has antioxidant and hepatoprotective effects at a level similar to that of silymarin, LEM, UDCA and DDB, which are known to have hepatoprotective effects; further, CA-HE50 has potential as a prophylactic and therapeutic agent in ALF.

Comparative Analysis of the Antioxidative and Hepatoprotective Activities of Dimethyl Diphenyl Bicarboxylate in Four Animal Models of Hepatic Injury

As a well-known hepatoprotective and antioxidant agent, dimethyl diphenyl bicarboxylate (DDB) has frequently been employed to remedy various liver diseases. However, it is still uncertain whether DDB exerts consistent hepatoprotective and antioxidative activities against varying degrees of hepatic damage. Therefore, DDB (100, 25, 5, or 50 mg/kg depending on the model) was administered to animals in four representative models of liver injury (CCl₄ chemical acute model, DMN subchronic model, TAA chronic model, and restraint stress psychological acute model). Horizontal comparative analysis indicated that DDB significantly lowered the excess serum AST and ALT levels in the CCl₄ and DMN models but not in the TAA and restraint stress models. In accordance with this result, DDB markedly reduced oxidative stress indices (hepatic MDA and ROS) but restored five main antioxidant components (GSH content, GSH-peroxidase, GSH-reductase, SOD, and catalase activity) in the CCl₄ and DMN models. DDB failed to normalize oxidative stressors in the restraint stress-induced injury model and restore these five antioxidant components in the TAA model. Overall, our results produced a comprehensive overview of the effects of DDB on oxidative stressors and the main antioxidative components using four animal models. These findings will provide valuable clues to guide therapeutic clinical applications.

Polyguluronate sulfate (PGS) attenuates immunological liver injury in vitro and in vivo

Hepatocyte damage, especially immunological liver injury, is a key process in the pathogenesis of hepatitis virus-induced liver diseases. The aim of this study was to investigate the protective effects of polyguluronate sulfate (PGS) against immunological liver damage. The results showed that PGS significantly reduced the H₂O₂-induced oxidative stress and increased the cell viability in HepG2 hepatocytes. PGS also suppressed the production of malondialdehyde (MDA), lactate dehydrogenase (LDH), TNF-α, and IL-6, while up-regulating the activity of SOD in HepG2 cells. Further, PGS (150 and 300mg/kg/day) significantly attenuated the elevation of serum glutamate pyruvate transaminase (ALT), aspartate aminotransferase (AST), total bilirubin (TBiL), in addition to liver MDA and NO levels in Con A-induced immunological liver injury within mice (P<0.05). Significant improvements of organ indexes (liver, spleen, and thymus) were observed in PGS-treated mice. PGS also significantly reduced the disorganization of hepatocytes and decreased the inflammatory cell infiltration caused by Con A treatment, suggesting that PGS was able to attenuate Con A-induced liver injury. In conclusion, PGS possesses significant hepatoprotective effects on immunological liver injury in vitro and in vivo, and this may be related to its antioxidant activities.

Protection from diclofenac-induced liver injury by Yulangsan polysaccharide in a mouse model

ETHNOPHARMACOLOGICAL RELEVANCE

Millettia pulchra Kurz var-laxior (Dunn) Z. Wei, a wild-growing plant of the family Fabaceae is known to possess multifarious medicinal properties. Yulangsan polysaccharide (YLSPS) is a chief ingredient of its root, which has been used in Chinese traditional medicine with a long history for remedy of acute or chronic hepatitis and jaundice.

AIM OF THE STUDY

To investigate the ability of the YLSPS to protect against diclofenac-induced hepatotoxicity in mice.

MATERIALS AND METHODS

Mice were orally treated with YLSPS daily 1h after the injection of diclofenac for 2 weeks. Dimethyl diphenyl bicarboxylate was used as a reference drug.

RESULTS

YLSPS effectively reduced the elevated levels of serum alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase and enhanced the reduction of superoxide dismutase, catalase, and glutathione peroxidase activities in the liver. Moreover, the content of malondialdehyde was reduced by treatment with YLSPS, and histological findings also confirmed the anti-hepatotoxic activity. In addition, YLSPS significantly inhibited proinflammatory mediators, such as tumor necrosis factor-alpha and interleukin 1 beta. YLSPS also enhanced mitochondrial antioxidants and inhibited cell death by preventing the down-regulation of Bcl-2 and the up-regulation and release of Bax along with caspase 9 and 3 activity; thus, these findings confirm the involvement of mitochondria in diclofenac-induced apoptosis.

CONCLUSION

The results indicate that protective effects of YLSPS against diclofenac-induced acute hepatic injury may rely on its effect on reducing oxidative stress, suppressing inflammatory responses, and improving drug-metabolizing enzyme activity in the liver.

Effects of Linderae radix extracts on a rat model of alcoholic liver injury

Traditional treatments have a poor effect on alcoholic liver diseases. Linderae radix (LR), the dried root of Lindera aggregata (Sims) Kosterm., has been frequently used in traditional Chinese medicine for treating various diseases, and has been shown to exhibit a protective effect on liver injury. In the present study, LR extracts were made using various solvents, and then administrated to rats to establish a model of ethanol-induced liver injury. The study aimed to investigate the therapeutic effects and potential mechanism of LR extracts on acute alcoholic liver injury. The serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), triglycercide (TG), cholesterol (TC), methane dicarboxylic aldehyde (MDA) and superoxide dismutase (SOD) were determined using an automatic biochemistry analyzer. In addition, pathological examination was performed by hematoxylin-eosin staining. The levels of MDA and SOD, and the expression levels of nuclear factor (NF)-κB, tumor necrosis factor (TNF)-α and interleukin (IL)-1β in liver tissue were investigated immunohistochemically. The expression of cytochrome P450 2E1 (CYP2E1) mRNA was quantified by reverse transcription-quantitative polymerase chain reaction. The results indicated that LR extracts improved the histopathological status and decreased the serum levels of ALT, AST, TG, TC and MDA. Furthermore, the levels of MDA and inflammatory mediators (NF-κB, TNF-α and IL-1β) were decreased in liver tissues, and the overexpression of CYP2E1 mRNA induced by ethanol treatment. LR extracts exhibited a protective effect on alcoholic liver injury and the mechanism may be associated with the anti-inflammatory and anti-oxidative action.

Hepatoprotective effects of Yulangsan polysaccharide against nimesulide-induced liver injury in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Yulangsan polysaccharide (YLSPS) is often used in popular folk medicine in the Guangxi Zhuang Autonomous Region of China as a chief ingredient of Millettia pulchra, which is used as a hepatic protection, anti-aging and memory improving agent.

AIM OF THE STUDY

This study was designed to investigate the protective effects of polysaccharides from Millettia pulchra Kurz var.laxior (Dunn) (Yulangsan polysaecharide, YLSPS) against nimesulide-induced hepatotoxicities in mice.

MATERIALS AND METHODS

Liver injury was induced in mice by administering nimesulide. Simultaneously, YLSPS was administered 2h prior to the administration of nimesulide. Dimethyl diphenyl bicarboxylate (DDB) was used as a reference drug.

RESULTS

Compared with the nimesulide group, YLSPS significantly decreased the activities of alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP) and the content of bilirubin in the serum. The anti-oxidative effect of YLSPS was observed from the increase of the superoxide dismutase (SOD) and catalase and glutathione peroxidase (GSH-Px) activities in the liver, both of which were decreased by nimesulide. Moreover, the content of malondialdehyde (MDA) was reduced, and histological findings also confirmed the anti-hepatotoxic activity. In addition, YLSPS significantly inhibited proinflammatory mediators, such as tumor necrosis factor-alpha (TNF-α) and interleukin 6 (IL-6). Additionally, YLSPS also enhanced the mitochondrial antioxidant and inhibited dead cells by preventing the down-regulation of Bcl-2, up-regulation and release of Bax along with caspase 9 and 3 activity, confirming the involvement of mitochondria in the nimesulide-induced apoptosis.

CONCLUSION

The protective effect of YLSPS against nimesulide-induced hepatic injury may rely on its ability to reduce oxidative stress and prevent nimesulide-induced hepatotoxicity by inhibiting critical control points of apoptosis.

Therapeutic effect of dimethyl dimethoxy biphenyl dicarboxylate on collagen-induced arthritis in rats

OBJECTIVE

To study the effect of oral administration of dimethyl dimethoxy biphenyl dicarboxylate (DDB) on adjusting angiogeneic/inflammatory mediators and ameliorating the pathology of bones in rats with collagen-induced arthritis (CIA).

METHODS

Wistar rat model of CIA was set up using bovine collagen type II. Fifty rats were divided into five groups randomly: normal, CIA model, DDB treatment, methotrexate (MTX) treatment, and combined DDB+MTX treatment. Ankle joints of rats were imaged with digital X-ray machine to show the destruction of joints. Fore and hind paw and knee joints were removed above the ankle joint then processed for haematoxylin and eosin staining. Plasma levels of vascular endothelial growth factor (VEGF), platelet derived growth factor, interleukin-8 (IL-8), IL-4, tumor necrosis factor α (TNF-α), and cyclooxygenase-2 (COX-2) were quantified by enzyme-linked immunosorbent assay. Nitric oxide levels were detected by Griess reagent.

RESULTS

Compared with the CIA model group, a remarkable reduction in various angiogenic (VEGF and IL-8) and inflammatory mediators (TNF-α, IL-4 and COX-2) after treatment with DDB either alone or combined with MTX P<0.05 or P<0.01). Histopathological and X-ray findings were confirmatory to the observed DDB anti-arthritic effect. The DDB-treated group showed amelioration in signs of arthritis which appeared essentially similar to normal.

CONCLUSION

Our data shed light on the therapeutic efficacy of DDB in experimental rheumatoid arthritis (RA) compared with a choice drug (MTX) and it may be offered as a second-line drug in the treatment of RA.

Hepatoprotective effects of Yulangsan polysaccharide against isoniazid and rifampicin-induced liver injury in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Yulangsan polysaccharide (YLSPS) is often used in popular folk medicine in the Guangxi Zhuang Autonomous Region of China as a chief ingredient of Millettia pulchra, which is used as an hepatic protection, anti-aging and memory improving agent. In this study, the hepatoprotective effects of YLSPS against isoniazid (INH) or rifampicin and isoniazid (RFP+INH)-induced liver injury were investigated in mice.

MATERIALS AND METHODS

The liver injury was induced by intragastric administration of INH or RFP+INH daily for 10 days. During the experiment, the model group received INH or RFP+INH only, and the normal control group received an equal volume of saline. Treatment groups received not only INH or RFP+INH but also the corresponding drugs, DDB (200mg/kg/day) or YLSPS (100, 200, and 400mg/kg/day) 2h after the administration of INH or RFP+INH.

RESULTS

Analysis experiments showed that YLSPS significantly alleviated liver injury as indicated by the decreased levels of ALT and AST and the increased levels of SOD, GSH and GSH-Px. Moreover, YLSPS could effectively reduce the pathological tissue damage. The research on the mechanisms underlying the hepatoprotective effect showed that YLSPS was able to reduce lipid peroxidation and activate the anti-oxidative defense system.

CONCLUSION

Our results show that YLSPS is effective in attenuating hepatic injury in the INH or RFP+INH-induced mouse model, and could be developed as a new drug for treatment of liver injury.

Anti-hepatitis B virus activities of α-DDB-FNC, a novel nucleoside-biphenyldicarboxylate compound in cells and ducks, and its anti-immunological liver injury effect in mice

Infection with hepatitis B virus (HBV) continues to be a major global cause of acute and chronic liver disease with high mortality. Herein, we examined both the anti-HBV and hepatoprotective activity of α-DDB-FNC. In human HBV-transfected liver cell line HepG2.2.15, α-DDB-FNC effectively suppressed the secretion of HBV antigens in a time and dose-dependent manner with 25.11% inhibition on HBeAg and 43.68% on HBsAg at 2.5 μM on day 9. Consistent with the HBV antigen reduction, α-DDB-FNC (2.5 μM) also reduced HBV DNA level by 77.74% extracellularly and 78.94% intracellularly on day 9. In the duck hepatitis B virus (DHBV) infected ducks, after α-DDB-FNC was given once daily for 10 days, the serum and liver DHBV DNA levels were reduced markedly with 96.81% and 97.21% at 10 mgkg(-1) on day 10, respectively. In Con A-induced immunological liver-injury mice, α-DDB-FNC significantly inhibited the elevation of serum ALT, AST, TBiL and liver MDA, NO levels. Furthermore, significant improvement of the liver was observed after α-DDB-FNC treatment both in ducks and mice, as evaluated by the histopathological analysis. In conclusion, our results demonstrated that α-DDB-FNC possesses both antiviral activity against HBV and hepatoprotective effect to Con A-induced liver-injury mice.

Thioacetamide intoxication triggers transcriptional up-regulation but enzyme inactivation of UDP-glucuronosyltransferases

Thioacetamide (TAA) is a potent hepatotoxicant and has been widely used to develop experimental liver fibrosis/cirrhosis models. Although the liver toxicity of TAA has been extensively studied, little is known about its potential influence on UDP-glucuronosyltransferases (UGTs) associated with the development of liver fibrosis. The study presented here aimed to uncover the regulation patterns of UGTs in TAA-induced liver fibrosis of rats. Potential counteracting effects of hepatoprotective agents were also determined. TAA treatment for 8 weeks induced a significant transcriptional up-regulation of the major UGT isoforms, including UGT1A1, UGT1A6, and UGT2B1, accompanied with the dramatic elevations of most typical serum biomarkers of liver function and fibrosis scores. Upon TAA intoxication, the mRNA and protein levels of the major UGT isoforms were increased to 1.5- to 2.5-fold and 2.5- to 3.3-fold of that of the normal control, respectively. The hepatoprotective agents Schisandra spp. lignans extract and dimethyl diphenyl bicarboxylate could largely abolish TAA-induced up-regulation of all three UGT isoforms. However, enzyme activities of UGTs remained unchanged after TAA treatment. The dissociation of protein expression and enzyme activity could possibly be attributed to the inactivating effects of TAA, upon a NADPH-dependent bioactivation, on UGTs. This study suggests that the transcriptional up-regulation of UGTs may be an alternative mechanism of their preserved activities in liver fibrosis/cirrhosis.

Myrica rubra Extracts Protect the Liver from CCl(4)-Induced Damage

The relationship between the expression of mitochondrial voltage-dependent anion channels (VDACs) and the protective effects of Myrica rubra Sieb. Et Zucc fruit extract (MCE) against carbon tetrachloride (CCl(4))-induced liver damage was investigated. Pretreatment with 50 mg kg(-1), 150 mg kg(-1) or 450 mg kg(-1) MCE significantly blocked the CCl(4)-induced increase in both serum aspartate aminotransferase (sAST) and serum alanine aminotransferase (sALT) levels in mice (P < .05 or .01 versus CCl(4) group). Ultrastructural observations of decreased nuclear condensation, ameliorated mitochondrial fragmentation of the cristae and less lipid deposition by an electron microscope confirmed the hepatoprotection. The mitochondrial membrane potential dropped from -191.94 ± 8.84 mV to -132.06 ± 12.26 mV (P < .01) after the mice had been treated with CCl(4). MCE attenuated CCl(4)-induced mitochondrial membrane potential dissipation in a dose-dependent manner. At a dose of 150 or 450 mg kg(-1) of MCE, the mitochondrial membrane potentials were restored (P < .05). Pretreatment with MCE also prevented the elevation of intra-mitochondrial free calcium as observed in the liver of the CCl(4)-insulted mice (P < .01 versus CCl(4) group). In addition, MCE treatment (50-450 mg kg(-1)) significantly increased both transcription and translation of VDAC inhibited by CCl(4). The above data suggest that MCE mitigates the damage to liver mitochondria induced by CCl(4), possibly through the regulation of mitochondrial VDAC, one of the most important proteins in the mitochondrial outer membrane.

Targeting TNF for Treatment of Cancer and Autoimmunity

Tumor necrosis factor-alpha (TNF-alpha) was first isolated two decades ago as a macrophageproduced protein that can effectively kill tumor cells. TNF-alpha is also an essential component of the immune system and is required for hematopoiesis, for protection from bacterial infection and for immune cell-mediated cytotoxicity. Extensive research, however, has revealed that TNF-alpha is one of the major players in tumor initiation, proliferation, invasion, angiogenesis and metastasis. The proinflammatory activities link TNF-alpha with a wide variety of autoimmune diseases, including psoriasis, inflammatory bowel disease, rheumatoid arthritis, systemic sclerosis, systemic lupus erythematosus, multiple sclerosis, diabetes and ankylosing spondylitis. Systemic inhibitors of TNF such as etanercept (Enbrel) (a soluble TNF receptor) and infliximab (Remicade) and adalimumab (Humira) (anti-TNF antibodies) have been approved for the treatment inflammatory bowel disease, psoriasis and rheumatoid arthritis. These drugs, however, exhibit severe side effects and are expensive. Hence orally active blockers of TNF-alpha that are safe, efficacious and inexpensive are urgently needed. Numerous products from fruits, vegetable and traditional medicinal plants have been described which can suppress TNF expression and TNF signaling but their clinical potential is yet uncertain.

Diphenyl Dimethyl Bicarboxylate in the Treatment of Viral Hepatitis, Adjuvant or Curative?

Diphenyl dimethyl bicarboxylate (DDB) has been used in some countries as hepatoprotectant adjuvant in the treatment of liver diseases, such as chronic viral hepatitis, chemical or drug induced hepatic damage. Its early confirmed efficacy is to normalize elevated blood alanine aminotransferase (ALT) from different etiologies, however, it can rarely affect the rest hepatic enzymes. In addition, the lowering or normalization of ALT in most cases occurs during DDB treatment, withdrawal of DDB administration results in ALT re-elevated. Hence, for a long time, it has been only used as adjuvant of liver disease therapy. It is still controversial that whether DDB can be beneficial to liver histology. The normalization of ALT in hepatitis does not indicate therapeutic efficacy if without substantial liver histology improvement. In recent years, more studies showed that DDB might have new therapeutical potentials in liver diseases, it may have the effect of anti-viral, anti-malignancy. These new findings were mostly based on the in vitro or animal experiments, more basic studies and clinical trials are needed to ascertain these efficacies, prior to that stage, it is recommended to be cautious to apply DDB clinically for anti-virus and anti-malignancy purposes.

An herbal formula, CGX, exerts hepatotherapeutic effects on dimethylnitrosamine-induced chronic liver injury model in rats

AIM: To evaluate the therapeutic effect of Chunggan extract (CGX), a modified traditional Chinese hepatotherapeutic herbal, on the dimethylnitrosamine (DMN)-induced chronic liver injury model in rats.

METHODS: Liver injuries were induced in Wistar rats by injection of DMN (ip, 10 mg/mL per kg) for 3 consecutive days per week for 4 wk. The rats were administered with CGX (po, 100 or 200 mg/kg per day) or distilled water as a control daily for 4 wk starting from the 15^th d of the DMN treatment. Biochemical parameters (serum albumin, bilirubin, ALP, AST and ALT), lipid peroxides, hydroxyproline, as well as histological changes in liver tissues were analyzed. In addition, gene expression of TNF-α, TGF-β, TIMP-1, TIMP-2, PDGF-β, and MMP-2, all of which are known to be associated with liver fibrosis, were analyzed using real-time PCR.

RESULTS: CGX administration restored the spleen weight to normal after having been increased by DMN treatment. Biochemical analysis of the serum demonstrated that CGX significantly decreased the serum level of ALP (P < 0.05), ALT (P < 0.01), and AST (P < 0.01) that had been elevated by DMN treatment. CGX administration moderately lowered lipid peroxide production and markedly lowered hydroxyproline generation caused by DMN treatment in accordance with histopathological examination. DMN treatment induced a highly up-regulated expression of TNF-α, TGF-β, TIMP-1, TIMP-2, PDGF-β, and MMP-2. Of these, the gene expression encoding PDGF-β and MMP-2 was still further enhanced 2 wk after secession of the 4-wk DMN treatment, and was remarkably ameliorated by CGX administration.

CONCLUSION: CGX exhibits hepatotherapeutic proper-ties against chronic hepatocellular destruction and consequential liver fibrosis.

A novel model of acute liver injury in mice induced by T cell-mediated immune response to lactosylated bovine serum albumin

The present study aimed to establish a murine liver injury model with T cell-mediated immune response to mimic the cellular immunological pathogenesis of hepatitis. Bovine serum albumin was conjugated with lactose by redox to prepare lactosylated bovine serum albumin (LacBSA). The liver injury was induced in C57BL/6 mice by a T cell-mediated immune response to LacBSA. After a systemic injection of LacBSA, which elicited immune response in mice sensitized twice with LacBSA, liver injury was observed with obvious increase of aminotransferase levels in serum and hepatocelluar damage in liver histology. However, the splenectomy before the elicitation significantly alleviated the liver injury. Direct contact between spleen T cells/nonparenchymal cells and hepatocytes was proved to be essential to induce the release of alanine aminotransferase in the culture supernatant. In addition, both levels of Fas mRNA in liver tissues and Fas Ligand in spleen cells were up-regulated at 6 h after the elicitation. The Fas mRNA expression was maintained in a relatively high level at 18 h while Fas Ligand began to decrease after 12 h. These results demonstrated that the T cell immune response to LacBSA could be successfully localized in the liver to induce an immunological liver injury in mice. The pathogenesis of the liver injury might involve the interaction between the liver-infiltrating lymphocytes and hepatocytes through Fas/FasL pathway.

Interferon signal transduction of biphenyl dimethyl dicarboxylate/amantadine and anti-HBV activity in HepG2 2.2.15

Biphenyl dimethyl dicarboxylate (DDB) is a hepatoprotectant, which is used as an adjuvant agent in a treatment for chronic hepatitis. Amantadine is an antiviral agent, which is utilized primarily in the treatment of influenza, but also, occasionally in the treatment of hepatitis C. In a previous study, we reported that DDB, coupled with amantadine, would exert an anti-HBV effect, via the induction of interferon-inducible gene expression in the HepG2 2.2.15 cell line. The primary objective of the present study was to determine whether or not DDB and/or amantadine exhibit anti-HBV properties, and what mechanisms of action might be involved in such properties. In our study, we were able to determine that DDB stimulates Jak/Stat signaling, and induces the expression of interferon alpha (IFN-alpha) stimulated genes, most notably 6-16 and ISG12. In addition, the antiviral effectors induced by IFN-alpha, PKR, OAS, and MxA, were regulated in the presence of DDB at its optimal concentration (250 microg/mL), to a degree commensurate with the degree of induction associated with the IFN-alpha treated group. Finally, we determined that the replication of pregenomic RNA and HBeAg was inhibited by DDB treatment, and this inhibition was maximized when coupled with the administration of amantadine (25 microg/mL). In conclusion, the results of this study demonstrated clearly that DDB, as well as the combination of DDB/amantadine, directly inhibited IFN-alpha signaling-mediated replication of HBV in infected hepatocytes, and thus may represent a novel treatment for chronic hepatitis B, which would be characterized principally by its improved safety over other treatment strategies.