Anti-bovine viral diarrhoea virus and hepatitis C virus activity of the cyclooxygenase inhibitor SC-560

New 1-phenyl-5-(1H-pyrrol-1-yl)-1H-pyrazole-3-carboxamides inhibit hepatitis C virus replication via suppression of cyclooxygenase-2

We report here the synthesis and mechanism of inhibition of pyrazolecarboxamide derivatives as a new class of HCV inhibitors. Compounds 6, 7, 8 and 16 inhibited the subgenomic HCV replicon 1b genotype at EC50 values between 5 and 8 μM and displayed an even higher potency against the infectious Jc1 HCV 2a genotype. Compound 6 exhibited an EC50 of 6.7 μM and selectivity index of 23 against HCV 1b, and reduced the RNA copies of the infectious Jc1 chimeric 2a clone by 82% at 7 μM. Evaluation of the mode of anti-HCV activity of 6 revealed that it suppressed HCV-induced COX-2 mRNA and protein expression, displaying an IC50 of 3.2 μM in COX-2 promoter-linked luciferase reporter assay. Conversely, the anti-HCV activity of 6 was abrogated upon over-expression of COX-2. These findings suggest that 6 as a representative of these pyrazolecarboxamides function as anti-HCV agents via targeting COX-2 at both the transcription and translation levels.

Synthesis and characterization of celecoxib derivatives as possible anti-inflammatory, analgesic, antioxidant, anticancer and anti-HCV agents

A series of novel N-(3-substituted aryl/alkyl-4-oxo-1,3-thiazolidin-2-ylidene)-4-[5-(4-methylphenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl]benzenesulfonamides 2a-e were synthesized by the addition of ethyl a-bromoacetate and anhydrous sodium acetate in dry ethanol to N-(substituted aryl/alkylcarbamothioyl)-4-[5-(4-methylphenyl)-3-(trifluoro-methyl)-1H-pyrazol-1-yl]benzene sulfonamides 1a-e, which were synthesized by the reaction of alkyl/aryl isothiocyanates with celecoxib. The structures of the isolated products were determined by spectral methods and their anti-inflammatory, analgesic, antioxidant, anticancer and anti-HCV NS5B RNA-dependent RNA polymerase (RdRp) activities evaluated. The compounds were also tested for gastric toxicity and selected compound 1a was screened for its anticancer activity against 60 human tumor cell lines. These investigations revealed that compound 1a exhibited anti-inflammatory and analgesic activities and further did not cause tissue damage in liver, kidney, colon and brain compared to untreated controls or celecoxib. Compounds 1c and 1d displayed modest inhibition of HCV NS5B RdRp activity. In conclusion, N-(ethylcarbamothioyl)-4-[5-(4-methylphenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl]benzenesulfonamide (1a) may have the potential to be developed into a therapeutic agent.

Aqueous extract of the edible Gracilaria tenuistipitata inhibits hepatitis C viral replication via cyclooxygenase-2 suppression and reduces virus-induced inflammation

Hepatitis C virus (HCV) is an important human pathogen leading to hepatocellular carcinoma. Using an in vitro cell-based HCV replicon and JFH-1 infection system, we demonstrated that an aqueous extract of the seaweed Gracilaria tenuistipitata (AEGT) concentration-dependently inhibited HCV replication at nontoxic concentrations. AEGT synergistically enhanced interferon-α (IFN-α) anti-HCV activity in a combination treatment. We found that AEGT also significantly suppressed virus-induced cyclooxygenase-2 (COX-2) expression at promoter transactivation and protein levels. Notably, addition of exogenous COX-2 expression in AEGT-treated HCV replicon cells gradually abolished AEGT anti-HCV activity, suggesting that COX-2 down-regulation was responsible for AEGT antiviral effects. Furthermore, we highlighted the inhibitory effect of AEGT in HCV-induced pro-inflammatory gene expression such as the expression of tumour necrosis factor-α, interleukin-1β, inducible nitrite oxide synthase and COX-2 in a concentration-dependent manner to evaluate the potential therapeutic supplement in the management of patients with chronic HCV infections.

Green tea phenolic epicatechins inhibit hepatitis C virus replication via cycloxygenase-2 and attenuate virus-induced inflammation

Chronic hepatitis C virus (HCV) infection is the leading risk factor for hepatocellular carcinoma (HCC) and chronic liver disease worldwide. Green tea, in addition to being consumed as a healthy beverage, contains phenolic catechins that have been used as medicinal substances. In the present study, we illustrated that the epicatechin isomers (+)-epicatechin and (−)-epicatechin concentration-dependently inhibited HCV replication at nontoxic concentrations by using in vitro cell-based HCV replicon and JFH-1 infectious systems. In addition to significantly suppressing virus-induced cyclooxygenase-2 (COX-2) expression, our results revealed that the anti-HCV activity of the epicatechin isomers occurred through the down-regulation of COX-2. Furthermore, both the epicatechin isomers additively inhibited HCV replication in combination with either interferon-α or viral enzyme inhibitors [2′-C-methylcytidine (NM-107) or telaprevir]. They also had prominent anti-inflammatory effects by inhibiting the gene expression of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and inducible nitrite oxide synthase as well as the COX-2 in viral protein-expressing hepatoma Huh-7 cells. Collectively, (+)-epicatechin and (−)-epicatechin may serve as therapeutic supplements for treating HCV-related diseases.

San-Huang-Xie-Xin-Tang extract suppresses hepatitis C virus replication and virus-induced cyclooxygenase-2 expression

Chronic hepatitis C virus (HCV) infection is associated with chronic inflammation of liver, which leads to the development of cirrhosis and hepatocellular carcinoma (HCC). Because of severe side effects and only a 50-70% cure rate in genotype 1 HCV-infected patients upon current standard treatment with pegylated interferon-α plus ribavirin, new therapeutic regimens are still needed. San-Huang-Xie-Xin-Tang (SHXT) is a transitional Chinese herbal formula, composed of Rhei rhizoma, Scutellaria radix and Coptidis rhizome, and possesses anti-inflammatory effect. Here, we describe a (+)-catechin-containing fraction extracted from SHXT, referred as SHXT-frC, exhibited effective inhibition of HCV replication, with selectivity index value (SI; CC50 /EC50) of 84, and displayed synergistic anti-HCV effects when combined with interferon-α, HCV protease inhibitor telaprevir or polymerase inhibitor 2'-C-methylcytidine. The activation of factor-κB (NF-κB) and cyclooxygenase-2 (COX-2) signalling pathway has particular relevance to HCV-associated HCC. SHXT-frC treatment also caused a concentration-dependent decrease in the induction of COX-2 and NF-κB expression caused by either HCV replication or HCV NS5A protein. Collectively, SHXT-frC could be an adjuvant treatment for patients with HCV-induced liver diseases.

Anti-hepatitis C virus activity of Acacia confusa extract via suppressing cyclooxygenase-2

Chronic hepatitis C virus (HCV) infection continues to be an important cause of morbidity and mortality by chronic hepatitis, cirrhosis and hepatocellular carcinoma (HCC) throughout the world. It is of tremendous importance to discover more effective and safer agents to improve the clinical treatment on HCV carriers. Here we report that the n-butanol-methanol extract obtained from Acacia confusa plant, referred as ACSB-M4, exhibited the inhibition of HCV RNA replication in the HCV replicon assay system, with an EC(50) value and CC(50)/EC(50) selective index (SI) of 5 ± 0.3 μg/ml and >100, respectively. Besides, ACSB-M4 showed antiviral synergy in combination with IFN-α and as HCV protease inhibitor (Telaprevir; VX-950) and polymerase inhibitor (2'-C-methylcytidine; NM-107) by a multiple linear logistic model and isobologram analysis. A complementary approach involving the overexpression of COX-2 protein in ACSB-M4-treated HCV replicon cells was used to evaluate the antiviral action at the molecular level. ACSB-M4 significantly suppressed COX-2 expression in HCV replicon cells. Viral replication was gradually restored if COX-2 was added simultaneously with ACSB-M4, suggesting that the anti-HCV activity of ACSB-M4 was associated with down-regulation of COX-2, which was correlated with the suppression of nuclear factor-kappaB (NF-κB) activation. ACSB-M4 may serve as a potential protective agent for use in the management of patients with chronic HCV infection.

Highly potent and selective inhibition of bovine viral diarrhea virus replication by γ-carboline derivatives

Several novel γ-carboline derivatives were identified as selective inhibitors of bovine viral diarrhea virus (BVDV) replication in cell cultures. Among them, 3,4,5-trimethyl-γ-carboline (SK3M4M5M) was the most active against BVDV (Nose strain) in MDBK cells, with a 50% effective concentration of 0.017±0.005μM and a selectivity index of 435. The compound inhibited viral RNA synthesis in a dose-dependent fashion. In a time of drug-addition experiment during a single viral replication cycle, SK3M4M5M lost its antiviral activity when first added at 8h or later after infection, which coincides with the onset of viral RNA synthesis. When selected γ-carboline derivatives, including SK3M4M5M, were examined for their inhibitory effect on the mutant strains resistant to some classes of nonnucleoside BVDV RNA-dependent RNA polymerase inhibitors, all of which target the top of the finger domain of the polymerase, the strains displayed cross-resistance to the γ-carboline derivatives. These results indicate that the γ-carboline derivatives may possibly target a hot spot of the RNA-dependent RNA polymerase. Although SK3M4M5M was highly active against BVDV, the compound proved inactive against hepatitis C virus (HCV) in HCV RNA replicon cells.