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Modified carbocyclic nucleosides (4a–g) constituting 7-deazapurine, 4′-methyl, exocyclic double bond and 2′,3′-hydroxy were synthesized. NOE and X-ray studies of 4c confirmed the α-configuration of 4′-methyl. The anti-HBV assay demonstrated 4e (IC(50) = 3.4 μM) without notable cytotoxicity (CC(50) = 87.5 μM) as a promising lead for future exploration.

Galectin-3 (Gal-3) is involved in many biological processes and pathogenesis of diseases in part through nuclear factor (NF)-κB activation. We demonstrated that Gal-3 expression was significantly induced by tumor necrosis factor (TNF)-α or phorbol 12-myristate 13-acetate in OM-10.1 and ACH-2 cells, which are considered as a model of HIV-1 latently infected cells. The expression of Gal-3 was also associated with their viral production. However, the induction of Gal-3 by TNF-α was not observed in their uninfected parental cells. Knockdown of Gal-3 resulted in the suppression of NF-κB activation and HIV-1 replication in the latently infected cells. The expression level of Gal-3 was highly correlated with that of HIV-1 Tat in the latently infected cells stimulated with TNF-α. Furthermore, colocalization and possible interaction of Gal-3 and Tat were observed in the stimulated cells. These results suggent that Gal-3 expression is closely correlated with HIV-1 expression in latently infected cells through NF-κB activation and the interaction with Tat.

Chronic hepatitis B virus (HBV) infection is currently treated with nucleoside/nucleotides analogs. They are potent inhibitors of HBV DNA polymerase, which also functions as reverse transcriptase. Although nucleoside/nucleotide analogs efficiently suppress HBV replication in liver cells, they cannot eradicate HBV DNA from liver cells and cure the disease. Therefore, it is still mandatory to identify and develop effective inhibitors that target a step other than reverse transcription in the viral replication cycle. HBV capsid assembly is a critical step for viral replication and an attractive target for inhibition of HBV replication. We conducted in silico screening of compounds expected to bind to the HBV capsid dimer-dimer interaction site. The selected compounds were further examined for their anti-HBV activity in vitro. Among the test compounds, novel pyrimidotriazine derivatives were found to be selective inhibitors of HBV replication in HepG2.2.15.7 cells. Among the compounds, 2-[(2,3-dichlorophenyl)amino]-4-(4-tert-butylphenyl)-8-methyl-4H,9H-pyrimido[1,2-a][1,3,5]triazin-6-one was the most active against HBV replication. Studies on its mechanism of action revealed that the compound interfered with HBV capsid assembly determined by a cell-free capsid assembly system. Thus, the pyrimidotriazine derivatives are considered to be potential leads for novel HBV capsid assembly inhibitors.

The potential antiviral activity of aristeromycin type of derivatives (I) is limited by associated toxicity due to its possible 5'-O-phosphorylation and S-adenosyl-l-homocysteine hydrolase (SAHase) inhibitory activity. Aristeromycin structure has major pharmacophoric motif as 5'-OH and adenosine base, which may have significant role in enzyme binding followed by activity and or toxicity. Thus, the structural optimization to alter this major motif by replacing with its bioisostere and changing the 5'-O conformation through stereochemistry reversal was of interest. Thus, the inverted stereochemistry at 4'-position coupled with bioisostere of adenosine base in the target compounds (6-7) to access antiviral potential. The stereoselective formation of a key stereoisomer (2a) was achieved exclusively from neplanocin sugar (1a) by reduction in a single step. The novel target molecules (6-7) were synthesized in 4 steps with 55-62% yield. Compound 6 was analyzed by single crystal X-ray diffraction, which confirms the stereoselective formation of α-analogs with highly puckered cyclopentane ring and 2'-endo conformation. The compound 6 shown significant anti-hepatitis B virus activity of 6.5μM with CC50>100μM and yielded a promising lead with novel structural feature.

The present study includes the exploration of new possible nucleoside mimetics based on 4-methoxy-7H-pyrrolo[2,3-d]pyrimidine carbocyclic nucleosides (4a-g), which were synthesized by 10-15 synthetic steps and characterized adequately. We report the anti-HCV activities and cytotoxicities of 4a-g. Compound 4a was analyzed by single crystal X-ray diffraction which showed some puckering in the cyclopentene ring with a 2'-endo conformation and anti-base disposition (χ = -125.7°).

Background The novel phenanthridinone derivative HA-719 has recently been identified as a highly potent and selective inhibitor of hepatitis C virus replication. To elucidate its mechanism of inhibition, we have isolated and analyzed a clone of hepatitis C virus replicon cells resistant to HA-719. Methods To isolate HA-719-resistant replicon cells, Huh-7 cells containing subgenomic hepatitis C virus replicons (genotype 1b) with a luciferase reporter (LucNeo#2) were cultured in the presence of G418 and escalating concentrations of HA-719. After several passages, total RNA was extracted from the growing cells, and Huh-7 cells were transfected with the extracted RNA. Limiting dilution of the transfected cells was performed to obtain an HA-719-resistant clone. Results The 50% effective concentration (EC50) of HA-719 for hepatitis C virus replication was 0.058 ± 0.012 µM in LucNeo#2 cells. The replicon cells capable of growing in the presence of G418 and 3 µM HA-719 were obtained after 18 passages (72 days). The HA-719-resistant clone LucNeo719R showed 98.3-fold resistant to the compound (EC50 = 5.66 ± 0.92 µM), but the clone had no cross-resistance to telaprevir (NS3 inhibitor), daclatasvir (NS5A inhibitor), and VX-222 (NS5B inhibitor). The sequence analysis for the wild-type and LucNeo719R identified 3, 2 and 7 mutations in NS3/4 A, NS4B, and NS5A, respectively, but no mutations in NS5B. Conclusion None of the amino acid mutations in the resistant clone corresponds to those reported to confer drug-resistance to current anti-hepatitis C virus agents, suggesting that the target of HA-719 for hepatitis C virus inhibition differs from those of the existing agents.

Cepharanthine (CEP) is a biscoclaurine amphipathic alkaloid isolated from the plant Stephania cepharantha Hayata. Although the effects of CEP on several types of cells have been investigated, those on dendritic cells (DCs) are poorly understood.To investigate the effect of CEP on the induction of apoptosis in murine DCs.The induction of Annexin V/propidium iodide-positive cells and permeability of mitochondrial membrane potential were evaluated in DCs treated with CEP. Cell-associated caspase activity and DNA fragmentation were analyzed by Dual Sensor: MitoCasp™ and agarose gel electrophoresis, respectively.The number of dead cells was increased by CEP treatment at concentrations more than 10 μg/ml. Flow cytometric analysis revealed that the cell death was found to be apoptosis, CEP treatment reduced mitochondrial membrane potential and upregulated the level of cleaved caspases, including caspase-9 and caspase-3/7, in a dose-dependent fashion. Furthermore, DNA fragmentation was observed in CEP-treated DCs.CEP is capable of inducing apoptosis and may be a potential agent against DC-mediated and allergic diseases.

Graphical abstract, On the basis of our previous study on antiviral agents against the severe acute respiratory syndrome (SARS) coronavirus, a series of nucleoside analogues whose 5′-hydroxyl groups are masked by various protective groups such as carboxylate, sulfonate, and ether were synthesized and evaluated to develop novel anti-hepatitis C virus (HCV) agents. Among these, several 5′-O-masked analogues of 6-chloropurine-2′-deoxyriboside (e.g., 5′-O-benzoyl, 5′-O-p-methoxybenzoyl, and 5′-O-benzyl analogues) were found to exhibit effective anti-HCV activity. In particular, the 5′-O-benzoyl analogue exhibited the highest potency with an EC50 of 6.1 μM in a cell-based HCV replicon assay. Since the 5′-O-unmasked analogue (i.e., 6-chloropurine-2′-deoxyriboside) was not sufficiently potent (EC50 = 47.2 μM), masking of the 5′-hydroxyl group seems to be an effective method for the development of anti-HCV agents. Presently, we hypothesize two roles for the 5′-O-masked analogues: One is the role as an anti-HCV agent by itself, and the other is as a prodrug of its 5′-O-demasked (deprotected) derivative.

Background A new series of 1-aromatic methyl-substituted 3-(3,5-dimethylbenzyl)uracil and N-3,5-dimethylbenzyl-substituted urea derivatives were synthesized and evaluated as non-nucleoside HIV-1 reverse transcriptase inhibitors. Methods A series of new 6-azido and 6-amino derivatives of 1-substituted-3-(3,5-dimethylbenzyl)uracils were synthesized using our previously reported method, and three acyclic derivatives were synthesized from urea. The anti-HIV-1 activities of these compounds were determined based on the inhibition of virus-induced cytopathogenicity in MT-4 cells. The cytotoxicities of the compounds were evaluated using the viability of mock-infected cells. Results Some of these compounds showed good-to-moderate activities against HIV-1 with half maximal effective concentration (EC50) values in the submicromolar or subnanomolar range. Compared with emivirine, compound 6-amino-3-(3,5-dimethylbenzyl)-1-(4-aminobenzyl)uracil showed significant anti-HIV-1 activity with an EC50 value of 10 nM and a high selectivity index of 1923. Preliminary structure–activity relationship studies and molecular modeling analyses were carried out to explore the major interactions between HIV-1 reverse transcriptase and the potent inhibitor 6-amino-3-(3,5-dimethylbenzyl)-1-(4-aminobenzyl)uracil; these results may be important for further development of this class of compounds as anti-HIV-1 agents. Conclusion The excellent activity of 6-amino-3-(3,5-dimethylbenzyl)-1-(4-aminobenzyl)uracil (EC50: 0.010 ± 0.006 µM, SI: >1923) may serve as the basis for conducting further investigations on the behavior of this class of compounds against drug-resistant mutants.

FIT-039 has recently been identified as a novel cyclin-dependent kinase 9 inhibitor with potent antiviral activity against a broad spectrum of DNA viruses, such as herpes simplex virus type 1 (HSV-1) and human cytomegaloviruses. In this study, FIT-039 was examined for its inhibitory effect on human immunodeficiency virus type 1 (HIV-1) replication in chronically infected cells. Its 50% effective concentration was 1.4-2.1μM, irrespective of the cells used for antiviral assays, while its 50% cytotoxic concentration was >20μM, indicating that FIT-039 is a selective inhibitor of HIV-1 replication. FIT-039 also inhibited HIV-1 RNA expression in a dose-dependent fashion. Since previous studies demonstrated that FIT-039 exhibited antiviral efficacy without noticeable adverse effects in HSV-1-infected mice, the compound should be further investigated for its clinical potential against HIV-1 infection.

Background The reverse transcriptase (RT) of human immunodeficiency virus type 1 (HIV-1) is an attractive target for the development of drugs used in the treatment of HIV-1 infection and acquired immune deficiency syndrome (AIDS). We have continued the search for novel anti-HIV-1 agents using the structure–activity relationships of the successful 1,3-disubstituted and 1,3,6-trisubstituted uracil-type HIV-1 RT inhibitors. Methods A series of new triazine analogs were synthesized using an established method. The anti-HIV-1 activities of these compounds were determined based on the inhibition of virus-induced cytopathogenicity in MT-4 cells. The cytotoxicity of the compounds was evaluated by assessing the viability of mock-infected cells. Results Some of the compounds showed good-to-moderate activities against HIV-1, with half-maximal effective concentrations (EC50) in the submicromolar range. In particular, a dihydro-1-(4-aminobenzyl)triazine analog showed satisfactory anti-HIV-1 activity with an EC50 of 0.110 µM and a selectivity index (SI) of 909. Furthermore, molecular modeling analyses were performed to explore the major interactions between HIV-1 RT and potent inhibitors. These results may be important for further development of this class of compounds as anti-HIV-1 agents. Conclusion The satisfactory anti-HIV-1 activity of triazine analogs may serve as the basis for further investigations of the behavior of this class of compounds against drug-resistant mutants.

The crystalline quality of GaAs and Ge heteroepitaxial films with microscopic charge imbalance and balance at heterointerfaces, grown on vicinal Si(1 1 0) substrates by molecular-beam epitaxy, has been characterized using X-ray diffraction and atomic force microscopy. Effects of microscopic charge balance and imbalance on the initial growth process have been investigated by comparing crystalline properties, such as surface roughness, residual strain, spread of the distribution of atomic interplanar spacing and spread due to mosaic structure, of GaAs films with those of Ge films. On a (1 1 0) substrate miscut 6° towards the [0 0 1] direction, the off-angles of GaAs and Ge films decreased by 0.8° towards the [0 0 1] direction, compared with off-angles of the respective substrates. This reflects an initial step-flow-like growth mode. The crystalline quality of GaAs films on Si(1 1 0) tilted towards [0 0 1] was improved by relaxing the microscopic charge imbalance through a well-controlled initial growth process, such as step-flow-like growth. However, increasing the off-angle does not always improve the crystalline quality of Ge films on vicinal Si(1 1 0), in spite of a microscopically balanced charge at the interface. Moreover, in Ge films on vicinal Si(1 1 0), the strong compressive strain is generated near step edges of the substrate, which is not sufficiently relieved by the thermal tensile strain generated during the cooling process after the growth. Good control of the initial growth process, by means of some relaxation process of microscopic charge imbalance and strain, or charge balance at the heterointerface, was found to be important for improving the crystalline quality of heteroepitaxial films on Si substrates.

Twelve oxopyranyl-based compounds like (I) are synthesized in three steps from kojic acid in relatively good yields and investigated for their cytotoxicity and anti-HCV activity in subgenomic HCV replicon cells.

Aggressive forms of adult T-cell leukemia (ATL) respond poorly to conventional anticancer chemotherapy, and new lead compounds are required for the development of drugs to treat this fatal disease. Recently, we developed ATL cell-selective proliferation inhibitors based on a tetrahydrotetramethylnaphthalene (TMN) skeleton 1, and here we report the design and synthesis of silicon analogs of TMN derivatives. Among them, compound 13 showed the most potent growth-inhibitory activity towards the ATL cell line S1T, though its selectivity for S1T over the non-ATL cell line MOLT-4 was only moderate. This result, as well as computational studies, suggests that sila-substitution (C/Si exchange) is useful for structure optimization of these inhibitors.

Dendritic cells (DCs) are specialized antigen presenting cells that connect innate and adaptive immunity. DCs are considered as a major target for controlling excessive immune responses. In this study, the effect of cepharanthine (CEP), a biscoclaurine alkaloid isolated from Stephania cepharantha Hayata, on murine DCs was examined in vitro. CEP inhibited antigen uptake by DCs at a concentration between 1 and 5 μg/ml. Although CEP did not inhibit the expression of costimulatory molecules and major histocompatibility complex (MHC) class I in DCs, the compound inhibited lipopolysaccharide (LPS)-induced DC maturation determined by the expression of costimulatory molecules and MHC class I. In addition, CEP could reduce the production of interleukin-6 and tumor necrosis factor-α in LPS-stimulated DCs. DCs treated with CEP were found to be a poor stimulator of allogeneic T cell proliferation and interferon-γ production from the cells. These results suggest that CEP may have great potential as an immunoregulatory agent against various autoimmune diseases and allergy.

A series of nucleoside analogues whose 5'-hydroxyl groups are masked by various protective groups were synthesized and evaluated to develop novel anti- hepatitis C virus (HCV) agents. Among the several analogues that showed anti-HCV potency, a 5'-O-benzoyl-2'-deoxyribonucleoside analogue exhibited high anti-HCV activity with an EC(50) of 6.1 microM.

Background We have previously found that the novel tetramethylnaphthalene derivative TMNAA selectively inhibits the proliferation of HTLV-1-infected T-cell lines but not HTLV-1-uninfected T-cell lines. Although its target molecule is still unknown, TMNAA did not affect NFB activity. Therefore, we further examined the antiproliferative activity of TMNAA against various T-cell lines in combination with cepharanthine (CEP), which is known to inhibit NFB.