Search

Objectives: As a host restriction factor, apolipoprotein B messenger RNA-editing enzyme catalytic polypeptide-like 3G (APOBEC3G or A3G) has been shown to suppress the replication of several viruses including hepatitis B virus (HBV). Recently, we reported that IMB-Z, a N-phenylbenzamide derivative, could inhibit Enterovirus 71 replication, and A3G mediated its antiviral activity. Whether IMB-Z exhibits an inhibitory effect on HBV replication has not been investigated., Material and Methods: HBV DNA, pregenomic RNA (pgRNA), core protein, and capsid levels were determined by a qPCR assay or Southern blot, Northern blot, Western blot, and particle gel assay, respectively. Mutation analysis of HBV DNAs was conducted by a differential DNA denaturation PCR assay. A3G encapsidation into HBV nucleocapsids was examined by Western blot analysis after ultracentrifugation and a co-immunoprecipitation (IP) assay between HBV core and A3G proteins., Results: In the present study, we found that IMB-Z could considerably inhibit HBV replication in HepAD38 cells. Interestingly, IMB-Z did not alter the HBV pgRNA production but could reduce the level of core protein, viral nucleocapsids, and core-associated DNA, as well as cccDNA intracellular amplification. Similar to the action of IMB-Z's inhibition of Enterovirus 71 replication, we found that IMB-Z's inhibition of HBV replication was associated with increased level of A3G. Mechanistically, we demonstrated that the inhibitory effect of IMB-Z is independent of the cytidine deaminase activity of A3G and is exerted by increasing its incorporation into viral nucleocapsids., Conclusions: Our results indicate that IMB-Z inhibits HBV through pharmacological induction A3G expression and incorporation into HBV nucleocapsids., Competing Interests: Competing interests None declared., (Copyright © 2022 Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College. Published by Elsevier Ltd.. All rights reserved.)

Viral entry inhibitors are absent in hepatitis C virus (HCV) treatment regimens although a dozen direct-acting antiviral (DAA) drugs are available now. Based on a previously identified HCV entry inhibitor L0909 , chemical space exploration and structure-activity relationship (SAR) studies led to the discovery of a new derived scaffold 2-((4-bisarylmethyl-piperazin-1-yl)methyl)benzonitrile. Several new scaffold derivatives exhibited higher in vitro anti-HCV activity at low nanomolar concentrations compared to L0909 . A biological study indicated that the high potency of active derivatives 3d , 3h , and 3i was primarily driven by the inhibitory effect on the virus entry stage. Moreover, an SPR experiment confirmed that this class of derivatives might target the HCV E1 protein. Pharmacokinetic studies indicated that compounds 3d and 3i are orally available and long-lasting in rat plasma after oral administration to rats by a single dose of 15 mg/kg. In conclusion, this work provided a novel 2-((4-bisarylmethyl-piperazin-1-yl)methyl)benzonitrile chemotype deserving further investigation into its antiviral therapeutic potential.

Synthetic nucleoside or nucleotide analogues played a key role to the development of antiviral agents in past decades. However, low membrane permeability and insufficient cellular phosphorylation impaired the biological activity of polar nucleoside drugs because they have to penetrate the cell membrane and be phosphorylated to active metabolite stepwise by intracellular enzymes. To overcome these limitations, diverse lipophilic prodrug modifications based on nucleoside mono-, di-, and triphosphate were designed and put into practice to efficiently deliver nucleoside into the target site, and bypass the rate-limited phosphorylation step. As the most successful prodrug strategy, ProTide technology has led to the discovery of three FDA-approved antiviral agents, including sofosbuvir, tenofovir alafenadmide, and remdesivir, which has been authorized for emergency use in patients of COVID-19 in the US. In recent years, nucleoside di- and triphosphate prodrugs have also made the significant progress. This review will focus on the summary of design approach and metabolic activation path of different nucleotide prodrug strategies. The potential application of nucleotide prodrugs for the treatment of COVID-19 was also described due to the pandemic of SARS-CoV-2., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Direct-acting antiviral agents (DAAs) represent a class of drugs targeting viral proteins and have been demonstrated to be very successful in combating viral infections in clinic. However, DAAs suffer from several inherent limitations, including narrow-spectrum antiviral profiles and liability to drug resistance, and hence there are still unmet needs in the treatment of viral infections. In comparison, host targeting antivirals (HTAs) target host factors for antiviral treatment. Since host proteins are probably broadly required for various viral infections, HTAs are not only perceived, but also demonstrated to exhibit broad-spectrum antiviral activities. In addition, host proteins are not under the genetic control of viral genome, and hence HTAs possess much higher genetic barrier to drug resistance as compared with DAAs. In recent years, much progress has been made to the development of HTAs with the approval of chemokine receptor type 5 antagonist maraviroc for human immunodeficiency virus treatment and more in the pipeline for other viral infections. In this review, we summarize various host proteins as antiviral targets from a medicinal chemistry prospective. Challenges and issues associated with HTAs are also discussed., (© 2020 Wiley Periodicals, Inc.)

Although the direct-acting antivirals revolutionized the hepatitis C virus (HCV) infection treatment in the last decade, more efforts are needed to reach the elimination of HCV in the absence of a vaccine. 4-(Piperazin-1-yl)-2-(( p -tolylamino)methyl)-benzonitrile (1) is a modest HCV inhibitor identified from an in-house screening using a HCV-infected Huh7.5 cell culture. Starting from it, the chemical optimization afforded a new 2-((4-arylpiperazin-1-yl)methyl)benzonitrile scaffold with significantly increased antiviral activity against HCV. A highly effective HCV inhibitor, 35 ( L0909 , EC 50 = 0.022 μM, SI > 600), was identified by the structure-activity relationship study. The biological study revealed that L0909 could block HCV replication by acting on the HCV entry stage. The high sensitivity to clinical resistant HCV mutants and synergistic effect with clinical drugs were observed for this compound. The further pharmaceutical studies demonstrated that L0909 is long-lasting, is orally available, and has low toxicity in vivo. These results show L0909 as a promising HCV entry inhibitor for single or combinational therapeutic potential.

Enterovirus 71 (EV71), a single-stranded positive-sense RNA virus, is the causative agent of hand, foot, and mouth disease (HFMD), for which no effective antiviral therapy is currently available. Apolipoprotein B messenger RNA-editing enzyme catalytic polypeptide-like 3G (APOBEC3G or A3G) is a cytidine deaminase that inhibits the replication of several viruses, such as human immunodeficiency virus-1, hepatitis B virus and hepatitis C virus. In our efforts toward understanding the antiviral spectrum and mechanism of A3G, we found that ectopic expression of A3G inhibited EV71 replication, whereas knockdown of endogenous A3G expression promoted EV71 replication. Moreover, inhibition of EV71 replication by IMB-Z, a N-phenylbenzamide derivative, is associated with increased levels of intracellular A3G, but reducing the level of A3G by RNA interference diminished the antiviral activity of IMB-Z. Mechanistically, we obtained evidence suggesting that the cytidine deaminase activity is not required for A3G inhibition of EV71 replication. Instead, we demonstrated that A3G can interact with viral 3D RNA-dependent RNA polymerase (RdRp) and viral RNA and be packaged into progeny virions to reduce its infectivity. Taken together, our results indicate that A3G is a cellular restriction factor of EV71 and mediator of the antiviral activity of IMB-Z. Pharmacological induction and/or stabilization of A3G is a potential therapeutic approach to treat diseases caused by EV71 infection, such as HFMD., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Enterovirus 71 (EV-A71) is the main causative pathogen of childhood hand, foot and mouth disease. Effective medicine is currently unavailable for the treatment of this viral disease. Using the fragment-hopping strategy, a series of 2-aryl-isoindolin-1-one compounds were designed, synthesized and investigated for their in vitro antiviral activity towards multiple EV-A71 clinical isolates (H, BrCr, Shenzhen98, Jiangsu52) in Vero cell culture in this study. The structure⁻activity relationship (SAR) studies identified 2-phenyl-isoindolin-1-ones as a new potent chemotype with potent antiviral activity against EV-A71. Ten out of the 24 tested compounds showed significant antiviral activity (EC 50 < 10 µM) towards four EV-A71 strains. Compounds A3 and A4 exhibited broad and potent antiviral activity with the 50% effective concentration (EC 50 ) values in the range of 1.23⁻1.76 μM. Moreover, the selectivity indices of A3 and A4 were significantly higher than those of the reference compound, pirodavir. The western blotting experiment indicated that the viral VP1 was significantly decreased at both the protein and RNA level in a dose-dependent manner following treatment with compound A3 . Moreover, compound A3 inhibited the viral replication by acting on the virus entry stage. In summary, this study led to the discovery of 2-aryl-isoindolin-1-ones as a promising scaffold with potent anti-EV-A71 activities, which deserves further in-depth studies.

Background: Human papillomaviruses (HPVs) are the primary causative agents for cervical cancer, and HPV oncoproteins E6 and E7 are known to be the main reason for the onset and maintenance of the malignancies. Therefore, inhibition of viral E6 and E7 oncoproteins expression represents a viable strategy to cervical cancer therapies. This study is to evaluate the antiviral effect of a novel N-Phenylbenzamide derivative, 3-(2-Chloropropyl amide)-4-methoxy-N-phenylbenzamide (L17), against HPV16 in vitro and identify its associated mechanism of action in cervical cancer cells., Methods: The cytotoxic effect of L17 was assessed by MTT assay. The mRNA and protein levels of E6 and E7 oncogenes were analyzed by quantitative real-time reverse transcription PCR (qRT-PCR) and Western blot, respectively. p53 and Rb protein levels were also detected by Western blot. The effect of L17 on cell cycle was analyzed by flow cytometry., Results: The cytotoxic effect of L17 was greater in cervical carcinoma cells than in normal cells. L17 significantly reduced the expression of HPV16 E6 and E7 mRNA and protein, at least partly by enhancing degradation of HPV16 E6 and E7 mRNA. Moreover, reduced expression of E6 and E7 induced by L17 resulted in the up-regulation of p53 and Rb expression, which subsequently induced CaSki cells arrest at G 0 /G 1 phase., Conclusions: L17 has antiviral activity through suppressing E6 and E7 oncogene expression and could inhibit CaSki cell proliferating by inducing cells arrest at G 0 /G 1 phase at nontoxic concentration, implying that L17 might be exploited as a candidate agent for HPV-associated cervical cancer prevention and treatment.

Backgroud: Influenza virus is still a huge threat to the world-wide public health. Host inosine-5'- monophosphate dehydrogenase (IMPDH) involved in the synthesis of guanine nucleotides, is known to be a potential target to inhibit the replication of viruses. Herein, we evaluated antiviral activity of a benzo-heterocyclic amine derivative N30, which was designed to inhibit IMPDH., Results: The results demonstrated that N30 inhibited the replication of H1N1, H3N2, influenza B viruses, including oseltamivir and amantadine resistant strains in vitro. Mechanistically, neuraminidase inhibition assay and hemagglutination inhibition assay suggested that N30 did not directly target the two envelope glycoproteins required for viral adsorption or release. Instead, the compound could depress the activity of IMPDH type II. Based on these findings, we further confirmed that N30 provided a strong inhibition on the replication of respiratory syncytial virus, coronavirus, enterovirus 71 and a diverse strains of coxsackie B virus., Conclusions: We identified the small molecule N30, as an inhibitor of IMPDH, might be a potential candidate to inhibit the replication of various viruses.

Background: The activation of ERK, p38 and JNK signal cascade in host cells has been demonstrated to up-regulate of enterovirus 71 (EV71)-induced cyclooxygenase-2 (COX-2)/ prostaglandins E2 (PGE₂) expression which is essential for viral replication. So, we want to know whether a compound can inhibit EV71 infection by suppressing COX-2/PGE₂ expression., Methods: The antiviral effect of formononetin was determined by cytopathic effect (CPE) assay and the time course assays. The influence of formononetin for EV71 replication was determined by immunofluorescence assay, western blotting assay and qRT-PCR assay. The mechanism of the antiviral activity of formononetin was determined by western blotting assay and ELISA assay., Results: Formononetin could reduce EV71 RNA and protein synthesis in a dose-dependent manner. The time course assays showed that formononetin displayed significant antiviral activity both before (24 or 12 h) and after (0-6 h) EV71 inoculation in SK-N-SH cells. Formononetin was also able to prevent EV71-induced cytopathic effect (CPE) and suppress the activation of ERK, p38 and JNK signal pathways. Furthermore, formononetin could suppress the EV71-induced COX-2/PGE₂ expression. Also, formononetin exhibited similar antiviral activities against other members of Picornaviridae including coxsackievirus B2 (CVB2), coxsackievirus B3 (CVB3) and coxsackievirus B6 (CVB6)., Conclusions: Formononetin could inhibit EV71-induced COX-2 expression and PGE₂ production via MAPKs pathway including ERK, p38 and JNK. Formononetin exhibited antiviral activities against some members of Picornaviridae. These findings suggest that formononetin could be a potential lead or supplement for the development of new anti-EV71 agents in the future.

A series of novel N -phenylbenzamide and N -phenylacetophenone compounds were synthesized and evaluated for their antiviral activity against HCV and EV71 (strain SZ-98). The biological results showed that three compounds ( 23 , 25 and 41 ) exhibited considerable anti-HCV activity (IC 50 =0.57–7.12 μmol/L) and several compounds ( 23 , 28 , 29 , 30 , 31 and 42 ) displayed potent activity against EV71 with the IC 50 values lower than 5.00 μmol/L. The potency of compound 23 (IC 50 =0.57 μmol/L) was superior to that of reported compounds IMB-1f (IC 50 =1.90 μmol/L) and IMB-1g (IC 50 =1.00 μmol/L) as anti-HCV agents, and compound 29 possessed the highest anti-EV71 activity, comparable to the comparator drug pirodavir. The efficacy in vivo and antiviral mechanism of these compounds warrant further investigations. [ABSTRACT FROM AUTHOR]

A series of novel indole-2-carboxylate derivatives were synthesized and assayed to determine their in vitro broad-spectrum antiviral activities. The biological results showed that some of the synthesized compounds exhibited potent broad-spectrum antiviral activity. Notably, compound 8f showed the highest SI value (17.1) to Cox B3 virus. Compound 14f showed both potent inhibitory activity against influenza A (IC50=7.53μmol/L) and the highest SI value (12.1). SAR results showed that the alkyloxy at the 4-position of indole ring was not crucial to the antiviral activities. Incorporation of an acetyl substituent at the amino group disfavored antiviral activity towards RNA viruses. Compound 8f showed the highest SI value (17.1) to Cox B3 virus. Compound 14f showed both potent inhibitory activity against influenza A (IC50=7.53μmol/L) and the highest SI value (12.1). [ABSTRACT FROM AUTHOR]

Abstract: A novel class of thioflavone and flavonoid derivatives has been prepared and their antiviral activities against enterovirus 71 (EV71) and the coxsackievirus B3 (CVB3) and B6 (CVB6) were evaluated. Compounds 7d and 9b showed potent antiviral activities against EV71 with IC50 values of 8.27 and 5.48μM, respectively. Compound 7f, which has been synthesized for the first time in this work, showed the highest level of inhibitory activity against both CVB3 and CVB6 with an IC50 value of 0.62 and 0.87μM. Compounds 4b, 7a, 9c and 9e also showed strong inhibitory activities against both the CVB3 and CVB6 at low concentrations (IC50=1.42−7.15μM), whereas compounds 4d, 7c, 7e and 7g showed strong activity against CVB6 (IC50=2.91–3.77μM) together with low levels of activity against CVB3. Compound 7d exhibited stronger inhibitory activity against CVB3 (IC50=6.44μM) than CVB6 (IC50>8.29μM). The thioflavone derivatives 7a, 7c, 7d, 7e, 7f and 7g, represent a new class of lead compounds for the development of novel antiviral agents. [Copyright &y& Elsevier]