Novel 3-sulphonamido-quinazolin-4(3H)-one derivatives: microwave-assisted synthesis and evaluation of antiviral activities against respiratory and biodefense viruses

N-Heterocycles as Promising Antiviral Agents: A Comprehensive Overview

Viruses are a real threat to every organism at any stage of life leading to extensive infections and casualties. N-heterocycles can affect the viral life cycle at many points, including viral entrance into host cells, viral genome replication, and the production of novel viral species. Certain N-heterocycles can also stimulate the host's immune system, producing antiviral cytokines and chemokines that can stop the reproduction of viruses. This review focused on recent five- or six-membered synthetic N-heterocyclic molecules showing antiviral activity through SAR analyses. The review will assist in identifying robust scaffolds that might be utilized to create effective antiviral drugs with either no or few side effects.

Methyl 2-((3-(3-methoxyphenyl)-4-oxo-3,4-dihydroquinazolin-2-yl)thio)acetate

A green synthetic procedure was developed for the two-step synthesis of methyl 2-((3-(3-methoxyphenyl)-4-oxo-3,4-dihydroquinazolin-2-yl)thio)acetate from anthranilic acid, using two green chemistry approaches: utilization of the DES and microwave-induced synthesis. The first step includes a synthesis of 2-mercapto-3-(3-methoxyphenyl)quinazolin-4(3H)-one which was performed in choline chloride:urea DES. In the second step S-alkylation of 2-mercapto-3-(3-methoxyphenyl)quinazolin-4(3H)-one was performed in a microwave-induced reaction. The desired compound was successfully obtained in a yield of 59% and was characterized by different spectral methods.

β-d-N 4-Hydroxycytidine Is a Potent Anti-alphavirus Compound That Induces a High Level of Mutations in the Viral Genome

Venezuelan equine encephalitis virus (VEEV) is a representative member of the New World alphaviruses. It is transmitted by mosquito vectors and causes highly debilitating disease in humans, equids, and other vertebrate hosts. Despite a continuous public health threat, very few compounds with anti-VEEV activity in cell culture and in mouse models have been identified to date, and rapid development of virus resistance to some of them has been recorded. In this study, we investigated the possibility of using a modified nucleoside analog, β-d-N ⁴-hydroxycytidine (NHC), as an anti-VEEV agent and defined the mechanism of its anti-VEEV activity. The results demonstrate that NHC is a very potent antiviral agent. It affects both the release of genome RNA-containing VEE virions and their infectivity. Both of these antiviral activities are determined by the NHC-induced accumulation of mutations in virus-specific RNAs. The antiviral effect is most prominent when NHC is applied early in the infectious process, during the amplification of negative- and positive-strand RNAs in infected cells. Most importantly, only a low-level resistance of VEEV to NHC can be developed, and it requires acquisition and cooperative function of more than one mutation in nsP4. These adaptive mutations are closely located in the same segment of nsP4. Our data suggest that NHC is more potent than ribavirin as an anti-VEEV agent and likely can be used to treat other alphavirus infections.IMPORTANCE Venezuelan equine encephalitis virus (VEEV) can cause widespread epidemics among humans and domestic animals. VEEV infections result in severe meningoencephalitis and long-term sequelae. No approved therapeutics exist for treatment of VEEV infections. Our study demonstrates that β-d-N ⁴-hydroxycytidine (NHC) is a very potent anti-VEEV compound, with the 50% effective concentration being below 1 μM. The mechanism of NHC antiviral activity is based on induction of high mutation rates in the viral genome. Accordingly, NHC treatment affects both the rates of particle release and the particle infectivity. Most importantly, in contrast to most of the anti-alphavirus drugs that are under development, resistance of VEEV to NHC develops very inefficiently. Even low levels of resistance require acquisition of multiple mutations in the gene of the VEEV-specific RNA-dependent RNA polymerase nsP4.

How to approach and treat viral infections in ICU patients

Patients with severe viral infections are often hospitalized in intensive care units (ICUs) and recent studies underline the frequency of viral detection in ICU patients. Viral infections in the ICU often involve the respiratory or the central nervous system and can cause significant morbidity and mortality especially in immunocompromised patients. The mainstay of therapy of viral infections is supportive care and antiviral therapy when available. Increased understanding of the molecular mechanisms of viral infection has provided great potential for the discovery of new antiviral agents that target viral proteins or host proteins that regulate immunity and are involved in the viral life cycle. These novel treatments need to be further validated in animal and human randomized controlled studies.

Chemical characteristics, synthetic methods, and biological potential of quinazoline and quinazolinone derivatives

The heterocyclic fused rings quinazoline and quinazolinone have drawn a huge consideration owing to their expanded applications in the field of pharmaceutical chemistry. Quinazoline and quinazolinone are reported for their diversified biological activities and compounds with different substitutions bring together to knowledge of a target with understanding of the molecule types that might interact with the target receptors. Quinazolines and quinazolinones are considered as an important chemical for the synthesis of various physiological significance and pharmacological utilized molecules. Quinazolines and quinazolinone are a large class of biologically active compounds that exhibited broad spectrum of biological activities such as anti-HIV, anticancer, antifungal, antibacterial, antimutagenic, anticoccidial, anticonvulsant, anti-inflammatory, antidepressant, antimalarial, antioxidant, antileukemic, and antileishmanial activities and other activities. Being considered as advantaged scaffold, the alteration is made with different substituent.

Development of (E)-2-((1,4-dimethylpiperazin-2-ylidene)amino)-5-nitro-N-phenylbenzamide, ML336: Novel 2-amidinophenylbenzamides as potent inhibitors of venezuelan equine encephalitis virus

Venezuelan equine encephalitis virus (VEEV) is an emerging pathogenic alphavirus that can cause significant disease in humans. Given the absence of therapeutic options available and the significance of VEEV as a weaponized agent, an optimization effort was initiated around a quinazolinone screening hit 1 with promising cellular antiviral activity (EC₅₀ = 0.8 μM), limited cytotoxic liability (CC₅₀ > 50 μM), and modest in vitro efficacy in reducing viral progeny (63-fold at 5 μM). Scaffold optimization revealed a novel rearrangement affording amidines, specifically compound 45, which was found to potently inhibit several VEEV strains in the low nanomolar range without cytotoxicity (EC₅₀ = 0.02–0.04 μM, CC₅₀ > 50 μM) while limiting in vitro viral replication (EC₉₀ = 0.17 μM). Brain exposure was observed in mice with 45. Significant protection was observed in VEEV-infected mice at 5 mg kg^–1 day^–1 and viral replication appeared to be inhibited through interference of viral nonstructural proteins.

Discovery of a novel compound with anti-venezuelan equine encephalitis virus activity that targets the nonstructural protein 2

Alphaviruses present serious health threats as emerging and re-emerging viruses. Venezuelan equine encephalitis virus (VEEV), a New World alphavirus, can cause encephalitis in humans and horses, but there are no therapeutics for treatment. To date, compounds reported as anti-VEEV or anti-alphavirus inhibitors have shown moderate activity. To discover new classes of anti-VEEV inhibitors with novel viral targets, we used a high-throughput screen based on the measurement of cell protection from live VEEV TC-83-induced cytopathic effect to screen a 340,000 compound library. Of those, we identified five novel anti-VEEV compounds and chose a quinazolinone compound, CID15997213 (IC₅₀ = 0.84 µM), for further characterization. The antiviral effect of CID15997213 was alphavirus-specific, inhibiting VEEV and Western equine encephalitis virus, but not Eastern equine encephalitis virus. In vitro assays confirmed inhibition of viral RNA, protein, and progeny synthesis. No antiviral activity was detected against a select group of RNA viruses. We found mutations conferring the resistance to the compound in the N-terminal domain of nsP2 and confirmed the target residues using a reverse genetic approach. Time of addition studies showed that the compound inhibits the middle stage of replication when viral genome replication is most active. In mice, the compound showed complete protection from lethal VEEV disease at 50 mg/kg/day. Collectively, these results reveal a potent anti-VEEV compound that uniquely targets the viral nsP2 N-terminal domain. While the function of nsP2 has yet to be characterized, our studies suggest that the protein might play a critical role in viral replication, and further, may represent an innovative opportunity to develop therapeutic interventions for alphavirus infection.

Alphaviruses occur worldwide, causing significant diseases such as encephalitis or arthritis in humans and animals. In addition, some alphaviruses, such as VEEV, pose a biothreat due to their high infectivity and lack of available treatments. To discover small molecule inhibitors with lead development potential, we used a cell-based assay to screen 348,140 compounds for inhibition of a VEEV-induced cytopathic effect. The screen revealed a scaffold with high inhibitory VEEV cellular potency and low cytotoxicity liability. While most previously reported anti-alphavirus compounds inhibit host proteins, evidence supported that this scaffold targeted the VEEV nsP2 protein, and that inhibition was associated with viral replication. Interestingly, compound resistance studies with VEEV mapped activity to the N-terminal domain of nsP2, to which no known function has been attributed. Ultimately, this discovery has delivered a small molecule-derived class of potent VEEV inhibitors whose activity is coupled to the nsP2 viral protein, a novel target with a previously unestablished biological role that is now implicated in viral replication.

Synthesis, Antiviral and Cytotoxicity Studies of Novel N-substituted Indophenazine Derivatives

A series of novel N-substituted indophenazine derivatives were synthesised and screened for antiviral activity against a panel of human pathogenic viruses. New compounds were synthesised through modifying the N-hydrogen of indophenazine moiety with different substitution and formaldehyde by Mannich reaction. The structure of the synthetic compounds was characterised by means of infra red and nuclear magnetic resonance spectral data. The compound 10H-indolo-2-Amino pyridine [3,2-b] quinoxalines inhibits Herpes simplex virus-1 and vaccinia virus at a concentration of 12 μg/ml, and the cytotoxicy was found to be 100 μg/ml. 4-Aminobenzene sulfonamide-10H-indolo [3,2-b] quinoxalines inhibit vaccinia virus at a concentration of 12 μg/ml and cytotoxicy was found to be 100 μg/ml. The anti-HIV activities of the new compounds were also screened for in vitro antiviral activity against replication of HIV-1 (IIIB) and HIV-2 (ROD) in MT-4 cells using zidovudine (AZT) as standard. Pthalimide derivative inhibited the replication of HIV-2 (EC₅₀=11.60 μg/ml and CC₅₀=61.63 μg/ml) in MT-4 cells.

Principles of antidote pharmacology: an update on prophylaxis, post-exposure treatment recommendations and research initiatives for biological agents

The use of biological agents has generally been confined to military-led conflicts. However, there has been an increase in non-state-based terrorism, including the use of asymmetric warfare, such as biological agents in the past few decades. Thus, it is becoming increasingly important to consider strategies for preventing and preparing for attacks by insurgents, such as the development of pre- and post-exposure medical countermeasures. There are a wide range of prophylactics and treatments being investigated to combat the effects of biological agents. These include antibiotics (for both conventional and unconventional use), antibodies, anti-virals, immunomodulators, nucleic acids (analogues, antisense, ribozymes and DNAzymes), bacteriophage therapy and micro-encapsulation. While vaccines are commercially available for the prevention of anthrax, cholera, plague, Q fever and smallpox, there are no licensed vaccines available for use in the case of botulinum toxins, viral encephalitis, melioidosis or ricin. Antibiotics are still recommended as the mainstay treatment following exposure to anthrax, plague, Q fever and melioidosis. Anti-toxin therapy and anti-virals may be used in the case of botulinum toxins or smallpox respectively. However, supportive care is the only, or mainstay, post-exposure treatment for cholera, viral encephalitis and ricin - a recommendation that has not changed in decades. Indeed, with the difficulty that antibiotic resistance poses, the development and further evaluation of techniques and atypical pharmaceuticals are fundamental to the development of prophylaxis and post-exposure treatment options. The aim of this review is to present an update on prophylaxis and post-exposure treatment recommendations and research initiatives for biological agents in the open literature from 2007 to 2009.

Activity of Isatine-Sulfadimidine Derivatives against 2009 Pandemic H1N1 Influenza Virus in Cell Culture

Background:

The development of antiviral drugs has provided crucial new means to mitigate or relieve the debilitating effects of many viral pathogens. New classes of inhibitors are essential to combat swine influenza viral infection.

Methods:

A series of isatine-sulfadimidine derivatives were screened for antiviral activity against swine influenza A/California/07/2009 (H1N1) virus in Madin–Darby canine kidney (MDCK) cell culture. Cytotoxicity of the synthesized compounds was also tested in uninfected MDCK cells.

Results:

All the compounds inhibit the influenza A (H1N1) in MDCK cells. The most active compounds, SPIII-5Br and SPIII-5H, inhibited virus-induced cytopathology by 50% at 27 and 30 μM, respectively, with 50% cytotoxicity occurring at a much higher dose (975–1,000 μM). The positive control compound ribavirin inhibits the replication of the virus at 18 μM and cytotoxic concentration was found to be >1,000 μM.

Conclusions:

SPIII-5Br and SPIII-5H exhibited potency in the same range as ribavirin and are suitable candidate molecules for further investigation.