Synthesis and structure-activity relationship study of arylsulfonamides as novel potent H5N1 inhibitors

Identification of a novel binding inhibitor that blocks the interaction between hSCARB2 and VP1 of enterovirus 71

Enterovirus 71 (EV-A71) infection causes severe hand-foot-and-mouth disease that leads to cardiopulmonary complications and death in young children under 5 years of age. Although there are available vaccines for EV-A71 C4, however, there are no efficient drugs for severe cases. Thus, there is an urgent need to find new direct-antiviral agents (DAAs) to control EV-A71 infection. In this study, we report our discovery of the EV-A71 capsid inhibitor PTC-209HBr, a small-molecule Bmi-1 inhibitor and an anticancer agent, and its derivatives that inhibit multiple enteroviruses with an EC50 at a submicromolar efficacy. The mechanism of action of PTC-209HBr was confirmed by time-of-addition, resistance selection and reverse genetics experiments, microscale thermophoresis (MST), viral binding and entry assays, coimmunoprecipitation (Co-IP) and immunofluorescence experiments (IF). Mechanistic studies indicated that PTC-209HBr inhibited EV-A71 infection by impeding the binding between VP1 and the receptor hSCARB2 during the early stage of EV-A71 infection through hindering viral entry into host cells. Collectively, these findings indicated that PCT-209HBr is a novel inhibitor of enteroviruses with a confirmed mechanism of action that can be further developed into EV-A71 DAAs.

Discovery of Aryl Benzoyl Hydrazide Derivatives as Novel Potent Broad-Spectrum Inhibitors of Influenza A Virus RNA-Dependent RNA Polymerase (RdRp)

Influenza A viruses possess a high antigenic shift, and the approved anti-influenza drugs are extremely limited, which makes the development of novel anti-influenza drugs for the clinical treatment and prevention of influenza outbreaks imperative. Herein, we report a series of novel aryl benzoyl hydrazide analogs as potent anti-influenza agents. Particularly, analogs 10b, 10c, 10g, 11p, and 11q exhibited potent inhibitory activity against the avian H5N1 flu strain with EC₅₀ values ranging from 0.009 to 0.034 μM. Moreover, compound 11q exhibited nanomolar antiviral effects against both the H1N1 virus and Flu B virus and possessed good oral bioavailability and inhibitory activity against influenza A virus in a mouse model. Preliminary mechanistic studies suggested that these compounds exert anti-influenza virus effects mainly by interacting with the PB1 subunit of RNA-dependent RNA polymerase (RdRp). These results revealed that 11q has the potential to become a potent clinical candidate to combat seasonal influenza and influenza pandemics.

In silico QSAR and molecular docking simulation of some novel aryl sulfonamide derivatives as inhibitors of H5N1 influenza A virus subtype

Background

This research provides a comprehensive analysis of QSAR modeling performed on 25 aryl sulfonamide derivatives to predict their effective concentration (EC50) against H5N1 influenza A virus by using some numerical information derived from structural and chemical features (descriptors) of the compounds to generate a statistically significant model. Subsequently, the molecular docking simulations were done so as to determine the binding modes of some potent ligands in the dataset with the M2 proton channel protein of the H5N1 influenza A virus as the target.

Results

In building the QSAR model, the genetic algorithm task was employed in the variable selection of the descriptors which are used to form the multi-linear regression equation. The model with descriptors, RDF100m, nO, and RDF45p, showed satisfactory internal and external validation parameters (R2train = 0.72963, R2adjusted = 0.67169, Q2cv = 0.598, $$ {R}_{\mathrm{pred}}^2= $$Rpred2= 0.67295, R2test = 0.6860) which passed the model criteria of acceptability. Docking simulation results of the more potent compounds (ligands 2, 3, and 8) revealed the formation of hydrophobic and hydrogen bonds with the binding pockets of M2 protein of influenza A virus.

Conclusion

The results in this study can help to advance the research in designing (in silico design) and synthesis of more potent aryl sulfonamides derivatives against H5N1 influenza virus.

QSAR study of N-substituted oseltamivir derivatives as potent avian influenza virus H5N1 inhibitors using quantum chemical descriptors and statistical methods

In silico modelling studies were executed on thirty two N-substituted oseltamivir derivatives as inhibitors of influenza virus H5N1.

Alternative Experimental Models for Studying Influenza Proteins, Host-Virus Interactions and Anti-Influenza Drugs

Ninety years after the discovery of the virus causing the influenza disease, this malady remains one of the biggest public health threats to mankind. Currently available drugs and vaccines only partially reduce deaths and hospitalizations. Some of the reasons for this disturbing situation stem from the sophistication of the viral machinery, but another reason is the lack of a complete understanding of the molecular and physiological basis of viral infections and host-pathogen interactions. Even the functions of the influenza proteins, their mechanisms of action and interaction with host proteins have not been fully revealed. These questions have traditionally been studied in mammalian animal models, mainly ferrets and mice (as well as pigs and non-human primates) and in cell lines. Although obviously relevant as models to humans, these experimental systems are very complex and are not conveniently accessible to various genetic, molecular and biochemical approaches. The fact that influenza remains an unsolved problem, in combination with the limitations of the conventional experimental models, motivated increasing attempts to use the power of other models, such as low eukaryotes, including invertebrate, and primary cell cultures. In this review, we summarized the efforts to study influenza in yeast, Drosophila, zebrafish and primary human tissue cultures and the major contributions these studies have made toward a better understanding of the disease. We feel that these models are still under-utilized and we highlight the unique potential each model has for better comprehending virus-host interactions and viral protein function.

Incorporation of privileged structures into 3-O-β-chacotriosyl ursolic acid can enhance inhibiting the entry of the H5N1 virus

The glycoprotein hemagglutinin of influenza virus plays a key role in the initial stage of virus infection, making it a potential target for novel influenza viruses entry inhibitors. Two "privileged fragments", 2-(piperidin-1-yl)ethan-1-amine and 2-(1,3-oxazinan-3-yl)ethan-1-amine were integrated into 3-O-β-chacotriosyl ursolic acid producing new derivatives 5 and 6 with improved activity against IAVs in vitro. Mechanistically, compound 6 was effective in inhibiting infection of H1-, H3-, and H5-typed influenza A viruses by interfering with the viral hemagglutinin. Furthermore, the docking studies were in agreement with the antiviral data. These results showed that the title compound 6 as a new lead compound was meriting further optimization and development.

Structure-aided optimization of 3-O-β-chacotriosyl ursolic acid as novel H5N1 entry inhibitors with high selective index

Currently, entry inhibitors contribute immensely in developing a new generation of anti-influenza virus drugs. Our earlier studies have identified that 3-O-β-chacotriosyl ursolic acid (1) could inhibit H5N1 pseudovirus by targeting hemagglutinin (HA). In the present study, a series of C-28 modified pentacyclic triterpene saponins via conjugation with a series of amide derivatives were synthesized and their antiviral activities against influenza A/Duck/Guangdong/99 virus (H5N1) in MDCK cells were evaluated. The SARs analysis of these compounds revealed that introduction of certain amide structures at the 17-COOH of ursolic acid could significantly enhance both their antiviral activity and selective index. This study indicated that the attachment of the methoxy group or Cl atom to the phenyl ring at the ortho- or para-position was crucial to improve inhibitory activity. Mechanism studies demonstrated that these title triterpenoids could bind tightly to the viral envelope HA to block the attachment of viruses to host cells, which was consistent with docking studies.

Discovery and SAR Research for Antivirus Activity of Novel Butenolide on Influenza A Virus H1N1 In Vitro and In Vivo

Influenza viruses (IV) cause substantial morbidity and mortality through routine seasonal spread and epidemics. A novel series of butenolides were discovered to be able to inhibit influenza H1N1 activity in vitro, and the SAR for anti-influenza activity was investigated. By optimization of the hit compound, compound 37 was obtained with an EC₅₀ of 6.7 μM against influenza A virus H1N1 as an inhibitor of NA and with low cytotoxicity on MDCK cells. Also, it can inhibit the expression of the influenza A virus gene in the lung of SPF KM mice to show antivirus activity in vivo. These results suggested that compound 37 could inhibit the influenza A virus H1N1 via targeting NA.