Identification of quinolone derivatives as effective anti-Dengue virus agents

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.

Identification of Polyphenol Derivatives as Novel SARS-CoV-2 and DENV Non-Nucleoside RdRp Inhibitors

The Coronavirus Disease 2019 (COVID-19) and dengue fever (DF) pandemics both remain to be significant public health concerns in the foreseeable future. Anti-SARS-CoV-2 drugs and vaccines are both indispensable to eliminate the epidemic situation. Here, two piperazine-based polyphenol derivatives DF-47 and DF-51 were identified as potential inhibitors directly blocking the active site of SARS-CoV-2 and DENV RdRp. Data through RdRp inhibition screening of an in-house library and in vitro antiviral study selected DF-47 and DF-51 as effective inhibitors of SARS-CoV-2/DENV polymerase. Moreover, in silico simulation revealed stable binding modes between the DF-47/DF-51 and SARS-CoV-2/DENV RdRp, respectively, including chelating with Mg²⁺ near polymerase active site. This work discovered the inhibitory effect of two polyphenols on distinct viral RdRp, which are expected to be developed into broad-spectrum, non-nucleoside RdRp inhibitors with new scaffold.

Emerging quinoline- and quinolone-based antibiotics in the light of epidemics

Pandemics are large-scale outbreaks of infectious disease that can greatly increase morbidity and mortality all the globe. Since past 1990 till twentieth century, these infectious diseases have been major threat all over the globe associated with poor hygiene and sanitation. In light of these epidemics, researches have gained enormous rise in the developing the potential therapeutic treatment. Thus, revolutionized antibiotics have led to the near eradication of such ailments. Around 50 million prescription of antibiotics written in US per year according to center for disease control and prevention (CDC) report. There is a wide range of antibiotics available which differ in their usage and their mechanism of action. Among these quinoline and quinolone class of antibiotics get attention as they show tremendous potential in fighting the epidemics. Quinoline and quinolone comprise of two rings along with substitutions at different positions which is synthetically obtained by structural modifications of quinine. Quinoline and quinolone antibiotics exhibit extensive activities approved by FDA in the treatment of the several ailments such as gastrointestinal infections, urinary tract infections, prostate inflammation, malaria, gonorrhea, skin infection, colorectal cancer, respiratory tract infections. These are active against both gram-negative and gram-positive bacteria. This basic core of quinoline and quinolone is vital due to its capability of targeting the pathogen causing disease and beneficial in treating the infectious disease. They inhibit the synthesis of nucleic acid of bacteria which results in the rupture of bacterial chromosome due to the interruption of enzymes such as DNA gyrase and topoisomerase IV. There are various quinoline and quinolone compounds that are synthetically derived by applying different synthesis approaches which show a wide range of pharmacological activities in several diseases. The most commonly used are fluoro, chloro, and hydroxychloro derivatives of quinoline and quinolone. These compounds are helpful in the treatment of numerous epidemics as a chief and combination therapy. These quinoline and quinolone pharmacophore fascinate the interest of researchers as they inhibit the entry of virus in host cell and cease its replication by blocking the host receptor glycosylation and proteolytic processing. They act as immune modulator by inhibiting autophagy and reduction of both lysosomal activity and production of cytokine. Therefore, quinoline and quinolone derivatives attain significance in area of research and treatment of various life-threatening epidemics such as SARS, Zika virus, Ebola virus, dengue, and COVID-19 (currently). In this chapter, the research and advancements of quinoline- and quinolone-based antibiotics in epidemic management are briefly discussed.

Insights on Dengue and Zika NS5 RNA-dependent RNA polymerase (RdRp) inhibitors

Over recent years, many outbreaks caused by (re)emerging RNA viruses have been reported worldwide, including life-threatening Flaviviruses, such as Dengue (DENV) and Zika (ZIKV). Currently, there is only one licensed vaccine against Dengue, Dengvaxia®. However, its administration is not recommended for children under nine years. Still, there are no specific inhibitors available to treat these infectious diseases. Among the flaviviral proteins, NS5 RNA-dependent RNA polymerase (RdRp) is a metalloenzyme essential for viral replication, suggesting that it is a promising macromolecular target since it has no human homolog. Nowadays, several NS5 RdRp inhibitors have been reported, while none inhibitors are currently in clinical development. In this context, this review constitutes a comprehensive work focused on RdRp inhibitors from natural, synthetic, and even repurposing sources. Furthermore, their main aspects associated with the structure-activity relationship (SAR), proposed mechanisms of action, computational studies, and other topics will be discussed in detail.

Antiviral Agents - Benzazine Derivatives

The review outlines the results of studies of the antiviral activity of quinoline, quinoxaline, and quinazoline derivatives published over the past 5 years. The supplied data indicate the enormous potential of benzazines for the design of effective antiviral drugs.