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.