4-Aminoquinoline compounds from the Spanish flu to COVID-19

Spotlight on 4-substituted quinolines as potential anti-infective agents: Journey beyond chloroquine

Continued emerging resistance of pathogens against the clinically approved candidates and their associated limitations continuously demand newer agents having better potency with a more suited safety profile. Quinoline nuclei containing scaffolds of natural and synthetic origin have been documented for diverse types of pharmacological activities, and a number of drugs are clinically approved. In the present review, we unprecedentedly covered the biological potential of 4-substituted quinoline and elaborated a rationale for its special privilege to afford the significant number of approved clinical drugs, particularly against infectious pathogens. Compounds with 4-substituted quinoline are well documented for antimalarial activity, but in the last two decades, they have been extensively explored for activity against cancer, tuberculosis, and several other pathogens including viruses, bacteria, fungi, and other infectious pathogens. In the present study, the anti-infective spectrum of this scaffold is discussed against viruses, mycobacteria, malarial parasites, and fungal and bacterial strains, along with recent updates in this area, with special emphasis on the structure-activity relationship.

The 'myth of Hydroxychloroquine (HCQ) as post-exposure prophylaxis (PEP) for the prevention of COVID-19' is far from reality

The efficacy of Hydroxychloroquine (HCQ) as post-exposure prophylaxis (PEP) for the prevention of COVID-19 was contentious. In this randomized control double-blind clinical trial, asymptomatic individuals with direct contact with laboratory-confirmed COVID-19 cases were randomized into PEP/HCQ (N = 574) and control/placebo (N = 594) group. The PEP/HCQ group received tablet HCQ 400 mg q 12 hourly on day one followed by 400 mg once weekly for 3 weeks, and the control/Placebo group received matching Placebo. The incidence of COVID-19 was similar (p = 0.761) in PEP [N = 24 out of 574, (4.2%)] and control [N = 27 out of 594, (4.5%)] groups. Total absolute risk reduction for the incidence of new-onset COVID-19 was -0.3% points with an overall relative risk of 0.91 (95% confidence interval, 0.52 to 1.60) and the number needed to treat (NNT) was 333 to prevent the incident of one case of COVID-19. The study found that, PEP with HCQ was not advantageous for the prevention of COVID-19 in asymptomatic individuals with high risk for SARS-CoV-2 infection. Though HCQ is a safer drug, the practice of irrational and indiscriminate use of HCQ for COVID-19 should be restrained with better pharmacovigilance.

Synthesis, characterization and antimicrobial property in vitro of supramolecular coordination polymers bearing brominated Schiff base ligand

In this study, two supramolecular coordination polymers of Co(II) and Zn(II) based on brominated Schiff base (E)-4-bromo-2-((quinolin-6-ylimino)methyl)phenol (HL) were synthesized and characterized by using elemental analysis, IR spectroscopy and NMR spectroscopy. Furthermore, the crystal structures of HL, CoL₂ (І) and ZnL₂ (II) were determined by single crystal X-ray analysis. It was revealed that the bromine-related interaction played important role in the self-assembly of HL supramolecular network. The crystal structural investigations revealed that І and II were isomorphous with the same geometry around the metal atom and similar structural feature. The stable four-membered chelate structure resulted from coordination between the metal(II) ion and deprotonated bidentate ligand. And supramolecular coordination polymers of І and II formed diverse architecture through multiple hydrogen bondings, π···π interactions and halogen-related interactions. Antimicrobial activities of polymers were tested toward four bacteria and five phytopathogenic fungi. І and II showed higher activities toward the tested microorganisms than HL. Furthermore, the photoluminescence results indicated that HL and II accompanied with better fluorescence properties in the ultraviolet region.

Potential of Quinine Sulfate for COVID-19 Treatment and Its Safety Profile: Review

The coronavirus disease 2019 (COVID-19) pandemic is currently the largest and most serious health crisis in the world. There is no definitive treatment for COVID-19. Vaccine administration has begun in various countries, but no vaccine is 100% effective. Some people are not protected after vaccination, and there are some groups of people who cannot be vaccinated therefore, research on COVID-19 treatment still needs to be done. Of the several drugs under study, chloroquine (CQ) and hydroxychloroquine (HCQ) are quite controversial, although they have good activity against SARS-CoV-2, both drugs have serious side effects. Indonesia with its wealth of natural ingredients has one potential compound, quinine sulfate (QS), which has the same structure and activity as CQ and HCQ and a better safety profile. The aim of this article was to review the potential of QS against the SARS-Cov-2 virus and outline its safety profile. We conclude that QS has the potential to be developed as a COVID-19 treatment with a better safety profile than that of CQ and HCQ.