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The ongoing COVID‐19 has not only caused millions of deaths worldwide, but it has also led to economic recession and the collapse of public health systems. The vaccines and antivirals developed in response to the pandemic have improved the situation markedly; however, the pandemic is still not under control with recurring surges. Thus, it is still necessary to develop therapeutic agents. In our previous studies, we designed and synthesized a series of novel 2‐anilinoquinazolin‐4(3H)‐one derivatives, and demonstrated inhibitory activity against severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) and MERS‐CoV in vitro. We then conducted in vivo studies using modified compounds that are suitable for oral administration. These compounds demonstrated no toxicity in rats and inhibited viral entry. Here, we investigated the in vivo efficacy of these drug candidates against SARS‐CoV‐2. Three candidate drugs, 7‐chloro‐2‐((3,5‐dichlorophenyl)amino)quinazolin‐4(3H)‐one (1), N‐(7‐chloro‐4‐oxo‐3,4‐dihydroquinazolin‐2‐yl)‐N‐(3,5‐dichlorophenyl)acetamide (2), and N‐(7‐chloro‐4‐oxo‐3,4‐dihydroquinazolin‐2‐yl)‐N‐(3,5‐difluorophenyl)acetamide (3) were administered orally to hACE2 transgenic mice at a dose of 100 mg/kg. All three drugs improved survival rate and reduced the viral load in the lungs. These results show that the derivatives possess in vivo antiviral efficacy similar to that of molnupiravir, which is currently being used to treat COVID‐19. Overall, our data suggest that 2‐anilinoquinazolin‐4(3H)‐one derivatives are promising as potential oral antiviral drug candidates against SARS‐CoV‐2 infection. [ABSTRACT FROM AUTHOR]

We previously reported the potent antiviral effect of the 2-aminoquinazolin-4-(3H)-one 1, which shows significant activity (IC50 = 0.23 μM) against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) with no cytotoxicity. However, it is necessary to improve the in vivo pharmacokinetics of compound 1 because its area under the curve (AUC) and maximum plasma concentration are low. Here, we designed and synthesized N-substituted quinazolinone derivatives that had good pharmacokinetics and that retained their inhibitory activity against SARS-CoV-2. These compounds were conveniently prepared on a large scale through a one-pot reaction using Dimroth rearrangement as a key step. The synthesized compounds showed potent inhibitory activity, low binding to hERG channels, and good microsomal stability. In vivo pharmacokinetic studies showed that compound 2b had the highest exposure (AUC24h = 41.57 μg∙h/mL) of the synthesized compounds. An in vivo single-dose toxicity evaluation of compound 2b at 250 and 500 mg/kg in rats resulted in no deaths and an approximate lethal dose greater than 500 mg/kg. This study shows that N-acetyl 2-aminoquinazolin-4-(3H)-one 2b is a promising lead compound for developing anti-SARS-CoV-2 agents. [ABSTRACT FROM AUTHOR]

Despite the continuing global crisis caused by coronavirus disease 2019 (COVID-19), there is still no effective treatment. Therefore, we designed and synthesized a novel series of 2-benzylaminoquinazolin-4(3 H )-one derivatives and demonstrated that they are effective against SARS-CoV-2. Among the synthesized derivatives, 7-chloro-2-(((4-chlorophenyl)(phenyl)methyl)amino)quinazolin-4(3 H )-one (Compound 39 ) showed highest anti-SARS-CoV-2 activity, with a half-maximal inhibitory concentration value greater than that of remdesivir (IC 50  = 4.2 μM vs. 7.6 μM, respectively), which gained urgent approval from the U.S. Food and Drug Administration. In addition, Compound 39 showed good results in various assays measuring metabolic stability, human ether a-go-go, Cytochromes P450 (CYPs) inhibition, and plasma protein binding (PPB), and showed better solubility and pharmacokinetics than our previous work., (© 2022 Korean Chemical Society, Seoul & Wiley‐VCH GmbH.)