Design, synthesis and biological evaluation of 2-aminoquinazolin-4(3H)-one derivatives as potential SARS-CoV-2 and MERS-CoV treatments

Enantioselective synthesis of 3-hydroxy- and 3-amino-3-alkynyl-2-oxindoles by the dimethylzinc-mediated addition of terminal alkynes to isatins and isatin-derived ketimines

A common protocol for enantioselective alkynylation of isatins and isatin-derived ketimines using terminal alkynes and Me2Zn in the presence of a catalytic amount of a chiral perhydro-1,3-benzoxazine with moderate to excellent enantioselectivity under mild reaction conditions is described. The additions to ketimines present a novel approach to chiral amines being derivatives of oxindoles. The reaction is broad in scope with respect to aryl- and alkyl-substituted terminal alkynes and isatin derivatives. In isatins, the alkynylation occurs at the Si face of the carbonyl group, whereas in the ketimine derivatives it occurs at the Re face of the imine.

Synthesis of 2,3-Fused Quinazolinones via the Radical Cascade Pathway and Reaction Mechanistic Studies by DFT Calculations

An efficient radical cascade cyclization of unactivated alkenes toward the synthesis of a series of ring-fused quinazolinones has been developed in moderate to excellent yields using commercially available ethers, alkanes, and alcohols, respectively, under a base-free condition in a short time without a transition metal as catalyst. Notably, the transformations can be carried out with the advantages of a broad substrate scope and high atomic economy. Density functional theory calculations and wavefunction analyses were performed to elucidate the radical reaction mechanism.

Exploring polyamine interactions and binding pockets in SARS-CoV-2 ORF3a

Ongoing global pandemic caused by coronavirus (COVID-19) requires urgent development of vaccines, treatments, and diagnostic tools. Open reading frame 3a (ORF3a) from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is considered to be a potential drug target for COVID-19 treatment. ORF3a is an accessory protein that plays a significant role in virus-host interactions and in facilitating host immune responses. Using putrescine, spermidine and spermine, an aliphatic polyamine for the activity suppression of ORF3a appears to be a promising approach in finding new targets for drug design. In this study, we explored the possible binding poses of polyamines to the ORF3a protein using a combination of various computational approaches i.e. pocket prediction, blind and site-specific molecular docking, molecular dynamics and ligand flooding simulations. The results showed that the tip of cytoplasmic domain and the upper tunnel of transmembrane domain of ORF3a provide a suitable binding site specific for the polyamines. MD simulations revealed the stability of spermidine binding in the upper tunnel pocket of ORF3a through salt bridge and hydrogen bond interactions between the amine groups of the ligand and negatively charged residues of ORF3a. These findings can be helpful in designing new therapeutic drugs.

Copper-promoted dehydrosulfurative carbon-nitrogen cross-coupling with concomitant aromatization for synthesis of 2-aminopyrimidines

Copper-promoted dehydrosulfurative C-N cross-coupling of 3,4-dihydropyrimidin-1H-2-thione with amine accompanied by concomitant aromatization to generate 2-aryl(alkyl)aminopyrimidine derivatives is described. The reaction proceeded well with a wide range of thiono substrates and aryl/aliphatic amines as the coupling partners, offering efficient access to biologically and pharmacologically valuable 2-aryl(alkyl)aminopyrimidines with rapid diversification.

Ligand-based design, synthesis, computational insights, and in vitro studies of novel N-(5-Nitrothiazol-2-yl)-carboxamido derivatives as potent inhibitors of SARS-CoV-2 main protease

The global outbreak of the COVID-19 pandemic provokes scientists to make a prompt development of new effective therapeutic interventions for the battle against SARS-CoV-2. A new series of N-(5-nitrothiazol-2-yl)-carboxamido derivatives were designed and synthesised based on the structural optimisation principle of the SARS-CoV Mpro co-crystallized WR1 inhibitor. Notably, compound 3b achieved the most promising anti-SARS-CoV-2 activity with an IC₅₀ value of 174.7 µg/mL. On the other hand, compounds 3a, 3b, and 3c showed very promising SARS-CoV-2 Mpro inhibitory effects with IC₅₀ values of 4.67, 5.12, and 11.90 µg/mL, respectively. Compound 3b docking score was very promising (-6.94 kcal/mol) and its binding mode was nearly similar to that of WR1. Besides, the molecular dynamics (MD) simulations of compound 3b showed its great stability inside the binding pocket until around 40 ns. Finally, a very promising SAR was concluded to help to design more powerful SARS-CoV-2 Mpro inhibitors shortly.

Novel Quinazolinone–Isoxazoline Hybrids: Synthesis, Spectroscopic Characterization, and DFT Mechanistic Study

Quinazolinone and isoxazoline systems have attracted much attention due to their interesting pharmacological properties. The association of these two pharmacophores in a single hybrid structure can boost the biological activity or bring a new one. Inspired by this new paradigm, in the present work we report the synthesis and spectroscopic characterization of new quinazolinone–isoxazoline hybrids. The target compounds were obtained via 1,3-dipolar cycloaddition reactions of arylnitriloxides and N-allylquinazolinone. The synthesized compounds were characterized using spectroscopic techniques such as IR, 1D NMR (1H and 13C), 2D NMR (COSY and HSQC), and high-resolution mass spectrometry (HRMS). The spectral data show that this reaction leads only to the 3,5-disubstituted isoxazoline regioisomer, and that the observed regiochemistry is not affected by the nature of the substituents in the phenyl ring of the dipole. In addition, a theoretical study was performed using density functional theory (DFT) to support the experimental results in regard to the regiochemistry of the studied reactions. The computational mechanistic study was in good agreement with the experimental data.

Optimization of 2-Aminoquinazolin-4-(3H)-one Derivatives as Potent Inhibitors of SARS-CoV-2: Improved Synthesis and Pharmacokinetic Properties

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.

Synthesis and biological evaluation of 2‐benzylaminoquinazolin ‐4( 3 H )‐one derivatives as a potential treatment for SARS‐CoV ‐2

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(3H)‐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(3H)‐one (Compound 39) showed highest anti‐SARS‐CoV‐2 activity, with a half‐maximal inhibitory concentration value greater than that of remdesivir (IC₅₀ = 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.

Anno 2021: Which antivirals for the coming decade?

Despite considerable progress in the development of antiviral drugs, among which anti-immunodeficiency virus (HIV) and anti-hepatitis C virus (HCV) medications can be considered real success stories, many viral infections remain without an effective treatment. This not only applies to infectious outbreaks caused by zoonotic viruses that have recently spilled over into humans such as severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2), but also ancient viral diseases that have been brought under control by vaccination such as variola (smallpox), poliomyelitis, measles, and rabies. A largely unsolved problem are endemic respiratory infections due to influenza, respiratory syncytial virus (RSV), and rhinoviruses, whose associated morbidity will likely worsen with increasing air pollution. Furthermore, climate changes will expose industrialized countries to a dangerous resurgence of viral hemorrhagic fevers, which might also become global infections. Herein, we summarize the recent progress that has been made in the search for new antivirals against these different threats that the world population will need to confront with increasing frequency in the next decade.