An efficient nano CuO-catalyzed synthesis and biological evaluation of quinazolinone Schiff base derivatives and bis-2,3-dihydroquinazolin-4(1H)-ones as potent antibacterial agents against Streptococcus lactis

Design and synthesis of new quinazolinone derivatives: investigation of antimicrobial and biofilm inhibition effects

New quinazolin-4-ones 9-32 were synthesized in an attempt to overcome the life-threatening antibiotic resistance phenomenon. The antimicrobial screening revealed that compounds 9, 15, 16, 18, 19, 20 and 29 are the most broad spectrum antimicrobial agents in this study with safe profile on human cell lines. Additionally, compounds 19 and 20 inhibited biofilm formation in Pseudomonas aeruginosa, which is regulated by quorum sensing system, at sub-minimum inhibitory concentrations (sub-MICs) with IC50 values 3.55 and 6.86 µM, respectively. By assessing other pseudomonal virulence factors suppression, it was found that compound 20 decreased cell surface hydrophobicity compromising bacterial cells adhesion, while both compounds 19 and 20 curtailed the exopolysaccharide production which constitutes the major component of the matrix binding biofilm components together. Also, at sub-MICs Pseudomonas cells twitching motility was impeded by compounds 19 and 20, a trait which augments the cells pathogenicity and invasion potential. Molecular docking study was performed to further evaluate the binding mode of candidates 19 and 20 as inhibitors of P. aeruginosa quorum sensing transcriptional regulator PqsR. The achieved results demonstrate that both compounds bear promising potential for discovering new anti-biofilm and quorum quenching agents against Pseudomonas aeruginosa without triggering resistance mechanisms as the normal bacterial life cycle is not disturbed.

Green Synthetic and Pharmacological Developments in the Hybrid Quinazolinone Moiety: An Updated Review

Bicyclic quinazolinone constitutes an important class of organic framework enveloping numerous biological properties which enthused organic and medicinal chemists to explore green synthetic strategies for the construction of quinazolinone hybrids with significantly improved pharmacodynamics and pharmacokinetic profiles. In this perspective, the present review summarizes the most recent green synthetic strategies, biological properties, structure-activity relationship, and molecular docking studies of the 4-quinazolinone-based scaffold. This review provides deeper insight into the hit-to-lead synthesis of quinazolinone derivatives in the development of clinically important therapeutic candidates.

Critical view on antimicrobial, antibiofilm and cytotoxic activities of quinazolin-4(3H)-one derived schiff bases and their Cu(II) complexes

A series of nine 2,3-disubstituted-quinazolin-4(3H)-one derived Schiff bases and their three Cu(II) complexes was prepared and tested for their antimicrobial activities against reference strains Staphylococcus aureus ATCC 29213 and Enterococcus faecalis ATCC 29212 and resistant clinical isolates of methicillin-resistant S. aureus (MRSA) and vancomycin-resistant E. faecalis (VRE). All the substances were tested in vitro against Mycobacterium tuberculosis H37Ra ATCC 25177, M. kansasii DSM 44162 and M. smegmatis ATCC 700084. While anti-enterococcal and antimycobacterial activities were insignificant, 3-[(E)-(2-hydroxy-5-nitrobenzylidene)amino]-2-(2-hydroxy-5-nitrophenyl)-2,3-dihydroquinazolin-4(1H)-one (SB3) and its Cu(II) complex (SB3-Cu) demonstrated bacteriostatic antistaphylococcal activity. In addition, both compounds, as well as the other two prepared complexes, showed antibiofilm activity, which resulted in a reduction of biofilm formation and eradication of mature S. aureus biofilm by 80% even at concentrations lower than the values of their minimum inhibitory concentrations. In addition, the compounds were tested for their cytotoxic effect on the human monocytic leukemia cell line THP-1. The antileukemic efficiency was improved by the preparation of Cu(II) complexes from the corresponding non-chelated Schiff base ligands.

Pd(II)-Catalyzed Cascade Annulation of o-Aminobenzoic Acids with CO, Amines, and Aldehydes to N3-/N1,N3-Substituted 2,3-Dihydroquinazolin-4(1H)-ones

The unprecedented Pd(II)-catalyzed cascade annulation of o-aminobenzoic acids with CO, amines, and aldehydes has been developed. This protocol provides an efficient and concise approach to selective construction of N3-substituted and N1,N3-disubstituted 2,3-dihydroquinazolin-4(1H)-ones mostly in moderate to excellent yields from simple and easily available starting materials under mild conditions featured with low cost, high step economy, broad substrate scope, and good product diversity.

Syntheses of 2-Iminoindolin-3-ones and 2-Alknyl-2,3-dihydroquinazolin-4(1H)-ones from 3-Diazoindolin-2-imines

3-Diazoindolin-2-imines reacted with nitrones to furnish 2-iminoindolin-3-ones through a Au(I)-catalyzed cascade oxygen transfer/imine exchange process. The prepared 2-iminoindolin-3-ones could be further transformed into 2-alknyl-2,3-dihydroquinazolin-4(1H)-ones through a Ag(I)-catalyzed reaction with terminal alkynes. A MeOH-triggered ring expansion mechanism involving cyclic iminium formation and nucleophilic addition is proposed for this novel alkynylation reaction. This two-step procedure provides a general and convenient approach to 2-alknyl-2,3-dihydroquinazolin-4(1H)-ones, which are privileged structures in medicinal chemistry.