Synthesis and evaluation of new quinazolin-4(3H)-one derivatives as potent antibacterial agents against multidrug resistant Staphylococcus aureus and Mycobacterium tuberculosis

Synthesis of 2-Amino-quinazolin-4(3H)-ones Using 2-Bromo-N-phenylbenzamide and Cyanamide Ullmann Cross-Coupling

Herein, an approach for synthesizing 2-amino-3-substituted quinoline-4(3H)-ones and N-phenylbenzamide derivatives was developed. A series of quinoline-4(3H)-ones were synthesized through Ullmann cross-coupling under air conditions using inexpensive, readily available cyanamide with 2-bromo-N-phenylbenzamide as the starting material, copper iodide as the catalyst, and potassium tert-butoxide as the base in dimethyl sulfoxide. Noteworthy aspects of this method include its cost-effectiveness, the accessibility of raw materials, wide substrate applicability, ligand-free, open-air conditions, and simple operating procedures. Furthermore, investigations under similar reaction conditions further show that substituting water, alcohols, phenols, amines, or mercaptans for cyanamide as the nucleophilic reagent can be used to prepare 2-functionalized N-phenylbenzamides.

Multifunctional O-phenanthroline silver(I) complexes for antitumor activity against colorectal adenocarcinoma cells and antimicrobial properties by multiple mechanisms

A series of O-phenanthroline silver(I) complexes were synthesized and characterized by infrared (IR) spectroscopy, mass spectrometry (MS), ¹H nuclear magnetic resonance (NMR) spectroscopy and single-crystal X-ray crystallography. The cytotoxicity of the silver(I) complex (P-131) was evaluated in the cancer cell lines HCT-116, HeLa, and MDA-MB-231 and the normal cell line LO2 via MTT assays. The 50% inhibition concentration (IC₅₀) of P-131 on HCT116 cell line is 0.86 ± 0.03 μM. It is far lower than the IC₅₀ value of cisplatin (9.08 ± 1.10 μM), the IC₅₀ value of normal cell LO2 (76.20 ± 0.48 μM) is much higher than that of cisplatin (3.99 ± 0.74 μM), indicating that its anticancer effect is stronger than that of cisplatin, and its biological safety is greater than that of cisplatin. Furthermore, anticancer mechanistic studies showed that P-131 inhibited cell proliferation by blocking DNA synthesis and acted temporally on the nucleus in dividing HCT-116 cells. Moreover, P-131 increased intracellular reactive oxygen species (ROS) levels in a dose-dependent manner. Notably, 10 mg/kg P-131 showed better antitumor effects than oxaliplatin in an HCT116 human colorectal xenograft mouse model without inducing toxicity. Moreover, the microdilution broth method was used to evaluate the antimicrobial properties of P-131 against Pseudomonas aeruginosa and Candida albicans. A biofilm eradication study was also performed using the crystal violet method and confocal laser scanning microscopy.

An Insight on the Prospect of Quinazoline and Quinazolinone Derivatives as Anti-tubercular Agents

Multiple potential drugs have been developed based on the heterocyclic molecules for the treatment of different symptoms. Among the existing heterocyclic molecules, quinazoline and quinazolinone derivatives have been found to exhibit extensive pharmacological and biological characteristics. One significant property of these molecules is their potency as anti-tubercular agents. Thus, both quinazoline and quinazolinone derivatives are modified using different functional groups as substituents for investigating their anti-tubercular activities. We present a summary of the reported anti-tubercular drugs, designed using quinazoline and quinazolinone derivatives, in this review.

Synthesis, antitumor activity, 3D-QSAR and molecular docking studies of new iodinated 4-(3H)-quinazolinones 3N-substituted

A novel series of 6-iodo-2-methylquinazolin-4-(3H)-one derivatives, 3a–n, were synthesized and evaluated for their in vitro cytotoxic activity. Compounds 3a, 3b, 3d, 3e, and 3h showed remarkable cytotoxic activity on specific human cancer cell lines when compared to the anti-cancer drug, paclitaxel. Compound 3a was found to be particularly effective on promyelocytic leukaemia HL60 and non-Hodgkin lymphoma U937, with IC₅₀ values of 21 and 30 μM, respectively. Compound 3d showed significant activity against cervical cancer HeLa (IC₅₀ = 10 μM). The compounds 3e and 3h were strongly active against glioblastoma multiform tumour T98G, with IC₅₀ values of 12 and 22 μM, respectively. These five compounds showed an interesting cytotoxic activity on four human cancer cell types of high incidence. The molecular docking results reveal a good correlation between experimental activity and calculated binding affinity on dihydrofolate reductase (DHFR). Docking studies proved 3d as the most potent compound. In addition, the three-dimensional quantitative structure–activity relationship (3D-QSAR) analysis exhibited activities that may indicate the existence of electron-withdrawing and lipophilic groups at the para-position of the phenyl ring and hydrophobic interactions of the quinazolinic ring in the DHFR active site.

New iodinated 4-(3H)-quinazolinones 3N-substituted with antitumor activity and 3D-QSAR and molecular docking studies as dihydrofolate reductase (DHFR) inhibitors.

The antibacterial activity of quinazoline and quinazolinone hybrids

Bacterial infections cause substantial morbidity and mortality across the world and pose serious threats to humankind. Drug resistance, especially multidrug resistance resulting from different defensive mechanisms in bacteria, is the leading cause of failure the chemotherapy, making it an urgent need to develop more effective antibacterials. Quinazoline and quinazolinone frameworks have received considerable attention due to their diversified therapeutic potential. In particular, quinazoline/quinazolinone hybrids could exert antibacterial activity through various mechanisms and are useful scaffolds for the discovery of novel antibacterials. This review principally emphases on the antibacterial potential, structure-activity relationships (SARs), and mechanism of action of quinazoline and quinazolinone hybrids, covering articles published between 2017 and 2021.

Synthesis and antibacterial evaluation of (E)-1-(1H-indol-3-yl) ethanone O-benzyl oxime derivatives against MRSA and VRSA strains

Infections caused due to multidrug resistant organisms have emerged as a constant menace to human health. Even though numerous antibiotics are currently available for treating infectious diseases, a great number of bacterial strains have acquired resistance to many of them. Among these, infections caused due to Staphylococcus aureus are predominant in adult and paediatric population. Indole is a prominent chemical scaffold found in many pharmacologically active natural products and synthetic drugs. A number of oxime ether containing compounds have attracted attention of researchers owing to their interesting biological properties. Current work details the synthesis of indole containing oxime ether derivatives and their evaluation for antimicrobial activity against a panel of bacterial and mycobacterial strains. Synthesized compounds demonstrated good to moderate activity against drug-resistant S. aureus including resistant to vancomycin. Among all, compound 5h was found to possess potent activity against susceptible as well as MRSA and VRSA strains of S. aureus with MIC of 1 µg/mL and 2-4 µg/mL respectively. In addition, compound 5h was found to be non-toxic to Vero cells and exhibited good selectivity index of >40. Further, 5h, E-9a and E-9b possessed good biofilm inhibition against S. aureus. With these assuring biological properties, synthesized compounds could be potential prospective antimicrobial agents.

β-Lactams against the Fortress of the Gram-Positive Staphylococcus aureus Bacterium

The biological diversity of the unicellular bacteria-whether assessed by shape, food, metabolism, or ecological niche-surely rivals (if not exceeds) that of the multicellular eukaryotes. The relationship between bacteria whose ecological niche is the eukaryote, and the eukaryote, is often symbiosis or stasis. Some bacteria, however, seek advantage in this relationship. One of the most successful-to the disadvantage of the eukaryote-is the small (less than 1 μm diameter) and nearly spherical Staphylococcus aureus bacterium. For decades, successful clinical control of its infection has been accomplished using β-lactam antibiotics such as the penicillins and the cephalosporins. Over these same decades S. aureus has perfected resistance mechanisms against these antibiotics, which are then countered by new generations of β-lactam structure. This review addresses the current breadth of biochemical and microbiological efforts to preserve the future of the β-lactam antibiotics through a better understanding of how S. aureus protects the enzyme targets of the β-lactams, the penicillin-binding proteins. The penicillin-binding proteins are essential enzyme catalysts for the biosynthesis of the cell wall, and understanding how this cell wall is integrated into the protective cell envelope of the bacterium may identify new antibacterials and new adjuvants that preserve the efficacy of the β-lactams.

Synthesis and biofilm inhibition studies of 2-(2-amino-6-arylpyrimidin-4-yl)quinazolin-4(3H)-ones

Synthesis of novel 4(3H)-quinazolinonyl aminopyrimidine derivatives has been achieved via quinazolinonyl enones which in turn were obtained from 2-acyl-4(3H)-quinazolinone. They have been assayed for biofilm inhibition against Gram-positive (methicillin-resistant Staphylococcus aureus (MRSA)) and Gram-negative bacteria (Acinetobacter baumannii). The analogues with 2,4,6-trimethoxy phenyl, 4-methylthio phenyl, and 3-bromo phenyl substituents (5h, 5j & 5k) have been shown to inhibit biofilm formation efficiently in MRSA with IC50 values of 20.7-22.4 μM). The analogues 5h and 5j have demonstrated low toxicity in human cells in vitro and can be investigated further as leads.

Synthesis and evaluation of new quinazoline-benzimidazole hybrids as potent anti-microbial agents against multidrug resistant Staphylococcus aureus and Mycobacterium tuberculosis

Owing to the rapid rise in antibiotic resistance, infectious diseases have become serious threat to public health. There is an urgent need to develop new antimicrobial agents with diverse chemical structures and novel mechanisms of action to overcome the resistance. In recent years, Quinazoline-benzimidazole hybrids have emerged as a new class of antimicrobial agents active against S. aureus and M. tuberculosis. In the current study, we designed and synthesized fifteen new Quinazoline-benzimidazole hybrids and evaluated them for their antimicrobial activity against S. aureus ATCC 29213 and M. tuberculosis H37Rv. These studies led to the identification of nine potent antibacterial agents 8a, 8b, 8c, 8d, 8f, 8g, 8h, 8i and 10c with MICs in the range of 4-64 μg/mL. Further, these selected compounds were found to possess potent antibacterial potential against a panel of drug-resistant clinical isolates which include methicillin and vancomycin-resistant S. aureus. The selected compounds were found to be less toxic to Vero cells (CC₅₀ = 40-≥200 μg/mL) and demonstrated a favourable selectivity index. Based on the encouraging results obtained these new benzimidazol-2-yl quinazoline derivatives have emerged as promising antimicrobial agents for the treatment of MDR- S. aureus and Mycobacterial infections.

1,2,3-Triazole-containing hybrids with potential antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA)

Methicillin-resistant Staphylococcus aureus (MRSA), as a classic reason for genuine skin and flimsy tissues diseases, is a worldwide general wellbeing risk and has already tormented humanity for a long history, creating a critical need for the development of new classes of antibacterials. 1,2,3-Triazole moiety, readily interact with diverse enzymes and receptors in organisms through weak bond interaction, is among the most common frameworks present in the bioactive molecules. 1,2,3-Triazole derivatives, especially 1,2,3-triazole-containing hybrids, possess broad-spectrum activity against a panel of clinically important bacteria including drug-resistant pathogens, so rational design of 1,2,3-triazole derivatives may open a door for the opportunities on the development of novel anti-MRSA agents. This review is an endeavour to highlight the current scenario of 1,2,3-triazole-containing hybrids with potential anti-MRSA activity, covering articles published between 2010 and 2020.

Exploration of the Structural Space in 4(3H)-Quinazolinone Antibacterials

We report herein the syntheses of 79 derivatives of the 4(3H)-quinazolinones and their structure-activity relationship (SAR) against methicillin-resistant Staphylococcus aureus (MRSA). Twenty one analogs were further evaluated in in vitro assays. Subsequent investigation of the pharmacokinetic properties singled out compound 73 ((E)-3-(5-carboxy-2-fluorophenyl)-2-(4-cyanostyryl)quinazolin-4(3H)-one) for further study. The compound synergized with piperacillin-tazobactam (TZP) both in vitro and in vivo in a clinically relevant mouse model of MRSA infection. The TZP combination lacks activity against MRSA, yet it synergized with compound 73 to kill MRSA in a bactericidal manner. The synergy is rationalized by the ability of the quinazolinones to bind to the allosteric site of penicillin-binding protein (PBP)2a, resulting in opening of the active site, whereby the β-lactam antibiotic now is enabled to bind to the active site in its mechanism of action. The combination effectively treats MRSA infection, for which many antibiotics (including TZP) have faced clinical obsolescence.

New potential drug leads against MDR-MTB: A short review

Multidrug resistant Mycobacterium tuberculosis (MDR-MTB) infections have created a critical health problem globally. The appalling rise in drug resistance to all the current therapeutics has triggered the need for identifying new antimycobacterial agents effective against multidrug-resistant Mycobacterium tuberculosis. Structurally unique chemical entities with new mode of action will be required to combat this pressing issue. This review gives an overview of the structures and outlines on various aspects of in vitro pharmacological activities of new antimycobacterial agents, mechanism of action and brief structure activity relationships in the perspective of drug discovery and development. This review also summarizes on recent reports of new antimycobacterial agents.

Promising antibacterial agents against multidrug resistant Staphylococcus aureus

Rapid emergence of multidrug resistant Staphylococcus aureus infections has created a critical health menace universally. Resistance to all the available chemotherapeutics has been on rise which led to WHO to stratify Staphylococcus aureus as high tier priorty II pathogen. Hence, discovery and development of new antibacterial agents with new mode of action is crucial to address the multidrug resistant Staphylococcus aureus infections. The egressing understanding of new antibacterials on their biological target provides opportunities for new therapeutic agents. This review underlines on various aspects of drug design, structure activity relationships (SARs) and mechanism of action of various new antibacterial agents and also covers the recent reports on new antibacterial agents with potent activity against multidrug resistant Staphylococcus aureus. This review provides attention on in vitro and in vivo pharmacological activities of new antibacterial agents in the point of view of drug discovery and development.