Synthesis and evaluation of new 4-oxoquinazolin-3(4H)-yl)benzoic acid and benzamide derivatives as potent antibacterial agents effective against multidrug resistant Staphylococcus aureus

(Heteroarylmethyl)benzoic Acids as a New Class of Bacterial Cystathionine γ-Lyase Inhibitors: Synthesis, Biological Evaluation, and Molecular Modeling

Antibiotic resistance is one of the most serious global health threats. Therefore, there is a need to develop antimicrobial agents with new mechanisms of action. Targeting of bacterial cystathionine γ-lyase (bCSE), an enzyme essential for bacterial survival, is a promising approach to overcome antibiotic resistance. Here, we described a series of (heteroarylmethyl)benzoic acid derivatives and evaluated their ability to inhibit bCSE or its human ortholog hCSE using known bCSE inhibitor NL2 as a lead compound. Derivatives bearing the 6-bromoindole group proved to be the most active, with IC50 values in the midmicromolar range, and highly selective for bCSE over hCSE. Furthermore, none of these compounds showed significant toxicity to HEK293T cells. The obtained data were rationalized by ligand-based and structure-based molecular modeling analyses. The most active compounds were also found to be an effective adjunct to several widely used antibacterial agents against clinically relevant antibiotic-resistant strains of such bacteria as Staphylococcus aureus, Klebsiella pneumoniae, and Pseudomonas aeruginosa. The most potent compounds, 3h and 3i, also showed a promising in vitro absorption, distribution, metabolism, and excretion (ADME) profile. Finally, compound 3i manifested potentiating activity in pneumonia, sepsis, and infected-wound in vivo models.

Allicin-inspired disulfide derivatives containing quinazolin-4(3H)-one as a bacteriostat against Xanthomonas oryzae pv. oryzae

BACKGROUND

Plant bacterial diseases have seriously affected the yield and quality of crops, among which rice bacterial leaf blight (BLB), caused by Xanthomonas oryzae pv. oryzae has seriously affected the yield of rice. As plant-pathogenic bacteria gradually become resistant to existing bactericides, it is necessary to find effective bactericides with novel structures.

RESULTS

Herein, a series of compounds containing quinazolin-4(3H)-one and disulfide moieties were designed and synthesized using a facile synthetic method. The bioassay results revealed that most target compounds possessed noticeable antibacterial activity against Xanthomonas oryzae pv. oryzae. Particularly, compound 2-(butyldisulfanyl) quinazolin-4(3H)-one (1) exhibited remarkable antibacterial activity with the half effective concentration (EC₅₀ ) of 0.52 μg mL^-1 . Additionally, compound 1 was confirmed to inhibit the growth of the bacteria, change the bacterial morphology, and increase the level of reactive oxygen species. Proteomics, and RT-qPCR analysis results indicated that compound 1 could downregulate the expression of Pil-Chp histidine kinase chpA encoded by the pilL gene, and the potting experiments proved that compound 1 exhibits significant protective activity against BLB.

CONCLUSIONS

Compound 1 may weaken the pathogenicity of Xanthomonas oryzae pv. oryzae by inhibiting the bacterial growth and blocking the pili-mediated twitching motility without inducing the bacterial apoptosis. This study indicates that such derivatives could be a promising scaffold to develop a bacteriostat to control BLB. © 2022 Society of Chemical Industry.

Antimicrobial, anticancer and immunomodulatory potential of new quinazolines bearing benzenesulfonamide moiety

Sulfonamides are privileged candidates with potent anti-methicillin-resistant Staphylococcus aureus (MRSA) activity and could replenish the MRSA antibiotic pipeline. The initial screening of a series of quinazolinone benzenesulfonamide derivatives 5-18 against multidrug-resistant bacterial and fungal strains revealed their potent activity. The promising compounds were conjugated with ZnONPs to study the effect of nanoparticle formation on the antimicrobial, cytotoxic and immunomodulatory activity. Compounds 5, 11, 16 and 18 revealed promising antimicrobial and cytotoxic activities with superior safety profiles and enhanced activity upon nanoformulation. The immunomodulatory potential of compounds 5, 11, 16 and 18 was assessed. Compounds 5 and 11 demonstrated an increase in spleen and thymus weight and boosted the activation of CD4⁺ and CD8⁺ T lymphocytes, confirming their promising antimicrobial, cytotoxic and immunomodulatory activity.

A study on the antibacterial activity and antimicrobial resistance of pyridinium cationic pillar[5]arene against Staphylococcus aureus and Escherichia coli

An increasing number of infections caused by multidrug-resistant (MDR) Staphylococcus aureus （S. aureus） and Escherichia coli （E. coli） have severely affected human society. Thus, it is essential to develop an alternative type of antibacterial agents that has a different bacterial resistance mechanism from that of traditional antibiotics. After the synthesis and structural characterization of a cationic pillar[5]arene with pyridinium groups (PP5), the antibacterial and antibiofilm activities as well as its microbial resistance were systematically investigated. In-depth evaluation of biological studies revealed that PP5 was an active antibacterial agent, with surprising antibiofilm formation ability against E. coli and S. aureus. From the results of differential scanning calorimetry and transmission electron microscopy, it was concluded that the microbicidal activity of PP5 was due to the physical disruption of the pathogen's membrane and the subsequent leakage of cytoplasmic components, which could greatly reduce the rapid generation of resistance. It was presented that the easily available PP5 has high activity to inhibit Gram-positive and Gram-negative bacteria and/or their biofilms with low cytotoxicity. This pillar[5]arene derivative can be used as a good candidate for controlling drug-resistant pathogenic bacterial infections and treating MDR bacteria.

Synthesis and cytotoxic evaluation of some novel 3-[2-(2-phenyl-thiazol-4-yl)-ethyl]-3H-pyrido[2,3-d]pyrimidin-4-one derivatives

Background and purpose

Pyridopyrimidine and its derivatives have a variety of chemical and biological significances. Thiazole-containing compounds have also been reported to have a wide range of biological activities. Due to the valuable cytotoxic effects of both thiazole and pyridopyrimidinone derivatives, a series of pyridopyrimidinone-thiazole hybrids were synthesized in the present study.

Experimental approach

Briefly, different acyl chlorides were reacted with 2-amino nicotinic acid followed by anhydride acetic to give the corresponding pyridobenzoxazinones. The aminothiazole derivative G was also prepared via a multistep procedure and incorporated into the benzoxazinones to furnish the target pyridopyrimidinone, K1-K5. Furthermore, the cytotoxic activity of the final compounds was determined against MCF-7 and HeLa cell lines using MTT assay.

Findings/Results

The results indicated that aromatic substitution on C2 of pyridopyrimidine nucleus was in favor of cytotoxic activity on both cell lines, of which, compound K5 bearing a chlorophenyl group showed the highest cytotoxicity.

Conclusion and implications

The results of the present study are valuable in terms of synthesis of hybrid molecules and also cytotoxic evaluations which can be useful for future investigations about the design of novel pyridopyrimidinone-thiazole hybrids possessing better cytotoxic activities.

Copper mediated one-pot synthesis of quinazolinones and exploration of piperazine linked quinazoline derivatives as anti-mycobacterial agents

A facile method was developed for the synthesis of quinazolinone derivatives in a one-pot condensation reaction via in situ amine generation using ammonia as the amine source and with the formation of four new C-N bonds in good to excellent yields. With the optimised method, we synthesized a library of piperazine linked quinazoline derivatives and the synthesized compounds were evaluated for their inhibitory activity against Mycobacterium tuberculosis. The compounds 8b, 8e, 8f, 8m, 8n and 8v showed potent anti-mycobacterial activity with MIC values of 2-16 μg mL-1. All the synthesized compounds follow Lipinski's rules for drug likeness.

Synthesis, In Silico and In Vitro Assessment of New Quinazolinones as Anticancer Agents via Potential AKT Inhibition

A series of novel quinazolinone derivatives (2–13) was synthesized and examined for their cytotoxicity to HepG2, MCF-7, and Caco-2 in an MTT assay. Among these derivatives, compounds 4 and 9 exhibited significant cytotoxic activity against Caco-2, HepG2, and MCF-7 cancer cells. Compound 4 had more significant inhibitory effects than compound 9 on Caco-2, HepG2, and MCF-7 cell lines, with IC₅₀ values of 23.31 ± 0.09, 53.29 ± 0.25, and 72.22 ± 0.14µM, respectively. The AKT pathway is one of human cancer’s most often deregulated signals. AKT is also overexpressed in human cancers such as glioma, lung, breast, ovarian, gastric, and pancreas. A molecular docking study was performed to analyze the inhibitory action of newly synthetic quinazolinone derivatives against Homo sapiens AKT1 protein. Molecular docking simulations were found to be in accordance with in vitro studies, and hence supported the biological activity. The results suggested that compounds 4 and 9 could be used as drug candidates for cancer therapy via its potential inhibition of AKT1 as described by docking study.

Design and synthesis of novel desfluoroquinolone-aminopyrimidine hybrids as potent anti-MRSA agents with low hERG activity

Despite the fact that the introduction of a fluorine atom at the C-6 position has resulted in the evolution of fluoroquinolones, fluoroquinolone-induced cardiac toxicity has drawn considerable attention. In this context, desfluoroquinolone-based hybrids with involvement of C-7 aminopyrimidine functional group were designed and synthesized. The biological results showed majority of these hybrids still demonstrated potent anti-MRSA activity with MIC values between 0.38 and 1.5 μg/mL, despite the lack of the typical C-6 fluorine atom. Particularly, the most active B14 exhibited activities at submicromolar concentrations against a panel of MRSA strains including vancomycin-intermediate strains, levofloxacin-resistant isolates, and linezolid-resistant isolates, etc. As expected, it also displayed highly selective toxicity toward bacterial cells and low hERG inhibition. Further resistance development study indicated MRSA is unlikely to acquire resistance against B14. The docking study revealed that two hydrogen bonds were formed between the C-7 substituent and the surrounding DNA bases, which might contribute to overcome resistance by reducing the dependence on the magnesium-water bridge interactions with topoisomerase IV. These results indicate a promising strategy for developing new antibiotic quinolones to combat multidrug resistance and cardiotoxicity.

Synthesis, molecular docking and molecular dynamic simulation studies of 2-chloro-5-[(4-chlorophenyl)sulfamoyl]-N-(alkyl/aryl)-4-nitrobenzamide derivatives as antidiabetic agents

A series of 2-chloro-5-[(4-chlorophenyl)sulfamoyl]-N-(alkyl/aryl)-4-nitrobenzamide derivatives (5a-5v) has been synthesized and confirmed by physicochemical(R_f, melting point) and spectral means (IR, ¹HNMR, ¹³CNMR). The results of in vitro antidiabetic study against α-glucosidase indicated that compound 5o bearing 2-CH₃-5-NO₂ substituent on phenyl ring was found to be the most active compound against both enzymes. The electron donating (CH₃) group and electron withdrawing (NO₂) group on a phenyl ring highly favoured the inhibitory activity against these enzymes. The docking simulations study revealed that these synthesized compounds displayed hydrogen bonding, electrostatic and hydrophobic interactions with active site residues. The structure activity relationship studies of these compounds were also corroborated with the help of molecular modeling studies. Molecular dynamic simulations have been done for top most active compound for validating its α-glucosidase and α-amylase inhibitory potential, RMSD analysis of ligand protein complex suggested the stability of top most active compound 5o in binding site of target proteins. In silico ADMET results showed that synthesized compounds were found to have negligible toxicity, good solubility and absorption profile as the synthesized compounds fulfilled Lipinski's rule of 5 and Veber's rule.

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.

The Synergy of Ciprofloxacin and Carvedilol against Staphylococcus aureus-Prospects of a New Treatment Strategy?

Staphylococcus aureus infections are common and difficult to treat. The increasing number of drug-resistant staphylococcal infections has created the need to develop new strategies for the treatment of these infections. The synergistic antimicrobial activity of different pharmaceuticals seems to be an interesting alternative. The aim of this study was to assess the synergistic activity of ciprofloxacin and carvedilol against S. aureus strains. The antibacterial potential of ciprofloxacin and carvedilol was evaluated according to the CLSI guidelines. The calcium content in S. aureus cells was measured using flow cytometry and atomic absorption spectroscopy. Moreover, confocal and scanning electron microscopy were used to determine the mechanism of antibacterial synergy of ciprofloxacin and carvedilol. The antibacterial effect of ciprofloxacin was higher in the presence of carvedilol than in S. aureus cultures containing the antibiotic only. A significant increase in S. aureus membrane permeability was also observed. The simultaneous administration of the tested compounds caused damage to S. aureus cells visualized by SEM. Enhancement of the antimicrobial action of ciprofloxacin by carvedilol was correlated with an increase in free calcium content in S. aureus cells, morphological changes to the cells, and a reduction in the ability to form bacterial aggregates.

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.

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

Staphylococcus aureus and Mycobacterium tuberculosis are major causative agents responsible for serious nosocomial and community-acquired infections impacting healthcare systems globally. Over several decades, these pathogens have developed resistance to multiple antibiotics significantly affecting morbidity and mortality. Thus, these recalcitrant pathogens are amongst the most formidable microbial pathogens for which international healthcare agencies have mandated active identification and development of new antibacterial agents for chemotherapeutic intervention. In our present work, a series of new quinazolin-4(3H)-one derivatives were designed, synthesized and evaluated for their antibacterial activity against ESKAP pathogens and pathogenic mycobacteria. The experiments revealed that 4'c, 4'e, 4'f and 4'h displayed selective and potent inhibitory activity against Staphylococcus aureus with MIC values ranging from 0.03-0.25 μg/mL. Furthermore, compounds 4'c and 4'e were found to be benign to Vero cells (CC₅₀ = >5 μg/mL) and displayed promising selectivity index (SI) > 167 and > 83.4 respectively. Additionally, 4'c and 4'e demonstrated equipotent MIC against multiple drug-resistant strains of S. aureus including VRSA, concentration dependent bactericidal activity against S. aureus and synergized with FDA approved drugs. Moreover, compound 4'c exhibited more potent activity in reducing the biofilm and exhibited a PAE of ∼2 h at 10X MIC which is comparable to levofloxacin and vancomycin. In vivo efficacy of 4'c in murine neutropenic thigh infection model revealed that 4'c caused a similar reduction in cfu as vancomycin. Gratifyingly, compounds 4d, 4e, 9a, 9b, 14a, 4'e and 4'f also exhibited anti-mycobacterial activity with MIC values in the range of 2-16 μg/mL. In addition, the compounds were found to be less toxic to Vero cells (CC₅₀ = 12.5->100 μg/mL), thus displaying a favourable selectivity index. The interesting results obtained here suggest the potential utilization of these new quinazolin-4(3H)-one derivatives as promising antibacterial agents for treating MDR-Staphylococcal and mycobacterial infections.

4(3H)-Quinazolinone derivatives: Promising antibacterial drug leads

Emergence of drug resistance has created unmet medical need for the development of new classes of antibiotics. Discovery of new antibacterial agents with new mode of action remains a high priority universally. 4(3H)-quinazolinone, a fused nitrogen heterocyclic compound has emerged as a biologically privileged structure, possessing a wide range of biological properties viz. anticancer, antibacterial, antitubercular, antifungal, anti-HIV, anticonvulsant, anti-inflammatory and analgesic activities. Promising antibacterial properties of quinazolinones have enthused the medicinal chemists to explore and develop this fused heterocyclic system for new antibacterial agents. Utilization of quinazolinone core for the design and synthesis of new antibacterial agents has recently gained momentum. This review aims to provide an overview of the structures and antibacterial activity of various 4(3H)-quinazolinone derivatives covering various aspects of in vitro and in vivo pharmacological activities and structure activity relationships (SARs).