Synthesis, spectral characterization of pyrazole derived Schiff base analogs: molecular dynamic simulation, antibacterial and DNA binding studies

Synthesis and mechanistic studies of 4-aminoquinoline-Isatin molecular hybrids and Schiff's bases as promising antimicrobial agents

In this investigation, to determine their potential as specific antibacterial agents, Schiff's bases (LT-SB1-23 and SB1-SB12) and novel quinoline-isatin hybrids were subjected to microbiological testing. The in-vitro screening against bacterial strains (Escherichia coli, Enterococcus faecalis, Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa, and Salmonella typhi) exhibited their antibacterial potential with many of the compounds showing inhibition range of 90-100 % at 200 μg/mL, against most of the tested strains. The MIC values of some of the compounds showed good antibacterial efficacy with values ranging from 32 to 128 μg/mL. Their bacterial growth inhibitory potential was further supported by disk diffusion and growth curve assays. Interestingly, one of the Schiff's bases (LT-SB7) displayed strong synergistic activity against E. coli and S. typhi with 16-64 folds reduction in MIC values. Additionally, it exhibited up to 85 % suppression of biofilm at ½MIC against AA209 environmental bacterial isolate and reduced the development of multidrug-resistant bacterial isolates. Promising compound LT-SB7 underwent 100 ns molecular dynamics simulations with biofilm-causing protein (PDB ID: 7C7U) to assess conformational changes and complex stability. Overall, this study identified compounds as effective antibacterial alternatives for the future.

Synthesis and antibacterial evaluation of quinoline-sulfonamide hybrid compounds: a promising strategy against bacterial resistance

Antibiotic-resistant bacteria are a serious global health threat, making infections harder to treat and increasing medical costs and mortality rates. To combat resistant bacterial strains, a series of compounds (QS1-12) were synthesized with an excellent yield of 85-92%. Initial assessments of these analogues as potential antibacterial agents were conducted through a preliminary screening against a panel of diverse bacterial strains. The results identified compound QS-3 as the most effective antibacterial candidate, exhibiting exceptional inhibitory activity against P. aeruginosa with a minimum inhibitory concentration (MIC) of 64 μg mL-1. Furthermore, QS-3 demonstrated a favorable synergistic effect when combined with ciprofloxacin. Notably, the compound displayed minimal cytotoxicity, inducing less than 5% lysis of red blood cells (RBCs). Significantly, QS-3 exhibited enhanced inhibitory activity, particularly against the antibiotic-resistant strains AA202 and AA290. In silico predictions of physicochemical properties underscored the drug-like qualities of the designed compounds. Additionally, molecular docking poses, ligPlot images, and a binding affinity of -8.0 kcal mol-1 further reinforced their potential as promising antibacterial agents. Briefly, the reported compound QS3 may be a future broad-range antibacterial agent.

Ezetimibe Anticancer Activity via the p53/Mdm2 Pathway

BACKGROUND

Ezetimibe is used to treat cardiovascular disease as it blocks the sterol transporter Niemann-Pick C1-Like 1 (NPC1CL1) protein. However, recent evidence indicates that Ezetimibe inhibits several cancers indirectly by reducing circulating cholesterol or via specific signalling pathways.

METHODS AND RESULTS

Our in silico studies indicate that Ezetimibe binds to the Tp53 binding domain in Mdm2, forming a more thermodynamically stable complex than nutlin3a. Furthermore, a docking study of the newly developed inhibitors-RG7388 and RG7112-was conducted. This further showed lower binding energies of -6.337 kcal/mol and -6.222 kcal/mol, respectively, when compared to the -7.919 kcal/mol exhibited by Ezetimibe. We show that Ezetimibe inhibits the growth of several cancer cell lines at concentrations that are not toxic to a normal cell line.

CONCLUSIONS

Thus, Ezetimibe is probably active against cancers that overexpress Mdm2. Moreover, inhibitors of RBBP6 may be combined with Ezetimibe for effective anticancer activity. Due to poor oral bioavailability, Ezetimibe must be administered parenterally for cancer treatment.

Introducing of novel class of pyrano[2,3-c]pyrazole-5-carbonitrile analogs with potent antimicrobial activity, DNA gyrase inhibition, and prominent pharmacokinetic and CNS toxicity profiles supported by molecular dynamic simulation

Microbiological DNA gyrase is recognized as an exceptional microbial target for the innovative development of low-resistant and more effective antimicrobial drugs. Hence, we introduced a one-pot facile synthesis of a novel pyranopyrazole scaffold bearing different functionalities; substituted aryl ring, nitrile, and hydroxyl groups. All new analogs were characterized with full spectroscopic data. The antimicrobial screening for all analogs was assessed against standard strains of Gm + ve and Gm-ve through in vitro considers. The screened compounds displayed very promising MIC/MBC values against some of the bacterial strains with broad or selective antibacterial effects. Of these, 4j biphenyl analog showed 0.5-2/2-8 µg/mL MIC/MBC for suppression and killing of Gm + ve and Gm-ve strains. Moreover, the antimicrobial screening was assessed for the most potent analogs against certain highly resistant microbial strains. Consequently, DNA gyrase supercoiling assay was done for all analogs using ciprofloxacin as reference positive control. Obviously, the results showed a different activity profile with potent analog 4j with IC50 value 6.29 µg/mL better than reference drug 10.2 µg/mL. Additionally, CNS toxicity testing was done using the HiB5 cell line for attenuation of GABA/NMDA expression to both 4j and ciprofloxacin compounds that revealed better neurotransmitter modulation by novel scaffold. Importantly, docking and dynamic simulations were performed for the most active 4j analog to investigate its interaction with DNA binding sites, which supported the in vitro observations and compound stability with binding pocket. Finally, a novel scaffold pyranopyrazole was introduced as a DNA gyrase inhibitor with prominent antibacterial efficacy and low CNS side effect toxicity better than quinolones.Communicated by Ramaswamy H. Sarma.

Synergistic antimicrobial activity, MD simulation studies and crystal structure of natural alcohol motif containing novel substituted cinnamates

A series of natural alcohols motif containing novel substituted cinnamates were developed and screened against five bacterial strains namely, Enterococcus faecal (E. faecalis), Escherichia coli (E. coli), Bacillus subtilis (B. subtilis), Pseudomonas aeruginosa (P. aeruginosa) and Klebsiella pneumonieae (K. pneumonieae). Among all cinnamates, YS17 was identified with 100% bacterial growth inhibition across the panel, except in E. faecalis with MIC values of 0.25 mg/mL against B. subtilis and P. aeruginosa whereas 0.125, 0.5 and 1 mg/mL against E. coli, K. pneumonieae and E. faecalis, respectively. The growth inhibitory property of YS17 was further validated by disk diffusion, synergistic study and in vitro toxicity assays. Interestingly, YS17 exhibits synergistic effect in combination with the standard drug Ampicillin (AMP). The single crystal structure analysis of YS4 and YS6 was also performed which reconfirmed their proposed structures. Molecular docking visualized significant non-covalent interactions between E. coli MetAP and YS17 and the structural and conformational changes were further analysed using MD simulation studies. Overall, the study provided a suitable core for further synthetic alterations for their optimization as an antibacterial agent. Communicated by Ramaswamy H. Sarma.

Design, Synthesis, Molecular Modeling and Biological Evaluation of Novel Pyrazole Benzimidazolone Derivatives as Potent Antioxidants

In the present study, we used benzimidazolone as a starting material to efficiently synthesize several hybrid compounds of pyrazole benzimidazolone derivatives by the 1,3-dipolar cycloaddition reaction. These compounds were obtained in average yields and were characterized by NMR (1H and 13C) and HRMS analysis. The antioxidant activity of the synthesized compounds 5(a-c) and 6(a-c) was evaluated using in vitro reduction assays, including ferric reducing antioxidant power (FRAP) and total antioxidant capacity (TAC). The results indicated that products 5c, 6b, and 6c exhibit higher antioxidant activity compared to the reference compounds and showed a remarkable ability to effectively remove the radical at IC50 (14.00 ± 0.14, 12.47± 0.02, and 12.82 ± 0.10 µM, respectively) under the TAC assessment. Conversely, compound 6c showed excellent activity at IC50 (68.97 ± 0.26 µM) in the FRAP assay. We carried out molecular docking and dynamics simulations to investigate the binding mode and stability of 5c, 6b, and 6c in the active site of human Peroxiredoxin 5. An ADMET study was conducted to determine the drug properties of the synthesized compounds.

Novel dihydrobenzofuran derivatives: design, synthesis, cytotoxic activity, apoptosis, molecular modelling and DNA binding studies

Pyrazoline derivatives (3a-3e) and (4a-4e) were designed and synthesized through chalcones (2a-2e) cyclization with NH2NH2/HCOOH and NH2CSNHNH2/CH3COOH, respectively. The molecular structures were elucidated by using various techniques such as UV-visible, FT-IR, 1H, 13C NMR spectroscopy and mass spectrometry. The purity of all synthesized compounds was checked by the liquid chromatography-mass spectrometry (LC-MS). Single X-ray crystallography was confirmed the molecular structure of analogs (2d, 3e and 4e). Anticancer activity of the all derivatives was screened against human cancer cell MCF-7 and HepG2 cell lines by MTT assay. The results of anticancer activity of novel analogs 2b, 3b and 3e exhibited promising activity against MCF-7 but low toxic against the HepG2 normal cell line. By using a flow cytometry-based technique, the anticancer effectiveness of potent compounds against the MCF-7 cancer cell line was further validated. DNA binding interactions of the novel analogs 3b and 3e were carried out with calf thymus DNA (Ct-DNA) using absorption, fluorescence, circular dichroism and cyclic voltammetry. In silico molecular modelling of pyrazoline derivatives were also studied using Schrödinger-Maestro v2021-2 against tyrosine kinase receptor with PDB ID: 1M17 to explore their best hits. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical was used to measure the antioxidant capacity of active pyrazoline derivatives. Using Swiss ADMET software, the ADMET characteristics of pyrazoline derivatives were also investigated.Communicated by Ramaswamy H. Sarma.