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

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.

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.