Objective: The study aimed to identify potent inhibitors with enhanced affinity for the ACE2 protein and validate their stability and efficacy against established inhibitors via molecular docking, machine learning, and MD simulations.

Methods: 202 ACE2 inhibitors (PDB ID:6LZG), comprising repurposed antiviral compounds and specific ACE2 inhibitors, were selected for molecular docking. The two most effective compounds obtained from docking were further analyzed using machine learning to identify potential compounds with enhanced ACE2-binding affinity. To refine the dataset, molecular decoys were generated through the Database of Useful Decoys: Enhanced (DUD-E) server, and Singular Value Decomposition (SVD) was applied for data preprocessing. The Tree-based Pipeline Optimization Tool (TPOT) was then utilized to optimize the machine learning pipeline. The most promising ML-predicted compounds were re-evaluated through docking and subjected to Molecular Dynamics (MD) simulations to evaluate their structural stability and interactions with ACE2. Finally, these compounds were evaluated against the top two pre-established inhibitors using various computational tools.

Results: The two best pre-established inhibitors were identified as Birinapant and Elbasvir, while the best machine-learning-predicted compounds were PubChem ID: 23658468 and PubChem ID: 117637105. Pharmacophore studies were conducted on the most effective machine-learning-predicted compounds, followed by a comparative ADME/T analysis between the best ML-screened and pre-established inhibitors. The results indicated that the top ML compound (PubChem ID: 23658468) demonstrated favorable BBB permeability and a high HIA index, highlighting its potential for therapeutic applications. The ML-screened ligand demonstrated structural stability with an RMSD (0.24 nm) and greater global stability (Rg: 2.08 nm) than Birinapant. Hydrogen bonding interactions further validated their strong binding affinity. MM/PBSA analysis confirmed the ML-screened compound's stronger binding affinity, with a binding free energy of - 132.90 kcal/mol, indicating enhanced stability in complex formation.

Conclusion: The results emphasize the efficacy of integrating molecular docking, machine learning, and molecular dynamics simulations in facilitating the rapid identification of novel inhibitors. PubChem ID: 23658468 demonstrates robust binding affinity to ACE2 and favorable pharmacokinetic properties, establishing it as a promising candidate for further investigation.

Objective: To evaluate the cholinesterase inhibition effect of the synthetic bis-Schiff base compounds and discover the electronic properties as well as binding affinities through computational studies.

Methods: The compounds were synthesized and screened against acetyl and butyrylcholinesterase inhibitory activities in-vitro, while DFT analysis and molecular docking studies were performed for the product compounds.

Results: Seven compounds, including 2a, 2b, 2e, 2c, 2d, 2i, and 2j, exhibited excellent AChE activity, while nine compounds showed potent BChE inhibition compared to galantamine (IC50 = 156.4 ± 1.13 μM). Furthermore, the recent study on molecules 2a-e has provided valuable insights into their mechanism of action as inhibitors of the enzyme ChE, which is crucial for understanding how to regulate this enzyme's activity. Through the use of Time-Dependent Density Functional Theory (TD-DFT), the electronic characteristics of these molecules were meticulously examined, revealing that the Highest Occupied Molecular Orbitals (HOMO) are extensively delocalized across the molecular frameworks of the most active 2a-e compounds. This suggests a significant degree of electron delocalization, which is often associated with chemical reactivity and stability. In comparison to standard galantamine, these compounds demonstrate a lower electrophilicity index, which is indicative of their increased biological efficacy and lower toxicity.

Conclusion: These derivatives showed excellent AChE and BChE activities with favorable electronic properties and superior binding affinities, highlighting their potential as effective inhibitors as therapeutic agents.

Methods: Six new derivatives, 2a-2f, containing a 4-oxybut-2-enoic acid moiety, were obtained by reacting amidrazones with maleic anhydride. The antimicrobial potency of compounds 2a-2f was studied using the microdilution method against the following bacterial strains: Escherichia coli, Yersinia enterocolitica, Pseudomonas aeruginosa, Staphylococcus aureus, Micrococcus luteus, Enterococcus faecalis, Gordonia rubripertincta, Mycobacterium smegmatis, and the fungal strain Candida albicans. Their antiproliferative activity was tested in cultures of human peripheral blood mononuclear cells stimulated with phytohemagglutinin. The bioavailability parameters of new compounds were predicted using Molinspiration software.

Results: Derivatives 2a-2c showed the strongest antibacterial activity, especially against Yersinia enterocolitica and Micrococcus luteus. Compounds 2d-2f inhibited the growth of Gordonia rubripertincta. Compounds 2a-2f exhibited low antiproliferative activity towards human peripheral blood mononuclear cells. However, it is necessary to evaluate whether all compounds are well absorbed after oral administration.

Discussion: The most promising antibacterial activity was demonstrated by derivatives possessing a 2-pyridyl substituent at the R1 position (2a-2c) or a phenyl ring at the R² position (2a, 2f).

Conclusion: Compound 2a demonstrated the highest antibacterial activity and selectivity in inhibiting the growth of Y. enterocolitica. Additionally, it exhibited low toxicity to human lymphocytes and demonstrated favorable bioavailability parameters. Therefore, its structure can be used as a starting point for designing new antimicrobials, such as targeted therapies for yersiniosis, beyond traditional antibiotics.

Methods: A series of tetrazole derivatives (6a–l) were synthesized via α-keto halogenation of 2,4-difluoroacetophenone, followed by cyclization, nucleophilic substitution, and subsequent coupling with various aryl carboxylic acids. The synthesized compounds were characterized using spectroscopic techniques, including ¹³C NMR, ¹H NMR, FT-IR, and HRMS. Their cytotoxic potential was assessed through an MTT assay across four human cancer cell lines. Other cytotoxic evaluations included apoptosis induction, cell cycle analysis, and EGFR-TK inhibition assays. Additionally, molecular docking studies were conducted to explore binding interactions, and in silico ADME predictions were performed to assess pharmacokinetic properties.

Results: The results obtained by the MTT assay indicated that compound 6d demonstrated significant cytotoxicity against A549 (lung cancer) cell lines, with an IC₅₀ value of 2.74 μM, compared to doxorubicin (IC₅₀ = 3.87 μM). Furthermore, cell cycle analysis and apoptosis suggested that 6d arrested the cell cycle in the S phase and triggered apoptosis in A549 cells. Docking studies and EGFR-TK inhibition assay proposed that 6l had good binding affinity towards EGFR enzyme and acts as a potential inhibitor (IC₅₀ 0.099 μM). The ADME analysis demonstrated favourable molecular properties, including acceptable lipophilicity, strong absorption, and high oral bioavailability.

Discussion: The synthesized tetrazole derivatives exhibited notable anticancer potential, with compound 6d inducing S-phase arrest and apoptosis in lung cancer cells, and 6l demonstrating strong EGFR inhibition. These biological effects were further supported by docking studies and favorable ADME profiles, providing mechanistic insight into their activity.

Conclusion: These findings indicate that the synthesized derivatives offer a promising approach for developing innovative and effective cancer therapies.