In this study, p-tert-butyl at position 2 and acetamide bridged 4-substituted piperazine/piperidine at position 5 bearing benzoxazole derivatives were evaluated for their in vitro inhibitory activity against AChE, BChE and Tyrosinase, which are important targets in reducing the adverse effects of Alzheimer’s disease. The most active 1 g inhibited the BChE at a concentration of 50 µM by 54 ± 0.75%. Molecular docking studies of the compounds against BChE (PDB: 4BDS) were performed with Schrödinger and AutoDock Vina and the results were compared. Schrödinger docking scores were found to be more consistent. Estimated ADME profiles and bioactivity scores of the compounds were calculated and found to be compatible with Lipinski and other limiting rules. Geometric optimization parameters, MEP analysis and HUMO and LUMO quantum parameters of the most active 1 g were calculated by using DFT/B3LYP theory and 6-311 G (d,p) base set and results was viewed.

In this study, a total of 17 piece 2,5-disubstituted benzoxazole derivatives were synthesized, 2 of which were not original, their antimicrobial activities were determined using microdilution method and their in vitro cytotoxic activities were investigated on MCF-7 and A549 cells by MTT test. When the activity results are examined, although the antibacterial effects of benzoxazole derivatives are weaker than standard drugs; 3N13 and 3N19 against Candida albicans isolate showed the closest activity to fluconazole with MIC: 16 µg/ml. The cytotoxicity test was measured at a concentration of 100 µM and a 24-h incubation period. The results showed that the compounds had weak activities against two cell lines. Molecular docking studies of synthesized compounds were performed on sterol 14α-demethylase protein (CYP51) and protein-ligand interactions of 3N13, the most effective derivative against C. albicans isolate, were showed (PDB: 5TZ1). Estimated ADME profiles of compounds were calculated and also 3N13’s were calculated HUMO-LUMO energies, molecular electrostatic potential analysis, and geometric optimization parameters with 6-311 G+ (d,p) base set using DFT/B3LYP theory, and the results were displayed.

A series of some novel 2-(p-tert-butylphenyl)-5-(3-substituted-propionamido)benzoxazole derivatives have been designed, synthesized, evaluated to antimicrobial activity, performed molecular docking studies against Penicillin Binding Protein 4 (PBP4) and active and allosteric site of PBP2a, were calculated some theoretical quantum parameters and absorption, distribution, metabolism, and excretion (ADME) descriptor. B9 acted at Minimum Inhibitory Concentration (MIC) =8 µg/ml against S. aureus, E. faecalis and their drug-resistant isolates and also formed with GLU145 (1.74Å) and ILE144 (1.89Å) two hydrogen bond at allosteric site of PBP2a with Glide emodel score: -42.168. ΔE of compound B9 had moderate value of all compounds with 0.14742.

In this study, the antimicrobial activities of previously synthesized 2-(substituted)oxazolo[4,5-b]pyridine derivatives toward six bacteria strains and twelve related drug-resistant isolates, and one fungus strain and two related drug-resistant isolates were investigated via the microdilution method. P6 (2-(4-trifluoromethylphenyl)oxazolo[4,5-b]pyridine) and P7 (2-(4-trifluoromethoxyphenyl)oxazolo[4,5-b]pyridine) showed better activity against E. faecalis isolate and E. coli isolate than ampicillin with a MIC of 16 μg mL⁻¹. In addition, P5 (2-(4-methoxyphenyl)oxazolo[4,5-b]pyridine) and P6 showed gentamicin-equivalent activity against P. aeruginosa, with a MIC of 16 μg mL⁻¹, while P7 showed better activity than gentamicin, with a MIC of 8 μg mL⁻¹. The compounds generally showed good to strong antimicrobial activities. Molecular docking and molecular dynamics simulations of the compounds were performed using the DNA gyrase enzyme, and the interactions were evaluated. The compounds showed an overlap at the DNA gyrase ATP binding site with similar protein–ligand interactions. Average RMSD values of the apo form, and P5-4KTN, P6-4KTN and P7-4KTN holo forms were measured to be 0.149 nm, 0.152 nm, 0.165 nm, and 0.146 nm, respectively. The P7 ligand stabilized the protein via further increasing its stability. HOMO–LUMO orbital energies and other electronic parameters derived from these energies, MEP and NBO analysis, and geometric optimization were obtained using DFT/B3LYP theory and the 6-311G(d,p) basis set. The LUMO–HOMO ΔE values for the most active compounds, P5, P6 and P7, are 4.3508, 4.4471, and 4.4852 eV, respectively. The predicted ADME profiles of the compounds were calculated, and they were compliant with Lipinski and other restrictive rules.

We previously synthesized a series of quinoline-2-carbaldehyde hydrazone derivatives and evaluated their antioxidant activities. In this study, the antimicrobial activities of these quinoline-2-carbaldehyde hydrazone derivatives were evaluated antimicrobial activity by the microdilution method, and there cytotoxic effect was investigated in MCF-7 and A549 cells by MTT assay. When the activity results were examined, although the antimicrobial activity of quinoline derivatives were equal or better than standard drugs in general, compound 4 (2 µg/mL) and 8 (1 µg/mL) against E. faecalis and 5 (8 µg/mL) against P. aeruginosa are the most effective derivatives of the series. Besides, disk diffusion test was applied to these three compounds, and significant zone formation was observed at 8 (7 mm) compared to vancomycin (9 mm). Compounds showed no antiproliferative in A549 and MCF-7 cell lines, and compound 4, 5, and 8, which showed the most effective antimicrobial activity, were examined in healthy cells (Beas-2b) and no effect on cell viability was found. To understand the mechanism of this action of these compounds against E. faecalis, molecular docking studies were performed on 15 different proteins, and it was concluded that the compounds interacted with FabH and not enough with other protein structures. The theoretical ADME profiles of compounds comply with Lipinski and other limiting rules. Also, some theoretical quantum parameters (HOMO-LUMO) of compounds, and both MEP analysis and geometric optimization analysis of 8 were calculated with 6–311 G (d,p) base set and DFT/B3LYP theory, and the results were shown.

The hybrid molecules bearing heterocyclic structures in the A or D rings of steroids have significant biological activity. 16 (E)-Hetereoarylidene steroids were synthesized from the reaction of different heteroaromatic carbaldehydes and trans-Dehydroepiandrosterone (DHEA) in a basic medium. Then, synthesis of the N-formyl pyrazoline substituted new DHEA derivatives were carried out from the reaction of hydrazine hydrate and 16 (E)-hetereoarylidene steroids. The structures of the synthesized compounds were elucidated by elemental analysis, FT-IR, ¹H NMR, and ¹³C NMR spectroscopy. To investigate the activation pathway of synthesized N-formyl pyrazoline substituted steroid derivatives, a molecular docking study was performed on human cytochrome P450-(CYP17A1: PDB ID 5IRQ) with the help of the free AutoDock Vina. 100 ns molecular dynamic simulation process was performed to monitor the behavior of the complex structure formed by CYP17A1 and to calculate the stability over time of 2a and 2d (-9.8 kcal/mol), which gave the lowest value according to the results obtained in the molecular docking study with AutoDock Vina. Accordingly, RMSD, RMSF, Rg, and SASA analyzes of 2a and 2d were performed, and MMPBSA was calculated. Lastly, the ADMET (absorption, distribution, metabolism, excretion, and toxicity) analyses of the novel steroid derivatives were investigated. Communicated by Ramaswamy H. Sarma Graphical Abstract