Synthesis, Molecular Docking, Molecular Dynamics, DFT and Antimicrobial Activity Studies of 5-substituted-2-(p-methylphenyl)benzoxazole Derivatives

Stereoselective synthesis and antibacterial potential of C-3 chloro β-lactams: Insights into DNA gyrase inhibition using in silico molecular docking

This study explores the development of novel antibacterial agents through the stereoselective synthesis of eight C-3 chloro-substituted ortho-/meta-/para-(2-benzo[d]oxazolyl)phenyl-β-lactams. These compounds were obtained via the reaction of 2-chloroethanoic acid and 4-chlorophenylethanoic acid with isomeric ortho-, meta- and para-(2-benzo[d]oxazolyl)phenyl Schiff bases, exclusively yielding trans-β-lactams with high stereoselectivity (J = 1.8-2.6 Hz) and excellent yields (78-93 %). The antibacterial potential of these chloro β-lactams was further evaluated against S. aureus and E. coli, revealing significant activity across all tested compounds. Notably, compounds 5a and 5f exhibited the highest potency, with binding energies of -7.65 and -8.17 kcal/mol against E. coli and -7.35 and -8.29 kcal/mol against S. aureus. The IC50 values further confirmed their strong inhibitory effects, with 5a and 5f displaying values of 39 ng/mL and 35 ng/mL against E. coli, and 32 ng/mL and 30 ng/mL against S. aureus. Molecular docking studies demonstrated strong hydrogen bonding interactions between the synthesized compounds and the active sites of DNA gyrase in E. coli (PDB ID: 1KZN) and S. aureus (PDB ID: 5BS3), indicating favourable binding affinity. These findings highlight the potential of stereoselective C-3 chloro β-lactams as promising antibacterial candidates targeting DNA gyrase.

A Sustainable Synthesis of Novel 2-(3,4-Disubstituted phenyl)benzoxazole Derivatives and Their Antiproliferative and Antibacterial Evaluation

This study describes the synthesis of O-alkylated benzaldehydes 1-8, Schiff bases 9-28, and benzoxazole derivatives 29-48 using microwave, ultrasound, and mechanochemical reactions, as well as reactions in deep eutectic solvents in excellent yields, and their antiproliferative and antibacterial activities. The in vitro evaluation of antiproliferative activity for the newly synthesised benzoxazole derivatives 29-48 against a diverse panel of human cancer cell lines, such as LN-229, Capan-1, HCT-116, NCI-H460, DND-41, HL-60, K-562, and Z-138 demonstrated that the majority of these benzoxazole derivatives displayed promising anticancer activity, particularly against non-small cell lung cancer (NSCLC) cells (NCI-H460). Notably, several derivatives showed enhanced activity compared to the included reference drug, etoposide. Considering the influence of substituents at position 5 of the benzoxazole ring and positions 3 and 4 of the phenyl ring on the antiproliferative activity, it is evident that derivatives 41-48 bearing a methoxy group at position 3 generally exhibit higher activity compared to compounds 29-40, which lack substitution at position 3. Furthermore, derivatives substituted at position 4 with a morpholine substituent, as well as those with an N,N-diethyl group, exhibited higher activity compared to other evaluated benzoxazole derivatives. The in vitro antibacterial evaluation against Gram-positive and Gram-negative bacteria revealed that benzoxazole derivative 47 exhibited notable activity, against the Gram-negative bacterium Pseudomonas aeruginosa (MIC = 0.25 μg/mL) and the Gram-positive bacterium Enterococcus faecalis (MIC = 0.5 μg/mL). The results point out that this class of benzoxazoles can be efficiently synthesized using eco-friendly methods and represent promising candidates for further design and optimization aimed at developing potent antiproliferative agents.

Synthesis, Antibacterial, and Antibiofilm Activities of Imidazo[2,1-b]Thiazole Chalcone Derivatives: In Vitro and In Silico Studies

In recent years, imidazothiazole-chalcone conjugates have emerged as notable pharmacophores with potential applications in discovering biologically active compounds. This study focuses on synthesizing novel imidazo[2,1-b]thiazole chalcone derivatives through a facile and conventional process adhering to several principles of green chemistry, facilitating scalable production. The synthesized compounds underwent comprehensive spectroscopic analysis, including 1H NMR, 13C NMR, LC-MS, and FT-infrared (IR) techniques. Theoretical FT-IR and NMR analysis, frontier molecular orbitals (FMOs), and global reactivity descriptors were calculated and interpreted. Furthermore, molecular electrostatic potential (MEP) surface, Mulliken atomic charge, electron localization function (ELF), localized orbital locator (LOL), and quantum theory of atoms in molecules (QTAIM) were analyzed. The newly synthesized compounds were screened in vitro for their antibacterial and antibiofilm activities. In addition, computational docking studies were performed to gain further insights into molecular interactions and found to support the results.

Identification of AChE targeted therapeutic compounds for Alzheimer's disease: an in-silico study with DFT integration

Alzheimer's disease (AD) is a progressive neurodegenerative condition marked by cognitive deterioration and changes in behavior. Acetylcholinesterase (AChE), which hydrolyzes acetylcholine, is a key drug target for treating AD. This research aimed to identify new AChE inhibitors using the IMPPAT database. We used known drugs as a basis to search for similar chemicals in the IMPPAT database and created a library of 127 plant-based compounds. Initial screening of these compounds was performed using molecular docking, followed by an analysis of their drug-likeness and ADMET properties. Compounds with favorable properties underwent density functional theory (DFT) calculations to assess their electronic properties such as HOMO-LUMO gap, electron density, and molecular orbital distribution. These descriptors provided insights into each compound's reactivity, stability, and binding potential with AChE. Promising candidates were further evaluated through molecular dynamics (MD) simulations over 100 ns and MMPBSA analysis for the last 30 ns. Two compounds, Biflavanone (IMPHY013027) with a binding free energy of - 130.394 kcal/mol and Calomelanol J (IMPHY007737) with - 107.908 kcal/mol, demonstrated strong binding affinities compared to the reference molecule HOR, which has a binding free energy of - 105.132 kcal/mol. These compounds exhibited promising drug-ability profiles in both molecular docking and MD simulations, indicating their potential as novel AChE inhibitors for AD treatment. However, further experimental validation is necessary to verify their effectiveness and safety.

Assessing the efficacy of cinnamon compounds against H. pylori through molecular docking, MD Simulations and ADMET analyses

Antibiotics are the drugs that are used for the management of microbial diseases. However, these conventional synthetic drugs can harmfully affect the human health. Since phytochemicals are extracted from natural sources and, are hence relatively safer for human health, they are the enticing alternatives in this regard. Cinnamon is also one of those plants which is being employed as herbal medication for centuries against certain microbial infections due its significant therapeutic effectiveness. A well-known pathogenic bacterium called H. pylori causes a wide range of illnesses in human body. This pathogen's pathogenicity is determined by certain virulent proteins. In this study, some of such proteins, which included virB4, virB8, and virB9 were selected to evaluate the therapeutic efficiency of cinnamon compounds. These proteins were identified in different isolates of H. pylori. The structural modelling of all these proteins were performed initially in order to proceed them for molecular docking analysis. While, the docking studies illustrated that one of the cinnamon compounds, cinnamyl acetate, showed significant binding interactions with virB4 and virB9. However, benzyl benzoate which is another cinnamon compound, docked well with virB8. Afterwards, the MD simulations were incorporated to explore the interaction motions and structural stability of all the docked complexes. In this regard, the resultant maps of Bfactor, eigenvalues and elastic network model, among other factors ensured the structural stabilities of all the respective complexes. After these crucial estimations, benzyl benzoate and cinnamyl acetate underwent the ADMET investigation to assess their pharmacokinetic characteristics. SwissADME and ADMETLab 2.0 server were employed for this investigation. The compiled findings these servers revealed that both, benzyl benzoate and cinnamyl acetate, exhibited a significant level of pharmacokinetic and drug-likeness conformity.

In silico studies of alkaloids and their derivatives against N-acetyltransferase EIS protein from Mycobacterium tuberculosis

Antibiotic resistance against Mycobacterium tuberculosis (M.tb.) has been a significant cause of death worldwide. The Enhanced intracellular survival (EIS) protein of the bacteria is an acetyltransferase that multiacetylates aminoglycoside antibiotics, preventing them from binding to the bacterial ribosome. To overcome the EIS-mediated antibiotics resistance of M.tb., we compiled 888 alkaloids and derivatives from five different databases and virtually screened them against the EIS receptor. The compound library was filtered down to 87 compounds, which underwent additional analysis and filtration. Moreover, the top 15 most prominent phytocompounds were obtained after the drug-likeness prediction and ADMET screening. Out of 15, nine compounds confirmed the maximum number of hydrogen bond interactions and reliable binding energies during molecular docking. Additionally, the Molecular dynamics (MD) simulation of nine compounds showed the three most stable complexes, further verified by re-docking with mutated protein. The density functional theory (DFT) calculation was performed to identify the HOMO-LUMO energy gaps of the selected three potential compounds. Finally, our selected top lead compounds i.e., Alkaloid AQC2 (PubChem85634496), Nobilisitine A (ChEbi68116), and N-methylcheilanthifoline (ChEbi140673) demonstrated more favourable outcomes when compared with reference compounds (i.e., 39b and 2i) in all parameters used in this study. Therefore, we anticipate that our findings will help to explore and develop natural compound therapy against multi and extensively drug-resistant strains of M.tb.Communicated by Ramaswamy H. Sarma.

Development of substituted benzylidene derivatives as novel dual cholinesterase inhibitors for Alzheimer's treatment

Leading pathological markers of Alzheimer's disease (AD) include Acetylcholinesterase (AChE), Butyrylcholinesterase (BuChE), Amyloid beta (Aβ) and reactive oxygen species (ROS). Indole derivatives were identified and optimized to improve the potency against AChE, BuChE, Aβ and ROS. The lead molecule IND-30 was found to be selective for AChE (selectivity ratio: 22.92) in comparison to BuChE and showed maximum inhibition potential for human AChE (IC50: 4.16 ± 0.063 μM). IND-30 was found to be safe on the SH-SY5Y cell line until the dose of 30 mM. Further, molecule IND-30 was evaluated for its ability to inhibit AChE-induced Aβ aggregation at 0.5, 10 and 20 μM doses. Approximately, 50% of AChE-induced Aβ aggregation was inhibited by IND-30. Thus, IND-30 was found to be multitargeting for AD.

DFT, ADMET and Molecular Docking Investigations for the Antimicrobial Activity of 6,6'-Diamino-1,1',3,3'-tetramethyl-5,5'-(4-chlorobenzylidene)bis[pyrimidine-2,4(1H,3H)-dione]

Heterocyclic compounds, including pyrimidine derivatives, exhibit a broad variety of biological and pharmacological activities. In this paper, a previously synthesized novel pyrimidine molecule is proposed, and its pharmaceutical properties are investigated. Computational techniques such as the density functional theory, ADMET evaluation, and molecular docking were applied to elucidate the chemical nature, drug likeness and antibacterial function of molecule. The viewpoint of quantum chemical computations revealed that the molecule was relatively stable and has a high electrophilic nature. The contour maps of HOMO-LUMO and molecular electrostatic potential were analyzed to illustrate the charge density distributions that could be associated with the biological activity. Natural bond orbital (NBO) analysis revealed details about the interaction between donor and acceptor within the bond. Drug likeness and ADMET analysis showed that the molecule possesses the agents of safety and the effective combination therapy as pharmaceutical drug. The antimicrobial activity was investigated using molecular docking. The investigated molecule demonstrated a high affinity for binding within the active sites of antibacterial and antimalarial proteins. The high affinity of the antibacterial protein was proved by its low binding energy (-7.97 kcal/mol) and a low inhibition constant value (1.43 µM). The formation of four conventional hydrogen bonds in ligand-protein interactions confirmed the high stability of the resulting complexes. When compared to known standard drugs, the studied molecule displayed a remarkable antimalarial activity, as indicated by higher binding affinity (B.E. -5.86 kcal/mol & Ki = 50.23 M). The pre-selected molecule could be presented as a promising drug candidate for the development of novel antimicrobial agents.

Antimicrobial Activity and DFT Studies of a Novel Set of Spiropyrrolidines Tethered with Thiochroman-4-one/Chroman-4-one Scaffolds

A novel series of 14 spiropyrrolidines bearing thiochroman-4-one/chroman-4-one, and oxindole/acenaphthylene-1,2-dione moieties were synthesized and characterized by spectroscopic techniques, as well as by three X-ray diffraction studies, corroborating the stereochemistry. Quantum chemical calculations studies, using the DFT approach, were performed to rationalize the stereochemical outcome. These N-heterocycles were evaluated for their antibacterial and antifungal activities against some pathogenic organisms. Several compounds displayed moderate to excellent activity towards the screened microbe strains in the study compared to Amoxicillin (AMX), Ampicillin (AMP), and Amphotericin B. Furthermore, a structural activity relationship (SAR) was established considering the synthesized compounds. Pharmacokinetic studies reveal that these derivatives exhibit an acceptable predictive ADMET profile (Absorption, Distribution, Metabolism, Excretion and Toxicity) and good drug-likeness.