Investigation of Novel Quinoline-Thiazole Derivatives as Antimicrobial Agents: In Vitro and In Silico Approaches

Synthesis of new N-(5,6-methylenedioxybenzothiazole-2-yl)-2-[(substituted)thio/piperazine]acetamide/propanamide derivatives and evaluation of their AChE, BChE, and BACE-1 inhibitory activities

In this study, the synthesis of N-(5,6-methylenedioxybenzothiazole-2-yl)-2-[(substituted)thio/piperazine]acetamide/propanamide derivatives (3a-3k) and to investigate their acetylcholinesterase (AChE), butyrylcholinesterase (BChE) and β-secretase 1 (BACE-1) inhibition activity were aimed. Mass, 1H NMR, and 13C NMR spectra were utilized to determine the structure of the synthesized compounds. Compounds 3b, 3c, 3f, and 3j showed AChE inhibitory activity which compound 3c (IC50 = 0.030 ± 0.001 µM) showed AChE inhibitory activity as high as the reference drug donepezil (IC50 = 0.0201 ± 0.0010 µM). Conversely, none of the compounds showed BChE activity. Compounds 3c and 3j showed the highest BACE-1 inhibitory activity and IC50 value was found as 0.119 ± 0.004 µM for compound 3j whereas IC50 value was 0.110 ± 0.005 µM for donepezil, which is one of the reference substance. Molecular docking studies have been carried out using the data retrieved from the server of the Protein Data Bank (PDBID: 4EY7 and 2ZJM). Using in silico approach behavior active compounds (3c and 3j) and their binding modes clarified.

Design and synthesis of phenoxy methyl-oxadiazole compounds against Alzheimer's disease

This study examines the synthesis and evaluation of 11 newly developed compounds as potential anti-Alzheimer's agents that occur via cholinesterase and β-secretase inhibition. The compounds were tested for their inhibitory activity against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) using the modified Ellman method. The results showed that several compounds exhibited significant inhibition of AChE, particularly compounds 6d, 7a, and 7e, which demonstrated high inhibitory activity at lower concentrations, with IC50 values of 0.120, 0.039, and 0.063 µM, respectively. However, the compounds showed limited effectiveness against BChE, with only a few compounds exhibiting moderate inhibition. Compound 7e showed an inhibitory effect against BACE-1 close to that of the standard drug. Structural analysis revealed that the compounds with substituted benzothiazole and thiazole moieties exhibited the most promising inhibitory activity. This study provides valuable insights into the potential of these synthesized derivatives as a treatment against Alzheimer's disease. Moreover, the structure, stability, and properties of the active compounds were further investigated using density functional theory calculations. As a final note, the utilization of molecular docking and molecular dynamics simulation studies allowed us to elucidate the action mechanism of the active compounds and gain insights into the structure-activity relationship against AChE and β-secretase proteins. These computational techniques provide valuable information on the binding modes, interactions with target enzymes, dynamic behavior, and conformational changes of the compounds, enabling a comprehensive understanding of their biological activity.

New N-(1,3,4-thiadiazole-2-yl)acetamide derivatives as human carbonic anhydrase I and II and acetylcholinesterase inhibitors

Various carbonic anhydrase (CA) enzyme isoforms are known today. In addition to the use of CA inhibitors as diuretics, antiepileptics and antiglaucoma agents, the inhibition of other specific isoforms of CA was reported to have clinical benefits in cancers. In this study, two groups of 1,3,4-thiadiazole derivatives were designed and synthesized to act as human CA I and II (hCA I and hCA II) inhibitors. The activities of these compounds were tested in vitro and evaluated in silico studies. The activity of the synthesized compounds was also tested against acetylcholinesterase (AChE) to evaluate the relation of the newly designed structures to the activity against AChE. The synthesized compounds were analyzed by 1H NMR,13C NMR and high-resolution mass spectroscopy (HRMS). The results displayed a better activity of all the synthesized compounds against hCA I than that of the commonly used standard drug, Acetazolamide (AAZ). The compounds also showed better activity against hCA II, except for compounds 5b and 6b. Only compounds 6a and 6c showed superior activity against AChE compared to the standard agent, tacrine (THA). In silico studies, including absorption, distribution, metabolism and excretion (ADME) and drug-likeness evaluation, molecular docking, molecular dynamic simulations (MDSs) and density functional theory (DFT) calculations, were compatible with the in vitro results and presented details regarding the structure-activity relationship.Communicated by Ramaswamy H. Sarma.

Design and synthesis of novel dithiazole carboxylic acid Derivatives: In vivo and in silico investigation of their Anti-Inflammatory and analgesic effects

Inflammation is a complex set of interactions that can occur in tissues as the body's defensive response to infections, trauma, allergens, or toxic compounds. Therefore, in almost all diseases, it can be observed because of primary or secondary reasons. Since it is important to control and even eliminate the symptoms of inflammation in the treatment of many diseases, anti-inflammatory and analgesic drugs are always needed in the clinic. Therefore, the discovery of new anti-inflammatory/analgesic drugs with increased effectiveness and safer side effect profiles is among the popular topics of medicinal chemistry. Therefore, in this study, in order to synthesize and diversify new molecules, we focused on the N,N-dithiazole carboxylic acid core and linked it with the chalcone functional group. The final eleven molecules were analyzed via HRMS, 1H NMR, and 13C NMR. The antinociceptive effects of the test compounds were examined by tail-clip, hot-plate, and formalin methods in mice, while their anti-inflammatory activities were investigated by carrageenan-induced inflammation tests in rats. The motor activities of the experimental animals were evaluated using an activity-meter device. Obtained findings revealed that none of the test compounds (10 mg/kg) were effective in the tail-clip and hot-plate tests. However, compounds 4b, 4c, 4f, 4 h, and 4 k in the serial shortened the paw-licking times of mice in the late phase of the formalin test indicating that these compounds had peripherally-mediated antinociceptive effects. The same compounds, moreover, showed potent anti-inflammatory effects by significantly reducing paw edema of rats in the inflammation tests. To provide an approach to pharmacological findings regarding possible mechanisms of action, the binding modes of the most active compounds were investigated by in silico approaches. The results of molecular docking studies indicated that the anti-inflammatory and analgesic activities of the compounds might be related to the inhibition of both COX-1 and COX-2 isoenzymes. Findings obtained from in silico studies showed that 4 k, which was chosen as a model for its analogs in the series, forms strong bindings to the basic residues (Arg120, Tyr355), side pocket loop area and deep hydrophobic regions of the enzyme. Moreover, results of the molecular dynamics simulation studies revealed that ligand-COX enzyme complexes are quite stable. Obtained results of in vivo and in silico studies are in harmony, and all together point out that compounds 4b, 4c, 4f, 4 h, and 4 k have significant anti-inflammatory and analgesic activities with good ADME profiles. The potential of the derivatives, whose pharmacological activities were revealed for the first time in this study, as anti-inflammatory and analgesic drug candidates, needs to be evaluated through comprehensive clinical studies.