Efficiency of newly prepared thiazole derivatives against some cutaneous fungi

Design, synthesis, antimicrobial screening and molecular modeling of novel 6,7 dimethylquinoxalin-2(1H)-one and thiazole derivatives targeting DNA gyrase enzyme

New 6,7-dimethylquinoxalin-2(1H)-one and hydrazineylidene thiazol-4-one derivatives were synthesized, and evaluated for their in vitro antimicrobial activity. The obtained results revealed marked antimicrobial potential against four bacterial, and two fungal strains. Both 6,7-dimethyl-3-(2-(4-nitrophenyl)-2-oxoethyl)quinoxalin-2(1H)-one (4d), and 2-(2-(9H-fluoren-9-ylidene)hydrazineyl)-5-(2-(p-tolyl)hydrazineylidene)thiazol-4(5H)-one (11b) displayed significant antibacterial and antifungal activities having MIC ranges (1.98-15.6 mg/mL) and (1.98-3.9 mg/mL) compared to Tetracycline and Amphotericin B as standard drugs. In addition, they showed noticeable inhibitory activity against DNA gyrase enzyme. Interestingly the thiazole derivative (11b) showed marked inhibitory activity against DNA gyrase with IC₅₀ = 7.82 ± 0.45 μM better than that of ciprofloxacin. The time-kill kinetics profile of the most active compounds against S. aureus and E. coli microorganisms displayed both concentration dependent and time dependent reduction in the number of viable cells. Furthermore, molecular docking study of both compounds in the DNA gyrase binding site was performed, showing agreement with the in vitro inhibitory activities.

New nematogenic conical-shaped supramolecular H-bonded complexes for solar energy investigations

New conical-shaped geometrical supramolecular H-bonded liquid crystal complexes were formed through 1:2 intermolecular interactions of H-bonding between flexible core (adipic acid, A) and lateral chloro-substituted azopyridines (Bn). The chains of the terminally alkoxy substituted base (n) were changed between 8 and 16 carbons. Mesomorphic and optical examinations of the prepared complexes were measured via differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). Fourier-transform infrared spectroscopy (FT-IR) was used to confirm the Fermi bands of the H- bonding interactions. Induced nematogenic mesophases that cover the whole lengths of alkoxy-chains were detected. The non-linear geometries of the designed supramolecular complexes were also confirmed via Density functional theory (DFT) calculations. It was found that the length of terminal alkoxy chain of the base moiety highly affects the geometrical structure of the investigated complexes. Moreover, it increases the thermodynamic energy and influences the geometrical parameters. The electrical properties of each of the acid component (A), the base (B16) and their 1:2 complex (A/2B16) were evaluated using the Keithley measurement-source unit. The optical properties studies showed that the influences in the optical absorption and the reduction of the energy gap of the complex compared to its individual components made the resulted supramolecular H-bonded complex soft material suitable for solar energy investigations.

Design, docking, and DFT investigations of 2,6-bis(3,4-dihydroxyphenyl)-3-phenethylpiperidin-4-one

In the present investigation, a totally of 673 newly designed 2,6-diphenyl piperidin-4-one derivatives are docked with 2B7N protein of Helicobacter pylori which causes peptic ulcer disease. The docking studies revealed that 2,6-bis(3,4-dihydroxyphenyl)-3-phenethylpiperidin-4-one (BDPO) is identified as the most promising new compound with active nature against 2B7N with a binding affinity value of -8.0 Kcal/mol. The molecular structure of BDPO has been analyzed by DFT based theoretical calculations at the B3LYP/6-311++G(d,p) level of theory using the Gaussian 16W program package. The molecular electrostatic potential, Frontier molecular energy gap, and Mulliken population analysis have been used to understand the reactive site of the molecule. The stability and hyper-conjugative interactions were studied by natural bond orbital analysis (NBO) based on a second-order perturbation approach. The thermodynamic properties like thermal energy, specific heat capacity, and entropy at different temperatures were also calculated. The calculated first-order hyper polarizability results show that the title compound is 25.3 times greater than that of standard reference material, urea. So the title molecule is a good non-linear material. Also, this molecule has Van der Waals attraction and steric effect. It undergoes local excitation for the first five excitations.

Antimicrobial evaluation of thiadiazino and thiazolo quinoxaline hybrids as potential DNA gyrase inhibitors; design, synthesis, characterization and morphological studies

A series of thiadiazino[5,6-b]quinoxaline and thiazolo[4,5-b]quinoxaline derivatives was designed and synthetized from the reaction of 2,3-dichloro-6-(morpholinosulfonyl)quinoxaline (2) with thiosemicarbazide or thiocarbohydrazide and thiourea derivatives to give nineteen quinoxaline derivatives 3-16. All the synthesized compounds were evaluated for in vitro antimicrobial potential against various bacteria and fungi strains that showed considerable antimicrobial activity against tested microorganisms. The most potent compounds 2, 7, 9, 10, 12 and 13c were exhibited bactericidal activity, in addition to fungistatic activity by dead live assay. Moreover, these compounds showed a significant result against all multi-drug resistance (MDRB) used especially compound 13c that displayed the best results with MICs of MDRB (1.95, 3.9, 2.6, 3.9 µg/mL) for stains used in this study, compared with Norfloxacin (1.25, 0.78, 1.57, 3.13 µg/mL). Also, cytotoxicity on normal cell (Vero cells ATCC CCL-81) by MTT assay was performed with lower toxicity results. Additionally, morphological studies, immunostimulatory potency and DNA gyrase inhibition assay of most active compounds was done. A molecular docking study has also been carried out to support the effective binding of the most promising compounds at the active site of the target enzyme S. aureus DNA gyrase (2XCT).

Role of sulphur-heterocycles in medicinal chemistry: An update

From many decades, S-heterocycles have maintained their status as an important part and core of FDA approved drugs and medicinally active compounds. With exhaustive exploration of nitrogen heterocycles in medicinal chemistry, researchers have shifted their interest towards other heterocycles, especially, S-heterocycles. Thus several attempts have been made to synthesize a variety of new sulphur containing compounds with high medicinal value and low toxicity profile, in comparison to previous N-heterocycles. Till today, S-heterocycle containing compounds have been largely reported as anticancer, antidiabetic, antimicrobial, antihypertension, antivral, antinflammatory etc. In this review, the authors have tried to provide a critical analysis of synthesis and medicinal attributes of sulphur containing heterocycles such as thiirane, thiophene, thiazole, thiopyran, thiazolidine etc reported within last five years to emphasize the significance and usefulness of these S-heterocycles in the drug discovery process.