A facile synthesis of quinoxalines by using SO₄²⁻/ZrO₂-TiO₂ as an efficient and recyclable heterogeneous catalyst

Quinoxaline derivatives have been synthesized in good to excellent yields by the cyclocondensation reaction of o-pheneylenediamine with substituted phenacyl bromides/benzil in the presence of SO42−/ZrO2-TiO2 as an efficient and heterogeneous catalyst. The catalyst can be recovered up to five catalytic cycles without significant loss in catalytic activity. The reported SO42−/ZrO2-TiO2 catalyst has been thoroughly characterized by using infrared spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and powder X-ray diffraction (XRD). Here, we have used ethanol as a green solvent in this cyclocondensation. This new method has several advantages, such as excellent yields, short reaction time, nontoxic, and easily recoverable catalyst.</p

Dicationic liquid mediated synthesis of tetrazoloquinolinyl methoxy phenyl 4-thiazolidinones and their antibacterial and antitubercular evaluation

In a search of new potentially active antitubercular agents here we have synthesized 3-substituted phenyl-2-(4-(tetrazolo[1,5-a]quinolin-4-ylmethoxy)phenyl)thiazolidin-4-ones (8a-l) and evaluated their antibacterial, particularly antitubercular activity. These have been conveniently synthesized by performing one-pot cyclocondensation of 4-(tetrazolo[1,5-a]quinolin-4-ylmethoxy)benzaldehyde, anilines and mercaptoacetic acid in dicationic ionic liquid, (3-methyl-1-[3-(methyl-1H-imidazolium-1-yl)propyl]-1H-imidazolium dibromide [C3(MIM)2-2Br]) and obtained excellent yields of (8a-l). 4-Thiazolidinones (8a-l) were thoroughly characterized by their spectral analyses. These compounds have been screened for their in vitro antitubercular activity against Mycobacterium tuberculosis H37Ra and Mycobacterium bovis (BCG). The compounds 8a, 8c, and 8e exhibited notable in vitro antitubercular activity compare to the reference, Rifampicin. Molecular docking study has also been performed to know the binding mode of these analogs in to the active site of DprE1 enzyme. The synthesized compounds were also evaluated for their in vitro antibacterial activity and amongst them compound 8k has shown moderate activity against both gram-negative and gram-positive bacterial strains.</p

Synthesis, antitubercular evaluation and molecular docking studies of phthalimide bearing 1,2,3-triazoles

In a search for safer and potent antitubercular agents, here a library of newly substituted dioxoisoindolinylmethyl-triazolyl-N-phenylacetamide derivatives (5a–l) has been synthesized via click chemistry approach. All synthesized compounds were evaluated for their antitubercular activity against Mycobacterium tuberculosis H37Rv (MTB). Among the screened compounds, 5d, 5e, 5h, and 5l showed good antitubercular activity. The compounds 5d and 5l have shown very effective antitubercular activity against Mycobacterium tuberculosis H37Rv (MTB) with MIC 12.5 μg/mL. All the newly synthesized compounds were thoroughly characterized by 1H NMR, 13C NMR, and HRMS spectral data. We further performed exploratory docking studies on the crystal structure of Mycobacterium tuberculosis enoyl reductase to demonstrate the mechanism of antitubercular activity.</p

Meglumine Sulfate: An Efficient Catalyst for the Synthesis of Quinoxalines

Meglumine Sulfate: An Efficient Catalyst for the Synthesis of Quinoxaline

Synthesis, anticancer and antimicrobial evaluation of new pyridyl and thiazolyl clubbed hydrazone scaffolds

A series of new hydrazones bearing pyridyl and thiazolyl scaffolds have been synthesized and evaluated for their in vitro anticancer and antimicrobial activities. The anticancer activity was evaluated against the A549 lung cancer cell line. The eight hydrazone derivatives have shown better anticancer activity than positive control doxorubicin against the A549 lung cancer cell line. The antimicrobial activity was evaluated against bacterial and fungal pathogens by using well diffusion method. The four hydrazone derivatives have displayed good antimicrobial activities. Molecular docking studies of the synthesized hydrazone derivatives revealed good binding via hydrogen bond interactions with key residues on active sites as well as neighboring residues with an active site of Focal adhesion kinase (PDB ID 2JKO). A computational study for the prediction of absorption, distribution, metabolism, and excretion (ADME) properties of all compounds has also been performed.</p

Theophylline Hydrogen Sulfate: A green and efficient catalyst for synthesis of 3,3-bis(1<i>H</i>-indol-3-yl)indolin-2-one derivatives

A new green protocol for the synthesis of 3,3-bis(1H-indol-3-yl)indolin-2-one derivatives by reacting isatin with indole in the presence of Theophylline Hydrogen Sulfate as a new solid acid, a highly effective and reusable catalyst. This reaction was carried out by using aqueous ethanol as a solvent system at room temperature with constant stirring. A highly effective solid acid catalyst, short reaction time, better to excellent yields of the products, safe and environmentally benign reaction conditions are some of the benefits of the present synthetic method.</p

DTP/SiO₂ Assisted Synthesis of New Benzimidazole-Thiazole Conjugates Targeting Antitubercular and Antioxidant Activities

A series of new substituted benzimidazole-thiazoles (9a–l) have been designed and synthesized using 2-aminothiazole as a starting material by using molecular hybridization approach. The newly synthesized compounds were characterized by 1H NMR, 13C NMR and HRMS analyses. The compounds (9a–l) were evaluated for their in vitro antitubercular activity against Mtb (MTCC 300) strain. Among the screened compounds 9a, 9b, 9c and 9d have displayed promising antitubercular activity with MIC 7.55, 4.60, 15.39 and 28.38 μg/mL, respectively. All the compounds were further evaluated for their DPPH radical scavenging activity. The compounds 9a, 9b and 9d were exhibited excellent radical scavenging activity. In addition to this, single crystal structure of compound 9a was also studied. Furthermore, the high potency of these molecules was supported by ADME properties prediction as well as molecular docking study to gain an insight into the binding mode and affinity toward mycobacterial InhA.</p

Synthesis of New Amide Linked Biphenoloxy 1,2,3-Triazoles as Antitubercular and Antimicrobial Agents

New 1,2,3-triazoles bearing biphenoloxymethyl and acetanilido moieties (5a-5l) have been synthesized, starting from 4-phenylphenol (1) following click chemistry approach. The synthesized compounds have been thoroughly characterized by their 1H NMR, 13C NMR and HRMS spectral data. These compounds were evaluated for their in vitro antitubercular activity against Mycobacterium tuberculosis H37Rv and antimicrobial activity against pathogenic microbia. Among the screened compounds, 5a and 5i have displayed notable antitubercular activity with MIC 25 µg/mL. Compounds 5a, 5b, 5c, 5 g, 5i and 5 l have shown effective inhibition against most of tested pathogens. Molecular docking results of compounds 5a and 5i show the binding modes of the synthesized compounds into the active site of mycobacterial enoyl reductase. The synthesized compounds have also been analyzed for their ADME properties. By considering all these results, the present research work will offer a promising lead series for discovery of emerging potent antitubercular agents.</p