Pyridine-2(1H)-thione in heterocyclic synthesis: synthesis and antimicrobial activity of some new thio-substituted ethyl nicotinate, thieno[2,3-b]pyridine and pyridothienopyrimidine derivatives

New substituted pyrazolones and dipyrazolotriazines as promising tyrosyl-tRNA synthetase and peroxiredoxin-5 inhibitors: Design, synthesis, molecular docking and structure-activity relationship (SAR) analysis

New substituted pyrazolone and dipyrazolotriazine derivatives have been synthesized, designed and well characterized as promising dual antimicrobial/antioxidant agents to overcome multidrug resistant bacteria (MDR), oxidative stress and their related diseases. Among all strains, S. aureus was found to be the most susceptible for all compounds except 10b and 12b. Out of the three investigated series, sulfonamide analogues 5a-c displayed excellent antibacterial activity with 5b (MIC = 7.61 μM) and 5a (MIC = 8.98 μM) displaying activity that exceeds the reference drug tetracycline (MIC = 11.77 μM). The same sulfonamide derivatives 5a-c demonstrates high ABTS scavenging capacity comparable to standard. Moreover, the structure-activity relationship (SAR) revealed that benzenesulfonamide is a crucial group for enhancing activity. Molecular docking studies of the potent analogues were performed by targeting the crystal structures of S. aureus tyrosyl-tRNA synthetase and human peroxiredoxin-5 enzymes and the obtained results supported well the in vitro data revealing stronger binding interactions. Pharmacokinetics prediction together with modeling outcomes suggests that our sulfonamide derivatives may serve as useful lead compounds for the treatment of infectious disease.

Synthesis and Biological Evaluation of New Pyridothienopyrimidine Derivatives as Antibacterial Agents and Escherichia coli Topoisomerase II Inhibitors

The growing resistance of bacteria to many antibiotics that have been in use for several decades has generated the need to discover new antibacterial agents with structural features qualifying them to overcome the resistance mechanisms. Thus, novel pyridothienopyrimidine derivatives (2a,b-a,b) were synthesized by a series of various reactions, starting with 3-aminothieno[2,3-b]pyridine-2-carboxamides (1a,b). Condensation of compounds 1a,b with cyclohexanone gave 1'H-spiro[cyclohexane-1,2'-pyrido[3',2':4,5]thieno[3,2-d]pyrimidin]-4'(3'H)-ones (2a,b), which in turn were utilized to afford the target 4-substituted derivatives (3a,b-8a,b). In vitro antibacterial activity evaluations of all the new compounds (2a,b-8a,b) were performed against six strains of Gram-negative and Gram-positive bacteria. The target compounds showed significant antibacterial activity, especially against Gram-negative strains. Moreover, the compounds (2a,b; 3a,b; 4a,b; and 5a,b) that exhibited potent activity against Escherichia coli were selected to screen their inhibitory activity against Escherichia coli topoisomerase II (DNA gyrase and topoisomerase IV) enzymes. Compounds 4a and 4b showed potent dual inhibition of the two enzymes with IC₅₀ values of 3.44 µΜ and 5.77 µΜ against DNA gyrase and 14.46 µΜ and 14.89 µΜ against topoisomerase IV, respectively. In addition, docking studies were carried out to give insight into the binding mode of the tested compounds within the E. coli DNA gyrase B active site compared with novobiocin.

Synthesis and Antibacterial Activities of Different Five-Membered Heterocyclic Rings Incorporated with Pyridothienopyrimidine

Certain pyridothienopyrimidine derivatives exhibit antiatheroscleorotic, antibacterial, antiviral, antidepressant, antidiabetic, antihypertensive, anticancer, antihistaminic, antiallergic, anti-inflammatory, spasmolytic, analgesic, and neurotropic activities. 4-Hydrazino-7,9-dimethylpyrido[3',2':4,5]thieno[3,2-d]pyrimidine (1) is a reported pyridothienopyrimidine derivative. In the current study, (1) has been reacted with different reagents to obtain 12 new pyridothienopyrimidine derivatives. The newly synthesized five-membered heterocyclic rings incorporated with pyridothienopyrimidines have been screened for their antibacterial activities. The results encourage further studies on other possible biological activities.

Novel phthalimide based analogues: design, synthesis, biological evaluation, and molecular docking studies

Pyrazolylphthalimide derivative 4 was synthesized and reacted with different reagents to afford the target compounds imidazopyrazoles 5-7, pyrazolopyrimidines 9, 12, 14 and pyrazolotriazines 16, 17 containing phthalimide moiety. The prepared compounds were established by different spectral data and elemental analyses. Additionally, all synthesized derivatives were screened for their antibacterial activity against four types of Gram + ve and Gram-ve strains, and for antifungal activity against two fungi micro-organisms by well diffusion method. Moreover, the antiproliferative activity was tested for all compounds against human liver (HepG-2) cell line in comparison with the reference vinblastine. Moreover, drug-likeness and toxicity risk parameters of the newly synthesized compounds were calculated using in silico studies. The data from structure-actvity relationship (SAR) analysis suggested that phthalimide derivative bearing 3-aminopyrazolone moiety, 4 illustrated the best antimicrobial and antitumor activities and might be considered as a lead for further optimization. To investigate the mechanism of the antimicrobial and anticancer activities, enzymatic assay and molecular docking studies were carried out on E. coli topoisomerase II DNA gyrase B and VEGFR-2 enzymes.