Synthesis of Novel Nalidixic Acid‐Based 1,3,4‐Thiadiazole and 1,3,4‐Oxadiazole Derivatives as Potent Antibacterial Agents

Abstract

Novel nalidixic acid-based 1,3,4-thia(oxa)diazoles, their thio ethers, sulfones, bis mercapto, and Mannich bases were synthesized and characterized by Infrared spectra, 1 H NMR, 13C NMR, and elemental analysis. These compounds were evaluated for their antibacterial activity against two Gram-positive and three Gram-negative bacteria. The preliminary bioassay showed that most of the compounds had better antibacterial activity than the parent compounds, 1,3,4-thia(oxa)diazoles, at the dosage 50 lg ⁄ mL toward five test bacteria. Four Mannich bases of nalidixic acid-based 1,3, 4-thiadiazole exhibited maximum antibacterial activity against Bacillus subtilis, Klebsiella pneumoniae, and Pseudomonas aeruginosa with minimum inhibitory concentration in the range of 6.25-125 lg ⁄ mL.

Synthesis and in vitroAntimicrobial Activity of Nalidixic Acid Hydrazones

“…Then in the second step, the obtained ester (1) was converted to appropriate hydrazide by the reaction with hydrazine hydrate. Finally in the third step of synthesis, the desired hydrazones of nalidixic acid (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16) were synthesized by a condensation reaction of nalidixic acid hydrazide (2) with various substituted (hetero)aromatic aldehydes. Using the aforementioned reactions, 12 new nalidixic acid-based hydrazones were obtained (3,4 and 7-16).…”

“…It acts against bacteria by selectively inhibiting the type II topoisomerase DNA gyrase and topoisomerase IV, enzymes that play a critical role in bacterial cell growth and division [2]. Structure activity relationship of compounds based on nalidixic acid [3][4][5] has led to a large group of synthetic antibacterial agents collectively known as the quinolones [6].…”

Synthesis of New -1,3,4-Thiadiazoles Substituted with Oxazepine and Benzoxazepine Moieties

“…Thiadiazoles are easily metabolized by biochemical reactions and they are noncarcinogenic in nature 2 . Thiadiazoles and their derivatives exhibit wide range of pharmacological activities such as antimicrobial activity 3 , antidepressant, cardiotonic 4 , antibacterial activity against Klebsiella pneumonia 5 , antitubercular 6,7 , anticonvulsant 8 , antileshmanial , analgesic 9 , antiinflammtory 10 , anticancer 11 , phosphodiesterase inhibitors 12 and effect on Tyrosinase enzyme 13 . This diversity of biological activity may be due to the presence of -N=C-S moity 14,15 .…”

Synthesis and antifungal activity of novel 2,5-disubstituted-1,3,4-oxadiazoles containing benzimidazole moiety

“…1,3,4-Oxadiazole derivatives have been reported to have a wide range of biological activities, including antiin ammatory, 1) anticancer, 2) antiviral, 3) antibacterial, 4) antifungal 5) and herbicidal 6) activities. Currently, many attentions are directed toward the discovery and development of novel 1,3,4-oxadiazole fungicides.…”