In vitro and in vivo assessment of newer quinoxaline-oxadiazole hybrids as antimicrobial and antiprotozoal agents.

A new series of N-(substituted-phenyl)-2-[5-(quinoxalin-2-yloxymethyl)-[1,3,4] oxadiazol-2-ylsulfanyl]-acetamides (5a-o) was designed and synthesised from the parent compound 2-hydroxy quinoxaline (1) through a multistep reaction sequence and was characterised by spectral and elemental analyses. All of the compounds synthesised were evaluated for their antimicrobial and antiprotozoal activities. The results revealed that quinoxaline-based 1,3,4-oxadiazoles displayed promising antibacterial, antifungal and anti-Trypanosoma cruzi activities compared with reference drugs, particularly the lead compound 5l in a short-term in vivo model in T.

Synthesis and biological evaluation of newer 1,3,4-oxadiazoles incorporated with benzothiazepine and benzodiazepine moieties.

A series of thiazepines and diazepines having 1,3,4-oxadiazole moiety were synthesized, and they were analyzed for their in vitro antimicrobial activity against several bacteria (Staphylococcus aureus, Staphylococcus pyogenes, Escherichia coli, and Pseudomonas aeruginosa) and fungi (Candida albicans, Aspergillus niger, and Aspergillus Clavatus) and protozoa (Entamoeba histolytica, Giardia lamblia, Trypanosoma cruzi and Leishmania mexicana). Few of the selected compounds were tested for their antitubercular activity. However, it was noticed that the potency of final analogs against each strain placed reliance on the type of substituent present on aryl ring of oxadiazole as well as presence of thiophene, pyridine, and furan at benzothiazepines and benzodiazepines.

The autoinducer synthases LuxI and AinS are responsible for temperature-dependent AHL production in the fish pathogen Aliivibrio salmonicida.

Background: Quorum sensing (QS) is a cell-to-cell communication system used by bacteria to regulate activities such as virulence, bioluminescence and biofilm formation. The most common QS signals in Gram-negative bacteria are N-acyl-homoserine lactones (AHLs). Aliivibrio salmonicida is the etiological agent of cold water vibriosis in Atlantic salmon, a disease which occurs mainly during seasons when the seawater is below 12°C.

New 2-benzylsulfanyl-nicotinic acid based 1,3,4-oxadiazoles: their synthesis and biological evaluation.

A novel series of 5-(2-benzylsulfanyl-pyridin-3-yl)-2-(substituted)-sulfanyl-1,3,4-oxadiazoles 6a-j were synthesized from key intermediate 5-(2-benzylsulfanyl-pyridin-3-yl)-3H-[1,3,4]oxadiazole-2-thione 5. Nucleophilic substitution reactions with different electrophiles (E+), such as haloacetate and haloalkyl groups, were performed to get target compounds 6a-j. Compounds were characterized by NMR, mass, IR spectra and C, H, N analyses.