5-Nitroimidazole-based 1,3,4-thiadiazoles: heterocyclic analogs of metronidazole as anti-Helicobacter pylori agents.

A series of 5-nitroimidazole-based 1,3,4-thiadiazoles were prepared and tested for antibacterial activity against Helicobacter pylori. The anti-H. pylori activity of target compounds along with the commercially available antimicrobial metronidazole was evaluated by comparing the inhibition-zone diameters determined by the paper disc diffusion bioassay. From our bioassay results against 20 clinical isolates it is evident that piperazinyl, 4-methylpiperazinyl, 3-methylpiperazinyl, and 3,5-dimethylpiperazinyl analogs (6a, 6b, 6e, and 6f, respectively) and pyrrolidine derivative 7 had strong activity at 0.5 µg/disc (average of inhibition zone > 20 mm) while metronidazole had no activity at this dose. Compound 6f containing the 3,5-dimethylpiperazinyl moiety at the 2-position of the 5-(1-methyl-5-nitro-1H-imidazol-2-yl)-1,3,4-thiadiazole skeleton was the most potent compound tested at low concentrations.

Discovery of a novel nitroimidazolyl-oxazolidinone hybrid with potent anti Gram-positive activity: Synthesis and antibacterial evaluation.

A number of linezolid analogues containing a nitroaryl-1,3,4-thiadiazole moiety, were prepared and evaluated as antibacterial agents against a panel of Gram-positive and Gram-negative bacteria. Among synthesized compounds, nitrofuran analogue 1b exhibited more potent inhibitory activity, with respect to other synthesized compounds and reference drug linezolid. The target compounds were also assessed for their cytotoxic activity against normal mouse fibroblast (NIH/3T3) cells using MTT assay. The results indicated that compound 1c exhibit potent antibacterial activity against Gram-positive bacteria at non-cytotoxic concentrations.