1,2,4-triazole-3-one Schiff bases disrupt cell membrane integrity of both Gram-positive and -negative bacteria.

Triazoles have significant antibacterial and antifungal properties that protect against dangerous fungus, bacteria, pathogens, and even antibiotic-resistant microbes that lead to infectious disorders and food degradation. Although they are known to target a number of essential metabolic pathways in bacterial cells, very little is known about how they affect the integrity of the cell membrane. In the current investigation, we compared the antibacterial activity of various distinct substituted 1,2,4-triazole-3-one Schiff base derivatives and found that bis-1,2,4-triazole-3-one Schiff bases have higher antibacterial activity against both Gram-positive and Gram-negative bacteria than 1,2,4-triazole-3-one Schiff bases. We further show that these compounds enhance ionic cell membrane permeability more than the other substituted components, and that the cell membrane is the first barrier that these molecules encounter during their action. Ion leakage is particularly detectable within minutes as the bacteria cells are treated with the minimum inhibitory concentration amounts of the compounds. The antibacterial activity of bis-1,2,4-triazole-3-one Schiff bases is superior to that of other substituted derivatives, and ions detectable by the conductivity measurements leak out from the bacteria. The loss of cell membrane integrity is also demonstrated by the propidium iodide uptake experiments. Therefore, we suggest that the disruption of the cell membrane integrity and ion leakage plays a role in the higher activity of triazole compounds against both Gram-negative and -positive bacteria.