Cytogenetic study of metronidazole and three metronidazole analogues in cultured human lymphocytes with and without metabolic activation

Chlorinated metronidazole as a promising alternative for treating trichomoniasis

Trichomoniasis is the most common non-viral, sexually transmitted infection affecting humans worldwide. The main treatment for trichomoniasis is metronidazole (MTZ). However, adverse effects and reports of resistance have stimulated the development of therapeutic alternatives. The ease of manipulation of the side chains of MTZ coupled with its safety makes this molecule attractive for the development of new drugs. In this context, we evaluated the activity of the chlorinated MTZ derivative, MTZ-Cl, on sensitive and resistant strains of Trichomonas vaginalis. MTZ-Cl presented a remarkable activity against both sensitive and resistant strains. In vitro and in vivo toxicity assays indicated that the new molecule is safe for future clinical trials. Furthermore, we noticed different rates of free radical production between the sensitive and resistant strains. MTZ-Cl induced a higher release of nitric oxide (NO, ~ 9000 a.u.) by both sensitive and resistant strains. However, the sensitive strain produced a greater amount of H₂O₂ (~ 1,800,000 a.u.) and superoxide radicals (~ 350,000 a.u.) in the presence of MTZ. In the resistant strain, production of these radicals was more prominent when MTZ-Cl was used. Collectively, these results suggest that NO is an important molecule in the trichomonacidal activity against resistant and sensitive strains, suggesting an alternative pathway for MTZ-Cl activation. We highlight the high trichomonacidal potential of MTZ-Cl, improving the effectiveness of treatment and reducing side effects. In addition, MTZ-Cl is derived from a well-established drug on the world market that presents low toxicity to human cells, suggesting its safety to proceed with future clinical trials.

Hydrophobicity of imidazole derivatives correlates with improved activity against human methanogenic archaea

Methanogenic archaea are involved in periodontitis in humans. They have also been implicated in digestive tract pathologies and obesity. These microorganisms are broadly resistant to antibiotics, except for metronidazole and ornidazole. In this study, eight imidazole derivatives were synthesised and their in vitro cytotoxicity and activity against six species of methanogenic archaea, including Methanobrevibacter smithii, Methanobrevibacter oralis, Methanosphaera stadtmanae, Methanobacterium beijingense, Methanosaeta concilii and Methanomassiliicoccus luminyensis, were tested. Whilst the effective half-maximum cytotoxic concentrations (EC50 values) of all compounds were ≤50 mg/L, minimum inhibitory concentrations (MICs) were 0.05-0.8 mg/L for most methanogenic archaea and 0.1-1mg/L for M. stadtmanae. These results indicated a >20-400 therapeutic index (EC50/MIC) for these compounds, which compared with metronidazole exhibited 1-log increased activity against methanogenic archaea cultured from the human microbiota. These compounds are therefore promising molecules for the treatment of methanogenic archaea-related infections.

A sub-acute study of metronidazole toxicity assessed in Egyptian Tilapia zillii

Metronidazole (MTZ), an antiparasitic and antibacterial compound, is one of the world's most widely used drugs. Despite being considered as a rodent mutagen and a carcinogen, it is still widely used in humans for the treatment of infections with anaerobic organisms. Therefore, the main objective of the current study was to evaluate the in vivo toxicity of MTZ using the micronucleus (MN) assay and random amplified polymorphism DNA (RAPD-PCR) analysis as well as histopathological examination in Tilapia zillii. Moreover, the protective effect of vitamin C (VitC) against toxicity of MTZ was investigated in the present study. Fish were treated with three doses of MTZ (5, 10 and 20 mg l(-1)) alone or in combination with VitC (200 mg kg(-1) food) at several time intervals (2 days, 7 days and 14 days). The results of the present study showed a significant effect of MTZ on micronucleus formation and changes in polymorphic band patterns as well as induction of different histopathological alterations in Tilapia zillii. The effects of the drug were reduced when fish were exposed to a combination of MTZ and VitC.