Metronidazole Interaction with Cu2+ and Zn2+: Speciation Study in Aqueous Solution and Biological Activity Evaluation

Metronidazole (2-methyl-5-nitro-1H-imidazole-1-ethanol, MNZ) is a well-known and widely used drug for its excellent activity against various anaerobic bacteria and protozoa. The purpose of this study is to elucidate the ability of MNZ to form metal complexes with Cu2+ and Zn2+ and to demonstrate that complexation increases its bioactivity profile against different pathogenic microorganisms. The interaction of MNZ with Cu2+ and Zn2+ was investigated in NaCl aqueous solution under different conditions of temperature (15, 25, and 37 °C) and ionic strength (0.15, 0.5, and 1 mol L-1) by potentiometric and spectrophotometric titrations. The obtained speciation models include two species for the Cu2+-containing system, namely, CuL and CuL2, and three species for the Zn2+-containing system, namely, ZnLH, ZnL, and ZnLOH. The formation constants of the species were calculated and their dependence on temperature and ionic strength evaluated. Comparison of the sequestering ability of MNZ under physiological conditions revealed a capacity toward Cu2+ higher than that toward Zn2+. A simulation under the same conditions also showed a significant percentage of the Cu2+-MNZ species. The biological assessments highlighted that the complexation of MNZ with Cu2+ has a relevant impact on the potency of the drug against two Trypanosoma spp. (i.e., T. b. brucei and T. b. rhodesiense) and one gram-(-) bacterial species (i.e., Escherichia coli). It is noteworthy that the increased potency upon complexation with Cu2+ did not result in cytotoxicity against MRC-5 human fetal lung fibroblasts and primary peritoneal mouse macrophages.

Fluorinated-Triazole-Modified ZnO and Its Application in Marine Antifouling

The accumulation of marine biological growth has irreversible negative effects on shipping and coastal fisheries. In this paper, a new antibacterial nanofiller—triazole fluoroaromatic hydrocarbon−modified nano−zinc oxide (ZnO−APTES−TRF)—was prepared by a Cu(I)−catalyzed azide–alkyne click chemical reaction. The modification of nano−ZnO with triazole ring fluoroaromatic hydrocarbons were testified by FT−IR, XPS, and EDS. The grafting rate of ZnO−APTES−TRF can reach 32.38%, which was verified by the TGA test. The ZnO−APTES−TRF was mixed with zinc acrylate resin to produce a low surface energy antifouling coating with a surface water contact angle of 106°. The bactericidal rate of ZnO−APTES−TRF against Escherichia coli, Staphylococcus aureus, and Pseudoalteromonas sp. can reach more than 98% due to the synergistic effect of triazole and fluorine. The 120−day marine experiment shows that the low surface energy antifouling coating of ZnO−APTES−TRF/ZA is expected to be widely used in the field of marine antifouling.

Computational study of quinoline-based thiadiazole compounds as potential antileishmanial inhibitors

Leishmaniasis is a severe disease caused by protozoan parasites of the genus Leishmania and it is accountable for sizable morbidity and mortality worldwide.