A green chemistry approach for preparation of metronidazole-zinc (ІІ) complexes: In vitro characterization, antimicrobial activity and promising cytotoxicity

Antibiotic-metal complexes attract the attention of pharmaceutical scientists who endeavor to increase the activity of antibiotics currently in use as those looking for new compounds possessing modified pharmacological and toxicological properties. This research proposed enhanced antimicrobial and cytotoxic activities of metronidazole and reduced irritancy of zinc chloride through complexation. The chemically green preparation of metronidazole: zinc (ІІ) complexes with different ratios: (A; 2:1), (B; 1:1) and (C; 1:2), revealed the formation of three complexes. The differences between their structures, physical and chemical properties were evaluated using morphological characteristics, DSC, XRD, FTIR, Mass spectrometry, and UV–Vis spectroscopy. The antimicrobial activities of the complexes were increased when compared to the parent drug where complex-C manifested the highest antibacterial activity (MIC = 0.625 mM and 10 mM for the bacterial strains and C. albicans, respectively). The antitumor efficacy of the complexes was studied against HepG2 and MCF-7 human cancer cell lines. Complex-A showed the highest cytotoxicity against HepG2 cells (IC50 = 17.2 μM), while, complex-C displayed the most cytotoxic activity against MCF-7 cells (IC50 = 29.0 μM). The in vivo skin irritancy study of the complexes on rats and their histological examination were assessed and showed no erythema and/or edema. Our results suggest the promising antimicrobial and antitumor activity of the prepared metronidazole-zinc complexes.