Carbon monoxide (CO) is an important signaling molecule which plays significant roles in the pathogenesis of cancer. CO is produced by enzymatic degradation of heme in mammals. Heme oxygenase 1 (HO-1) catalyzes the breakdown of heme into CO, ferrous iron, and biliverdin. CO induces HO-1 and inhibits cell proliferation. Cancer cells exposed to several stress factors (hypoxia, reactive oxygen species, cis-platin, and oxidative stress), and HO-1 displays cytoprotective role against oxidative stress and inhibits apoptosis, metastases, angiogenesis, and cell proliferation processes. Therefore, metal containing CO-releasing molecules (CORMs) have been designed as an effective cancer treatment strategy. CORMs are responsible for releasing controlled amounts of CO to cells and tissues. Thus, we synthesized [Mn(CO)₃(bpy)L]X manganese containing CORMs [bpy = 2,2′-bipyridine, X = hexafluorophosphate (PF₆), trifluoromethanesulfonate (OTf), L = imidazole, methylimidazole, benzimidazole, N-benzylbenzimidazole, N-(4-chlorobenzyl)benzimidazole] to release CO in human invasive ductal breast (MCF-7) cell line. In vitro experiments indicated that the compounds inhibited cell proliferation and exhibited cytotoxic effect on breast cancer cells. Moreover, side groups of the compounds enhanced the anticancer effects in MCF-7 cell line. These manganese containing CORMs gave promising results and may be used as a drug template for effective treatment of invasive ductal breast carcinoma.

Five silver(I) complexes, namely chloro[1-methallyl-3-benzyl)benzimidazol-2-ylidene] silver (6), chloro[1-methallyl-3-(2,3,5,6-tetramethylbenzyl)benzimidazol-2-ylidene]silver (7), chloro[1-methallyl-3-(3,4,5-trimethoxylbenzyl)benzimidazol-2-ylidene]silver (8), chloro[1-methallyl- 3-(naphthylmethyl)benzimidazol-2-ylidene]silver (9), and chloro [1-methallyl-3-(anthracen-9-yl- methyl)benzimidazol-2-ylidene]silver (10), were prepared starting from their corresponding benzimidazolium salts and silver oxide in 71–81% yields. A single-crystal X-ray structure of 7 was determined. These five Ag-NHC complexes were evaluated for their antimicrobial and biofilm formation inhibition properties. Complex 10 exhibited high antimicrobial activities comparable to those obtained with standard drugs such as Fluconazole in contact with Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Acinetobacter baumannii, and Candida albicans. The latter complex has been shown to be very efficient in antibiofilm activity, with 92.9% biofilm inhibition at 1.9 μg/mL on Escherichia coli. Additionally, the molecules were optimized with DFT-based computational methods for obtaining insight into the structure/reactivity relations through the relative energies of the frontier orbitals. The optimized molecules were also analyzed by molecular docking method against DNA gyrase of Escherichia coli and CYP51 from Candida albicans.