Synthesis, antimicrobial and antiproliferative activities of new self-assembly benzimidazole-bridged aren ruthenium rectangles in human breast cancer cells

Some novel benzimidazole-bridged aren ruthenium rectangle compounds of the general structure [{Ru₂(p-cymene)₂(µ₄-OO∩OO)}₂(µ₄-bbim)]⁴⁺ (bbim = 1,1′-butyl-2-ene-di(benzimidazole) were obtained from the corresponding double-nuclear arene ruthenium compounds [Ru₂(p-cymene)₂(µ₄-OO∩OO)Cl₂] (OO∩OO = 2,5-dioxido-1,4-benzoquinonato (dobq), 2,5-dichloro-1,4-benzoquinonato (dClbq), 2,5-dibromo-1,4-benzoquinonato (dBrbq), oxalato (oxa), and 5,8-dioxido-1,4-naphtoquinonato (donq) via reaction with the bbim molecule and AgCF₃SO₃. The antiproliferative activity and anti-cancer properties of the tetranuclear arene ruthenium compounds were evaluated against the human breast cancer cell line (MDA-231-MB). Compound 2 showed the highest antiproliferative effect among the compounds during 24- and 48-h administration. In addition, all other compounds exhibited very good cancer cell selectivity and very low micromolar cytotoxicity. The antimicrobial activities of the synthesized compounds were also determined against various test microorganisms. Evaluations were carried out using the disk diffusion method and the dilution method. In particular, the compounds exhibited more potential antibacterial effects against Gram negative bacteria than against Gram positive bacteria and showed a superior antifungal effect against Candida species. The results revealed the benzimidazole-bridged aren ruthenium rectangle compounds to be very strong and potent inhibitors.