Chlorido-containing ruthenium(ii) and iridium(iii) complexes as antimicrobial agents
作者:Mallesh Pandrala、Fangfei Li、Marshall Feterl、Yanyan Mulyana、Jeffrey M. Warner、Lynne Wallace、F. Richard Keene、J. Grant Collins
DOI:10.1039/c3dt32775b
日期:——
A series of polypyridyl-ruthenium(II) and -iridium(III) complexes that contain labile chlorido ligands, [M(tpy)Cl}2μ-bbn}]2/4+ Cl-Mbbn; where M = Ru or Ir; tpy = 2,2′:6′,2′′-terpyridine; and bbn = bis[4(4′-methyl-2,2′-bipyridyl)]-1,n-alkane (n = 7, 12 or 16)} have been synthesised and their potential as antimicrobial agents examined. The minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) of the series of metal complexes against four strains of bacteria – Gram positive Staphylococcus aureus (S. aureus) and methicillin-resistant S. aureus (MRSA), and Gram negative Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aeruginosa) – have been determined. All the ruthenium complexes were highly active and bactericidal. In particular, the Cl-Rubb12 complex showed excellent activity against all bacterial cell lines with MIC values of 1 μg mL−1 against the Gram positive bacteria and 2 and 8 μg mL−1 against E. coli and P. aeruginosa, respectively. The corresponding iridium(III) complexes also showed significant antimicrobial activity in terms of MIC values; however and surprisingly, the iridium complexes were bacteriostatic rather than bactericidal. The inert iridium(III) complex, [Ir(phen)2}2μ-bb12}]6+ where phen = 1,10-phenanthroline) exhibited no antimicrobial activity, suggesting that it could not cross the bacterial membrane. The mononuclear model complex, [Ir(tpy)(Me2bpy)Cl]Cl2 (where Me2bpy = 4,4′-dimethyl-2,2′-bipyridine), was found to aquate very rapidly, with the pKa of the iridium-bound water in the corresponding aqua complex determined to be 6.0. This suggests the dinuclear complexes [Ir(tpy)Cl}2μ-bbn}]4+ aquate and deprotonate rapidly and enter the bacterial cells as 4+ charged hydroxo species.
一系列含有易替换氯配体的聚吡啶铬(II)和铱(III)复合物[M(tpy)Cl}2μ-bbn}]2/4+ Cl-Mbbn; 其中 M = Ru 或 Ir; tpy = 2,2′:6′,2′′-三吡啶; bbn = 二[4(4′-甲基-2,2′-联吡啶)]-1,n-烷烃 (n = 7, 12 或 16)}已被合成,并考察了其作为抗微生物剂的潜力。已确定一系列金属复合物对四种细菌株的最小抑制浓度(MIC)和最小杀菌浓度(MBC)——革兰阳性金黄色葡萄球菌(S. aureus)和耐甲氧西林金黄色葡萄球菌(MRSA),以及革兰阴性大肠杆菌(E. coli)和铜绿假单胞菌(P. aeruginosa)。所有铬复合物均表现出高度活性和杀菌效果。特别是,Cl-Rubb12复合物在对所有细菌细胞系的MIC值方面表现出优异的活性,针对革兰阳性细菌的MIC值为1 μg mL−1,对E. coli和P. aeruginosa的MIC值分别为2 μg mL−1和8 μg mL−1。相应的铱(III)复合物在MIC值方面也表现出显著的抗微生物活性;然而,令人惊讶的是,铱复合物是抑菌的,而不是杀菌的。惰性的铱(III)复合物[Ir(phen)2}2μ-bb12}]6+ 其中 phen = 1,10-菲啰啉}未表现出任何抗微生物活性,表明它无法穿过细菌膜。单核模型复合物[Ir(tpy)(Me2bpy)Cl]Cl2(其中 Me2bpy = 4,4′-二甲基-2,2′-联吡啶)被发现水合非常迅速,相应水合复合物中铱键合水的pKa值被测定为6.0。这表明二核复合物[Ir(tpy)Cl}2μ-bbn}]4+迅速水合并脱质子,作为4+带电羟基物种进入细菌细胞。