Octahedral ruthenium (II) polypyridyl complexes as antimicrobial agents against mycobacterium

Abstract

Tuberculosis is one of the world’s deadliest infectious disease with 1.5 millions deaths annually. It is imperative to discover novel compounds with potent activity against M. tuberculosis. In this study, susceptibilities of M. smegmatis to the octahedral ruthenium(II) polypyridyl complexes, 1 {[(bpy)3Ru] (PF6)2 (bpy = 2,2′-bipyridine)}, 2 {[(phen)2Ru(dppz)](PF6)2 (phen = 1,10-phenanthroline, dppz = dipyridophenazine)} and 3 {[(phen)3Ru](PF6)2} were measured by broth microdilution and reported as the MIC values. Toxicities of complex 3 to LO2 and hepG2 cell lines were also measured. Complex 2 inhibited the growth of M. smegmatis with MIC value of 2 µg/mL, while complex 3 was bactericidal with MIC value of 26 µg/mL. Furthermore, the bactericidal activity of complex 3 was dependent on reactive oxygen species production. Complex 3 showed no cytotoxicity against LO2 and hepG2 cell lines at concentration as high as 64 µg/mL, paving the way for further optimization and development as a novel antibacterial agent for the treatment of M. tuberculosis infection.

Recent Advances on Octahedral Polypyridyl Ruthenium(II) Complexes as Antimicrobial Agents

“…Recently, our group discovered that two typical octahedral ruthenium(II) complexes could selectively inhibit the growth of Mycobacterium smegmatis (Figure 2) [52]. The results revealed that complex 2 [(phen) 2 Ru(dppz)](PF 6 ) 2 (dppz = dipyridophenazine) could notably inhibit the growth of M. smegmatis with the minimum inhibitory concentration (MIC) value of 2 μg/mL, while complex 3 [Ru(phen) 3 ](PF 6 ) 2 was bactericidal with an MIC value of 26 μg/mL.…”

“…Antimicrobial activities of octahedral ruthenium complexes. ( A ) Strains including E. coli ATCC25922 and M. smegmatis mc2155 were used as indicator strains; ( B ) chemical structures of complexes ( 1 – 3 ) (reproduced from Reference [52]).…”

Recent Studies on the Antimicrobial Activity of Transition Metal Complexes of Groups 6–12

“…More importantly, both complexes showed stronger antibacterial effects (MIC = 4-8 µg/mL) than gentamicin as the control (MIC = 16 µg/mL) against two strains of MRSA (MR 4393 and MR 4549). Liao et al have reported a study involving octahedral ruthenium(II) complexes as antimicrobial agents against the mycobacterium M. smegmatis[95]. The complex 28(Figure 7) selectively inhibited M. smegmatis growth with MIC of 2 µg/mL comparable to those of norfloxacin and rifampicin (MIC of 2 and 1 µg/mL, respectively).…”

Targeted Theranostic of Cryptococcal Encephalitis by a Novel Polypyridyl Ruthenium Complex

“…On the disks, positive control drug fluconazole exhibited obviously antifungal inhibition zone diameter with 15.5 ± 0.58 mm at the dose of 0.1 μg (Figure 2A,B), which was consistent with the reports. 30 Among the complexes, RC-5 and RC-6 showed weak antifungal activity, while RC-7 exhibited strong activity, which was evaluated by the largest antifungal diameter of the inhibition zone (18.2 ± 0.19 mm) compared with its congeners (RC-5, 7.16 ± 0.03 mm; RC-6, 7.27 ± 0.21 mm) at the same dose of 0.1 μg (Figure 2A,B). Besides, the antifungal diameter of the inhibition zone of RC-7 significantly larger than that of fluconazole at the same dose (p < 0.05; Figure 2A,B), suggesting that RC-7 would be a potential antifungus candidate.…”