Synthesis, structure and antibacterial activity of dinitrosyl iron complexes (DNICs) dimers functionalized with 5-(nitrophenyl) -4-H-1,2,4-triazole-3-thiolyls

Novel Type of Tetranitrosyl Iron Salt: Synthesis, Structure and Antibacterial Activity of Complex [FeL’2(NO)2][FeL’L”(NO)2] with L’-thiobenzamide and L”-thiosulfate

“…Being effective low-toxic exogenous nitric oxide (NO) donors complementary to a human organism, low-molecular dinitrosyl complexes of tetrahedral iron involving two nitrosyl and two sulfur-containing ligands, as structural analogs of the active sites of dinitrosyl [1Fe-2S] proteins, are promising for practical application in medicine, which is the reason for the increasing interest in fundamental studies of their structural features [ 3 , 4 , 5 ]. As follows from our investigations, the activity of dinitrosyl complexes of tetrahedral iron (DNICs) and their dimers ( Figure 1 A,B) as antibacterial agents is comparable and/or higher than that of antibiotics used in clinics [ 6 , 7 , 8 , 9 , 10 ].…”

“…The difference between νNO-sym and νNO-asym (ΔνNO) is 70 cm −1 . This value of splitting of the νNO vibration doublet suggests non-equivalence of the NO groups, as with dimers of 1,2,4-triazolethiolyls of µ-NCS structural type [ 10 , 28 ], which appears in the inconsiderable change in the N-O and Fe-N bond lengths within the margin of error.…”

“…The kinetic dependence for complex I goes to a “plateau” in 300 s, and the amount of NO formed (~5.0 nM) does not decrease by 500 s of the experiment, which indicates the formation of long-lived nitrosyl intermediates of this complex, which may be responsible for prolonged NO donor activity. Based on the data of X-ray analysis and molecular modeling for complex I , it can be assumed that mononuclear dinitrosyl [1Fe-2S] intermediates are responsible for prolonged NO release, as with antibacterial DNIC dimers with 5-nitrophenyl-4 H-1,2,4-triazole-3-thiolyls [ 10 ], which were studied earlier.…”

“…Comparison of the antibacterial, cytotoxic and NO-donating properties of complex I and DNICs with thiolyls studied earlier [ 9 , 10 , 42 , 43 , 44 ] leads to some important points.…”

“…Most of these complexes were efficient inhibitors of biofilm formation [ 9 ]. Three DNIC dimers with 5-(nitrophenyl)-4-H-1,2,4-triazole-3-thiolyls exhibited an equal growth-inhibiting effect on M. luteus and E. coli and inhibited biofilm formation at a wide range of concentrations [ 10 ]. As was found for complex I , DNICs with nitrothiophenols or dimethylthiourea [ 9 ] and 5-(nitrophenyl)-4-H-1,2,4-triazole-3-thiolyls [ 10 ], the antibiofilm activity of DNICs is comparable to that of antibiotics.…”