In vitro comparative cytotoxicity study of a novel biocidal iodo-thiocyanate complex

Abstract

Novel biocides, which avoid the induction of cross-resistance to antibiotics, are an urgent societal requirement. Here, we compared the cytotoxic and bactericidal effects of a new antimicrobial agent, the iodo-thiocyanate complex (ITC), with those of the common antiseptics, hydrogen peroxide (HO), povidone iodine (PVP-I) and Lugol's iodine (Lugol). The antimicrobials were co-incubated for 10 min with HeLa and Escherichia coli cells in the presence and absence of organic matter (Dulbecco's modified Eagle's medium, supplemented with 10% fetal bovine serum). The cytotoxic concentrations of ITC were equivalent to its bactericidal concentrations (7.8 μg ml). By contrast, cytotoxic effects of HO, PVP-I and Lugol were apparent at concentrations lower than their bactericidal concentrations (250, 250 and 125 μg ml, respectively). The cellular effects of ITC were not quenched by organic matter, unlike the other antiseptics. ITC, PVP-I and Lugol had hemolytic effect on horse erythrocytes at high concentrations, while HO showed no hemolysis. ITC, at 30 or 300 μg ml, did not cause DNA breakage in HeLa cells as assessed by an in vitro comet assay in the absence of S9 metabolic activation, whereas HO caused extensive single-strand DNA breaks. The pronounced antimicrobial potency of ITC and its favorable cytotoxicity profile suggests that ITC should be considered for antiseptic applications.

Comparison of thiocyanate and selenocyanate for potentiation of antimicrobial photodynamic therapy

“…An antimicrobial mouth rinse was devised to take advantage of naturally occurring salivary peroxidases, which contained 4 mM H 2 O 2 and 1 mM KSCN at pH 5.5 . Tonoyan et al described an antibacterial system containing H 2 O 2 , thiocyanate and iodide that produced antibacterial ROS and iodine species under the action of peroxidases . Can selenocyanate improve upon these antimicrobial applications of thiocyanate?…”

Ex vivo decontamination of yeast-colonized dentures by iodine–thiocyanate complexes

“…A recent paper described on HeLa cells a beneficial balance between the active concentration and the toxic one for iodine–thiocyanate complexes produced in a non-enzymatic manner, by comparison with other biocide molecules such as hydrogen peroxide. 27 Further studies will have to analyze the interference between this solution of iodine–thiocyanate complexes and the oral microbial ecology. The efficacy of the iodothiocyanate complexes prepared without peroxidase activity has already been demonstrated in vitro on Pseudomonas aeruginosa and on Staphylococcus aureus both in suspension and in biofilms.…”

Oral peroxidases: From antimicrobial agents to ecological actors (Review)

“…The presence of SCN − at higher concentrations in the saliva should limit the metabolism of I − (oxidation, iodination of tyrosine and iodination of proteins) ( 12 , 62 , 63 ). However, certain studies have suggested a synergy between the two substrates ( 64 ), whereas others have documented the in vitro formation of iodine-SCN − complexes as a more active/stable antimicrobial component, as compared with OI − and OSCN − alone ( 65 – 68 ).…”