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

• Published in: Toxicology in vitro Vol. 50; pp. 264 - 273
• Main Authors: Tonoyan, Lilit, Boyd, Aoife, Fleming, Gerard T.A., Friel, Ruairi, Gately, Carol M., Mc Cay, Paul H., O'Flaherty, Vincent
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.08.2018; Elsevier Science Ltd
• Subjects: Antibiotics; Antiinfectives and antibacterials; Antimicrobial agents; Antiseptics; Bioassays; Biocides; Breakage; Comet assay; Cross-resistance; Cytotoxicity; Damage detection; Deoxyribonucleic acid; DNA; DNA damage; E coli; Erythrocytes; HeLa cytotoxicity; Hydrogen peroxide; In vitro comet assay; Iodine; Iodo-thiocyanate complex (ITC); Lugol's iodine; Metabolic activation; Metabolic rate; Organic matter; Povidone; Povidone iodine; Thiocyanates; Toxicity; PBS; HeLa cytotoxicity; Hydrogen peroxide; Iodo-thiocyanate complex (ITC); Povidone iodine; In vitro comet assay; PVP-I; DAPI; MTT; DMEM; SD; cfu; FBS; Lugol's iodine; ITC; hRBD
• ISSN: 0887-2333; 1879-3177
• DOI: 10.1016/j.tiv.2018.03.014

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 (H2O2), 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−1). By contrast, cytotoxic effects of H2O2, PVP-I and Lugol were apparent at concentrations lower than their bactericidal concentrations (250, 250 and 125 μg ml−1, 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 H2O2 showed no hemolysis. ITC, at 30 or 300 μg ml−1, did not cause DNA breakage in HeLa cells as assessed by an in vitro comet assay in the absence of S9 metabolic activation, whereas H2O2 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. •Cytotoxic concentration of ITC was equivalent to its bactericidal concentration.•Cytotoxicity of H2O2, PVP-I and Lugol was apparent at sub-bactericidal levels.•Bactericidal and cytotoxic activities of ITC were not impacted by organic matter.•ITC did not cause breakage of DNA in HeLa cells in an in vitro comet assay.•ITC is a suitable candidate for antiseptic and therapeutic applications.