Premium
Comparison of the Microbicidal activity of monochloramine and iodine
Author(s) -
Arnitz R.,
Nagl M.,
Gottardi W.
Publication year - 2015
Publication title -
letters in applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.698
H-Index - 110
eISSN - 1472-765X
pISSN - 0266-8254
DOI - 10.1111/lam.12490
Subject(s) - lipophilicity , chemistry , iodine , chloramine , candida albicans , chlorine , staphylococcus aureus , halogen , aqueous solution , oxidizing agent , nuclear chemistry , medicinal chemistry , bacteria , stereochemistry , alkyl , microbiology and biotechnology , organic chemistry , biology , genetics
Recently, we showed that monochloramine ( NH 2 Cl) has a significantly stronger bactericidal and fungicidal activity than chloramine T despite its lower oxidizing power. This phenomenon was explained by increased penetration because of the higher lipophilicity and smaller bulk of NH 2 Cl. As iodine (I 2 ) has an even fivefold higher bulk than NH 2 Cl, a comparison of both compounds regarding their microbicidal activity became the aim of this study. Aqueous solutions of I 2 at a concentration of 10·7 μ mol l −1 killed 10 6 colony forming units per millilitre ( CFU ml −1 ) of Escherichia coli , Staphylococcus aureus or Pseudomonas aeruginosa to the detection limit of 10 2 CFU ml −1 within 1 min at 20°C and pH 7·1, while a concentration of 36–355 μ mol l −1 of NH 2 Cl was needed to achieve the same effect. Aspergillus fumigatus was inactivated within 5 min by 36 μ mol l −1 I 2 and by 355 μ mol l −1 NH 2 Cl, Candida albicans within 1 min by 10·7 μ mol l −1 I 2 and by 355 μ mol l −1 NH 2 Cl. The lipophilicity of I 2 , determined with the octanol/water method, was three powers of 10 higher than that of NH 2 Cl. The at least 10‐fold stronger microbicidal activity of iodine suggests that the hindrance of penetration of the bulky molecule is outweighed by enhanced lipophilicity. Significance and Impact of the Study The microbicidal activity of active halogen compounds increases not only with their reactivity, but also with higher lipophilicity and lower bulk, as shown recently. In this study, iodine showed a higher microbicidal activity than monochloramine and a 1000‐fold higher lipophilicity. Therefore, the lipophilicity of a disinfectant may be more important than the bulk for bactericidal activity. These facts should be considered upon the design of new antiseptics and their clinical application.