Practical use of povidone-iodine antiseptic in the maintenance of oral health and in the prevention and treatment of common oropharyngeal infections

Kanagalingam, J.; Feliciano, R.; Hah, J. H.; Labib, H.; Le, T. A.; Lin, J.-C.

The active moiety, non PVP-bound ('free') iodine is released into solution from the PVP-I complex. PVP itself has no microbicidal activity but rather delivers the free iodine to target cell membranes. It is this free iodine that mediates the basic mechanism of action (oxidation of amino acids and nucleic acids in biological structures), which is difficult, if not impossible, to counteract. This basic mechanism of action leads to strong microbicidal activity expressed by multiple modes of action that include the disruption of microbial metabolic pathways, as well as destabilisation of the structural components of cell membranes, causing irreversible damage to the pathogen. Consumed free iodine is then replaced by PVPbound iodine. The concentration of free iodine is the determining factor of the microbicidal action of PVP-I (43) (44) (45) . PVP-I exposure leads to destruction of cytosolic and nuclear structures in bacteria and damage to the cell wall in fungi (26, 46) . In a study investigating the virucidal activity of different disinfectants, electron micrographs revealed how exposure to iodine led to degeneration of the nucleoproteins of viral particles, which was the main mechanism of action (47) . However, disruption of surface proteins essential for the spread of enveloped viruses has also been noted (48) . In addition to a direct killing action on bacteria, PVP-I also inhibits the release of pathogenic factors such as exotoxins, endotoxins and tissue-destroying enzymes (49) . Furthermore, iodine is a scavenger of free radical oxygen species, contributing to anti-inflammatory properties (50) .