Hypothiocyanite
Hypothiocyanite is the anion [OSCN]− and the conjugate base of hypothiocyanous acid (HOSCN). It is an organic compound part of the thiocyanates as it contains the functional group SCN. It is formed when an oxygen is singly bonded to the thiocyanate group. Hypothiocyanous acid is a fairly weak acid; its dissociation constant is 5.3.
Hypothiocyanite (also named hypothiocyanate) is formed by peroxidase catalysis of hydrogen peroxide and thiocyanate:
Hypothiocyanite occurs naturally in the antimicrobial immune system of the human respiratory tract in a redox reaction catalyzed by the enzyme lactoperoxidase. It has been researched extensively for its capabilities as an alternative antibiotic as it is harmless to human body cells while being cytotoxic to bacteria. The exact processes for making hypothiocyanite have been patented as such an effective antimicrobial has many commercial applications.
Lactoperoxidase-catalysed reactions yield short lived intermediary oxidation products of SCN−, providing antibacterial activity.
The major intermediary oxidation product is hypothiocyanite OSCN−, which is produced in an amount of about 1 mol per mol of hydrogen peroxide. At the pH optimum of 5.3, the OSCN− is in equilibrium with HOSCN. The uncharged HOSCN is considered to be the greater bactericidal of the two forms. At pH 7, it was evaluated that HOSCN represents 2% compare to OSCN− 98%.
The action of (OSCN)- against bacteria is reported to be caused by sulfhydryls (SH) oxidation.
The oxidation of -SH groups in the bacterial cytoplasmic membrane results in loss of the ability to transport glucose and also in leaking of potassium ions, amino acids and peptide.
OSCN− has also been identified as an antimicrobial agent in milk, saliva, tears, and mucus.
OSCN− is considered as safe product as it is not mutagenic.
Initially, this particular lactoperoxidase-catalyzed compound was originally discovered while viewing the specific environment of cystic fibrosis patients' weakened respiratory immune system against bacterial infection.
Symptoms of cystic fibrosis include an inability to secrete sufficient quantities of SCN− which results in a shortage of necessary hypothiocyanite, resulting in increasing mucous viscosity, inflammation and bacterial infection in the respiratory tract.
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