The therapeutic potential of thiocyanate and hypothiocyanous acid against pulmonary infections.

Hypothiocyanous acid (HOSCN) is an endogenous oxidant produced by peroxidase oxidation of thiocyanate (SCN−), an ubiquitous sulfur-containing pseudohalide synthesized from cyanide. HOSCN serves as a potent microbicidal agent against pathogenic bacteria, viruses, and fungi, functioning through thiol-targeting mechanisms, independent of currently approved antimicrobials. Additionally, SCN− reacts with hypochlorous acid (HOCl), a highly reactive oxidant produced by myeloperoxidase (MPO) at sites of inflammation, also producing HOSCN. This imparts both antioxidant and antimicrobial potential to SCN−. In this review, we discuss roles of HOSCN/SCN− in immunity and potential therapeutic implications for combating infections. [Display omitted] • Hypothiocyanous acid (HOSCN) is an endogenous oxidant that demonstrates antimicrobial activities against viruses, bacteria and fungi. • Multiple preclinical studies reported benefits of promoting HOSCN formation in vivo to treat pulmonary infections. • HOSCN is better tolerated by mammalian cells than other chordata peroxidase-derived oxidants, such as hypochlorous acid. • Some bacterial strains are resistant to HOSCN, primarily via similar oxidoreductase mechanisms to those reported in mammalian cells. • HOSCN/SCN- treatment holds promise for viral, bacterial, and fungal infections, but potential toxicity and HOSCN resistance must be considered. [ABSTRACT FROM AUTHOR]