Abstract
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.