Thiocyanate (SCN)

Thiocyanate is a pseudohalide anion (SCN-) that serves as a critical metabolite in human physiology, primarily known for its role in cyanide detoxification and innate immunity [1, 3]. It is not a therapeutic protein target but rather a small molecule that modulates the activity of specific enzymes and transporters [2]. Biologically, thiocyanate is a substrate for heme peroxidases, such as lactoperoxidase (LPO), which oxidize it to hypothiocyanite (OSCN-), a potent antimicrobial agent essential for mucosal defense in the lungs and oral cavity [4]. However, thiocyanate also acts as a competitive inhibitor of the sodium-iodide symporter (NIS), which can lead to decreased iodine uptake in the thyroid and subsequent goitrogenic effects [5]. Clinically, thiocyanate levels are utilized as biomarkers for tobacco smoke exposure and are monitored during the management of cyanide poisoning with sodium thiosulfate [1, 6]. Understanding thiocyanate dynamics is also relevant in cystic fibrosis research, where impaired thiocyanate transport is linked to increased susceptibility to lung infections [4].

Other names

RhodanideThiocyanate anionSulfocyanate

Thiocyanate acts as a competitive inhibitor of the Sodium-Iodide Symporter (NIS), which prevents the accumulation of iodide in the thyroid gland [5]. Additionally, it serves as a substrate for peroxidase enzymes like lactoperoxidase (LPO) and myeloperoxidase (MPO) to generate hypothiocyanite (OSCN-), a key component of the innate immune system's antimicrobial response [4].