Ebselen is a synthetic organoselenium compound (2-phenyl-1,2-benzisoselenazol-3(2H)-one, C13H9NOSe, MW 274.18) with the rare ability to act as a functional glutathione peroxidase (GPx) enzyme mimetic. Its selenium atom can form reversible covalent selenosulfide bonds with protein cysteine residues, giving it a remarkably broad pharmacological profile. Originally developed by Daiichi Sankyo (Japan) / Rhône-Poulenc Rorer, it has completed multiple human clinical trials and is widely used as a research tool across virology, neuroscience, oncology and immunology.

In a landmark Nature 2020 paper (Jin et al.), Ebselen was identified as the most potent inhibitor of the SARS-CoV-2 main protease (Mpro, also called 3CLpro) from a structure-based screen of over 10,000 compounds. The Mpro enzyme cleaves the viral polyprotein and is essential for coronavirus replication. A follow-up Science Advances 2020 study (Menendez et al.) used molecular dynamics to show that Ebselen binds Mpro at two sites: the catalytic Cys145 and a distant allosteric pocket that regulates catalytic-site access. Note that later studies (ACS Pharmacol. Transl. Sci. 2020) have shown the inhibition is attenuated by DTT, indicating covalent cysteine targeting.

Unlike stoichiometric antioxidants (NAC, ascorbate) that are consumed in a 1:1 ratio with ROS, Ebselen acts as a catalytic enzyme mimetic — it turns over continuously in the presence of GSH or other thiols, capable of reducing multiple equivalents of hydroperoxides. It also uniquely handles peroxynitrite (ONOO–), a highly reactive nitrogen species that conventional antioxidants cannot efficiently detoxify. Additionally, its covalent cysteine-modifying activity gives it pharmacological effects (enzyme inhibition, signaling modulation) beyond simple redox buffering.

Ebselen has been investigated in human clinical trials for: acute ischemic stroke (Phase III, Japan — Yamaguchi et al., Stroke 1998), bipolar disorder, Meniere's Disease (inner ear), noise-induced hearing loss, Type 1 diabetes, and Type 2 diabetes mellitus. It has an established human safety and tolerability profile from multiple completed studies. It is also being explored as a potential COVID-19 therapeutic via Mpro inhibition.

Ebselen is a GPx4 mimetic — it catalytically reduces lipid hydroperoxides, the same reaction performed by GPx4, which is the central gatekeeper of ferroptosis (an iron-dependent, non-apoptotic cell death pathway). By substituting for GPx4 activity, Ebselen blocks ferroptotic cell death. This makes it a critical tool compound for ferroptosis research, which is a rapidly growing field with implications in cancer therapy, neurodegeneration (Alzheimer's, Parkinson's), ischemia-reperfusion injury, and acute kidney injury.

Ebselen is soluble in DMSO (recommended for preparing concentrated stock solutions). It also dissolves in chloroform (~20 mg/mL), ethanol, methanol, acetone, and acetonitrile. For cell-based assays, prepare a concentrated DMSO stock and dilute into aqueous media — keep final DMSO concentration ≤0.1% v/v. For animal studies, common vehicles include DMSO/PEG300/saline combinations. Stock solutions should be aliquoted and stored at -20°C, protected from light.

Ebselen covalently modifies a cysteine residue in indoleamine 2,3-dioxygenase 1 (IDO1), an immunosuppressive enzyme that degrades tryptophan in the tumor microenvironment and promotes immune evasion. IDO1 inhibition reactivates anti-tumor T-cell responses, making Ebselen a chemical biology probe for IDO1 and a lead for cancer immunotherapy research. The inhibition is reversible by DTT.

Ebselen is classified as Acute Toxicity Category 3 (oral and inhalation) and carries GHS06/GHS08/GHS09 hazard pictograms. Handle in a fume hood with appropriate PPE (gloves, lab coat, eye protection). Avoid ingestion, inhalation, and skin/eye contact. It is classified as a hazardous substance (WGK 3 in Germany) and is toxic to aquatic life with long-lasting effects. Do not dispose down drains. Always consult the MSDS/SDS before use.

Yes. While Ebselen alone is active against MRSA and some Gram-positive bacteria, its combination with silver (Ag+) has been shown to be effective against clinically challenging multidrug-resistant Gram-negative bacteria. Silver ions disrupt the bacterial outer membrane, facilitating Ebselen's intracellular access to its bacterial targets. This combination is an active area of antimicrobial research.

Every batch ships with a Certificate of Analysis (COA) including HPLC purity, NMR structural confirmation, and MS data. MSDS/SDS, solubility datasheets, and Certificates of Origin are available on request. Sample evaluation policy is available for qualified institutions — please contact us for details.