L-Se-methylselenocysteine (SMC) is an organic selenium compound resembling methionine, featuring a side chain with a methylseleno group. This compound, a derivative of Se-methylselenocysteine, demonstrates anti-tumor effects. As a naturally occurring organic selenium compound, methylselenocysteine is prevalent in plants like garlic, onions, and broccoli, offering potential antioxidant and chemopreventive activities.SMC functions as an amino acid analog of cysteine, with a methylseleno group replacing the sulfur atom in cysteine. This unique composition allows SMC to bind to glutathione peroxidase, exerting

antioxidant effects and showcasing significant preventive activity in animal models.