Sarcosine-13C3 (N-Methylglycine-13C3, Sarcosin-13C3) is the 13C-labeled Sarcosine (HY-101037). Sarcosine (N-Methylglycine), an endogenous amino acid, is a competitive glycine transporter type I (GlyT1) inhibitor and N-methyl-D-aspartate (NMDA) receptor co-agonist. Sarcosine increases the glycine concentration, resulting in an indirect potentiation of the NMDA receptor. Sarcosine is commonly used for the research of schizophrenia[1][2].