S-Adenosyl-L-methionine-d3 (S-Adenosyl methionine-d3) methylbenzenesulfonate is the deuterium labeled S-Adenosyl-L-methionine methylbenzenesulfonate[1]. S-Adenosyl-L-methionine (S-Adenosyl methionine) is an orally active methyl group donor. S-Adenosyl-L-methionine is a dietary supplement with potent antidepressant effects. S-Adenosyl-L-methionine also has anti-proliferative, pro-apoptotic and anti-metastatic roles in cancers. S-Adenosyl-L-methionine has the potential for, cancer, liver disease and osteoarthritis research[2][3][4].