N-Methylheliamine, also known as O-methylcorypalline or as 6,7-dimethoxy-2-methyl-1,2,3,4-tetrahydroisoquinoline, is a tetrahydroisoquinoline and cyclized phenethylamine alkaloid found in Pachycereus pringlei and other cacti. It is known to be a weak monoamine oxidase inhibitor (MAOI), specifically of monoamine oxidase B (MAO-B) (K<sub>i</sub> = 29üM).