Tetrahydroharman

Tetrahydroharman(e), also known as 1-methyl-1,2,3,4-tetrahydro-β-carboline, is a general name for one of two isomers:

1. (1S)-1-methyl-2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indole
2. Calligonine ((1R)-1-methyl-2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indole)

Calligonine is a major alkaloid constituent of the roots of Calligonum minimum and the bark of Elaeagnus angustifolia. When taken internally, it has the effect of substantially lowering blood pressure for an extended period of time, similar to reserpine.