Melatonin discovery

Of much interest is the recent discovery of substances closely related to the harmala alkaloids in animals. One of these is adrenoglomerulotropine, a hormone of the pineal body, the chemical identity of which has been indicated as 2,3,4,9-tetrahydro-6-methoxy-i-methyl-iH-pyrido (3,4,6) indole. This substance is identical to 6-methoxyletrahydroharman which has been shown to be formed in vivo from 5-methoxy tryptamine and acetaldehyde. 6-methoxytetrahydroharman is an isomer of tetrahydro-harmine, one of the alkaloids in Banisteriopsis, and in the African Leptactinia densillora. One more substance, 6-methoxyharmalan, has been shown to derive, at least in vitro, from melatonin, which results from the methylation of acetylserotonin. The enzyme which makes this possible, hydroxyindole O-methyl transferase, has only been found in the pineal body. (Naranjo, in Efron et al. 

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