3-Methoxytyramine

3-Methoxytyramine, also known as 3-methoxy-4-hydroxyphenethylamine, is a human trace amine and the major metabolite of the monoamine neurotransmitter dopamine. It is formed by the introduction of a methyl group to dopamine by the enzyme catechol-O-methyltransferase. 3-MT can be further metabolized by the enzyme monoamine oxidase to form homovanillic acid, which is then typically excreted in the urine.

Occurrence

3-Methoxytyramine occurs naturally in the prickly pear cactus, and is in general widespread throughout the Cactaceae. It has also been found in crown gall tumors on Nicotiana sp.
In humans, 3-methoxytyramine is a trace amine that occurs as a metabolite of dopamine.

Biological activity

Originally thought to be physiologically inactive, 3-MT was subsequently found to act as an agonist of the rodent and human TAAR1. 3-MT can induce weak hyperlocomotion in mice and this effect is partially attenuated in TAAR1 knockout mice.