|CompTox Dashboard (EPA)|
|Chemical and physical data|
|Molar mass||214.263 g/mol g·mol−1|
|3D model (JSmol)|
|Melting point||232–234 °C (450–453 °F)|
|(what is this?)|
Various plants contain harmaline including Peganum harmala (Syrian rue) as well as the hallucinogenic beverage ayahuasca, which is traditionally brewed using Banisteriopsis caapi. Present at 3% by dry weight, the harmala alkaloids may be extracted from the Syrian rue seeds.
Harmaline is a central nervous system stimulant and a "reversible inhibitor of MAO-A (RIMA)". This means that the risk of a hypertensive crisis, a dangerous high blood pressure crisis from eating tyramine-rich foods such as cheese, is likely lower with harmaline than with irreversible MAOIs such as phenelzine.
The harmala alkaloids are psychoactive in humans. Harmaline is shown to act as an acetylcholinesterase inhibitor. Harmaline also stimulates striatal dopamine release in rats at very high dose levels. Since harmaline is a reversible inhibitor of monoamine oxidase A, it could, in theory, induce both serotonin syndrome and hypertensive crises in combination with tyramine, serotonergics, catecholaminergics drugs or prodrugs. Harmaline containing plants and tryptamine containing plants are used in ayahuasca brews. The inhibitory effects on monoamine oxidase allows dimethyltryptamine (DMT), the psychoactively prominent chemical in the mixture, to bypass the extensive first-pass metabolism it undergoes upon ingestion; allowing a psychologically active quantity of the chemical to exist in the brain for a perceivable period of time. Harmaline forces the anabolic metabolism of serotonin into normelatonin or n-acetylserotonin, and then to melatonin, the body's principal sleep-regulating hormone and a powerful antioxidant.
A study found that a single injection of 40 mg/kg in rats or 3 x 25 mg/kg spread over 3 days had visible neurotoxic effects.
Harmala alkaloids are considered Schedule 9 prohibited substances under the Poisons Standard (October 2015). A Schedule 9 substance is a substance which may be abused or misused, the manufacture, possession, sale or use of which should be prohibited by law except when required for medical or scientific research, or for analytical, teaching or training purposes with approval of Commonwealth and/or State or Territory Health Authorities.
Harmaline and Harmalol are considered Schedule III controlled substances by the Controlled Drugs and Substances Act. Every person found to be in possession of a Schedule III drug is guilty of an indictable offence and liable to imprisonment for a term not exceeding three years; or for a first offence, guilty on summary conviction, to a fine not exceeding one thousand dollars or to imprisonment for a term not exceeding six months, or to both. Every person found to be trafficking a Schedule III drug is guilty of an indictable offence and liable to imprisonment for a term not exceeding ten years, or is guilty on summary conviction (first time offenders) and liable to imprisonment for a term not exceeding eighteen months.