A novel indolethylamine N-methyltransferase (RmNMT) from the cane toad (Rhinella marina) was identified and characterized. This enzyme catalyzes the biosynthesis of psychedelic alkaloids such as DMT, 5-methoxy-DMT, and bufotenin, which accumulate in toad skin and parotid glands and have been used ceremonially by Mesoamerican peoples. RmNMT is an effective catalyst not subject to product inhibition and exhibits substrate promiscuity, enabling production of various substituted indolethylamines for purification, pharmacological screening, and metabolic stability assays. Binding evaluations at serotonin receptors showed that primary amines have enhanced affinity at the 5-HT1A receptor compared with tertiary amines. Except for 6-substituted derivatives, N,N-dimethylation protected against catabolism by liver microsomes.
An enzyme from cane toad (Rhinella marina), named RmNMT, efficiently produces N,N-dimethylated indolethylamines, including psychedelic compounds like N,N-dimethyltryptamine. Unlike similar enzymes in mammals and fungi, RmNMT is highly efficient and promiscuous, enabling the bioproduction of new-to-nature indolethylamine derivatives. N,N-Dimethylated indolethylamines showed reduced binding and activation at 5-HT1A and 5-HT2A receptors compared to primary amines, yet only these tertiary amines induced hallucinogenic behavior in mice, suggesting metabolic stability is key. This discovery establishes a platform for producing and screening novel indolethylamines for potential psychiatric medicines.