25CN-NBOH (or NBOH-2C-CN) is a compound indirectly derived from the phenethylamine series of hallucinogens, which was discovered in 2014 by a group of researchers at the University of Copenhagen. This compound is notable as one of the most selective agonist ligands for the 5-HT2A receptor yet discovered, with a pKi of 8.88 at the human 5-HT2A receptor and with 100x selectivity for 5-HT2A over 5-HT2C, and 46x selectivity for 5-HT2A over 5-HT2B.[1][2][3][4] In animal studies, 25CN-NBOH was found to partially substitute for DOI but was considerably weaker at inducing a head-twitch response in mice.[5][6] Another in vivo evaluation of 25CN-NBOH concluded that "Given its distinct in vitro selectivity for 5-HT2A over non 5-HT2 receptors and its behavioral dynamics, 25CN-NBOH appears to be a powerful tool for dissection of receptor-specific cortical circuit dynamics, including 5-HT2A related psychoactivity."[7] Additional in vivo investigations with this ligand is emerging.[8][9] At tritiated version of 25CN-NBOH has also been accessed and used for more detailed investigations of the binding to 5-HT2 receptors and autoradiography.[10]
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https://en.wikipedia.org/wiki/25CN-NBOH