Chemistry:25CN-NBOH

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25CN-NBOH, also known as NBOH-2C-CN or as N-(2-hydroxybenzyl)-4-cyano-2,5-dimethoxyphenethylamine, is a psychedelic drug of the phenethylamine, 2C, and 25-NB (NBOH) families.[1][2] It was developed and described in 2011 at the University of Copenhagen.[3][4]

The drug is one of the most selective agonists of the serotonin 5-HT2A receptor known.[5][6][3][7][2] However, findings on its selectivity have varied, with some studies finding as little as 10-fold selectivity for the serotonin 5-HT2A receptor over the serotonin 5-HT2C receptor.[8][2][7] A much more selective derivative of 25CN-NBOH, TGF-8027, has since been described.[8]

A tritiated version of 25CN-NBOH has also been developed and used for more detailed investigations of the binding to serotonin 5-HT2 receptors and autoradiography.[9] In 2025, 25CN-NBOH was suggested as a possible alternative and replacement of DOI for use in scientific research.[10]

Interactions

Pharmacology

Pharmacodynamics

Actions

25CN-NBOH activities
Target Affinity (Ki, nM)
5-HT1A >10,000
5-HT1B >10,000
5-HT1D >10,000
5-HT1E >10,000
5-HT1F ND
5-HT2A 0.81–27 (Ki)
0.38–8.59 (EC50)
66–150% (Emax)
5-HT2B 30–75 (Ki)
59–145 (EC50)
57–60% (Emax)
5-HT2C 42–132 (Ki)
4.79–350 (EC50)
78–114% (Emax)
5-HT3 >10,000
5-HT4 ND
5-HT5A 6,591–>10,000
5-HT6 310–573
5-HT7 5,256–>10,000
α1A >10,000
α1B >10,000
α1D >10,000
α2A 803–>10,000
α2B 1,226–>10,000
α2C 543–2,900
β1 >10,000
β2 1,609
β3 >10,000
D1–D3 >10,000
D4 2,900–>10,000
D5 >10,000
H1 2,100–>10,000
H2 1,505
H3 >10,000 (guinea pig)
H4 >10,000
M1–M5 >10,000
I1 ND
σ1 (rat) 280–284
σ2 (rat) 120–575
MOR >10,000
DOR >10,000
KOR 4,200–>10,000
TAAR1 ND
SERT >10,000 (Ki)
NET >10,000 (Ki)
DAT >10,000 (Ki)
Notes: The smaller the value, the more avidly the drug binds to the site. All proteins are human unless otherwise specified. Refs: [2][1][3][5][7][6][11][12][13][14]

25CN-NBOH is one of the most selective agonists of the serotonin 5-HT2A receptor yet discovered, with an affinity (Ki) of 1.32 nM at the human serotonin 5-HT2A receptor, 100-fold selectivity for the serotonin 5-HT2A receptor over the serotonin 5-HT2C receptor, and 46-fold selectivity for the serotonin 5-HT2A receptor over the serotonin 5-HT2B receptor.[5][6][3][7] However, another study found that 25CN-NBOH only had around 25-fold selectivity for the serotonin 5-HT2A receptor over the serotonin 5-HT2B and 5-HT2C receptors.[2][7] In any case, in 2020, 25CN-NBOH and the related drug (S,S)-DMBMPP were described as the most selective serotonin 5-HT2A receptor agonists discovered to date.[2] Subsequently, in 2025, it was reported that 25CN-NBOH had only 10-fold selectivity for the serotonin 5-HT2A receptor over the serotonin 5-HT2C receptor in the Gq dissociation assay, whereas its more recent derivative TGF-8027 showed 49-fold selectivity in the same assay.[8]

Effects

25CN-NBOH was found to partially substitute for DOI in drug discrimination tests but was considerably weaker at inducing the head-twitch response (HTR) in mice.[15][16] As with DOI, 25CN-NBOH has shown a biphasic or inverted U-shaped dose–response curve in terms of HTR induction.[15][17] In addition, as with many other psychedelics, tolerance and tachyphylaxis develop to the HTR induced by 25CN-NBOH.[17] A study 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."[17]

25CN-NBOH induces the HTRs also referred to as "wet dog shakes" (WDS) in rodents and the cortical fingerprint of serotonin-2A-receptor-mediated shaking behavior has been investigated in detail.[18]

Additional in-vivo investigations with this ligand are emerging.[19][20][21][22][23][24][25][26][27][28][29]

Selected examples:

Chronic administration in mice lead to desensitization of the serotonin 5-HT2A receptor (measured via HTR) and increased startle amplitude[30] whereas it does not effect reversal learning in mice.[31] 25CN-NBOH was shown to increase the production of CTGF in chondrocytes.[32] In rats, 25CN-NBOH induce a reduction in conditioned fear that was countered by pretreatment with the serotonin 5-HT2A receptor inverse agonist MDL100907.[33]

Notably, a single-dose of 25CN-NBOH enhances cognitive flexibility and reversal learning in mice weeks after administration[34] as well as functional plasticity and antidepressant like effects in rats through mechanisms independent of structural plasticity.[35]

Chemistry

Structure

File:25CN-NBOH.webm

The structure of 25CN-NBOH in complex with an engineered Gαq heterotrimer of the serotonin 5-HT2A receptor has been determined by cryoelectron microscopy (cryo-EM), showing a distinct binding mode when compared to LSD.[11]

Synthesis

25CN-NBOH is readily available from 2C-H in 57% over 4 steps.[36]

Physicochemical properties

The HCl-salt of 25CN-NBOH precipitates as a single and stable polymorph. The aqueous solubility of this salt is 8.5 mg/mL, leading to a solution with a pH of 6.24. A solution of 25CN-NBOH in water or buffer (pH 7.24) does not show any signs of degradation after 1 month at 25°C. The presence of an intramolecular hydrogen bond may help explain the high membrane permability.[37]

Detection

A bioanalytical method for the detection of 25CN-NBOH has been developed.[38]

Analogues

The tendency of the 4-cyano substitution to confer high selectivity for the serotonin 5-HT2A receptor had previously been observed with DOCN,[39] but this drug was not sufficiently potent to be widely adopted as a research ligand. 25CN-NBOH is still slightly less selective for 5-HT2A than the more complex cyclized derivative 2S,6S-DMBMPP ((2S,6S)-2-(2,5-dimethoxy-4-bromobenzyl)-6-(2-methoxyphenyl)piperidine),[40] in binding assays, however it is also less complex to synthesize and has higher efficacy and selectivity in functional assays as a partial agonist of the serotonin 5-HT2A receptor. Other analogues of 25CN-NBOH include 2C-CN and TGF-8027.

History

25CN-NBOH was first described in the scientific literature by Martin Hansen at the University of Copenhagen in 2011.[3] It was subsequently described more prominently, with its binding selectivity for the serotonin 5-HT2A receptor highlighted, by Hansen and colleagues in 2014 and 2015.[5][15] A review covering the literature on 25CN-NBOH up to 2020 was published in 2021.[1] 25CN-NBOH was suggested as a possible alternative and replacement of DOI for use in scientific research in 2025.[10]

Society and culture

Canada

25CN-NBOH is a controlled substance in Canada under phenethylamine blanket-ban language.[41]

Hungary

25CN-NBOH is illegal in Hungary.[42]

United Kingdom

This substance is a Class A drug in the United Kingdom as a result of the N-benzylphenethylamine catch-all clause in the Misuse of Drugs Act 1971.[43]


United States

25CN-NBOH is not an explicitly controlled substance in the United States.[44] However, it could be considered a controlled substance under the Federal Analogue Act if intended for human consumption.

See also

References

  1. ↑ 1.0 1.1 1.2 "25CN-NBOH: A Selective Agonist for in vitro and in vivo Investigations of the Serotonin 2A Receptor". ChemMedChem 16 (21): 3263–3270. November 2021. doi:10.1002/cmdc.202100395. PMID 34288515. https://researchprofiles.ku.dk/da/publications/2c6e1992-259c-48e1-a72b-bd80cfbc0a53. 
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 "DARK Classics in Chemical Neuroscience: NBOMes". ACS Chem Neurosci 11 (23): 3860–3869. December 2020. doi:10.1021/acschemneuro.9b00528. PMID 31657895. 
  3. ↑ 3.0 3.1 3.2 3.3 3.4 Hansen M (2011). Design and Synthesis of Selective Serotonin Receptor Agonists for Positron Emission Tomography Imaging of the Brain (Ph.D. thesis). University of Copenhagen.
  4. ↑ "CNS Medicinal Chemistry in the Kristensen Group". Department of Drug Design and Pharmacology. University of Copenhagen. 25 March 2019. https://drug.ku.dk/disciplines/medicinal-chemistry/kristensen-group/. 
  5. ↑ 5.0 5.1 5.2 5.3 "Synthesis and structure-activity relationships of N-benzyl phenethylamines as 5-HT2A/2C agonists". ACS Chemical Neuroscience 5 (3): 243–249. March 2014. doi:10.1021/cn400216u. PMID 24397362. 
  6. ↑ 6.0 6.1 6.2 "Detailed Characterization of the In Vitro Pharmacological and Pharmacokinetic Properties of N-(2-Hydroxybenzyl)-2,5-Dimethoxy-4-Cyanophenylethylamine (25CN-NBOH), a Highly Selective and Brain-Penetrant 5-HT2A Receptor Agonist". J Pharmacol Exp Ther 361 (3): 441–453. June 2017. doi:10.1124/jpet.117.239905. PMID 28360333. 
  7. ↑ 7.0 7.1 7.2 7.3 7.4 "Effect of 5-HT2A and 5-HT2C receptors on temporal discrimination by mice". Neuropharmacology 107: 364–375. August 2016. doi:10.1016/j.neuropharm.2016.03.038. PMID 27020041. 
  8. ↑ 8.0 8.1 8.2 "Discovery of Highly Selective 5-HT2A Agonists Using Structure-Guided Design". J Med Chem 68 (19). September 2025. doi:10.1021/acs.jmedchem.5c01855. PMID 40997862. 
  9. ↑ "The selective 5-HT2A receptor agonist 25CN-NBOH: Structure-activity relationship, in vivo pharmacology, and in vitro and ex vivo binding characteristics of [3H]25CN-NBOH". Biochemical Pharmacology 177. July 2020. doi:10.1016/j.bcp.2020.113979. PMID 32298690. 
  10. ↑ 10.0 10.1 "The Utility of DOI For the Study of Serotonin 2A and 2C Receptors". Molecular Pharmacology 108 (1). 2025. doi:10.1016/j.molpha.2025.100093. PMID 41447818. 
  11. ↑ 11.0 11.1 "Structure of a Hallucinogen-Activated Gq-Coupled 5-HT2A Serotonin Receptor" (in English). Cell 182 (6): 1574–1588.e19. September 2020. doi:10.1016/j.cell.2020.08.024. PMID 32946782. 
  12. ↑ "Discovery of β-Arrestin-Biased 25CN-NBOH-Derived 5-HT2A Receptor Agonists". J Med Chem 65 (18): 12031–12043. September 2022. doi:10.1021/acs.jmedchem.2c00702. PMID 36099411. 
  13. ↑ "Introducing Conformational Restraints on 25CN-NBOH: A Selective 5-HT2A Receptor Agonist". ACS Med Chem Lett 14 (3): 319–325. March 2023. doi:10.1021/acsmedchemlett.3c00014. PMID 36923922. 
  14. ↑ "Identification of 5-HT2A receptor signaling pathways associated with psychedelic potential". Nat Commun 14 (1). December 2023. doi:10.1038/s41467-023-44016-1. PMID 38102107. 
  15. ↑ 15.0 15.1 15.2 "Hallucinogen-like effects of 2-([2-(4-cyano-2,5-dimethoxyphenyl) ethylaminomethyl)phenol (25CN-NBOH), a novel N-benzylphenethylamine with 100-fold selectivity for 5-HT2A receptors, in mice"]. Psychopharmacology 232 (6): 1039–1047. March 2015. doi:10.1007/s00213-014-3739-3. PMID 25224567. 
  16. ↑ "Chronic treatment with a metabotropic mGlu2/3 receptor agonist diminishes behavioral response to a phenethylamine hallucinogen". Psychopharmacology 236 (2): 821–830. February 2019. doi:10.1007/s00213-018-5118-y. PMID 30448990. 
  17. ↑ 17.0 17.1 17.2 "Tolerance and Tachyphylaxis to Head Twitches Induced by the 5-HT2A Agonist 25CN-NBOH in Mice". Frontiers in Pharmacology 9. 2018. doi:10.3389/fphar.2018.00017. PMID 29467649. 
  18. ↑ "Cortical Correlates of Psychedelic-Induced Shaking Behavior Revealed by Voltage Imaging" (in en). International Journal of Molecular Sciences 24 (11): 9463. May 2023. doi:10.3390/ijms24119463. ISSN 1422-0067. PMID 37298417. 
  19. ↑ "5-HT2 Receptor Regulation of Mitochondrial Genes: Unexpected Pharmacological Effects of Agonists and Antagonists". The Journal of Pharmacology and Experimental Therapeutics 357 (1): 1–9. April 2016. doi:10.1124/jpet.115.228395. PMID 26787771. 
  20. ↑ "The 5-hydroxytryptamine 2A receptor agonists DOI and 25CN-NBOH decrease marble burying and reverse 8-OH-DPAT-induced deficit in spontaneous alternation". Neuropharmacology 183. February 2021. doi:10.1016/j.neuropharm.2019.107838. PMID 31693871. https://researchprofiles.ku.dk/da/publications/62e9c284-ca42-42d1-8832-f6b3b12afbbc. 
  21. ↑ "Risperidone Treatment after Transient Ischemia Induces Hypothermia and Provides Neuroprotection in the Gerbil Hippocampus by Decreasing Oxidative Stress". International Journal of Molecular Sciences 20 (18): 4621. September 2019. doi:10.3390/ijms20184621. PMID 31540405. 
  22. ↑ "Acute serotonin 2A receptor activation impairs behavioral flexibility in mice". Behavioural Brain Research 395. October 2020. doi:10.1016/j.bbr.2020.112861. PMID 32814148. 
  23. ↑ "Serotonin Receptor 2A Activation Promotes Evolutionarily Relevant Basal Progenitor Proliferation in the Developing Neocortex". Neuron 108 (6): 1113–1129.e6. December 2020. doi:10.1016/j.neuron.2020.09.034. PMID 33080227. 
  24. ↑ "Acute Lysergic Acid Diethylamide Does Not Influence Reward-Driven Decision Making of C57BL/6 Mice in the Iowa Gambling Task" (in English). Frontiers in Pharmacology 11. 2020. doi:10.3389/fphar.2020.602770. PMID 33343373. 
  25. ↑ "Gs signaling pathway distinguishes hallucinogenic and nonhallucinogenic 5-HT2AR agonists induced head twitch response in mice". Biochemical and Biophysical Research Communications 598: 20–25. April 2022. doi:10.1016/j.bbrc.2022.01.113. PMID 35149433. 
  26. ↑ "Serotonin Receptor 5-HT2A Regulates TrkB Receptor Function in Heteroreceptor Complexes". Cells 11 (15): 2384. August 2022. doi:10.3390/cells11152384. PMID 35954229. 
  27. ↑ "Rearing behaviour in the mouse behavioural pattern monitor distinguishes the effects of psychedelics from those of lisuride and TBG" (in English). Frontiers in Pharmacology 14. 2023-02-16. doi:10.3389/fphar.2023.1021729. PMID 36874002. 
  28. ↑ "Psychedelic compounds directly excite 5-HT2A layer V medial prefrontal cortex neurons through 5-HT2A Gq activation". Transl Psychiatry 15 (1). 2025. doi:10.1038/s41398-025-03611-0. PMID 41052972. 
  29. ↑ "A Single Dose of a Psychedelic Drug Repairs Prefrontal Cortex Synaptic Physiology in a Mouse Model of Prenatal Alcohol Exposure". Brain and Behavior 16 (4). April 2026. doi:10.1002/brb3.71406. PMID 42007539. 
  30. ↑ "The Chronic Treatment With 5-HT2A Receptor Agonists Affects the Behavior and the BDNF System in Mice". Neurochemical Research 45 (12): 3059–3075. December 2020. doi:10.1007/s11064-020-03153-5. PMID 33095437. 
  31. ↑ "The selective 5-HT2A receptor agonist 25CN-NBOH does not affect reversal learning in mice". Behavioural Pharmacology 32 (5): 448–452. August 2021. doi:10.1097/FBP.0000000000000626. PMID 33595957. 
  32. ↑ "Regulatory mechanism of CCN2 production by serotonin (5-HT) via 5-HT2A and 5-HT2B receptors in chondrocytes". PLOS ONE 12 (11). 2017-11-16. doi:10.1371/journal.pone.0188014. PMID 29145495. Bibcode: 2017PLoSO..1288014H. 
  33. ↑ "A Complex Impact of Systemically Administered 5-HT2A Receptor Ligands on Conditioned Fear". The International Journal of Neuropsychopharmacology 24 (9): 749–757. September 2021. doi:10.1093/ijnp/pyab040. PMID 34228806. 
  34. ↑ "Single-dose psychedelic enhances cognitive flexibility and reversal learning in mice weeks after administration". Psychedelics 1 (3): 29–35. 2025-04-22. doi:10.61373/pp025r.0002. ISSN 2997-268X. PMID 40809535. PMC 12341394. https://genomicpress.kglmeridian.com/view/journals/psychedelics/aop/article-10.61373-pp025r.0002/article-10.61373-pp025r.0002.xml. 
  35. ↑ "Psychedelics produce enduring behavioral effects and functional plasticity through mechanisms independent of structural plasticity". Neuropsychopharmacology 51 (3): 641–649. November 2025. doi:10.1038/s41386-025-02272-3. PMID 41224969. 
  36. ↑ "An improved, scalable synthesis of the selective serotonin 2A receptor agonist 25CN-NBOH" (in en). SynOpen 05 (2): a–1524–4439. 2021-06-08. doi:10.1055/a-1524-4439. ISSN 2509-9396. 
  37. ↑ "Improved synthesis and physicochemical characterization of the selective serotonin 2A receptor agonist 25CN-NBOH" (in en). Beilstein Journal of Organic Chemistry 22 (1): 175–184. 2026-01-22. doi:10.3762/bjoc.22.11. ISSN 1860-5397. PMID 41602740. 
  38. ↑ "A quantitative method for the selective 5-HT2A agonist 25CN-NBOH in rat plasma and brain". Journal of Pharmaceutical and Biomedical Analysis 199. May 2021. doi:10.1016/j.jpba.2021.114016. PMID 33784574. 
  39. ↑ "Comparisons of hallucinogenic phenylisopropylamine binding affinities at cloned human 5-HT2A, -HT(2B) and 5-HT2C receptors". Naunyn-Schmiedeberg's Archives of Pharmacology 359 (1): 1–6. January 1999. doi:10.1007/PL00005315. PMID 9933142. 
  40. ↑ "Extensive rigid analogue design maps the binding conformation of potent N-benzylphenethylamine 5-HT2A serotonin receptor agonist ligands". ACS Chemical Neuroscience 4 (1): 96–109. January 2013. doi:10.1021/cn3000668. PMID 23336049. 
  41. ↑ "Controlled Drugs and Substances Act". https://laws-lois.justice.gc.ca/eng/acts/c-38.8/FullText.html. 
  42. ↑ "A Magyarországon megjelent, a Kábítószer és Kábítószer-függőség Európai Megfigyelő Központjának Korai Jelzőrendszerébe (EMCDDA EWS) 2005 óta bejelentett ellenőrzött anyagok büntetőjogi vonatkozású besorolása" (in Hungarian). September 2015. http://www.daath.hu/incoming/designer_jogi_lista_20150903_BSZKI_Daath_kieg.pdf. 
  43. ↑ "The Misuse of Drugs Act 1971 (Ketamine etc.) (Amendment) Order 2014" (in en). http://www.legislation.gov.uk/uksi/2014/1106/made. 
  44. ↑ Orange Book: List of Controlled Substances and Regulated Chemicals (January 2026), United States: U.S. Department of Justice: Drug Enforcement Administration (DEA): Diversion Control Division, January 2026, https://www.deadiversion.usdoj.gov/schedules/orangebook/orangebook.pdf 



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