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CBN (cannabinol)

From the cannabis plant.

From the cannabis plant. The 3D structure of the molecule, how it was discovered, and how it relates to the cannabinoid receptors; at three levels for Everyone, Students and Experts, with sources.

MoleculePubChem 2543Last updated:

What's on this page?

Interactive 3D · real anatomy and real data

Where in your body are the cannabinoid receptors?

About 1.4 MB to download.

Level
Reproductive organs

Regions

How to read it Choose a region, or tap a glowing point on the map.

  • Solid light is the CB1 receptor, a ring is CB2. Each region has its own color; the color only tells regions apart.
  • The strength of the light is the receptor gene level measured in human tissue (Human Protein Atlas). That is why the liver’s point is dim: a healthy liver has few receptors.
  • With the layer selector above you can also see other receptors, the enzymes that make and break down endocannabinoids, and the liver enzymes that break down CBD and THC.
  • Every piece of information shows its source and the type of evidence (human, animal, cell). You can change the reading level above.
  • Drag to rotate. Use the + and − buttons to zoom; on a computer, Ctrl or ⌘ with the scroll wheel, on a phone, two fingers.

C21H26O2 · 310.4 g/mol · PubChem 2543

CBN is the first cannabinoid isolated in pure form from cannabis: it was isolated in Cambridge at the end of the 19th century. The plant does not make it directly; it forms when THC reacts with air and slowly degrades, which is why there is more of it in cannabis that has been stored for a long time. It binds to the CB1 receptor more weakly than THC. Maioli 2022ReviewWood 1899Chemistry labFairbairn 1976Chemistry labAdams 1940Chemistry labFelder 1995Cell / labShowalter 1996Cell / labMcPartland 2007ReviewQueiroz 2025ReviewHerring 1998AnimalCorroon 2021Review

Student level

CBN's formula is C₂₁H₂₆O₂: it has four fewer hydrogens than THC, because one of THC's rings has been oxidized into a flat (aromatic), benzene-like ring. In an experiment with cannabis stored for a long time, light reduced THC but did not increase CBN, while oxidation by air in the dark did increase CBN. Its structure was confirmed in 1940 by Adams's total synthesis. At cloned human receptors, it bound more strongly to CB2 than to CB1, whereas THC was equally potent at both. Maioli 2022ReviewWood 1899Chemistry labFairbairn 1976Chemistry labAdams 1940Chemistry labFelder 1995Cell / labShowalter 1996Cell / labMcPartland 2007ReviewQueiroz 2025ReviewHerring 1998AnimalCorroon 2021Review

Expert level: method notes and numbers

CBN's formula is C₂₁H₂₆O₂: it has four fewer hydrogens than THC, because one of THC's rings has been oxidized into a flat (aromatic), benzene-like ring. In an experiment with cannabis stored for a long time, light reduced THC but did not increase CBN, while oxidation by air in the dark did increase CBN. Its structure was confirmed in 1940 by Adams's total synthesis. At cloned human receptors, it bound more strongly to CB2 than to CB1, whereas THC was equally potent at both. Maioli 2022ReviewWood 1899Chemistry labFairbairn 1976Chemistry labAdams 1940Chemistry labFelder 1995Cell / labShowalter 1996Cell / labMcPartland 2007ReviewQueiroz 2025ReviewHerring 1998AnimalCorroon 2021ReviewShowalter 1996: Ki at CB2 96.3 ± 14 nM (THC 36.4 ± 10 nM). Figures for CB1 affinity are inconsistent: one meta-analysis could not confirm the numerical validity of pooled values for CBN (McPartland 2007), while another review placed THC and CBN in the "high-affinity" group (Queiroz 2025); so only the direction is given instead of a number ("weaker than THC", Maioli 2022 full text). Herring 1998 describes CBN as a cannabinoid with little central nervous system effect. Corroon 2021: no published clinical study was found that examined CBN's effect on sleep with validated scales or polysomnography.

The 3D shape on the map is the structure computed by PubChem (not measured). PubChemComputer modelKim 2013Computer model

Identifiers and citation

IUPAC name
6,6,9-trimethyl-3-pentylbenzo[c]chromen-1-ol
InChIKey
VBGLYOIFKLUMQG-UHFFFAOYSA-N
Formula and weight
C21H26O2 · 310.4 g/mol

How to cite: cbd.school editorial team. CBN (cannabinol). Endocannabinoid system 3D map, cbd.school. Last updated October 24, 2026. https://cbd.school/learn/endocannabinoid-system-map/molekuller/cbn/

Molecule identifiers from the PubChem (NCBI) record; 3D shape is the conformer computed by PubChem. The map, text and downloaded images are CC BY-SA 4.0. An independent expert review has not been done yet. All licenses

Other pages of the map

Overview: what the endocannabinoid system is, the feedback brake at the synapse, CBD's targets, lesson mode, data and licenses.

Sources

Show 12 references
  1. National Center for Biotechnology Information. PubChem Compound database: anandamide (CID 5281969), 2-AG (CID 5282280), Δ9-THC (CID 16078), cannabidiol (CID 644019), cannabinol (CID 2543). Formula, molecular weight, IUPAC name and InChIKey are values computed by PubChem. A 3D conformer exists only for THC, CBD and CBN; it is not experimental but a model computed by PubChem. PubChem does not generate conformers for anandamide and 2-AG, which have more than 15 rotatable bonds. Accessed October 24, 2026. Source Computer model
  2. Kim S, Bolton EE, Bryant SH. PubChem3D: conformer ensemble accuracy. J Cheminform. 2013;5(1):1. PMID 23289532 · doi:10.1186/1758-2946-5-1 Computer model
  3. Maioli C, Mattoteia D, Amin HIM et al. Cannabinol: History, Syntheses, and Biological Profile of the Greatest "Minor" Cannabinoid. Plants (Basel). 2022;11(21):2896. PMID 36365350 · doi:10.3390/plants11212896 Review
  4. Wood TB, Spivey WTN, Easterfield TH. III.—Cannabinol. Part I. J Chem Soc Trans. 1899;75:20-36. · doi:10.1039/ct8997500020 Chemistry lab
  5. Fairbairn JW, Liebmann JA, Rowan MG. The stability of cannabis and its preparations on storage. J Pharm Pharmacol. 1976;28(1):1-7. PMID 6643 · doi:10.1111/j.2042-7158.1976.tb04014.x Chemistry lab
  6. Adams R, Baker BR, Wearn RB. Structure of Cannabinol. III. Synthesis of Cannabinol, 1-Hydroxy-3-n-amyl-6,6,9-trimethyl-6-dibenzopyran. J Am Chem Soc. 1940;62(8):2204-7. · doi:10.1021/ja01865a083 Chemistry lab
  7. Felder CC, Joyce KE, Briley EM et al. Comparison of the pharmacology and signal transduction of the human cannabinoid CB1 and CB2 receptors. Mol Pharmacol. 1995;48(3):443-50. PMID 7565624 Cell / lab
  8. Showalter VM, Compton DR, Martin BR, Abood ME. Evaluation of binding in a transfected cell line expressing a peripheral cannabinoid receptor (CB2): identification of cannabinoid receptor subtype selective ligands. J Pharmacol Exp Ther. 1996;278(3):989-99. PMID 8819477 Cell / lab
  9. McPartland JM, Glass M, Pertwee RG. Meta-analysis of cannabinoid ligand binding affinity and receptor distribution: interspecies differences. Br J Pharmacol. 2007;152(5):583-93. PMID 17641667 · doi:10.1038/sj.bjp.0707399 Review
  10. Queiroz CM, de Oliveira Koren L, da Silva CRP et al. Chemical diversity, receptor binding affinity, and pharmacology of phytocannabinoids: Insights into neuronal mechanisms. Prog Brain Res. 2025;296:1-28. PMID 40967679 · doi:10.1016/bs.pbr.2025.07.006 Review
  11. Herring AC, Koh WS, Kaminski NE. Inhibition of the cyclic AMP signaling cascade and nuclear factor binding to CRE and kappaB elements by cannabinol, a minimally CNS-active cannabinoid. Biochem Pharmacol. 1998;55(7):1013-23. PMID 9605425 · doi:10.1016/s0006-2952(97)00630-8 Animal
  12. Corroon J. Cannabinol and Sleep: Separating Fact from Fiction. Cannabis Cannabinoid Res. 2021;6(5):366-371. PMID 34468204 · doi:10.1089/can.2021.0006 Review