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From the plant

CBNCannabinol

An oxidation product of Δ9-THC that builds up in aged cannabis; the first cannabinoid isolated (1899).

Hemp exemption
Level of detail

C₂₁H₂₆O₂

CAS 521-35-7

Family
PhytocannabinoidMinor
Origin
Degradation product
First described
1899
Molar mass
310.44 g/mol

Updated on

In plain terms

CBN is not made by the plant: it appears when THC oxidises in air, which is why aged cannabis contains more of it. It binds cannabinoid receptors less strongly than THC. In a large placebo-controlled trial it did not significantly improve sleep quality, the study's primary outcome.

Receptors and activity

Target network

CB1Partial agonistKi = 211 nM · rat[3H]HU-243 displacement, transfected COS-7 (rat CB1); 392.2 nM on brain synaptosomes; less efficacious than Δ9-THC on adenylate cyclase (Maioli 2022)
  • Activates
  • Blocks or inhibits
  • Binds or modulates

The lower the cited value, the closer the target sits to CBN: one ring per factor of 100. A target with no measured value stays on the edge.

Where these targets live

Where each target has been found in humans, according to the cited studies. The map shows the target, not an effect of CBN.

Brain, side view
Body, front view
Blood

CB1CB1 found in 7 regions of the body

  1. Basal gangliadenseMost dense in basal ganglia outflow nuclei1
  2. CerebellumdenseVery dense in the cerebellum1
  3. HippocampusdenseVery high concentrations in the hippocampus2
  4. AmygdaladenseHigh concentrations in the amygdala2
  5. CortexpresentPresent throughout the neocortex2
  6. Adipose tissuepresentExpressed in adipose tissue3
  7. GutpresentColonic epithelium, smooth muscle and plexus4

Map sources

  1. Herkenham M et al. Cannabinoid receptor localization in brain. Proc Natl Acad Sci U S A, 1990 (new tab)
  2. Glass M et al. Cannabinoid receptors in the human brain: a detailed anatomical and quantitative autoradiographic study in the fetal, neonatal and adult human brain. Neuroscience, 1997 (new tab)
  3. Engeli S et al. Activation of the peripheral endocannabinoid system in human obesity. Diabetes, 2005 (new tab)
  4. Wright K et al. Differential expression of cannabinoid receptors in the human colon: cannabinoids promote epithelial wound healing. Gastroenterology, 2005 (new tab)

Cited values

  1. CB1Partial agonistKi = 211 nM · rat45 out of 100

    Rhee et al. 1997, J Med Chem 40:3228 (table 1) (new tab) · [3H]HU-243 displacement, transfected COS-7 (rat CB1); 392.2 nM on brain synaptosomes; less efficacious than Δ9-THC on adenylate cyclase (Maioli 2022)

  2. CB2AgonistKi = 126 nM · human48 out of 100

    Rhee et al. 1997, J Med Chem 40:3228 (table 1) (new tab) · [3H]HU-243 displacement, transfected COS-7 (human CB2); adenylate cyclase inhibition EC50 261.2 nM

  3. TRPA1AgonistEC50 = 180 nM · rat46 out of 100

    De Petrocellis et al. 2011, Br J Pharmacol: TRP channels (new tab) · intracellular Ca2+ (fluorescence), HEK-293 rat TRPA1

  4. TRPM8AntagonistIC50 = 210 nM · rat45 out of 100

    De Petrocellis et al. 2011, Br J Pharmacol: TRP channels (new tab) · inhibition of the icilin response, HEK-293 rat TRPM8

  5. TRPV4Modulatorno measured value cited
Bar length follows the measured value (Ki, Kd, EC50 or IC50), on one scale shared by every entry, from 100 µM to 0.1 nM. A target with no cited value has no bar.

Measured effects

Psychoactive intensityIntensity of the felt effect (« feel drug effect », « high ») on a validated scale, compared with placebo.

Effect reported, size not measuredLow confidence

300 mg orally, in patients · Lavender 2026

Measured anxietyAnxiety measured on a validated scale, often during a laboratory stressor; it can fall or rise depending on the dose.

Not measured

Cognitive impairmentLower performance on attention, memory or speed tests, compared with placebo.

Effect reported, size not measured · increaseVery low confidence

300 mg orally, in patients · Lavender 2026

SleepinessReported sleepiness or measured sedation, compared with placebo.

Not distinct from placeboLow confidence

up to 50 mg orally · Karniol 1975

Reported hungerReported hunger or measured food intake, compared with placebo.

Not measured

Levels computed from placebo-controlled human trials: difference from placebo on 100, at the dose and route stated. Read the method

Pharmacology

CBN is the first phytocannabinoid ever isolated: in Cambridge, Wood, Spivey and Easterfield obtained a 'red oil' from charas in 1896, whose acetylation gave a crystalline derivative in 1899, the corresponding phenol taking the name cannabinol (Maioli et al., 2022). Its structure was only established in 1940, through Roger Adams's total synthesis. No biosynthetic pathway has been identified for CBN or its acid: it is a degradation artefact of Δ9-THC, which aromatises through air oxidation (Maioli et al., 2022; Walsh et al., 2021). In storage, THC lost in air and darkness raises CBN, whereas THC lost to light does not (Fairbairn et al., 1976). Radwan et al. (2021) rank it among the 'major' cannabinoids, whereas Hanuš et al. (2016), Walsh et al. (2021) and Maioli et al. (2022) regard it as minor. A study in transfected COS-7 cells reports Ki values of 211.2 nM at rat CB1 and 126.4 nM at human CB2, against 80.3 and 32.2 nM for Δ9-THC in the same assay (Rhee et al., 1997); McPartland et al. (2007) nonetheless judge pooled CBN values not numerically valid. It activates rat TRPA1 (EC50 0.18 µM) and blocks rat TRPM8 (IC50 0.21 µM; De Petrocellis et al., 2011). In a randomised placebo-controlled trial in 293 adults reporting poor sleep, 20 mg of CBN for seven nights did not significantly improve sleep quality, the primary outcome (OR 2.26; 95% CI 0.93-5.52; p = 0.082), but reduced the number of awakenings, a secondary outcome; adding CBD changed nothing, and the study was industry-funded (Bonn-Miller et al., 2024). In France, CBN has been expressly excluded since 2024 from the generic class of benzo[c]chromene derivatives classified as narcotics.

Key sources.

History

Source
Present in cannabis as a degradation product: air oxidation of Δ9-THC (and of THCA), mainly during storage

Biosynthetic pathway

No enzymatic pathway has been identified (Maioli et al., 2022). Δ9-THC aromatises through air oxidation; in storage, THC lost in air and darkness raises CBN, whereas THC lost to light does not (Fairbairn et al., 1976). Traces of CBNA in some hemp samples suggest the same oxidation of THCA.

Classification

Family, origin and source verification

Family

Phytocannabinoid › Minor

Presence in the plant

Artefact: formed by oxidation, light, heat or solvent

Chemistry

Type CBN · C5 side chain · neutral form

Verification

Every fact on this entry was checked against its primary sources on 20 October 2026.

Wikipedia (English)

Cannabinol (new tab)

Article paired by the molecule's structure (InChIKey), revision read on 19 October 2026. Read as a second opinion, never cited as a source.

References

  1. Maioli et al. 2022, Plants: history, origin, pharmacology of CBN (new tab)PMID 36365350
  2. Fairbairn, Liebmann & Rowan 1976, J Pharm Pharmacol: storage stability (new tab)PMID 6643
  3. Rhee et al. 1997, J Med Chem 40:3228 (table 1) (new tab)PMID 9379442
  4. De Petrocellis et al. 2011, Br J Pharmacol: TRP channels (new tab)PMID 21175579
  5. Bonn-Miller et al. 2024, Exp Clin Psychopharmacol: sleep trial (new tab)PMID 37796540
  6. Wood, Spivey & Easterfield 1899, J Chem Soc Trans 75:20: Cannabinol, Part I (new tab)DOI 10.1039/CT8997500020

Identifiers

Names

Common name
Cannabinol
IUPAC name
6,6,9-trimethyl-3-pentylbenzo[c]chromen-1-ol

Identifiers

Formula
C₂₁H₂₆O₂
CAS
521-35-7
PubChem CID
2543(new tab)
ChEBI
3360(new tab)
InChIKey
VBGLYOIFKLUMQG-UHFFFAOYSA-N
SMILES
CCCCCC1=CC(=C2C(=C1)OC(C3=C2C=C(C=C3)C)(C)C)O

Machine-readable entry (JSON)

LLM ingestion format: a structured superset of the entry (identifiers, binding, versioned legal status). Full corpus.

In the Journal