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ECHA InfoCard | 100.216.772 |
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Formula | C21H26O2 |
Molar mass | 310.437 g·mol−1 |
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Melting point | 76–77 °C (169–171 °F) [1] |
Solubility in water | Insoluble in water, [2] soluble in methanol [3] and ethanol [4] mg/mL (20 °C) |
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Cannabinol (CBN) is a mildly psychoactive phytocannabinoid that acts as a low affinity partial agonist at both CB1 and CB2 receptors. This activity at CB1 and CB2 receptors constitutes interaction of CBN with the endocannabinoid system (ECS).
Although CBN shares the same mechanism of action as other phytocannabinoids (e.g., Delta-9-tetrahydrocannabinol, Δ9-THC), it has a lower affinity for CB1 receptors, meaning that much higher doses of CBN are required in order to experience effects, such as mild sedation.
It was the first cannabinoid to be isolated from cannabis and was discovered in 1896.
Both THC and CBN activate the CB1 (Ki = 211.2 nM) and CB2 (Ki = 126.4 nM) receptors. [5] Each compound acts as a low affinity partial agonist at CB1 receptors with THC demonstrating 5x–10× greater affinity to the CB1 receptor. [5] [6] [7] [8] [9] [10] Like THC, CBN has a higher selectivity for CB2 receptors [5] [8] which are located throughout the central and peripheral nervous system, but are primarily associated with immune function. CB2 receptors are known to be located on immune cells throughout the body, including macrophages, T cells, and B cells. These immune cells have been shown to decrease production of immune-related chemical signals (e.g., cytokines) or undergo apoptosis as a consequence of CB2 agonism by CBN. [11] In cell culture, CBN demonstrates antimicrobial effects, particularly in instances of antibiotic-resistant bacteria. [12] CBN has also been reported to act as an ANKTM1 channel agonist at high concentrations (>20nM). [6] While some phytocannabinoids have been shown to interact with nociceptive and immune-related signaling via transient receptor potential channels (e.g., TRPV1 and TRPM8), there is currently limited evidence to suggest that CBN acts in this way. [6] [13] In preclinical rodent studies, CBN, anandamide and other CB1 agonists have demonstrated inhibitory effects on GI motility, reversible via CB1R blockade (i.e., antagonism). [6]
In considering the efficacy of cannabis-based products, there remains controversy surrounding a concept termed “the entourage effect”. This concept describes a widely reported but poorly-understood synergistic effect of certain cannabinoids when phytocannabinoids are coadministered with other naturally-occurring chemical compounds in the cannabis plant (e.g., flavonoids, terpenoids, alkaloids). This entourage effect is often cited to explain the superior efficacy observed in some studies of whole-plant-derived cannabis therapeutics as compared to isolated or synthesized individual cannabis constituents. [14]
The table highlights several common cannabinoids along with putative receptor targets and therapeutic properties. Exogenous (plant-derived) phytocannabinoids are identified with an asterisk while remaining chemicals represent well-known endocannabinoids (i.e., endogenously produced cannabinoid receptor ligands).
Full Name | Known Receptor Targets | Putative Therapeutic Properties |
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Cannabichromene (CBC) | ||
Cannabidiol (CBD) |
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Cannabigerol (CBG) | ||
Cannabinol (CBN) |
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Tetrahydrocannabinol (THC) / Delta-9-Tetrahydrocannabinol (Δ9-THC) |
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2-Arachidonoylglycerol (2-AG) | ||
Anandamide (AEA) | Anti-oxidative properties [16] |
In the brain, the canonical mechanism of CB1 receptor activation is a form of short-term synaptic plasticity initiated via retrograde signaling of endogenous CB1 agonists such as 2AG or AEA (two primary endocannabinoids). This mechanism of action is called depolarization-induced suppression of inhibition (DSI) or depolarization-induced suppression of excitation (DSE), [18] depending on the classification of the presynaptic neuron acted upon by the retrograde messenger (see diagram at left). In the case of CB1R agonism on the presynaptic membrane of a GABAergic interneuron, activation leads to a net effect of increased activity, while the same activity on a glutamatergic neuron leads to the opposite net effect. The release of other neurotransmitters is also modulated in this way, particularly dopamine, dynorphin, oxytocin, and vasopressin. [18]
When administered orally, CBN demonstrates a similar metabolism to Δ9-THC, with the primary active metabolite produced through the hydrolyzation of C9 as part of first-pass metabolism in the liver. The active metabolite generated via this process is called 11-OH-CBN, which is 2x as potent as CBN, and has demonstrated activity as a weak CB2 antagonist. This metabolism starkly contrasts that of Δ9-THC in terms of potency, given that 11-OH-THC has been reported to have 10× the potency of Δ9-THC.
Due to high lipophilicity and first-pass metabolism, there is low bioavailability of CBN and other cannabinoids following oral administration. CBN metabolism is mediated in part by CYP450 isoforms 2C9 and 3A4. The metabolism of CBN may be catalyzed by UGTs (UDP-glucuronosyltransferases), with a subset of UGT isoforms (1A7, 1A8, 1A9, 1A10, 2B7) identified as potential substrates associated with CBN glucuronidation. The bioavailability of CBN following administration via inhalation (e.g., smoking or vaporizing) is approximately 40% that of intravenous administration.
A small study of six cannabis users found a highly variable half life of 32 ± 17 hours upon intravenous administration. [19] Similar to CBD, CBN is metabolized by the CYP2C9 and CYP3A4 liver enzymes and thus the half-life is sensitive to genetic factors that effect the levels of these enzymes. [20]
This section needs additional citations for verification .(November 2023) |
Cannabinoid receptor agonists are categorized into four groups based on chemical structure. CBN, as one of the many phytocannabinoids derived from Cannabis Sativa L , is considered a classical cannabinoid. Other examples of compounds in this group include dibenzopyran derivatives such as Δ9-THC, well-known for underlying the subjective "high" experienced by cannabis users, as well as Δ8-THC, and their synthetic analogs. In contrast, endogenously produced cannabinoids (i.e., endocannabinoids), which also exert effects through CB agonism, are considered eicosanoids, distinguished by notable differences in chemical structure.
Compared to Δ9-THC, one additional aromatic ring confers CBN with a slower and more limited metabolic profile (see § CBN Formation & Metabolism). In contrast to THC, CBN has no double bond isomers nor stereoisomers. CBN can degrade into HU-345 from oxidation. In the case of oral administration of CBN, first-pass metabolism in the liver involves the addition of a hydroxyl group at C9 or C11, increasing the affinity and specificity of CBN for both CB1 and CB2 receptors (see 11-OH-CBN).
CBN was the first cannabinoid to be isolated from cannabis extract in the late 1800s. Specifically, it was discovered by Barlow Wood, Newton Spivey, and Easterfield in 1896. [21] In the early 1930s, CBN's structure was identified by Cahn, [22] [23] marking the first development of a cannabis extract. Its structure and chemical synthesis were achieved by 1940, followed by some of the first preclinical research studies to determine the effects of individual cannabis-derived compounds in vivo . [8]
CBN is not listed in the schedules set out by the United Nations' Single Convention on Narcotic Drugs from 1961 nor their Convention on Psychotropic Substances from 1971, [24] so the signatory countries to these international drug control treaties are not required by these treaties to control CBN.
According to the 2018 Farm Bill, [25] extracts from the Cannabis sativa L. plant, including CBN, are legal under US federal law as long as they have a delta-9 Tetrahydrocannabinol (THC) concentration of 0.3% or less. [26] [27]
This diagram represents the biosynthetic and metabolic pathways by which phytocannabinoids (e.g., CBD, THC, CBN) are created in the cannabis plant. Starting with CBG-A, the acidic forms of certain phytocannabinoids are generated via enzymatic conversion. From there, decarboxylation (i.e., catalyzed by combustion or heat) yields the most well-known metabolites present in the cannabis plant. CBN is unique in that it does not arise from a pre-existing acidic form, but rather is generated through the oxidation of THC.
CBN is unique among phytocannabinoids in that its biosynthetic pathway involves conversion directly from Δ9-THC, rather than from an acidic precursor form of CBN (e.g., Δ9-THC arises through decarboxylation of THC-A). CBN can be found in trace amounts in the Cannabis plant, found mostly in cannabis that is aged and stored, allowing for CBN formation through the oxidation of the cannabis plant's main psychoactive and intoxicating chemical, tetrahydrocannabinol (THC). This process of oxidation occurs via exposure to heat, oxygen, and/or light. Although reports are limited, CBN-A has also been measured at very low levels in the cannabis plant, thought to have formed via hydrolyzation of THC-A (see Phytocannabinoid Biosynthesis diagram, below).
Tetrahydrocannabinol (THC) is a cannabinoid found in cannabis. It is the principal psychoactive constituent of cannabis and one of at least 113 total cannabinoids identified on the plant. Although the chemical formula for THC (C21H30O2) describes multiple isomers, the term THC usually refers to the delta-9-THC isomer with chemical name (−)-trans-Δ9-tetrahydrocannabinol. It is a colorless oil.
Anandamide (ANA), also referred to as N-arachidonoylethanolamine (AEA) is a fatty acid neurotransmitter belonging to the fatty acid derivative group known as N-acylethanolamine (NAE). Anandamide takes its name from the Sanskrit word ananda, meaning "joy, bliss, delight," plus amide. Anandamide, the first discovered endocannabinoid, engages with the body's endocannabinoid system by binding to the same cannabinoid receptors that THC found in cannabis acts on. Anandamide can be found within tissues in a wide range of animals. It has also been found in plants, such as the cacao tree.
Cannabinoids are several structural classes of compounds found in the cannabis plant primarily and most animal organisms or as synthetic compounds. The most notable cannabinoid is the phytocannabinoid tetrahydrocannabinol (THC) (delta-9-THC), the primary psychoactive compound in cannabis. Cannabidiol (CBD) is also a major constituent of temperate cannabis plants and a minor constituent in tropical varieties. At least 100 distinct phytocannabinoids have been isolated from cannabis, although only four have been demonstrated to have a biogenetic origin. It was reported in 2020 that phytocannabinoids can be found in other plants such as rhododendron, licorice and liverwort, and earlier in Echinacea.
Cannabinoid receptors, located throughout the body, are part of the endocannabinoid system of vertebrates– a class of cell membrane receptors in the G protein-coupled receptor superfamily. As is typical of G protein-coupled receptors, the cannabinoid receptors contain seven transmembrane spanning domains. Cannabinoid receptors are activated by three major groups of ligands:
Tetrahydrocannabivarin is a homologue of tetrahydrocannabinol (THC) having a propyl (3-carbon) side chain instead of pentyl (5-carbon), making it non-psychoactive in lower doses. It has been shown to exhibit neuroprotective activity, appetite suppression, glycemic control and reduced side effects compared to THC, making it a potential treatment for management of obesity and diabetes. THCV was studied by Roger Adams as early as 1942.
WIN 55,212-2 is a chemical described as an aminoalkylindole derivative, which produces effects similar to those of cannabinoids such as tetrahydrocannabinol (THC) but has an entirely different chemical structure.
11-Hydroxy-Δ9-tetrahydrocannabinol, usually referred to as 11-hydroxy-THC is the main active metabolite of tetrahydrocannabinol (THC), which is formed in the body after Δ9-THC is consumed.
Cannabigerol (CBG) is a non-psychoactive cannabinoid and minor constituent of cannabis. It is one of more than 120 identified cannabinoids found in the plant genus Cannabis. The compound is the decarboxylated form of cannabigerolic acid (CBGA), the parent molecule from which other cannabinoids are biosynthesized.
Cannabinoid receptor 1 (CB1), is a G protein-coupled cannabinoid receptor that in humans is encoded by the CNR1 gene. And discovered, by determination and characterization in 1988, and cloned in 1990 for the first time. The human CB1 receptor is expressed in the peripheral nervous system and central nervous system. It is activated by endogenous cannabinoids called endocannabinoids, a group of retrograde neurotransmitters that include lipids, such as anandamide and 2-arachidonoylglycerol; plant phytocannabinoids, such as docosatetraenoylethanolamide found in wild daga, the compound tetrahydrocannabinol which is an active constituent of the psychoactive drug cannabis; and synthetic analogs of tetrahydrocannabinol. CB1 is antagonized by the phytocannabinoid tetrahydrocannabivarin at low doses and at higher doses, it activate the CB1 receptor as an agonist, but with less potency than tetrahydrocannabinol.
Δ9-Tetrahydrocannabutol is a phytocannabinoid found in cannabis that is a homologue of tetrahydrocannabinol (THC), the main active component of Cannabis. Structurally, they are only different by the pentyl side chain being replaced by a butyl side chain. THCB was studied by Roger Adams as early as 1942
Cannabichromene (CBC), also called cannabichrome, cannanbichromene, pentylcannabichromene or cannabinochromene, exhibits anti-inflammatory properties in vitro, which may, theoretically, contribute to cannabis analgesic effects. It is a phytocannabinoid, one of the hundreds of cannabinoids found in the Cannabis plant. It bears structural similarity to the other natural cannabinoids, including tetrahydrocannabinol (THC), tetrahydrocannabivarin (THCV), cannabidiol (CBD), and cannabinol (CBN), among others. CBC and cannabinols are present in cannabis. It is not scheduled by the Convention on Psychotropic Substances.
A cannabinoid receptor antagonist, also known simply as a cannabinoid antagonist or as an anticannabinoid, is a type of cannabinoidergic drug that binds to cannabinoid receptors (CBR) and prevents their activation by endocannabinoids. They include antagonists, inverse agonists, and antibodies of CBRs. The discovery of the endocannabinoid system led to the development of CB1 receptor antagonists. The first CBR inverse agonist, rimonabant, was described in 1994. Rimonabant blocks the CB1 receptor selectively and has been shown to decrease food intake and regulate body-weight gain. The prevalence of obesity worldwide is increasing dramatically and has a great impact on public health. The lack of efficient and well-tolerated drugs to cure obesity has led to an increased interest in research and development of CBR antagonists. Cannabidiol (CBD), a naturally occurring cannabinoid and a non-competitive CB1/CB2 receptor antagonist, as well as Δ9-tetrahydrocannabivarin (THCV), a naturally occurring cannabinoid, modulate the effects of THC via direct blockade of cannabinoid CB1 receptors, thus behaving like first-generation CB1 receptor inverse agonists, such as rimonabant. CBD is a very low-affinity CB1 ligand, that can nevertheless affect CB1 receptor activity in vivo in an indirect manner, while THCV is a high-affinity CB1 receptor ligand and potent antagonist in vitro and yet only occasionally produces effects in vivo resulting from CB1 receptor antagonism. THCV has also high affinity for CB2 receptors and signals as a partial agonist, differing from both CBD and rimonabant.
An N-acylethanolamine (NAE) is a type of fatty acid amide where one of several types of acyl groups is linked to the nitrogen atom of ethanolamine, and highly metabolic formed by intake of essential fatty acids through diet by 20:4, n-6 and 22:6, n-3 fatty acids, and when the body is physically and psychologically active,. The endocannabinoid signaling system (ECS) is the major pathway by which NAEs exerts its physiological effects in animal cells with similarities in plants, and the metabolism of NAEs is an integral part of the ECS, a very ancient signaling system, being clearly present from the divergence of the protostomian/deuterostomian, and even further back in time, to the very beginning of bacteria, the oldest organisms on Earth known to express phosphatidylethanolamine, the precursor to endocannabinoids, in their cytoplasmic membranes. Fatty acid metabolites with affinity for CB receptors are produced by cyanobacteria, which diverged from eukaryotes at least 2000 Million years ago (MYA), by brown algae which diverged about 1500 MYA, by sponges, which diverged from eumetazoans about 930 MYA, and a lineages that predate the evolution of CB receptors, as CB1 – CB2 duplication event may have occurred prior to the lophotrochozoan-deuterostome divergence 590 MYA. Fatty acid amide hydrolase (FAAH) evolved relatively recently, either after the evolution of fish 400 MYA, or after the appearance of mammals 300 MYA, but after the appearance of vertebrates. Linking FAAH, vanilloid receptors (VR1) and anandamide implies a coupling among the remaining ‘‘older’’ parts of the endocannabinoid system, monoglyceride lipase (MGL), CB receptors, that evolved prior to the metazoan–bilaterian divergence, but were secondarily lost in the Ecdysozoa, and 2-Arachidonoylglycerol (2-AG).
Tetrahydrocannabinolic acid is a precursor of tetrahydrocannabinol (THC), an active component of cannabis.
The entourage effect is a hypothesis that cannabis compounds other than tetrahydrocannabinol (THC) act synergistically with it to modulate the overall psychoactive effects of the plant.
Tetrahydrocannabiphorol (THCP) is a potent phytocannabinoid, a CB1 and CB2 receptor agonist which was known as a synthetic homologue of tetrahydrocannabinol (THC), but for the first time in 2019 was isolated as a natural product in trace amounts from Cannabis sativa.
Δ-8-tetrahydrocannabinol is a psychoactive cannabinoid found in the cannabis plant. It is an isomer of delta-9-tetrahydrocannabinol, the compound commonly known as THC, with which it co-occurs in hemp; natural quantities of ∆8-THC found in hemp are low. Psychoactive effects are similar to that of Δ9-THC, with central effects occurring by binding to cannabinoid receptors found in various regions of the brain.
Δ9-Tetrahydrocannabiorcol (Δ9-THCC, (C1)-Δ9-THC) is a phytocannabinoid found in Cannabis pollen. It is a homologue of THC and THCV with the alkyl side chain replaced by a smaller methyl group. Unlike THC and THCV, THCC has negligible affinity for the CB1 and CB2 cannabinoid receptors because of the smaller methyl group and does not have psychoactive effects as a result, but conversely it is significantly more potent than THC or THCV as an activator of the TRPA1 calcium channel which plays an important role in pain perception, and it has been shown to produce analgesic effects via activation of spinal TRPA1 channels. THCC was studied by Roger Adams as early as 1942.
Hexahydrocannabinol (HHC) is a hydrogenated derivative of tetrahydrocannabinol (THC). It is a naturally occurring phytocannabinoid that has rarely been identified as a trace component in Cannabis sativa, but can also be produced synthetically by firstly acid cyclization of cannabidiol and then hydrogenation of tetrahydrocannabinol. The synthesis and bioactivity of HHC was first reported in 1940 by Roger Adams.
Tetrahydrocannabihexol is a phytocannabinoid, the hexyl homologue of tetrahydrocannabinol (THC) which was first isolated from Cannabis plant material in 2020 along with the corresponding hexyl homologue of cannabidiol, though it had been known for several decades prior to this as an isomer of the synthetic cannabinoid parahexyl. Another isomer Δ8-THCH is also known as a synthetic cannabinoid under the code number JWH-124, though it is unclear whether this occurs naturally in Cannabis, but likely is due to Δ8-THC itself being a degraded form of Δ9-THC. THC-Hexyl can be synthesized from 4-hexylresorcinol and was studied by Roger Adams as early as 1942.