User:Mkf pm801/Cannabinol

Cannabinol (CBN) is a mildly psychoactive cannabinoid 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), which is responsible for regulating many important functions in the body. Through its mechanism of partial agonism at the CB1R, CBN is thought to interact with other kinds of neurotransmission (e.g., dopaminergic, serotonergic, cholinergic, and noradrenergic).

CBN was the first cannabis compound to be isolated from cannabis extract in the late 1800s. Its structure and chemical synthesis were achieved by 1940 , followed by some of the first pre-clinical research studies to determine the effects of individual cannabis-derived compounds in vivo. Although CBN shares the same mechanism of action as other more well-known phytocannabinoids (e.g., delta-9 tetrahydrocannabinol or D9THC), it has a lower affinity for CB1 receptors, meaning that much higher doses of CBN are required in order to experience physiologic effects (e.g., mild sedation) associated with CB1R agonism. Although scientific reports are conflicting, the majority of findings suggest that CBN has a slightly higher affinity for CB2 as compared to CB1. Although CBN has been marketed as a sleep aid in recent years, there is a lack of scientific evidence to support these claims, warranting skepticism on the part of consumers.

Chemical Structure
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 D9THC, well-known for underlying the subjective “high” experienced by cannabis users, as well as D8THC, 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 D9THC, one additional aromatic ring confers CBN with a slower and more limited metabolic profile - see CBN Formation & Metabolism, below. 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).

Formation & Metabolism
CBN is unique among phytocannabinoids in that its biosynthetic pathway involves conversion directly from D9THC, rather than from an acidic precursor form of CBN (e.g., D9THC 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.

When administered orally, CBN demonstrates a similar metabolism to D9THC, 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 D9THC in terms of potency, given that 11-OH-THC has been reported to have 10x the potency of D9THC.

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.

Pharmacology
CBN was the first cannabis compound to be isolated from cannabis extract in the late 1800s. 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.

Both THC and CBN activate the CB1 (Ki = 211.2 nM) and CB2 (Ki = 126.4 nM) receptors. Each compound acts as a low affinity partial agonist at CB1 receptors with THC demonstrating 10-13x greater affinity to the CB1 receptor. Compared to THC, CBN has an equivalent or higher affinity to CB2 receptors, 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. In cell culture, CBN demonstrates antimicrobial effects, particularly in instances of antibiotic-resistant bacteria. CBN has also been reported to act as an ANKTM1 channel agonist at high concentrations (>20nM). 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. In preclinical rodent studies, CBN, anandamide and other CB1 agonists have demonstrated inhibitory effects on GI motility, reversible via CB1R blockade (i.e., antagonism).

In considering the efficacy of cannabis-based products, there remains controversy surrounding a concept termed “the entourage effect”. This concept describes a widely-observed but poorly-understood synergistic effect of cannabinoid activity 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.

Common Cannabinoids - Putative Receptor Targets & Therapeutic Properties
The below 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).

Neurotransmitter Interactions
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), depending on the classification of the presynaptic neuron acted upon by the retrograde messenger. 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.

Therapeutic Potential
Although CBN is widely marketed as a sleep aid, there is currently no published scientific evidence to support this claim. Most clinical studies date prior to 1980, with mixed results further clouded by a lack of validated sleep questionnaires, physiological data, and appropriate sample sizes. While ongoing clinical trials seek to elucidate the role of CBN in sleep, the general public should exercise skepticism regarding these claims. As of November 2022, there are just three ongoing clinical trials to evaluate the medical use of CBN-containing products. These studies aim to evaluate the efficacy of CBN-containing products in the context of Epidermolysis Bullosa, insomnia disorder, and osteoarthritis of the knee. Ongoing reports from these studies will yield much-needed scientific data in these areas.

Despite lacking clinical evidence, some research findings in molecular and cellular biology suggest that therapeutic mechanisms may arise through non-CB receptor activation. For example, studies in cell culture have shown that CBN interferes with neuroblastoma progression, an effect that persists even in the absence of CB1/2R expression.

Scientists and clinicians remain determined to elucidate the therapeutic potential of cannabinoids, suggesting collaborative strategies such as the creation of a “cannabinoid receptor interaction matrix” (CRIM) to bolster ongoing efforts to disentangle the complex effects of ECS modulation throughout the body. Future research seeking to evaluate CBN-containing therapeutics in sleep and other areas must utilize validated clinical metrics and reproducible methods of physiologic monitoring (e.g., polysomnography in the study of sleep) to determine whether CBN may truly offer efficacy in these domains.

Although clinical research of CBN remains in its infancy, investigations of therapeutic profiles of other cannabinoids, such as D9THC and CBD, have led to three cannabis-based medications that are FDA-approved in the United States (see Table under 'Cannabinol and the Controlled Substances Act').

Legal status
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, so the signatory countries to these international drug control treaties are not required by these treaties to control CBN.

United States
According to the 2018 Farm Bill, 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 percent or less. However, as of 2022 in the United States, CBN and other cannabis extracts remain illegal under federal law to prescribe for medical use or to use as an ingredient in dietary supplements or other foods, and sales or possession of CBN could potentially be prosecuted under the Federal Analogue Act. In December 2016, the Drug Enforcement Administration added marijuana extracts, which are defined as any "extract containing one or more cannabinoids that has been derived from any plant of the genus Cannabis, other than the separated resin", to Schedule I. Despite legislative obstacles presented by the federal government, cannabis laws at the state level have evolved substantially since the late 1990's. As of February 2022, more than 37 states, 3 territories, and the District of Columbia have enacted state laws allowing the medical use of cannabis. In 2013, the Department of Justice issued a memorandum advising attorneys to pursue federal prosecution of cannabis-related activity by individuals and/or entities only in instances where state legislation fails to protect any of eight specific federal safety interests listed therein (e.g., Preventing the distribution of marijuana to minors). As a consequence, cannabis products in the United States are essentially regulated at the state level, while hemp products with <0.3% THC (i.e., those pertinent to the 2018 Farm Bill) are regulated by the FDA and FTC. The vast majority of recreational cannabis products are not derived from hemp and contain notably high percentages of THC. For example, more than 90% of THC-containing products in CO contain greater than 15% THC.

Cannabinol and the Controlled Substances Act
While only tetrahydrocannabinols are listed separately from marijuana in Schedule I, the language used to define “marihuana” includes all chemical constituents present in the Cannabis sativa L plant (i.e., “every compound, manufacture, salt, derivative, mixture, or preparation of such plant, its seeds or resin”). For this reason, cannabinol and other cannabinoids derived from the cannabis plant, along with their analogs, all technically remain classified as schedule I substances under federal law. Despite this, there are currently three cannabis-based medications that have obtained FDA-approval (see table below).

Cannabinol and the 2018 Farm Bill (Agriculture Improvement Act of 2018)?
While the Controlled Substances Act does not define hemp, this 2018 legislation defines it as cannabis (i.e., the plant itself along with its extracts such as terpenes and cannabinoids) that contains a THC concentration equal to or less than 0.3% by weight. This legislation also requires all cultivation of hemp to be tightly regulated at the state level with required THC testing. If hemp cultivation is taking place with no evidence of THC testing at the state level, the United States Department of Agriculture and/or the FDA have explicit authority to issue a plan for such testing.