2-Arachidonoylglycerol (2-AG) is an endocannabinoid, an endogenous agonist of the CB1 receptor and the primary endogenous ligand for the CB2 receptor. It is an ester formed from the omega-6 fatty acid arachidonic acid and glycerol. It is present at relatively high levels in the central nervous system, with cannabinoid neuromodulatory effects. It has been found in maternal bovine and human milk. The chemical was first described in 1994-1995, although it had been discovered some time before that. The activities of phospholipase C (PLC) and diacylglycerol lipase (DAGL) mediate its formation. 2-AG is synthesized from arachidonic acid-containing diacylglycerol (DAG).
2-Arachidonyl glyceryl ether is a putative endocannabinoid discovered by Lumír Hanuš and colleagues at the Hebrew University of Jerusalem, Israel. It is an ether formed from the alcohol analog of arachidonic acid and glycerol. Its isolation from porcine brain and its structural elucidation and synthesis were described in 2001.
G protein-coupled receptor 55 also known as GPR55 is a G protein-coupled receptor that in humans is encoded by the GPR55 gene.
Cannabinoid receptor type 1 (CB1), also known as cannabinoid receptor 1, is a G protein-coupled cannabinoid receptor that in humans is encoded by the CNR1 gene. The human CB1 receptor is expressed in the peripheral nervous system and central nervous system. It is activated by: endocannabinoids, a group of retrograde neurotransmitters that include anandamide and 2-arachidonoylglycerol (2-AG); plant phytocannabinoids, such as the compound THC which is an active ingredient of the psychoactive drug cannabis; and, synthetic analogs of THC. CB1 is antagonized by the phytocannabinoid tetrahydrocannabivarin (THCV).
The cannabinoid receptor type 2, abbreviated as CB2, is a G protein-coupled receptor from the cannabinoid receptor family that in humans is encoded by the CNR2 gene. It is closely related to the cannabinoid receptor type 1, which is largely responsible for the efficacy of endocannabinoid-mediated presynaptic-inhibition, the psychoactive properties of tetrahydrocannabinol, the active agent in cannabis, and other phytocannabinoids (plant cannabinoids). The principal endogenous ligand for the CB2 receptor is 2-arachidonoylglycerol (2-AG).
BAY 59-3074 is a drug which is a cannabinoid receptor partial agonist developed by Bayer AG. It has analgesic effects and is used in scientific research. It is orally active in animals, and has modest affinity for both CB1 and CB2 receptors, with Ki values of 48.3nM at CB1 and 45.5nM at CB2.
AM-411 is an analgesic drug that is a cannabinoid agonist. It is a derivative of Δ8-THC substituted with an adamantyl group at the 3-position, demonstrating that the binding pocket for the alkyl chain at this position can accommodate significant bulk.
JWH-051 is an analgesic drug which is a cannabinoid agonist. Its chemical structure is closely related to that of the potent cannabinoid agonist HU-210, with the only difference being the removal of the hydroxyl group at position 1 of the aromatic ring. It was discovered and named after John W. Huffman.
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 antagonist, 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, is a non-competitive CB1/CB2 receptor antagonist. And 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.
GW-405,833 (L-768,242) is a drug that acts as a potent and selective partial agonist for the cannabinoid receptor subtype CB2, with an EC50 of 0.65 nM and selectivity of around 1200x for CB2 over CB1 receptors. Animal studies have shown it to possess antiinflammatory and anti-hyperalgesic effects at low doses, followed by ataxia and analgesic effects when the dose is increased. Selective CB2 agonist drugs such as GW-405,833 are hoped to be particularly useful in the treatment of allodynia and neuropathic pain for which current treatment options are often inadequate.
CB-13 (CRA13, SAB-378) is a cannabinoid drug, which acts as a potent agonist at both the CB1 and CB2 receptors, but has poor blood–brain barrier penetration, and so produces only peripheral effects at low doses, with symptoms of central effects such as catalepsy only appearing at much higher dose ranges. It has antihyperalgesic properties in animal studies, and has progressed to preliminary human trials.
Repinotan (BAYx3702), an aminomethylchroman derivative, is a selective 5-HT1A receptor full agonist with high potency and efficacy. It has neuroprotective effects in animal studies, and was trialed in humans for reducing brain injury following head trauma. It was subsequently trialed up to phase II for treatment of stroke, but while side effects were mild and consisted mainly of nausea, repinotan failed to demonstrate sufficient efficacy to justify further clinical trials. However, repinotan continues to be investigated for other applications, and was found to be effective at counteracting the respiratory depression produced by morphine, though with slight reduction in analgesic effects.
RVD-Hpα (pepcan-12) is an endogenous neuropeptide found in human and mammalian brain, which was originally proposed to act as a selective agonist for the CB1 cannabinoid receptor. It is a 12-amino acid polypeptide having the amino acid sequence Arg-Val-Asp-Pro-Val-Asn-Phe-Lys-Leu-Leu-Ser-His and is an N-terminal extended form of hemopressin, a 9-AA polypeptide derived from the α1 subunit of hemoglobin which has previously been shown to act as a CB1 inverse agonist. All three polypeptides have been isolated from various mammalian species, with RVD-Hpα being one of the more abundant neuropeptides expressed in mouse brain, and these neuropeptides represent a new avenue for cannabinoid research distinct from the previously known endogenous lipid-derived cannabinoid agonists such as anandamide. Recently it was shown that RVD-Hpα (also called Pepcan-12) is a potent negative allosteric modulator at CB1 receptors, together with other newly described N-terminally extended peptides (pepcans).
A-834,735 is a drug developed by Abbott Laboratories that acts as a potent cannabinoid receptor full agonist at both the CB1 and CB2 receptors, with a Ki of 12 nM at CB1 and 0.21 nM at CB2. Replacing the aromatic 3-benzoyl or 3-naphthoyl group found in most indole derived cannabinoids, with the 3-tetramethylcyclopropylmethanone group of A-834,735 and related compounds, imparts significant selectivity for CB2, with most compounds from this group found to be highly selective CB2 agonists with little affinity for CB1. However low nanomolar CB1 binding affinity is retained with certain heterocyclic 1-position substituents such as (N-methylpiperidin-2-yl)methyl (cf. AM-1220, AM-1248), or the (tetrahydropyran-4-yl)methyl substituent of A-834,735, resulting in compounds that still show significant affinity and efficacy at both receptors despite being CB2 selective overall.
SER-601 (COR-167) is a drug which acts as a potent and selective cannabinoid CB2 receptor agonist, based on a quinolone-3-carboxylic acid core structure, with 190 times selectivity for CB2 over the related CB1 receptor. It has analgesic effects in animal studies, as well as neuroprotective effects, but without a "cannabis high" due to its low affinity for CB1. A number of related compounds are known, almost all of which have high selectivity for CB2.
AM-630 (6-Iodopravadoline) is a drug that acts as a potent and selective inverse agonist for the cannabinoid receptor CB2, with a Ki of 32.1 nM at CB2 and 165x selectivity over CB1, at which it acted as a weak partial agonist. It is used in the study of CB2 mediated responses and has been used to investigate the possible role of CB2 receptors in the brain. AM-630 is significant as one of the first indole derived cannabinoid ligands substituted on the 6-position of the indole ring, a position that has subsequently been found to be important in determining affinity and efficacy at both the CB1 and CB2 receptors, and has led to the development of many related derivatives.
AM-2233 is a drug that acts as a highly potent full agonist for the cannabinoid receptors, with a Ki of 1.8 nM at CB1 and 2.2 nM at CB2 as the active (R) enantiomer. It was developed as a selective radioligand for the cannabinoid receptors and has been used as its 131I derivative for mapping the distribution of the CB1 receptor in the brain. AM-2233 was found to fully substitute for THC in rats, with a potency lower than that of JWH-018 but higher than WIN 55,212-2.
4-O-Methylhonokiol is a neolignan, a type of phenolic compound. It is found in the bark of Magnolia grandiflora and in M. virginiana flowers.
