AM-251 is an inverse agonist at the CB1 cannabinoid receptor. AM-251 is structurally very close to rimonabant; both are biarylpyrazole cannabinoid receptor antagonists. In AM-251, the p-chloro group attached to the phenyl substituent at C-5 of the pyrazole ring is replaced with a p-iodo group. The resulting compound exhibits slightly better binding affinity for the CB1 receptor (with a Ki value of 7.5 nM) than rimonabant, which has a Ki value of 11.5 nM, AM-251 is, however, about two-fold more selective for the CB1 receptor when compared to rimonabant. Like rimonabant, it is additionally a μ-opioid receptor antagonist that attenuates analgesic effects.
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.
N-Arachidonyl glycine receptor, also known as G protein-coupled receptor 18 (GPR18), is a protein that in humans is encoded by the GPR18 gene. Along with the other previously "orphan" receptors GPR55 and GPR119, GPR18 has been found to be a receptor for endogenous lipid neurotransmitters, several of which also bind to cannabinoid receptors. It has been found to be involved in the regulation of intraocular pressure.
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 docosatetraenoylethanolamide found in wild daga, the compound THC which is an active constituent 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 (CB1), which is largely responsible for the efficacy of endocannabinoid-mediated presynaptic-inhibition, the psychoactive properties of tetrahydrocannabinol (THC), the active agent in cannabis, and other phytocannabinoids (plant cannabinoids). The principal endogenous ligand for the CB2 receptor is 2-Arachidonoylglycerol (2-AG).
Pravadoline (WIN 48,098) is an antinflammatory and analgesic drug with an IC50 of 4.9 μM and a Ki of 2511 nM at CB1, related in structure to nonsteroidal anti-inflammatory drugs (NSAIDs) such as indometacin. It was developed in the 1980s as a new antiinflammatory and prostaglandin synthesis inhibitor, acting through inhibition of the enzyme cyclooxygenase (COX).
O-806 is a drug which is a cannabinoid derivative that is used in scientific research. It is described as a mixed agonist/antagonist at the cannabinoid receptor CB1, meaning that it acts as an antagonist when co-administered alongside a more potent CB1 agonist, but exhibits weak partial agonist effects when administered by itself.
O-823 is a drug which is a cannabinoid derivative that is used in scientific research. It is described as a mixed agonist/antagonist at the cannabinoid receptor CB1, meaning that it acts as an antagonist when co-administered alongside a more potent CB1 agonist, but exhibits weak partial agonist effects when administered by itself.
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, 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.
JWH-007 is an analgesic chemical from the naphthoylindole family, which acts as a cannabinoid agonist at both the CB1 and CB2 receptors. It was first reported in 1994 by a group including the noted cannabinoid chemist John W. Huffman. It was the most active of the first group of N-alkyl naphoylindoles discovered by the team led by John W Huffman, several years after the family was initially described with the discovery of the N-morpholinylethyl compounds pravadoline (WIN 48,098), JWH-200 (WIN 55,225) and WIN 55,212-2 by the Sterling Winthrop group. Several other N-alkyl substituents were found to be active by Huffman's team including the n-butyl, n-hexyl, 2-heptyl, and cyclohexylethyl groups, but it was subsequently determined that the 2-methyl group on the indole ring is not required for CB1 binding, and tends to increase affinity for CB2 instead. Consequently, the 2-desmethyl derivative of JWH-007, JWH-018, has slightly higher binding affinity for CB1, with an optimum binding of 9.00 nM at CB1 and 2.94 nM at CB2, and JWH-007 displayed optimum binding of 9.50 nM at CB1 and 2.94 nM at CB2.
JWH-098 is a synthetic cannabinoid receptor agonist from the naphthoylindole family. It is the indole 2-methyl derivative of a closely related compound JWH-081, but has markedly different affinity for the CB1 and CB2 receptors. While JWH-081 is around ten fold selective for CB1 over CB2, in JWH-098 this is reversed, and it is around four times weaker than JWH-081 at CB1 while being six times more potent at CB2, giving it a slight selectivity for CB2 overall. This makes JWH-098 a good example of how methylation of the indole 2-position in the naphthoylindole series tends to increase CB2 affinity, but often at the expense of CB1 binding.
SR144528 is a drug that acts as a potent and highly selective CB2 receptor inverse agonist, with a Ki of 0.6 nM at CB2 and 400 nM at the related CB1 receptor. It is used in scientific research for investigating the function of the CB2 receptor, as well as for studying the effects of CB1 receptors in isolation, as few CB1 agonists that do not also show significant activity as CB2 agonists are available. It has also been found to be an inhibitor of sterol O-acyltransferase, an effect that appears to be independent from its action on CB2 receptors.
WIN 54,461 (6-Bromopravadoline) is a drug that acts as a potent and selective inverse agonist for the cannabinoid receptor CB2.
O-1269 is a drug that is a diarylpyrazole derivative, related to potent cannabinoid antagonist drugs such as rimonabant and surinabant. However O-1269 and several related drugs were unexpectedly found to act as full or partial agonists at the cannabinoid receptors rather than antagonists, and so produce the usual effects expected of cannabinoid agonists in animal tests, such as sedation and analgesic effects. The N-heptyl homolog O-1270 and the N-propyl homolog O-1399 also act as cannabinoid agonists with similar potency in vivo, despite weaker binding affinity at cannabinoid receptors compared to the pentyl homolog O-1269. Agonist-like and atypical cannabinoid activity has also been observed with a number of related compounds.
O-2050 is a drug that is a classical cannabinoid derivative, which acts as an antagonist for the CB1 receptor. This gives it an advantage in research over many commonly used cannabinoid antagonists, such as rimonabant, which at higher doses act as inverse agonists at CB1 as well as showing off-target effects. However, while O-2050 acts as a silent antagonist in vitro, some tests in vivo have suggested it may show agonist activity under certain circumstances.
PSB-SB-487 is a coumarin derivative which is an antagonist at the former orphan receptor GPR55. Unlike older GPR55 antagonists such as O-1918, PSB-SB-487 has good selectivity over the related receptor GPR18, with an IC50 of 113nM at GPR55 vs 12500nM at GPR18. However it has poorer selectivity over other related receptors, acting as a weak antagonist at CB1 with a Ki of 1170nM, and a partial agonist at CB2 with a Ki of 292nM.
PSB-SB-1202 is a coumarin derivative which is an agonist at the cannabinoid receptors CB1 and CB2, with a CB1 Ki of 32nM and a CB2 Ki of 49nM. It is also a weak antagonist at the related receptor GPR55, with an IC50 of 6350nM, but has no significant affinity for GPR18.
PSB-CB5 (CID-85469571) is a compound which acts as an antagonist at the former orphan receptor GPR18, and is the first selective antagonist characterised for this receptor, with an IC50 of 279nM, and good selectivity over related receptors (over 36x selectivity vs CB1 and GPR55, and 14x vs CB2.) As all previously known antagonists for GPR18 also antagonise GPR55, it has been difficult to separate the effects of these two receptor targets, so the discovery of a selective GPR18 antagonist is expected to be useful in research into the actions of this receptor.
