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 113 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.
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.
Cannabivarin (CBV), also known as cannabivarol, is considered a non-psychoactive cannabinoid — it does not produce the euphoric side effects found in THC. Minor amounts of CBV are found in the hemp plant Cannabis sativa. It is an analog of cannabinol (CBN) with the side chain shortened by two methylene bridges (-CH2-). CBV is an oxidation product of tetrahydrocannabivarin (THCV, THV).
THC-O-acetate is the acetate ester of THC. The term THC-O-acetate and its variations are commonly used for two types of the substance, dependent on which cannabinoid it is synthesized from. The difference between Δ8-THC and Δ9-THC is bond placement on the cyclohexene ring.
Dimethylheptylpyran is a synthetic analog of THC, which was invented in 1949 during attempts to elucidate the structure of Δ9-THC, one of the active components of Cannabis. DMHP is a pale yellow, viscous oil which is insoluble in water but dissolves in alcohol or non-polar solvents.
CP 47,497 or (C7)-CP 47,497 is a cannabinoid receptor agonist drug, developed by Pfizer in the 1980s. It has analgesic effects and is used in scientific research. It is a potent CB1 agonist with a Kd of 2.1 nM.
AMG-3 (part of the AM cannabinoid series) is an analgesic drug which is a cannabinoid agonist. It is a derivative of Δ8-THC substituted with a dithiolane group on the 3-position side chain. AMG-3 is a potent agonist at both CB1 and CB2 receptors with a Ki of 0.32 nM at CB1 and 0.52 nM at CB2, and its particularly high binding affinity has led to it being used as a template for further structural development of novel cannabinoid drugs. It has sedative and analgesic effects, with analgesia lasting for up to 36 hours after administration.
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.
MN-25 (UR-12) is a drug invented by Bristol-Myers Squibb, that acts as a reasonably selective agonist of peripheral cannabinoid receptors. It has moderate affinity for CB2 receptors with a Ki of 11 nM, but 22x lower affinity for the psychoactive CB1 receptors with a Ki of 245 nM. The indole 2-methyl derivative has the ratio of affinities reversed however, with a Ki of 8 nM at CB1 and 29 nM at CB2, which contrasts with the usual trend of 2-methyl derivatives having increased selectivity for CB2 (cf. JWH-018 vs JWH-007, JWH-081 vs JWH-098).
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.
KM-233 is a synthetic cannabinoid drug which is a structural analog of Δ8-tetrahydrocannabinol (THC), the less active but more stable isomer of the active component of Cannabis. KM-233 differs from Δ8-THC by the pentyl side chain being replaced by a 1,1-dimethylbenzyl group. It has high binding affinity in vitro for both the CB1 and CB2 receptors, with a CB2 affinity of 0.91 nM and 13-fold selectivity over the CB1 receptor. In animal studies, it has been found to be a potential treatment for glioma, a form of brain tumor. Many related analogues are known where the 1,1-dimethylbenzyl group is substituted or replaced by other groups, with a fairly well established structure-activity relationship.
FUBIMINA is a synthetic cannabinoid that is the benzimidazole analog of AM-2201 and has been used as an active ingredient in synthetic cannabis products. It was first identified in Japan in 2013, alongside MEPIRAPIM.
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.
11-Hydroxyhexahydrocannabinol is an active metabolite of tetrahydrocannabinol (THC) and a metabolite of the trace cannabinoid hexahydrocannabinol (HHC).
H4CBD is a cannabinoid that was first synthesized by Alexander R. Todd in 1940 derived from the catalytic hydrogenation of cannabidiol.
JWH-138 (THC-Octyl, Δ8-THC-C8) is a synthetic cannabinoid first synthesized by Roger Adams and studied heavily by John W. Huffman, with a Ki of 8.5nM at the CB1 cannabinoid receptor. THC-Octyl and its hydrogenated analog HHC-Octyl was synthesized and studied by Roger Adams as early as 1942.
Hexahydrocannabiphorol is a semi-synthetic cannabinoid derivative which has been marketed since around 2021. It is believed to be made from the hydrogenation of tetrahydrocannabiphorol (THCP). THCP is only reported as a trace component of cannabis in 2019. HHCP was studied by Roger Adams as early as 1942.
Hexahydrocannabihexol (HHCH) is a semi-synthetic cannabinoid derivative. It was first synthesised by Roger Adams in 1942 and found to be more potent than either the pentyl or heptyl homologues, or the unsaturated tetrahydrocannabinol analogue. HHCH was first identified as a designer drug in Sweden in September 2023.
Hexahydrocannabutol is a semi-synthetic cannabinoid derivative, the hydrogenated derivative of tetrahydrocannabutol (THCB). It was first synthesised by Roger Adams in 1942 and produces only weak cannabinoid-like effects in animals. More recently it has been sold as an ingredient in grey-market cannabinoid products.
