Tetrahydrocannabinol (THC) 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. THC is a terpenoid found in cannabis and, like many pharmacologically active phytochemicals, it is assumed to be involved in the plant's evolutionary adaptation against insect predation, ultraviolet light, and environmental stress. THC was first discovered and isolated by Israeli chemist Raphael Mechoulam in Israel in 1964. It was found that, when smoked, THC is absorbed into the bloodstream and travels to the brain, attaching itself to endocannabinoid receptors located in the cerebral cortex, cerebellum, and basal ganglia. These are the parts of the brain responsible for thinking, memory, pleasure, coordination and movement.
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.
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).
HU-210 is a synthetic cannabinoid that was first synthesized in 1988 from (1R,5S)-myrtenol by a group led by Raphael Mechoulam at the Hebrew University. HU-210 is 100 to 800 times more potent than natural THC from cannabis and has an extended duration of action. HU-210 has a binding affinity of 0.061 nM at CB1 and 0.52 nM at CB2 in cloned human cannabinoid receptors compared to delta-9-THC of 40.7 nM at CB1. HU-210 is the (–)-1,1-dimethylheptyl analog of 11-hydroxy- Δ8- tetrahydrocannabinol; in some references it is called 1,1-dimethylheptyl- 11-hydroxytetrahydrocannabinol. The abbreviation "HU" stands for Hebrew University.
JWH-133(Dimethylbutyl-deoxy-Delta-8-THC) is a potent selective CB2 receptor agonist with a Ki of 3.4nM and selectivity of around 200x for CB2 over CB1 receptors. It was discovered by and named after, John W. Huffman.
Parahexyl is a synthetic homologue of THC which was invented in 1941 during attempts to elucidate the structure of Δ9-THC, one of the active components of cannabis.
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.
Machaerium is a genus of flowering plants in the family Fabaceae, and was recently assigned to the informal monophyletic Dalbergia clade of the Dalbergieae. It contains the following species:
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.
JWH-200 (WIN 55,225) is an analgesic chemical from the aminoalkylindole family that acts as a cannabinoid receptor agonist. Its binding affinity, Ki at the CB1 receptor is 42 nM, around the same as that of THC, but its analgesic potency in vivo was higher than that of other analogues with stronger CB1 binding affinity in vitro, around 3 times that of THC but with less sedative effect, most likely reflecting favourable pharmacokinetic characteristics. It was discovered in 1991 by Sterling Drug as a potential analgesic following the earlier identification of related compounds such as pravadoline and WIN 55,212-2.
Perrottetinene is a naturally occurring cannabinoid compound found in liverworts from the genus Radula native to Japan, New Zealand and Costa Rica, namely Radula perrottetii, Radula marginata and Radula laxiramea, along with a number of similar compounds. Its chemical structure closely resembles that of THC, the main active component of marijuana but with a cis rather than trans conformation and a bibenzyl tailchain instead of pentyl. The absolute configuration of perrottetinene was established in 2008 by an enantioselective total synthesis.
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.
Cannabidiol-dimethylheptyl (CBD-DMH or DMH-CBD) is a synthetic homologue of cannabidiol where the pentyl chain has been replaced by a dimethylheptyl chain. Several isomers of this compound are known. The most commonly used isomer in research is (−)-CBD-DMH, which has the same stereochemistry as natural cannabidiol, and a 1,1-dimethylheptyl side chain. This compound is not psychoactive and acts primarily as an anandamide reuptake inhibitor, but is more potent than cannabidiol as an anticonvulsant and has around the same potency as an antiinflammatory. Unexpectedly the “unnatural” enantiomer (+)-CBD-DMH, which has reversed stereochemistry from cannabidiol, was found to be a directly acting cannabinoid receptor agonist with a Ki of 17.4nM at CB1 and 211nM at CB2, and produces typical cannabinoid effects in animal studies, as does its 7-OH derivative.
8,9-Dihydrocannabidiol is a synthetic cannabinoid that is closely related to cannabidiol (CBD) itself.
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.
Δ-3-Tetrahydrocannabinol is a synthetic isomer of tetrahydrocannabinol, developed during the original research in the 1940s to develop synthetic routes to the natural products Δ8-THC and Δ9-THC found in the cannabis plant. While the normal trans configuration of THC is in this case flattened by the double bond, it still has two enantiomers as the 9-methyl group can exist in an (R) or (S) conformation. The (S) enantiomer has similar effects to Δ9-THC though with several times lower potency, while the (R) enantiomer is many times less active or inactive, depending on the assay used. It has been identified as a component of vaping liquid products.
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 hydrogenation of cannabis extracts. The synthesis and bioactivity of HHC was first reported in 1940 by Roger Adams using tetrahydrocannabinol prepared from cannabidiol.
11-Hydroxyhexahydrocannabinol is an active metabolite of tetrahydrocannabinol (THC) and a metabolite of the trace cannabinoid hexahydrocannabinol (HHC).
Delta-11-Tetrahydrocannabinol is a rare isomer of tetrahydrocannabinol, developed in the 1970s. It can be synthesised from Δ8-THC by several different routes, though only the enantiomer is known. In recent studies in 2022 it was found to "significantly reduce" the effects of Δ9-THC and has been suggested as antagonist of the CB1 receptor in humans, with the cited study showing "one partial success in the quest for an antagonist is the fact that D9,11-THC was found to significantly reduce the effect of D9-THC." and did not substitute for THC in rhesus monkeys. It has been identified as a component of grey market "vaping liquids" sold for use in humans.
