Cannabis, also known as hemp or marijuana, evolved about 28 million years ago on the eastern plateau of Tibet, according to a pollen study published in May. The plant, a close relative of the common hops found in beer, still grows wild in Central Asia. Cannabinoids are natural compounds found in the plant Cannabis sativa. Of the more than 480 different compounds found in the plant, only about 66 are called cannabinoids.
Research shows that the effect of cannabinoids could be modulated by aromatic compounds produced by the cannabis plant, called terpenes. Like THC, these synthetic cannabinoids attack the brain's cannabinoid receptor type 1 (CB1R), responsible for the psychoactive effects of THC in cannabis. The structure of the main psychoactive phytocannabinoid, tetrahydrocannabinol (THC), was determined in Israel by Mechoulam and Gaoni in 1964. The clarification of the ECS also sheds light on the human fascination with cannabis, which appears to be the only plant that produces a potent phytocannabinoid activator of CB 1 R. As hydrophobic molecules, endocannabinoids cannot travel unaided long distances in the aqueous medium surrounding the cells from which they are released and, by therefore, they act locally on nearby target cells.
Endocannabinoids, on the other hand, are described as retrograde transmitters because they generally travel “backwards” against the usual flow of synaptic transmitters. Later, Devane et al characterized a first cannabinoid receptor (CB 1 R) in rat and human brains. Pharmaceutical or medicinal cannabinoids come in a variety of products, including raw (botanical) cannabis that can be vaporized for medicinal purposes, as well as oils, liquids and oral sprays. Cannabinoids can be administered through smoking, vaporization, oral ingestion, transdermal patch, intravenous injection, sublingual absorption, or rectal suppository.
The most abundant cannabinoid is CBD, which is believed to have anxiolytic effects, possibly counteracting the psychoactive effects of THC. Liquid chromatography (LC) techniques are also possible and, unlike GC methods, can differentiate between acidic and neutral forms of cannabinoids. For example, CBG, CBC and CBD are not known to be psychologically active agents, while THC, CBN and CBDL, along with some other cannabinoids, are known to have varying degrees of psychoactivity. Before the 1980s, it was speculated that cannabinoids produced their physiological and behavioral effects through a nonspecific interaction with cell membranes, rather than interacting with specific membrane-bound receptors.
Most phytocannabinoids are almost insoluble in water, but are soluble in lipids, alcohols, and other non-polar organic solvents. This discovery opened the door to many of the later advances in the field of endocannabinoid system (ECS) research.