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By Robert G. Bell

Robert Bell

The chemistry of cannabis is interesting and a bit complex. As mentioned in Marijuana 101, the marijuana flowers and leaves contain hundreds of compounds, including a mixture of approximately 85 phytocannabinoids unique only to the marijuana plant. Cannabinoids are produced in epidermal glands on the leaves, stems, and the bracts of the female marijuana plant. The flower itself has no epidermal glands, but it has the highest cannabinoid content in the plant, possibly due to the accumulation of resin secreted by the supporting bracteole. It has been postulated the marijuana plants secrete the cannabinoids as a defense mechanism against herbivores and harmful UV radiation.

The terms “cannabinoids” and “phytocannabinoids” generally refer to a group of C21 terpenophenolic compounds. The cannabinoids are divided into 10 closely related classes, many of which differ by a single chemical moiety. According to the Americans for Safe Access (ASA), there are over 483 different identifiable chemical constituents known to exist in cannabis. Some of these constituents include nitrogenous compounds, amino acids, proteins, glycoproteins, enzymes, sugars and related compounds, hydrocarbons, alcohols, acids, esters, aldehydes, ketones, fatty acids, lactones, steroids, terpenes, non-cannabinoid phenols, flavonoids, vitamins, pigments and elements.

Cannabinoids are generally aryl-substituted monoterpenes that are lipid soluble and neutral. The concentration of tetrahydrocannabinol (THC) in marijuana can range from 0.5% to 20%. Hashish consists of dried cannabis resin and compressed flowers with THC ranges from 2% to more than 20%. Oils prepared from marijuana or hash using an organic solvent to extract THC produce concentrations between 15% and 70%. Waxes made from cannabis, called “budder,” form a potent cannabis concentrate that can exceed 99% THC.

As aromatic terpenoids, cannabinoids have very low solubility in water but good solubility in most organic solvents, lipids, and alcohols.

MarijuanaLeafThe most potent psychoactive cannabinoid is (-)-trans- Δ9-tetrahydrocannabinol ((6aR,10aR)-delta-9-tetrahydrocannabinol), THC) which is usually attributable to the high experienced when ingesting marijuana. It also may help treat symptoms such as nausea and vomiting that are associated with a number of maladies. THC was isolated in 1964 by Mechoulam and Gaoni at the Weizmann Institute of Science. Two other cannabinoids, cannabinol and cannabidiol, possess similar properties but have less of a psychoactive effect than THC. It is these cannabinoids that are felt to have the most promise medicinally.

Tetrahydrocannabinolic acid (THCA) is the precursor of the active component of cannabis, tetrahydrocannabinol (THC). Heating by any means (drying, smoking, vaporization) decarboxylates the THCA to THC. THCA is not psychoactive, as is THC, and is known to offer anti-inflammatory effects and neuroprotection.

And just to fill in some chemistry from the 14th edition of the Merck Index, THC has a boiling point of 200˚C, specific rotation (20) of -150.5˚ (c= 0.53 in CHCl3) and a UV maximum (in ethanol) of 283 (log ɛ = 3.21) and 276 (log ɛ = 3.20).

Next up, the pharmacology of pot. Or have you forgot?

Robert G. Bell, Ph.D., is president and owner of Drug and Biotechnology Development LLC, a consultancy to the pharmaceutical industry and academia for biological, drug, and device development.