Article by Travis Cesarone, Cannabis Life Network
A century ago, cannabis was respected but not well understood in the scientific literature. The intoxicating ingredient, THC, was officially isolated in 1964. (1) After 56 years, an isomer of THC, Delta-10-THC, was identified in cannabis extract for the first time. But, how many different variations and isomers of THC are truly in cannabis, and how many more can exist if we go beyond the realm of quantitative data?
Seven double-bond isomers
There is a ring on one side of the THC molecule that contains a single double-bond – atoms that are bonded with two pairs of electrons. The position of this double-bond in the ring depicts the Delta-‘number’ of each THC isomer. There are seven possible double-bond isomers in THC, and each one has several potential spatial orientations (stereoisomers). There are even THC isomers with an enantiomer (a molecule that mirrors another).
I did manage to briefly cover several isomers of THC in a 45-minute phone call with Dr. Markus Roggen – the founder of the Health Canada licensed cannabis and psilocybin research lab, Complex Biotech Discovery Ventures (CBDV), and CLN’s contributing scientist. But, we will stick with the basics for now and explore different THC isomers with greater detail in future releases.
D9 is the common form of intoxicating THC that everyone talks about in the cannabis space. It is a colorless and viscous oil. This is a partial agonist at both CB1 and CB2 receptors and is most commonly used as an antiemetic in clinical settings. (2)
Delta-8: a natural and synthetic isomer of THC
D8-THC is the second most common known isomer of THC. It is less intoxicating, with a lighter cerebral high since it only activates the CB1 receptor. Pure D8 should be a clear and very thick oil, and cannot be pink without impurities, (saline for example)!
The plant does produce small amounts of natural D8-THC. Alternatively, this form of THC is legal in the USA as long it’s derived from hemp. This is often achieved semi-synthetically by converting CBD with strong acids; a clay leached with sulphuric acid, known as C-bleach or T-41, is common in the industry. Normally, the plant transfers CBD (or CBG) into D8 and D9-THC with natural enzymes. A future installment will explore Delta-8-THC in further detail.
Delta-8’s double-bond is one position to the left of Delta-9’s. If we instead move the double-bond to the right of Delta-9-THC, it will land on the tenth position of the cyclohexene ring. This cannabinoid is known as Delta-10 THC. (3)
Delta-10 THC is currently available to labs in the United States, but not yet in Canada. It is not naturally produced by cannabis and is therefore produced exclusively via (semi-)synthesis.
This isomer of THC is produced by further isomerizing Delta-10-THC with specific catalysts, which swings the ring one more position towards the center of the molecule.
Another variant of D6a(10a)-THC was administered to humans in 1972. (4) There are (R) and (S) forms (enantiomers) of this cannabinoid‘s pure structure as well. (5) Another study on humans, published in 1987, determined that the (R) variant is non-intoxicating and much less active at CB2 and CB1 receptors compared to D9. Whereas the (S) variant of D6a(10a) was reported to be intoxicating, but with a third of THC’s potency. (6)
Delta-7-THC and D6a(7)-THC
Each position on the cyclohexene ring can hold THC’s double-bond, but each time this bond changes so does the molecule’s arrangement. We have so far gone around from D8 to D6a(10a) and covered four isomers of THC in cannabis and beyond natural sources. But, the ring has six positions, so there are still at least two isomers of THC left to discuss.