Tetrahydrocannabiphorol

Tetrahydrocannabiphorol (THCP) is a potent phytocannabinoid, a CB1 and CB2 agonist which was known as a synthetic homologue of THC, but for the first time in 2019 was isolated as a natural product in trace amounts from Cannabis sativa. It is structurally similar to Δ9-THC, the main active component of cannabis, but with the pentyl side chain extended to heptyl. Since it has a longer side chain, its cannabinoid effects are "far higher than Δ9-THC itself." Tetrahydrocannabiphorol has a reported binding affinity of 1.2 nM at CB1, approximately 33 times that of Δ9-THC (40 nM at CB1).

THCP was studied by Roger Adams as early as 1942.

Delta-3-THCP


The Δ3/Δ6a(10a) isomer Δ3-THCP was synthesised in 1941, and was found to have around the same potency as Δ3-THC, unlike the hexyl homologue parahexyl which was significantly stronger.

Delta-8-THCP


The Δ8 isomer is also known as a synthetic cannabinoid under the code name JWH-091. It's unconfirmed whether or not Δ8-THCP is found naturally in cannabis plants, but likely is due to Δ8-THC itself being a degraded form of Δ9-THC. JWH-091 has approximately double the binding affinity at the CB1 receptor (22 nM ± 3.9 nM) in comparison to Δ9-THC (40.7 nM ± 1.7 nM) or Δ8-THC (44 nM ± 12 nM), but appears significantly lower in vitro than the binding activity of Δ9-THCP (Ki = 1.2 nM)

Natural occurrence in cannabis
The Δ9 isomer of THCP occurs naturally in cannabis, but in small amounts. A 2021 study reported the content of Δ9-THCP ranging from 0.0023% to 0.0136% (w/w) (approximately 0.02–0.13 mg/g) without correlation to THC percentage in Δ9-THC-dominant strains of cannabis; that study failed to detect THCP in CBD-dominant strains.