THCB

The main cannabinoid receptor in the brain, responsible for THC’s intoxicating effects. Reported receptor-binding values suggest that THCB has approximately 2.7x stronger CB1 binding affinity than Delta-9-THC. However, these values were obtained from different experimental studies rather than a direct same-assay comparison, so the exact multiplier should be considered approximate.

Although THCB has a shorter four-carbon side chain than Delta-9-THC, docking research suggests that this shorter chain may fit CB1 particularly effectively in a different way. Instead of extending into the longer hydrophobic channel used by Delta-9-THC, THCB’s butyl side chain is predicted to fit into a smaller hydrophobic pocket near the entrance of this channel, where it can form strong interactions with the receptor. This has been proposed as an explanation for THCB’s unexpectedly higher CB1 affinity, although the binding position is based on computational modelling rather than direct measurement.

Animal research confirms THC-like cannabinoid activity as a partial CB1 agonist, but also suggests that THCB may require a higher dose than Delta-9-THC to produce clear effects. In mouse testing, pronounced THCB effects were mainly observed around 20 mg/kg, while Delta-9-THC typically produces comparable effects at around 10 mg/kg in similar testing. This corresponds to a rough dose potency of approximately 0.5x Delta-9-THC. Importantly, this only compares the amount required to produce an effect. It does not show that THCB has a lower maximum effect.

Combining the 2.7x stronger reported CB1 binding, supportive docking evidence and roughly 0.5x in vivo dose potency suggests a theoretical psychoactive potency of around 1.3x Delta-9-THC. Comparative Emax data are still missing, which is important because Emax would show the maximum CB1 effect THCB can ultimately produce and whether that maximum could exceed Delta-9-THC.

The main cannabinoid receptor in the immune system, involved in regulating immune cell activity and inflammatory responses. Reported binding values suggest that THCB has approximately 0.71x the CB2 binding affinity of Delta-9-THC.

Animal research also suggests that CB2 contributes to some of THCB’s pain-reducing effects. In the mouse formalin test, blocking CB2 reduced the effect of THCB, indicating that the cannabinoid receptor was involved in the response.

This supports functional involvement of CB2 beyond receptor binding alone. However, direct THCB-specific CB2 functional activity has not yet been established, so it remains unknown how strongly THCB exactly can activate CB2. Whether this mechanism produces meaningful pain-reducing, immune or anti-inflammatory effects in humans has also not been confirmed.

THCB metabolism has been studied in mice but not humans. Researchers identified 13 metabolites, with hydroxylation occurring mainly at the 2′, 3′, 8 and 11 positions, followed by oxidation of metabolites into carboxylic acids.

An 11-OH-THCB pathway is therefore established in mice. Whether 11-OH-THCB remains psychoactive and how it compares to the intoxicating effects of 11-OH-THC , has not directly been researched.