CBC

The main cannabinoid receptor in the brain, responsible for THC’s intoxicating effects. CBC has generally shown weak and inconsistent interaction with CB1. One commonly cited binding study reported a Ki of approximately 713 nM, compared with roughly 35 nM for Delta-9-THC, corresponding to approximately 0.05× the CB1 binding affinity of Delta-9-THC in that assay.

Functional studies provide stronger evidence that CBC has little meaningful CB1 activity. CBC failed to activate human CB1 in one study, producing only a negligible response. A later study found detectable CB1 activation by (-)-CBC only at the very high concentration of 30 µM, while (+)-CBC remained inactive. This weak functional activity is consistent with CBC being considered non-intoxicating rather than producing THC-like psychoactive effects.

The main cannabinoid receptor in the immune system, involved in regulating immune cell activity and inflammatory responses. CBC binds CB2 more strongly than CB1, although still weak compared other cannabinoids. In one direct binding study, CBC showed a Ki of approximately 256 nM, compared with approximately 8.5 nM for Delta-9-THC, corresponding to approximately 0.03× the CB2 binding affinity of Delta-9-THC in that assay.

Despite this lower binding affinity, functional studies indicate meaningful CB2 agonism. In one human CB2 assay, CBC reached approximately 52% of the maximum response produced a full agonist, compared with approximately 22% for Delta-9-THC. CBC therefore produced approximately 2.4× the maximal CB2 response of Delta-9-THC in this assay. More recent research found that (-)-CBC activated human CB2 with an EC50 of approximately 1.5 µM and reached about 60% of the full agonist response, while (+)-CBC remained largely inactive. CBC therefore appears capable of relatively strong CB2 signalling despite its comparatively low binding affinity, although the biological importance of this activity has not been established clinically in humans.

TRPA1 is an ion channel involved in sensing chemical irritation, temperature and pain-related signals. CBC is a comparatively potent TRPA1 agonist, with an EC50 of approximately 90 nM reported in some TRPA1 channels. CBC can subsequently desensitize the channel, with an IC50 of approximately 370 nM reported for inhibition of a later TRPA1 response.

Newer experiments using human TRPA1 confirmed that both CBC enantiomers can activate the channel. At 30 µM, (-)-CBC produced approximately 50% of the response of the reference agonist cinnamaldehyde, while (+)-CBC produced approximately 38%. TRPA1 therefore appears to be one of the better-supported non-cannabinoid-receptor targets of CBC, although its contribution to CBC’s effects in humans remains uncertain.

TRPV1 is an ion channel involved in sensing heat, chemical irritation and pain-related signals. CBC acts as a TRPV1 agonist, with a reported EC50 of approximately 24.2 µM in human TRPV1-expressing cells. However, its efficacy was relatively low, producing less than 10% of the maximal calcium response generated by ionomycin.

CBC therefore interacts with TRPV1 considerably less potently than with TRPA1. This interaction may contribute to effects on sensory and pain-related signalling, but the concentrations required are relatively high and its physiological importance in humans has not been established.

TRPV3 is a temperature-sensitive ion channel expressed particularly in the skin and other tissues, where it participates in temperature sensing, sensory signalling and regulation of cellular responses. CBC has been reported to activate TRPV3 channels with an EC50 of approximately 1.9 µM.

CBC can also desensitize TRPV3 after activation, although this only occurs at substantially higher concentrations. These findings suggest that CBC can modulate TRPV3 signalling, but the physiological importance of this interaction has not been established in humans.

TRPV4 is a broadly expressed ion channel involved in sensing temperature, mechanical forces and changes in the cellular environment. CBC activates TRPV4 channels with an EC50 of approximately 0.6 µM, making TRPV4 one of the more sensitive TRP targets identified for CBC.

In the same experimental system, CBC produced about 23% of the maximal calcium response and desensitized subsequent TRPV4 activation with an IC50 of approximately 9.9 µM. These findings demonstrate direct modulation of TRPV4, but they do not yet establish a clinically relevant effect in humans.

PPARγ is a nuclear receptor that regulates gene expression and is involved in processes including metabolism, cellular differentiation and inflammatory signalling. CBC has been identified as a PPARγ agonist, although its activity appears relatively weak. A concentration-response study did not reach a maximal effect at the highest CBC concentration tested of 25 µM, meaning an exact EC50 could not be established and is considered greater than 25 µM.

CBC was less potent at PPARγ than Delta-9-THC in the same study, for which an EC50 of approximately 21.2 µM was reported. PPARγ activation could contribute to some of CBC’s effects on cellular and inflammatory signalling, but the relatively high concentrations required and lack of direct human evidence make the physiological relevance of this mechanism unknown.

Anandamide is one of the body’s main endogenous cannabinoids and can activate both CB1 and CB2 receptors. Its signalling is partly regulated by cellular uptake and subsequent metabolism. CBC inhibits cellular uptake of anandamidewith an IC50 of approximately 12.3 µM.

In the same assay, CBD showed an IC50 of approximately 25.3 µM, meaning CBC inhibited anandamide uptake at roughly half the concentration required for CBD. By slowing cellular removal of anandamide, CBC could theoretically increase or prolong local endocannabinoid signalling without directly activating CB1 itself. However, this mechanism has been demonstrated in cell models and its importance in humans remains unknown.

Human metabolism of CBC has only recently been characterized in detail. Laboratory studies using human cytochrome P450 enzymes identified 8-hydroxy-CBC and 6′,7′-epoxy-CBC as two major oxidative metabolites, together with smaller amounts of 1″-hydroxy-CBC

CBC can additionally undergo glucuronidation through several enzymes. Human pharmacokinetic data such as absolute bioavailability, elimination half-life and circulating metabolite concentrations remain poorly defined.