Cannabis (Cannabis sativa)
Structural requirements for potent direct inhibition of human cytochrome P450 1A1 by cannabidiol: role of pentylresorcinol moiety.
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Our recent work has shown that cannabidiol (CBD) exhibits the most potent direct inhibition of human cytochrome P450 1A1 (CYP1A1) among the CYP enzymes examined. However, the mechanism underlying this CBD inhibition remains to be clarified. Thus, to elucidate the structural requirements for the potent inhibition by CBD, the effects of CBD and its structurally related compounds on CYP1A1 activity were investigated with recombinant human CYP1A1. Olivetol, which corresponds to the pentylresorcinol moiety of CBD, inhibited the 7-ethoxyresorufin O-deethylase activity of CYP1A1; its inhibitory effect (IC50=13.8 µM) was less potent than that of CBD (IC50=0.355 µM). In contrast, d-limonene, which corresponds to the terpene moiety of CBD, only slightly inhibited CYP1A1 activity. CBD-2'-monomethyl ether (CBDM) and CBD-2',6'-dimethyl ether inhibited CYP1A1 activity with IC50 values of 4.07 and 23.0 µM, respectively, indicating that their inhibitory effects attenuated depending on the level of methylation on the free phenolic hydroxyl groups in the pentylresorcinol moiety of CBD. Cannabidivarin inhibited CYP1A1 activity, although its inhibitory potency (IC50=1.85 µM) was lower than that of CBD. The inhibitory effects of Δ(9)-tetrahydrocannabinol and cannabielsoin (IC50s ≈10 µM), which contain a free phenolic hydroxyl group and are structurally constrained, were less potent than that of CBDM, which contains a free phenolic hydroxyl group and is rotatable between pentylresorcinol and terpene moieties. These results suggest that the pentylresorcinol structure in CBD may have structurally important roles in direct CYP1A1 inhibition, although the whole structure of CBD is required for overall inhibition.
1 . Cannabidiol (id=NPDI-BfJ7dA)
In Vitro Enzyme Inhibition Experiment
Inhibition was detected. Cutoff used — Not specified
- CYP1A1 4173297
Recombinant expression system
Baculovirus-insect cells
Cytochrome B5 No
Results
Estimated from Fig 4a. CBD 1 μM.
Table 1
| Sample | Compound measured | Value | Measurement | Study sequence | Additional information | N replicates |
|---|
Experimental Conditions
Commercially available
200 μL
NADPH
5 min
2 . Cannabidiol-2'-monomethyl ether (id=NPDI-E6xHTA)
In Vitro Enzyme Inhibition Experiment
Inhibition was detected. Cutoff used — Not specified
- CYP1A1 4173297
Recombinant expression system
Baculovirus-insect cells
Cytochrome B5 No
Results
%inhibition estimated from Fig 3
Table 1
| Sample | Compound measured | Value | Measurement | Study sequence | Additional information | N replicates |
|---|
Experimental Conditions
Commercially available
200 μL
NADPH
5 min
3 . Cannabidiol-2',6'-dimethyl ether (id=NPDI-9ju4Lw)
In Vitro Enzyme Inhibition Experiment
Inhibition was detected. Cutoff used — Not specified
- CYP1A1 4173297
Recombinant expression system
Baculovirus-insect cells
Cytochrome B5 No
Results
%inhibition estimated from Fig 3 at 25 μM.
Table 1.
| Sample | Compound measured | Value | Measurement | Study sequence | Additional information | N replicates |
|---|
Experimental Conditions
Commercially available
200 μL
NADPH
5 min
4 . Cannabidvarin (id=NPDI-ZmjyHw)
In Vitro Enzyme Inhibition Experiment
Inhibition was detected. Cutoff used — Not specified
- CYP1A1 4173297
Recombinant expression system
Baculovirus-insect cells
Cytochrome B5 No
Results
%inhibition estimated from Fig 4a.
Table 1
| Sample | Compound measured | Value | Measurement | Study sequence | Additional information | N replicates |
|---|
Experimental Conditions
Commercially available
200 μL
NADPH
5 min
5 . THC (id=NPDI-iJRQWg)
In Vitro Enzyme Inhibition Experiment
Inhibition was detected. Cutoff used — not specified
- CYP1A1 4173297
Recombinant expression system
Baculovirus-insect cells
Cytochrome B5 Not available
Results
Fig 5
Table 1
| Sample | Compound measured | Value | Measurement | Study sequence | Additional information | N replicates |
|---|
Experimental Conditions
Commercially available
200 μL
NADPH
5 min