Cannabis (Cannabis sativa)
Characterization of the structural determinants required for potent mechanism-based inhibition of human cytochrome P450 1A1 by cannabidiol
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We previously demonstrated that cannabidiol (CBD) was a potent mechanism-based inhibitor of human cytochrome P450 1A1 (CYP1A1). However, the moiety of CBD that contributes to the potent mechanism-based inhibition of human CYP1A1 remains unknown. Thus, the effects of compounds structurally related to CBD on CYP1A1 activity were examined with recombinant human CYP1A1 in order to characterize the structural requirements for potent inactivation by CBD. When preincubated in the presence of NADPH for 20min, olivetol, which corresponds to the pentylresorcinol moiety of CBD, enhanced the inhibition of the 7-ethoxyresorufin O-deethylase activity of CYP1A1. In contrast, d-limonene, which corresponds to the terpene moiety of CBD, failed to inhibit CYP1A1 activity in a metabolism-dependent manner. Pentylbenzene, which lacks two free phenolic hydroxyl groups, also did not enhance CYP1A1 inhibition. On the other hand, preincubation of the CBD-2'-monomethyl ether (CBDM) and CBD-2',6'-dimethyl ether (CBDD) enhanced the inhibition of CYP1A1 activity. Inhibition by cannabidivarin (CBDV), which possessed a propyl side chain, was strongly potentiated by its preincubation. Orcinol, which has a methyl group, augmented CYP1A1 inhibition, whereas its derivative without an alkyl side chain, resorcinol, did not exhibit any metabolism-dependent inhibition. The preincubation of CBD-hydroxyquinone did not markedly enhance CYP1A1 inhibition. We further confirmed that olivetol, CBDM, CBDD, CBDV, and orcinol, as well as CBD (kinact=0.215min(-1)), inactivated CYP1A1 activity; their kinact values were 0.154, 0.0638, 0.0643, 0.226, and 0.0353min(-1), respectively. These results suggest that the methylresorcinol structure in CBD may have structurally important roles in the inactivation of CYP1A1.
1 . Cannabidiol (id=NPDI-b6F8pQ)
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
% inhibition estimated from Figure 2 at 20 min.
IC50 at 0 min - 0.671
IC50 at 20 min (table 1)
Kinact/KI converted from /min/mmol to /min/μM (table 2).
All other values from Table 2.
| Sample | Compound measured | Value | Measurement | Study sequence | Additional information | N replicates |
|---|
Experimental Conditions
Commercially available
200 µL
30 min
NADPH
20 µL
180 µL
5 min
NADPH with precipitant
2 . Cannbidiol-2'-monomethyl ether (id=NPDI-DqfMEw)
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
%inhibition estimated from Figure 2.
IC50pre-incubation at 0 min (Table 1).
IC50pre-incubation at 20 min - 1.90
Kinact/KI converted from /min/mmol to /min/μM (table 2).
All other values from Table 2.
| Sample | Compound measured | Value | Measurement | Study sequence | Additional information | N replicates |
|---|
Experimental Conditions
Commercially available
200 µL
30 min
NADPH
20 µL
180 µL
5 min
NADPH with precipitant
3 . CBD-dimethyl ether (id=NPDI-pQrX0g)
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
%inhibitionpre-incubation at estimated 50 μM at 20 min (Figure 2).
IC50pre-incubation at 0 min (Table 1)
IC50pre-incubation at 20 min - 7.68
Kinact/KI converted from /min/mmol to /min/μM (Table 2)
All other values from Table 2.
| Sample | Compound measured | Value | Measurement | Study sequence | Additional information | N replicates |
|---|
Experimental Conditions
Commercially available
200 µL
30 min
NADPH
20 µL
180 µL
5 min
NADPH with precipitant
4 . Cannabidivarin (id=NPDI-wnmeug)
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
%inhibition estimated from Fig 2 at 20 min, ~0.5 μM CBDV.
IC50 at 0 min (table 1).
IC50 at 20 min 0.0677
Kinact/KI converted from /min/mmol to /min/μM (table 2).
All other values from Table 2.
| Sample | Compound measured | Value | Measurement | Study sequence | Additional information | N replicates |
|---|
Experimental Conditions
Commercially available
200 µL
30 min
NADPH
20 µL
180 µL
5 min
NADPH with precipitant