Cannabis (Cannabis sativa)
In Vitro Inhibition of Carboxylesterase 1 by Major Cannabinoids and Selected Metabolites
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The escalating use of medical cannabis and significant recreational use of cannabis in recent years has led to a higher potential for metabolic interactions between cannabis or one or more of its components and concurrently used medications. Although there have been a significant number of in vitro and in vivo assessments of the effects of cannabis on cytochrome P450 and UDP-glucuronosyltransferase enzyme systems, there is limited information regarding the effects of cannabis on the major hepatic esterase, carboxylesterase 1 (CES1). In this study, we investigated the in vitro inhibitory effects of the individual major cannabinoids and metabolites Δ9-tetrahydrocannabinol (THC), cannabidiol (CBD), cannabinol (CBN), 11-nor-THC-carboxylic acid, and 11-hydroxy-THC on CES1 activity. S9 fractions from human embryonic kidney 293 cells stably expressing CES1 were used in the assessment of cannabinoid inhibitory effects. THC, CBD, and CBN each exhibited substantial inhibitory potency, and were further studied to determine their mechanism of inhibition and kinetic parameters. The inhibition of CES1 by THC, CBD, and CBN was reversible and appears to proceed through a mixed competitivenoncompetitive mechanism. The inhibition constant (Ki) values for THC, CBD, and CBN inhibition were 0.541, 0.974, and 0.263 mM (0.170, 0.306, and 0.0817 mg/ml), respectively. Inhibition potency was increased when THC, CBD, and CBN were combined. Compared with the potential unbound plasma concentrations attainable clinically, the Ki values suggest a potential for clinically significant inhibition of CES1 by THC and CBD. CBN, however, is expected to have a limited impact on CES1. Carefully designed clinical studies are warranted to establish the clinical significance of these in vitro findings.
1 . Inhibition of CES1 by CBD (id=NPDI-a3nUTg)
In Vitro Enzyme Inhibition Experiment
Inhibition was detected. Cutoff used —
90% inhibition
- CES1
Cell fraction Human kidney S9 fraction
Results
Table 2
| Sample | Compound measured | Value | Measurement | Study sequence | Additional information | N replicates |
|---|
Experimental Conditions
20 microG/ml
Commercially available
100 µL
15 min
0, 100, 500, 1000, 2500, 5000 µM
0 - 10 µg/mL
2 . Evaluation of Time-Dependent CES1 Inhibition by CBD (0 min) (id=NPDI-gAcr3g)
In Vitro Enzyme Inhibition Experiment
Inhibition was detected. Cutoff used —
Not provided
- CES1
Cell fraction Human kidney S9 fraction
Results
IC50 pre-incubation 0 min (A) = 7.73 µM
IC50 pre-incubation 30 min (B) = 12.1 µM
B/A = 1.57
| Sample | Compound measured | Value | Measurement | Study sequence | Additional information | N replicates |
|---|
Experimental Conditions
20 µg/mL
Commercially available
100 µL
15 min
1 mM
30 min
0 min
0 - 50 µg/mL
3 . Evaluation of Time-Dependent CES1 Inhibition by CBD (30 min) (id=NPDI-sciDeA)
In Vitro Enzyme Inhibition Experiment
Inhibition was detected. Cutoff used —
Not provided
- CES1
Cell fraction Human kidney S9 fraction
Results
IC50 pre-incubation 0 min (A) = 7.73 µM
IC50 pre-incubation 30 min (B) = 12.1 µM
B/A = 1.57
| Sample | Compound measured | Value | Measurement | Study sequence | Additional information | N replicates |
|---|
Experimental Conditions
20 µg/mL
Commercially available
100 µL
15 min
1 mM
30 min
30 min
0 - 50 µg/mL
4 . Evaluation of Time-Dependent CES1 Inhibition by CBN (30 min) (id=NPDI--0E9EQ)
In Vitro Enzyme Inhibition Experiment
Inhibition was detected. Cutoff used —
Not provided
- CES1
Cell fraction Human kidney S9 fraction
Results
IC50 pre-incubation 0 min (A) = 4.03 µM
IC50 pre-incubation 30 min (B) = 8.51 µM
B/A = 2.11
| Sample | Compound measured | Value | Measurement | Study sequence | Additional information | N replicates |
|---|
Experimental Conditions
20 µg/mL
Commercially available
100 µL
15 min
1 mM
30 min
30 min
0 - 50 µg/mL
5 . Evaluation of Time-Dependent CES1 Inhibition by CBN (0 min) (id=NPDI-2KocMg)
In Vitro Enzyme Inhibition Experiment
Inhibition was detected. Cutoff used —
Not provided
- CES1
Cell fraction Human kidney S9 fraction
Results
IC50 pre-incubation 0 min (A) = 4.03 µM
IC50 pre-incubation 30 min (B) = 8.51 µM
B/A = 2.11
| Sample | Compound measured | Value | Measurement | Study sequence | Additional information | N replicates |
|---|
Experimental Conditions
20 µg/mL
Commercially available
100 µL
15 min
1 mM
30 min
0 min
0 - 50 µg/mL
6 . Inhibition of CES1 by CBN (id=NPDI-LI0O-A)
In Vitro Enzyme Inhibition Experiment
Inhibition was detected. Cutoff used —
90% inhibition
- CES1
Cell fraction Human kidney S9 fraction
Results
Table 2
| Sample | Compound measured | Value | Measurement | Study sequence | Additional information | N replicates |
|---|
Experimental Conditions
20 microG/ml
Commercially available
100 µL
15 min
0, 100, 500, 1000, 2500, 5000 µM
0 - 10 µg/mL
7 . Inhibition of CES1 by THC (id=NPDI-AIeEmg)
In Vitro Enzyme Inhibition Experiment
Inhibition was detected. Cutoff used —
90% inhibition
- CES1
Cell fraction Human kidney S9 fraction
Results
Table 2
| Sample | Compound measured | Value | Measurement | Study sequence | Additional information | N replicates |
|---|
Experimental Conditions
20 microG/ml
Commercially available
100 µL
15 min
0, 100, 500, 1000, 2500, 5000 µM
0 - 10 µg/mL
8 . Evaluation of Time-Dependent CES1 Inhibition by THC (0 min) (id=NPDI-t5Bygg)
In Vitro Enzyme Inhibition Experiment
Inhibition was detected. Cutoff used —
Not provided
- CES1
Cell fraction Human kidney S9 fraction
Results
IC50 pre-incubation 0 min (A) = 3.91 µM
IC50 pre-incubation 30 min (B) = 11.2 µM
B/A = 2.85
| Sample | Compound measured | Value | Measurement | Study sequence | Additional information | N replicates |
|---|
Experimental Conditions
20 µg/mL
Commercially available
100 µL
15 min
1 mM
30 min
0 min
0 - 50 µg/mL
9 . Evaluation of Time-Dependent CES1 Inhibition by THC (30 min) (id=NPDI-8d0Lug)
In Vitro Enzyme Inhibition Experiment
Inhibition was detected. Cutoff used —
Not provided
- CES1
Cell fraction Human kidney S9 fraction
Results
IC50 pre-incubation 0 min (A) = 3.91 µM
IC50 pre-incubation 30 min (A) = 11.2 µM
B/A = 2.85
| Sample | Compound measured | Value | Measurement | Study sequence | Additional information | N replicates |
|---|
Experimental Conditions
20 µg/mL
Commercially available
100 µL
15 min
1 mM
30 min
30 min
0 - 50 µg/mL