Cannabis (Cannabis sativa)
Cytochrome P450 enzymes involved in the metabolism of tetrahydrocannabinols and cannabinol by human hepatic microsomes CSV JSON

In this study, tetrahydrocannabinols (THCs) were mainly oxidized at the 11-position and allylic sites at the 7α-position for Δ8-THC and the 8β-position for Δ9-THC by human hepatic microsomes. Cannabinol (CBN) was also mainly metabolized to 11-hydroxy-CBN and 8-hydroxy-CBN by the microsomes. The 11-hydroxylation of three cannabinoids by the microsomes was markedly inhibited by sulfaphenazole, a selective inhibitor of CYP2C enzymes, while the hydroxylations at the 7α-(Δ8-THC), 8β-(Δ9-THC) and 8-positions (CBN) of the corresponding cannabinoids were highly inhibited by ketoconazole, a selective inhibitor of CYP3A enzymes. Human CYP2C9-Arg expressed in the microsomes of human B lymphoblastoid cells efficiently catalyzed the 11-hydroxylation of Δ8-THC (7.60 nmol/min/nmol CYP), Δ9-THC (19.2 nmol/min/nmol CYP) and CBN (6.62 nmol/min/nmol CYP). Human CYP3A4 expressed in the cells catalyzed the 7α-(5.34 nmol/min/nmol CYP) and 7β-hydroxylation (1.39 nmol/min/nmol CYP) of Δ8-THC, the 8β-hydroxylation (6.10 nmol/min/nmol CYP) and 9α,10α-epoxidation (1.71 nmol/min/nmol CYP) of Δ9-THC, and the 8-hydroxylation of CBN (1.45 nmol/min/nmol CYP). These results indicate that CYP2C9 and CYP3A4 are major enzymes involved in the 11-hydroxylation and the 8-(or the 7-) hydroxylation, respectively, of the cannabinoids by human hepatic microsomes. In addition, CYP3A4 is a major enzyme responsible for the 7α- and 7β-hydroxylation of Δ8-THC, and the 9α,10α-epoxidation of Δ9-THC.

Cannabis (Cannabis sativa)

17303175

1 . Inhibition of 8-hydroxylation of cannabinol by ketoconazole (id=NPDI-I4dv_g)

In Vitro Enzyme Inhibition Experiment

Inhibition was detected.  Cutoff used —

Not provided

cannabinol

ketoconazole

8-hydroxycannabinol

  • CYP3A

Cell fraction Pooled human liver microsomes -7999662

Results

Table 1

Sample Compound measured Value Measurement Study sequence Additional information N replicates

Experimental Conditions

10 microG

Commercially available

20 min

NADPH
NADPH regenerating system

64 µM

10 µM

2 . Inhibition of 11-hydroxylation of cannabinol by sulfaphenazole (id=NPDI-8flCOQ)

In Vitro Enzyme Inhibition Experiment

Inhibition was detected.  Cutoff used —

Not provided

cannabinol

sulfaphenazole

11-hydroxycannabinol

  • CYP2C

Cell fraction Pooled human liver microsomes -7999662

Results

Table 1

Sample Compound measured Value Measurement Study sequence Additional information N replicates

Experimental Conditions

10 microG

Commercially available

20 min

NADPH
NADPH regenerating system

64 µM

50 µM

3 . Inhibition of 7-alpha-hydroxylation of delta-8-THC by ketoconazole (id=NPDI-M13k5Q)

In Vitro Enzyme Inhibition Experiment

Inhibition was detected.  Cutoff used —

Not provided

ketoconazole

7-alpha-hydroxy-delta-8-tetrahydrocannabinol

  • CYP3A

Cell fraction Pooled human liver microsomes -7999662

Results

Table 1

Sample Compound measured Value Measurement Study sequence Additional information N replicates

Experimental Conditions

10 microG

Commercially available

20 min

NADPH
NADPH regenerating system

64 µM

10 µM

4 . Inhibition of 11-hydroxylation of delta-8-THC by sulfaphenazole (id=NPDI-42-g8Q)

In Vitro Enzyme Inhibition Experiment

Inhibition was detected.  Cutoff used —

Not available

sulfaphenazole

11-hydroxy-delta-8-tetrahydrocannabinol

  • CYP2C

Cell fraction Pooled human liver microsomes -7999662

Results

Table 1

Sample Compound measured Value Measurement Study sequence Additional information N replicates

Experimental Conditions

10 microG

Commercially available

20 min

NADPH
NADPH regenerating system

64 µM

50 µM

5 . Inhibition of 8-beta-hydroxylation of delta-9-THC by ketoconazole (id=NPDI-rbqhsA)

In Vitro Enzyme Inhibition Experiment

Inhibition was detected.  Cutoff used —

Not provided

ketoconazole

8-beta-hydroxy-delta-9-tetrahydrocannabinol

  • CYP3A

Cell fraction Pooled human liver microsomes -7999662

Results

Table 1

Sample Compound measured Value Measurement Study sequence Additional information N replicates

Experimental Conditions

10 microG

Commercially available

20 min

NADPH
NADPH regenerating system

64 µM

10 µM

6 . Inhibition of 11-hydroxylation of delta-9-THC by sulfaphenazole (id=NPDI-qmmKqA)

In Vitro Enzyme Inhibition Experiment

Inhibition was detected.  Cutoff used —

Not provided

sulfaphenazole

11-hydroxy-delta-9-tetrahydrocannabinol

  • CYP2C

Cell fraction Pooled human liver microsomes -7999662

Results

Table 1

Sample Compound measured Value Measurement Study sequence Additional information N replicates

Experimental Conditions

10 microG

Commercially available

20 min

NADPH
NADPH regenerating system

64 µM

50 µM

7 . Weak Inhibition of 11-hydroxylation of cannabinol by 7,8-benzoflavone (id=NPDI-YQ1c2Q)

In Vitro Enzyme Inhibition Experiment

Negligible Inhibition was detected.  Cutoff used —

Not provided

cannabinol

alpha-naphthoflavone

11-hydroxycannabinol

  • CYP1A

Cell fraction Pooled human liver microsomes -7999662

Results

Table 1

Sample Compound measured Value Measurement Study sequence Additional information N replicates

Experimental Conditions

10 microG

Commercially available

20 min

NADPH
NADPH regenerating system

64 µM

10 µM

8 . No Inhibition of 8-hydroxylation of cannabinol by 7,8-benzoflavone (id=NPDI-v8ghug)

In Vitro Enzyme Inhibition Experiment

Negligible Inhibition was detected.  Cutoff used —

Not provided

cannabinol

alpha-naphthoflavone

8-hydroxycannabinol

  • CYP1A

Cell fraction Pooled human liver microsomes -7999662

Results

Table 1

Sample Compound measured Value Measurement Study sequence Additional information N replicates

Experimental Conditions

10 microG

Commercially available

20 min

NADPH
NADPH regenerating system

64 µM

10 µM

9 . Weak Inhibition of 11-hydroxylation of cannabinol by ketoconazole (id=NPDI-VpD-Xg)

In Vitro Enzyme Inhibition Experiment

Negligible Inhibition was detected.  Cutoff used —

Not provided

cannabinol

ketoconazole

11-hydroxycannabinol

  • CYP3A

Cell fraction Pooled human liver microsomes -7999662

Results

Table 1

Sample Compound measured Value Measurement Study sequence Additional information N replicates

Experimental Conditions

10 microG

Commercially available

20 min

NADPH
NADPH regenerating system

64 µM

10 µM

10 . Weak Inhibition of 8-hydroxylation of cannabinol by sulfaphenazole (id=NPDI-uxfWFg)

In Vitro Enzyme Inhibition Experiment

Negligible Inhibition was detected.  Cutoff used —

Not provided

cannabinol

sulfaphenazole

8-hydroxycannabinol

  • CYP2C

Cell fraction Pooled human liver microsomes -7999662

Results

Table 1

Sample Compound measured Value Measurement Study sequence Additional information N replicates

Experimental Conditions

10 microG

Commercially available

20 min

NADPH
NADPH regenerating system

64 µM

50 µM

11 . Weak Inhibition of 11-hydroxylation of delta-8-THC by 7,8-benzoflavone (id=NPDI-RCBEtw)

In Vitro Enzyme Inhibition Experiment

Negligible Inhibition was detected.  Cutoff used —

Not provided

alpha-naphthoflavone

11-hydroxy-delta-8-tetrahydrocannabinol

  • CYP1A

Cell fraction Pooled human liver microsomes -7999662

Results

Table 1

Sample Compound measured Value Measurement Study sequence Additional information N replicates

Experimental Conditions

10 microG

Commercially available

20 min

NADPH
NADPH regenerating system

64 µM

10 µM

12 . No inhibition of 7-alpha-hydroxylation of delta-8-THC by 7,8-benzoflavone (id=NPDI-EYnQkA)

In Vitro Enzyme Inhibition Experiment

Negligible Inhibition was detected.  Cutoff used —

Not provided

alpha-naphthoflavone

7-alpha-hydroxy-delta-8-tetrahydrocannabinol

  • CYP1A

Cell fraction Pooled human liver microsomes -7999662

Results

Table 1

Sample Compound measured Value Measurement Study sequence Additional information N replicates

Experimental Conditions

10 microG

Commercially available

20 min

NADPH
NADPH regenerating system

64 µM

10 µM

13 . Weak Inhibition of 11-hydroxylation of delta-8-THC by ketoconazole (id=NPDI-M8-Oxw)

In Vitro Enzyme Inhibition Experiment

Negligible Inhibition was detected.  Cutoff used —

Not provided

ketoconazole

11-hydroxy-delta-8-tetrahydrocannabinol

  • CYP3A

Cell fraction Pooled human liver microsomes -7999662

Results

Table 1

Sample Compound measured Value Measurement Study sequence Additional information N replicates

Experimental Conditions

10 microG

Commercially available

20 min

NADPH
NADPH regenerating system

64 µM

10 µM

14 . Weak Inhibition of 7-alpha-hydroxylation of delta-8-THC by sulfaphenazole (id=NPDI-5Fz7kg)

In Vitro Enzyme Inhibition Experiment

Negligible Inhibition was detected.  Cutoff used —

Not provided

sulfaphenazole

7-alpha-hydroxy-delta-8-tetrahydrocannabinol

  • CYP2C

Cell fraction Pooled human liver microsomes -7999662

Results

Table 1

Sample Compound measured Value Measurement Study sequence Additional information N replicates

Experimental Conditions

10 microG

Commercially available

20 min

NADPH
NADPH regenerating system

64 µM

50 µM

15 . No inhibition of 8-beta-hydroxylation of delta-9-THC by 7,8-benzoflavone (id=NPDI-THVK4A)

In Vitro Enzyme Inhibition Experiment

Negligible Inhibition was detected.  Cutoff used —

Not provided

alpha-naphthoflavone

8-beta-hydroxy-delta-9-tetrahydrocannabinol

  • CYP1A

Cell fraction Pooled human liver microsomes -7999662

Results

Table 1

Sample Compound measured Value Measurement Study sequence Additional information N replicates

Experimental Conditions

10 microG

Commercially available

20 min

NADPH
NADPH regenerating system

64 µM

10 µM

16 . Weak Inhibition of 11-hydroxylation of delta-9-THC by 7,8-benzoflavone (id=NPDI-IQtjvw)

In Vitro Enzyme Inhibition Experiment

Negligible Inhibition was detected.  Cutoff used —

Not provided

alpha-naphthoflavone

11-hydroxy-delta-9-tetrahydrocannabinol

  • CYP1A

Cell fraction Pooled human liver microsomes -7999662

Results

Table 1

Sample Compound measured Value Measurement Study sequence Additional information N replicates

Experimental Conditions

10 microG

Commercially available

20 min

NADPH
NADPH regenerating system

64 µM

10 µM

17 . Weak Inhibition of 11-hydroxylation of delta-9-THC by ketoconazole (id=NPDI-abEayg)

In Vitro Enzyme Inhibition Experiment

Negligible Inhibition was detected.  Cutoff used —

Not provided

ketoconazole

11-hydroxy-delta-9-tetrahydrocannabinol

  • CYP3A

Cell fraction Pooled human liver microsomes -7999662

Results

Table 1

Sample Compound measured Value Measurement Study sequence Additional information N replicates

Experimental Conditions

10 microG

Commercially available

20 min

NADPH
NADPH regenerating system

64 µM

10 µM

18 . Weak Inhibition of 8-beta-hydroxylation of delta-9-THC by sulfaphenazole (id=NPDI-Yr3jng)

In Vitro Enzyme Inhibition Experiment

Negligible Inhibition was detected.  Cutoff used —

Not provided

sulfaphenazole

8-beta-hydroxy-delta-9-tetrahydrocannabinol

  • CYP2C

Cell fraction Pooled human liver microsomes -7999662

Results

Table 1

Sample Compound measured Value Measurement Study sequence Additional information N replicates

Experimental Conditions

10 microG

Commercially available

20 min

NADPH
NADPH regenerating system

64 µM

50 µM