Catalytic activity of cytochrome P450 isozymes purified from rat liver in converting 11-oxo-delta 8-tetrahydrocannabinol to delta 8-tetrahydrocannabinol-11-oic acid.
Cytochrome P450 isozymes purified from rat hepatic microsomes were able to catalyse the oxidation of 11-oxo-delta 8-tetrahydrocannabinol (11-oxo-delta 8-THC) to delta 8-THC-11-oic acid in the presence of NADPH, cytochrome P450 reductase and dilauroylphosphatidylcholine. The catalytic activities (nmol/min/nmol P450) of cytochrome P450s, UT-2 (IIC11), UT-4 (IIA2), UT-5 (IIC13), PB-1, PB-2 (IIC6), PB-4 (IIB1), MC-1 (IA2), MC-5 (IA1) and IF-3 (IIA1), were 0.69, 0.08, 0.07, 0.23, 0.46, 0.02, 0.06, 0.07 and 0.34, respectively, whereas the activities of cytochrome P450s, PB-5 (IIB2) and DM (IIE1), were less than 0.02 nmol/min/nmol P450. Cytochrome P450 IIC11 showed the highest catalytic activity of the cytochromes examined. The mechanism for the oxidation of 11-oxo-delta 8-THC to delta 8-THC-11-oic acid by cytochrome P450 IIC11 was established as being an oxygenation since one atom of oxygen-18 was exclusively incorporated into the carboxylic acid formed under 18O2. The antibody raised to cytochrome P450 IIC11 inhibited by 60% the hepatic microsomal oxidation of 11-oxo-delta 8-THC to delta 8-THC-11-oic acid in male rats. These results indicate that cytochrome P450 IIC11 is a major form of the cytochrome to catalyse the oxidation of 11-oxo-delta 8-THC to delta 8-THC-11-oic acid in the hepatic microsomes of male rats and that the oxidation of aldehyde to carboxylic acid is a catalytic activity common to most isozymes of P450.
Watanabe
K
K
Department of Hygienic Chemistry, Faculty of Pharmaceutical Sciences, Hokuriku University, Kanazawa, Japan.
Matsunaga
T
T
Narimatsu
S
S
Yamamoto
I
I
Imaoka
S
S
Funae
Y
Y
Yoshimura
H
H
D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D003577:Cytochrome P-450 Enzyme System / Q000276:immunology / Q000302:isolation & purification* / Q000378:metabolism; D013759:Dronabinol / Q000031:analogs & derivatives* / Q000378:metabolism; D005260:Female; D007527:Isoenzymes / Q000276:immunology / Q000302:isolation & purification* / Q000378:metabolism; D007700:Kinetics; D008297:Male; D013058:Mass Spectrometry; D008862:Microsomes, Liver / Q000201:enzymology*; D010084:Oxidation-Reduction; D010105:Oxygenases / Q000037:antagonists & inhibitors; D051381:Rats; D011919:Rats, Inbred Strains
D000906:Antibodies; D007527:Isoenzymes; C009411:delta(6)-tetrahydrocannabinol-7-oic acid; C020443:11-oxo-delta(8)-tetrahydrocannabinol; D013759:Dronabinol; D003577:Cytochrome P-450 Enzyme System; D010105:Oxygenases