Biomaterial Database

Chlorzoxazone metabolism by winter flounder liver microsomes: evidence for existence of a CYP2E1-like isoform in teleosts. 1998

K L Wall, and J Crivello

Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut, 06269, USA.

Winter flounder (Pleuronectes americanus) liver microsomes metabolized chlorzoxazone (CZX), a CYP2E1 (cytochrome P450 2E1)- specific substrate, to a single product, 6-OH CZX. The liver microsomal fraction had the highest level of activity, which varied among fish, ranging from 60 to 220 pmol/mg/min. CZX metabolism was linearly related to microsomal protein and dependent on NADPH. The optimal pH range for this activity was from 7.2 to 8.0. Maximal activity was found at 18-22 degreesC (154 +/- 62 pmol/mg/min) but was detectable at all temperatures tested. CZX 6-hydroxylation displayed first-order kinetics as shown by Lineweaver-Burk plots. The average apparent Km, 280 microM, was higher than that reported for human liver microsomes but similar to the Km determined for human CYP2E1 expressed in vaccinia virus. Vmax values ranged from 65 to 141 pmoles/mg/min. The CYP2E1-specific inhibitors, diethyldithiocarbamate (DDC) and aniline, significantly reduced 6-OH CZX production by 80 and 35%, respectively. 7,8-Benzoflavone and ethoxyresorufin, both CYP1A-specific inhibitors, did not significantly inhibit CZX metabolism nor did trioleandomycin (TAO) a CYP3A-specific inhibitor. Diethyldithiocarbamate (DDC), at 50 microM, had no significant effect on winter flounder liver microsomal ethoxyresorufin-O-deethylase activity (EROD), a CYP1A-specific activity. 7,8-Benzoflavone, at 10 microM, inhibited EROD activity by 60%. This is the first report of CYP2E1 activity in teleost liver microsomes.

UI	MeSH Term	Description	Entries
D008297	Male		Males
D008862	Microsomes, Liver	Closed vesicles of fragmented endoplasmic reticulum created when liver cells or tissue are disrupted by homogenization. They may be smooth or rough.	Liver Microsomes,Liver Microsome,Microsome, Liver
D009125	Muscle Relaxants, Central	A heterogeneous group of drugs used to produce muscle relaxation, excepting the neuromuscular blocking agents. They have their primary clinical and therapeutic uses in the treatment of muscle spasm and immobility associated with strains, sprains, and injuries of the back and, to a lesser degree, injuries to the neck. They have been used also for the treatment of a variety of clinical conditions that have in common only the presence of skeletal muscle hyperactivity, for example, the muscle spasms that can occur in MULTIPLE SCLEROSIS. (From Smith and Reynard, Textbook of Pharmacology, 1991, p358)	Centrally Acting Muscle Relaxants,Central Muscle Relaxants,Relaxants, Central Muscle
D010078	Oxazines	Six-membered heterocycles containing an oxygen and a nitrogen.
D002753	Chlorzoxazone	A centrally acting central muscle relaxant with sedative properties. It is claimed to inhibit muscle spasm by exerting an effect primarily at the level of the spinal cord and subcortical areas of the brain. (From Martindale, The Extra Pharmacopoea, 30th ed, p1202)	Paraflex,Parafon,Parafon Forte DSC
D004050	Ditiocarb	A chelating agent that has been used to mobilize toxic metals from the tissues of humans and experimental animals. It is the main metabolite of DISULFIRAM.	Diethyldithiocarbamate,Diethylcarbamodithioic Acid,Diethyldithiocarbamic Acid,Dithiocarb,Ditiocarb Sodium,Ditiocarb, Ammonium Salt,Ditiocarb, Bismuth Salt,Ditiocarb, Lead Salt,Ditiocarb, Potassium Salt,Ditiocarb, Sodium Salt,Ditiocarb, Sodium Salt, Trihydrate,Ditiocarb, Tin(4+) Salt,Ditiocarb, Zinc Salt,Imuthiol,Sodium Diethyldithiocarbamate,Thiocarb,Zinc Diethyldithiocarbamate,Ammonium Salt Ditiocarb,Bismuth Salt Ditiocarb,Diethyldithiocarbamate, Sodium,Diethyldithiocarbamate, Zinc,Lead Salt Ditiocarb,Potassium Salt Ditiocarb,Sodium Salt Ditiocarb,Sodium, Ditiocarb,Zinc Salt Ditiocarb
D004791	Enzyme Inhibitors	Compounds or agents that combine with an enzyme in such a manner as to prevent the normal substrate-enzyme combination and the catalytic reaction.	Enzyme Inhibitor,Inhibitor, Enzyme,Inhibitors, Enzyme
D005260	Female		Females
D005432	Flounder	Common name for two families of FLATFISHES belonging to the order Pleuronectiformes: left-eye flounders (Bothidae) and right-eye flounders (Pleuronectidae). The latter is more commonly used in research.	Plaice,Platichthys,Pleuronectes,Pseudopleuronectes,Halibut,Pleuronectes platessa,Flounders
D000814	Aniline Compounds	Compounds that include the aminobenzene structure.	Phenylamine,Phenylamines,Anilines,Compounds, Aniline