Cytochrome isoforms

Oxidative metabolism occurs with all of the statins, though the extent of metabolism and importance in the inactivation of the various compounds are different. Usually, more than one cytochrome isoform is implicated in the metabolism of various statins, though many of these have only very limited functional significance. In Tabs. 4.2 and 4.3, only those cytochromes which play a significant role... 

As reported by Russel et al., carried out metabolic smdies showed that pyrethroids are mainly metabolized by oxidation and ester cleavage, which are mediated by cytochrome isoforms and carboxylesterases, respectively (Russel et al. 2011). The biodegradation of synthetic pyrethroids is involved in the resistance of insects, in addition carboxylesterases, cytochromes P450 (CYPs) and GSTs (glutathione-5 -transferases) have all been implicated in this resistance. Intense bands of carboxy-lesterase activity in nondenaturing polyacrylamide gel had been associated with resistance to synthetic pyrethroids in various species, however, resistance... 

Aprepitant, which inhibits the cytochrome P450 isoform, CYP3A4, is metabolised by it. As a result,... 

Fuhr U, Strobl G, Manaut F, Anders E-M, Sorgel F, Lopez-de-brinas E, et al. Quinolone antibacterial agents relationship between structure and in vitro inhibition of human cytochrome P450 isoform CYP1A2. Mol Pharmacol 1993 43 191-9. 

ISOFORMS OF CYTOCHROME P450 HYDROXYLATE A MYRIAD OF XENOBIOTICS IN PHASE 1 OF THEIR METABOLISM... 

The major mono oxygenases in the endoplasmic reticulum are cytochrome P450s—so named because the enzyme was discovered when it was noted that preparations of microsomes that had been chemically reduced and then exposed to carbon monoxide exhibited a distinct peak at 450 nm. Among reasons that this enzyme is important is the fact that approximately 50% of the drugs humans ingest are metabolized by isoforms of cytochrome P450 these enzymes also act on various carcinogens and pollutants. 

Isoforms of Cytochrome P450 Make Up a Superfamily of Heme-Containing Enzymes... 

They are widely distributed across species. Bacteria possess cytochrome P450s, and P450cani (involved in the metabolism of camphor) of Pseudomonas putida is the only P450 isoform whose crystal stmcture has been established. 

At least six isoforms of cytochrome P450 are present in the endoplasmic reticulum of human hver, each with wide and somewhat overlapping substrate specificities and acting on both xenobiotics and endogenous compounds. The genes for many isoforms of P450 (from both humans and animals such as the rat) have been isolated and smdied in detail in recent years. 

Most isoforms of cytochrome P450 are inducible. For instance, the administration of phenobar-bital or of many other drugs causes hypertrophy of the... 

Olesen, O. V. Linnet, K. (2001). Contributions of five human cytochrome P450 isoforms to the N-demethylation of clozapine in vitro at low and high concentrations. /. Clin. Pharmacol., 41, 823-32. 

Easterbrook, J., Liu, C., Sakai, Y. and Li, A.P. (2001) Effects of organic solvents on the activities of cytochrome P450 isoforms, UDP-dependent glucuronyl transferase, and phenol sulfotransferase in human hepatocytes. Drug Metabolism and Disposition The Biological Fate of Chemicals, 29, 141-144. 

CYP2D6 The principal isoenzyme (isoform) of cytochrome P-450 involved in the metabolism of psychotropic drugs. 

Cytochrome P450 (EC 1.14.14.1) enzymes are well known for their ability to metabolize the majority of drugs, to detoxify environmental pollutants, and to activate some classes of carcinogens [93]. The most highly expressed subfamily is CYP 3A, which includes the isoforms CYP 3A4, CYP 3A5, CYP 3A7, and CYP 3A43 [93, 94]. The most abundant isoform is CYP 3A4, which corresponds to 30% of the total P450 content in the liver and about 70% of the total P450 content in the... 

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