PT  - JOURNAL ARTICLE
AU  - Alexander Michael Real
AU  - Shangyu Hong
AU  - Pavlos Pissios
TI  - Nicotinamide <em>N</em>-Oxidation by CYP2E1 in Human Liver Microsomes
AID  - 10.1124/dmd.112.049734
DP  - 2013 Mar 01
TA  - Drug Metabolism and Disposition
PG  - 550--553
VI  - 41
IP  - 3
4099  - http://dmd.aspetjournals.org/content/41/3/550.short
4100  - http://dmd.aspetjournals.org/content/41/3/550.full
SO  - Drug Metab Dispos2013 Mar 01; 41
AB  - Excess nicotinamide, a form of vitamin B3, is metabolized through two enzymatic systems and eventually excreted from the body. The first system starts with the methylation of nicotinamide by nicotinamide N-methyltransferase, which can subsequently be oxidized by aldehyde oxidase. The second enzymatic system oxidizes nicotinamide to nicotinamide N-oxide. It is located in the endoplasmic reticulum of hepatocytes but the precise enzyme is unknown. We have used human liver microsomes in combination with selective cytochrome P450 inhibitors, specific substrates, and antibodies to identify CYP2E1 as the main activity producing nicotinamide N-oxide. Our results suggest the potential use of nicotinamide N-oxide as a biomarker of CYP2E1 activity from urine or blood samples.