Cytochrome P450 2A6 Phenotyping Based on Dietary Caffeine Intake in a Japanese Population of Non-smokers

Title:Cytochrome P450 2A6 Phenotyping Based on Dietary Caffeine Intake in a Japanese Population of Non-smokers

Volume: 6 Issue: 2

Author(s): Miyuki Kimura, Makiko Shimizu, Kazuma Kiyotani, Kazuko Nakagawa, Tetsuya Kamataki and Hiroshi Yamazaki

Affiliation:

Keywords: Caffeine intake, CYP2A6, Japanese, phenotyping, urine samples, whole gene deletion

Abstract: Phenotyping of cytochrome P450 2A6 (CYP2A6) was determined by assessing urinary caffeine metabolites in a Japanese population with a high frequency of CYP2A6 whole-gene deletion (CYP2A6*4). The levels of 1,7-dimethyluric acid (17U), 1-methylxanthine (1X), and 1,7-dimethylxanthine (17X) were measured in non-smokers whose CYP2A6 and NAT2 genotypes had been determined. Low 17U/1X ratios were observed in accumulated overnight urine samples of subjects genotyped as CYP2A6*4/*4 after caffeine treatment. The individual 17U/1X ratios in spot urine samples were almost constant before and 2–8 h after caffeine treatment, with or without prior abstention from dietary caffeine. The average 17U/1X ratios obtained from subjects with CYP2A6*4/*4 or CYP2A6*1/*4 genotypes were significantly lower than those from subjects with wild-type CYP2A6*1/*1 under dietary caffeine consumption. The present results suggest that impaired CYP2A6 function associated with CYP2A6*4/*4 could be determined using the 17U/1X ratios in spot urine samples under normal dietary caffeine consumption in Japanese non-smokers, without the need for additional caffeine administration or prior abstention from caffeine.

Cite this article as:

Kimura Miyuki, Shimizu Makiko, Kiyotani Kazuma, Nakagawa Kazuko, Kamataki Tetsuya and Yamazaki Hiroshi, Cytochrome P450 2A6 Phenotyping Based on Dietary Caffeine Intake in a Japanese Population of Non-smokers, Drug Metabolism Letters 2012; 6 (2) . https://dx.doi.org/10.2174/1872312811206020067