title: A preliminary investigation of the impact of catechol-O-methyltransferase genotype on the absorption and metabolism of green tea catechins.
abstract: OBJECTIVE
  Green tea is thought to possess many beneficial effects on human health. However, the extent of green tea polyphenol biotransformation may affect its proposed therapeutic effects. Catechol-O-methyltransferase (COMT), the enzyme responsible for polyphenolic methylation, has a common polymorphism in the genetic code at position 158 reported to result in a 40% reduction in enzyme activity in in vitro studies. The current preliminary study was designed to investigate the impact of COMT genotype on green tea catechin absorption and metabolism in humans.
  
  
  METHODS
  Twenty participants (10 of each homozygous COMT genotype) were recruited, and plasma concentration profiles were produced for epigallocatechin gallate (EGCG), epigallocatechin (EGC), epicatechin gallate (ECG), epicatechin (EC) and 4'-O-methyl EGCG after 1.1 g of Sunphenon decaffeinated green tea extract (836 mg green tea catechins), with a meal given after 60 min.
  
  
  RESULTS
  For the entire group, EGCG, EGC, EC, ECG and 4'-O-methyl EGCG reached maximum concentrations of 1.09, 0.41, 0.33, 0.16 and 0.08 μM at 81.5, 98.5, 99.0, 85.5 and 96.5 min, respectively. Bimodal curves were observed for the non-gallated green tea catechins EGC and EC as opposed to single-peaked curves for the gallated green tea catechins EGCG and ECG. No significant parametric differences between COMT genotype groups were found.
  
  
  CONCLUSIONS
  In conclusion, the COMT Val(158/108)Met does not appear to have a dramatic influence on EGCG absorption and elimination. However, further pharmacokinetic research is needed to substantiate these findings.
authors: Department of Food and Nutritional Sciences, University of Reading, PO Box 226, Whiteknights, Reading, Berkshire RG6 6AP, UK. r.j.moore@reading.ac.uk
authors: Rosalind J
authors: RJ
authors: Miller
authors: Kim G
authors: KG
authors: Jackson
authors: Tony
authors: T
authors: Dadd
authors: Beate
authors: B
authors: Nicol
authors: Joanne L
authors: JL
authors: Dick
authors: Andrew E
authors: AE
authors: Mayes
authors: A Louise
authors: AL
authors: Brown
authors: Anne M
authors: AM
authors: Minihane
mesh_terms: D019943:Amino Acid Substitution; D002392:Catechin / Q000031:analogs & derivatives / Q000032:analysis / Q000097:blood / Q000378:metabolism*; D002394:Catechol O-Methyltransferase / Q000235:genetics*; D019587:Dietary Supplements / Q000032:analysis; D005260:Female; D056726:Genetic Association Studies; D006720:Homozygote; D006801:Humans; D007408:Intestinal Absorption; D007700:Kinetics; D008297:Male; D008745:Methylation; D008875:Middle Aged; D010636:Phenols / Q000008:administration & dosage / Q000737:chemistry; D010865:Pilot Projects; D010936:Plant Extracts / Q000008:administration & dosage / Q000737:chemistry; D020641:Polymorphism, Single Nucleotide; D013662:Tea / Q000737:chemistry
chemical_list: D010636:Phenols; D010936:Plant Extracts; D013662:Tea; C074269:Sunphenon; D002392:Catechin; C045651:epigallocatechin gallate; D002394:Catechol O-Methyltransferase; C057580:gallocatechol