Catechins pharmacokinetics

Early studies (in the 1970s) on the pharmacokinetics of (+)-catechin revealed that this flavanol is absorbed from the gastrointestinal tract following administration to healthy volunteers (4.2 g in the form of gelatin capsules) [100]. (+)-Catechin was excreted in the urine together with several unidentified metabolites, and the amount excreted within 24 h was about 7.5% of the administered dose. 

Lee, M.J., Maliakal, R, Chen, L.S., Meng, X.F., Bondoc, F.Y., Prabhu, S., Lambert, G., Mohr, S., and Yang, C.S., Pharmacokinetics of tea catechins after ingestion of green tea and (-)-epigallocatechin-3-gallate by humans formation of different metabolites and individual variability. Cancer Epidemiol. Biomarkers Prev., 11, 1025, 2002. 

It is very important to know the bioavailability and biotransformation of tea catechins in humans because the pharmacokinetics, absorption, distribution, metabolism, and excretion of green tea determine its potential bioactivities in disease prevention in... 

The pharmacokinetics parameters of catechin metabolites are listed in table 7.2. Intact tea catechins, EC, ECG, EGC, and EGCG in human plasma and urine, are detected but with low concentrations. To determine the content of conjugated metabolites of catechins, blood and urine samples are treated with p-glucuronidase and sulfatase to remove the glucuonic or sulfate group prior to high-performance liquid chromatography (HPLC) analysis. 

Pharmacokinetic parameters of tea catechin metabolites in human plasma after oral consumption... 

Mean and range of pharmacokinetics data of total tea catechins (free and conjugate) in humans... 

There may be a difference in the pharmacokinetics parameters when catechins are given in pure or mixed form orally to humans. For 1,050 mg EC in the pure form, Cmax was 1.53 pM, but it was 0.11 pM based on 75 mg intake, while for 75 mg EC... 

Pharmacokinetics of tea catechins in humans need to be studied further. Large inter- and intraindividual variations in the pharmacokinetic parameters of tea catechins and their metabolites have been reported in humans. To better understand benefits of tea against cancer and other diseases, future research may focus on the target tissue levels of specific catechins and their metabolites. 

Wermeifle M, Turin E, Griffiths LA. Identification of the major urinary metabolites of (+)-catechin and 3-0-methyl-(+)-catechin in man. Eur J Drug Metab Pharmacokinet 1983 8(l) 77-84. 

---