Pharmacokinetics of gallic acid and its relative bioavailability from tea in healthy humans

Gallic acid (GA), a food component that is especially abundant in tea, is a n antimutagenic, anticarcinogenic and anti-inflammatory agent. We conducted a study using acidum gallicum tablets that contained 10% GA and 90% glucos e and a black tea brew that contained 93% of its GA in free form to determi ne the pharmacokinetics and relative bioavailability of GA in healthy human s. After the administration of a single oral dose of acidum gallicum tablet s or tea teach containing 0.3 mmol GA) to 10 volunteers, plasma and urine s amples were collected over various time intervals. Concentrations of GA and its metabolite, 4-O-methylgallic acid (40MGA), were determined, and the ph armacokinetic parameters were calculated. GA from both the tablets and tea was rapidly absorbed and eliminated with mean half-lives of 1.19 +/- 0.07 a nd 1.06 +/- 0.06 h and mean maximum concentrations of 1.83 +/- 0.16 and 2.0 9 +/- 0.22 mu mol/L (plasma), respectively. After oral administration of th e tablets and black tea, 36.4 +/- 4.5 and 39.6 +/- 5.1% of the GA dose were extracted in urine as GA and 40MGA, respectively. The relative bioavailabi lity of GA from tea compared with that from the tablets was 1.06 +/- 0.26, showing that GA is as available from drinking tea as it is from swallowing tablets of GA.