Quantification of trans-resveratrol and its metabolites in rat plasma and tissues by HPLC.

trans-Resveratrol, a polyphenol from grapes, is being recognized as a bioactive agent with potential beneficial effects on health. However, little is known about its distribution in the organism mainly because of the lack of accurate and precise detection methods. Consequently the aim of the present study was to develop a methodology of extraction and quantification of trans-resveratrol and its metabolites in plasma, brain, testis, liver, lungs and kidney by HPLC. To this end, the time of homogenization and liquid extraction were adapted to the different tissues. The methods were validated using homogenized tissues spiked with pure trans-resveratrol. The precision (% R.S.D.) ranged from 3.7% in testis to 13.2% in lungs. Recoveries were 98.5+/-3.2% (liver), 100.1+/-1.8% (kidney), 96.5+/-7.6% (lungs), 99.0+/-0.7% (brain) and 103+/-2.7% (testicle). The limits of detection ranged from 5.5 nM in testis to 11.2 nM in kidney. After validation, the methods were applied to the assessment of the bioavailability and distribution of trans-resveratrol in rats after the intravenous administration of 15 mg/kg. At 90 min, trans-resveratrol and its glucuronide and sulfate conjugates were widely distributed in all the tissues studied. The highest concentrations (nmol/g tissue) were found in kidney (resveratrol: 1.45+/-0.35; glucuronide: 2.91+/-0.19; sulfate: not detected), and the lowest in brain (resveratrol: 0.17+/-0.04; glucuronide: not detected; sulfate: 0.04+/-0.01). In conclusion, accurate and reproducible methods have been described to identify target tissues of resveratrol as a first step to understand its mechanisms of action in vivo.