Meng X., Maliakal P., Lu H., Lee M.J., Yang C.S. (2004) Urinary and plasma levels of resveratrol and quercetin in humans, mice, and rats after ingestion of pure compounds and grape juice. J Agric Food Chem 52:935-42 PubMed (14969553)

Compound Mean content
Resveratrol 0.08 mg/100 ml
Quercetin 0.38 mg/100 ml