Detection, stability and redox effects of black currant anthocyanin glycosides in vivo: Positive identification by mass spectrometry

Anthocyanins are ingested as the red and blue coloured pigments in berries and red wine. They are potent antioxidants and their redox actions might positively affect health. It is therefore of interest to device a method to determine these compounds in blood and excreta, and to determine their stability, their biokinetics, and the forms in which they are absorbed and excreted. In the present study we have examined their stability in urine, their urinary excretion in rabbits, and their presence in human plasma and urine from a single volunteer. Urine samples containing anthocyanins can be stored for at least 7 months at 80 degreesC, provided they are acidified during collection, added an internal standard and stored at pH around 1.8. Black currant anthocyanins are absorbed and excreted quickly with a peak plasma concentration around I h after a single dose. Within 0.5-2 hours after dosing, the redox capacity of plasma was significantly increased in the rabbits. Urinary excretion peaked at 1-4 h and was almost complete within 24 h in both rabbits and man. Based on UV spectra and retention times, only unchanged glucosides and rutinosides were observed in all samples. Positive identification of the four anthocyanin glycosides in a human urine sample was obtained by LC-API-MS.