Distribution of betalain pigments in red blood cells after consuption of cactus pear fruits and increased resistance of the cells to ex vivo induced oxidative hemolysis in humans

Betalain pigments are bioavailable phytochemicals recently acknowledged as natural radicalscavengers. This work, which extends previous research on the postabsorbitive fate of dietarybetalains, investigated the distribution of betanin and indicaxanthin in red blood cells (RBCs) isolatedfrom healthy volunteers (n ) 8), before and during the 1-8 h interval after a cactus pear fruit meal,and the potential antioxidative activity of the pigments in these cells. A peak concentration ofindicaxanthin (1.03 ( 0.2 íM) was observed in RBCs isolated at 3 h after fruit feeding, whereas theconcentration at 5 h was about half, and even smaller amounts were measured at 8 h. Indicaxanthinwas not detected at 1 h. Betanin (30.0 ( 5.2 nM) was found only in RBCs isolated at 3 h from fruitfeeding. In comparison with homologous RBCs before fruit ingestion, a significant delay (P < 0.05)of the onset of an ex vivo cumene hydroperoxide (cumOOH)-induced hemolysis was evident in theRBCs isolated at 3 h (33.0 ( 4.5 min) and at 5 h (16.0 ( 2.0 min). Neither vitamins C and E nor GSHwas modified in the RBCs at any time point. Blood collected from the same volunteers after a 12-hfasting was incubated with the purified betalains in the range of 5-25 íM, to enrich the erythrocyteswith either betanin or indicaxanthin, and then the cells were exposed to cumOOH. When comparedto the relevant nonenriched cells, the betalain-enriched erythrocytes exhibited an enhanced resistanceto the cumOOH-induced hemolysis, which was positively correlated (r 2 ) 0.99) to the amount of theincorporated compound. On a micromolar basis, betanin and indicaxanthin showed a comparableeffectiveness. Taken together, these findings provide evidence that human RBCs incorporate dietarybetalains and support the concept that these phytochemicals may offer antioxidative protection tothe cells.