Intestinal absorption and antioxidant activity of betalain: A nitrogen-containing pigment from table beets and cactus pear fruit juice

Abstract

The purpose of this study was to elucidate the gastrointestinal pharmacokinetics of betalains, violet betacyanins (betanin and its isomer) from red beetroot (Beta vulgaris L.var. rubra) and yellow betaxanthin (indicaxanthin) from cactus pear fruit (Opuntia ficus-indica L.) juice. The absorption dynamics and sites of both pigments were investigated by LC-MS or DAD-HPLC using portal blood collected at five to ten minute intervals over a 30-min period after intubation in ligated gastric or small intestinal loops in rats. The antioxidant capacities of both pigments were measured using the ORAC assay. Indicaxanthin and betacyanin showed a maximum serum concentration at 5 or 10 minutes, respectively, after injection into the small intestine in rats. Moreover, betanin and its isomer were absorbed from both the stomach and small intestine. On the other hand, indicaxanthin was absorbed from the small intestine, but not from the stomach. However, the antioxidant capacity of indicaxanthin in vitro was higher than that of betacyanin (13.6 and 4.2 mmol TE/g, respectively). These results indicate that both pigments may be absorbed from the gastrointestinal tract via different pathways.