Lysophosphatidylcholine enhances carotenoid uptake from mixed micelles by Caco-2 human intestinal cells

Despite the interest in the beneficial roles of dietary carotenoids inhuman health, little is known about their solubilization from foods to mixed bil e micelles during digestion and the intestinal uptake from the micelles. We investigated the absorption of carotenoids solubilized in mixed micelles b y differentiated Caco-2 human intestinal cells, which is a useful model for studying the absorption of dietary compounds by intestinal cells. The mice lles were composed of 1 mu mol/L carotenoids, 2 mmol/L sodium taurocholate, 100 mu mol/L monoacylglycerol, 33.3 mu mol/L fatty acid and phospholipid ( 0-200 mu mol/L. The phospholipid content of micelles had profound effects o n the cellular uptake of carotenoids. Uptake of micellar beta -carotene and lutein was greatly suppressed by phosphatidylcholine (PC) in a dose-depend ent manner, whereas lysophosphatidylcholine (lysoPC), the lipolysis product of PC by phospholipase A(2) (PLA(2)), markedly enhanced both P-carotene an d lutein uptake. The addition of PLA2 from porcine pancreas to the medium a lso enhanced the uptake of carotenoids from micelles containing PC. Caco-2 cells could take up 15 dietary carotenoids, including epoxy carotenoids, su ch as violaxanthin, neoxanthin and fucoxanthin, from micellar carotenoids, and the uptakes showed a linear correlation with their lipophilicity, defin ed as the distribution coefficient in 1-octanol/water (log P-ow). These res ults suggest that pancreatic PLA2 and lysoPC are important in regulating th e absorption of carotenoids in the digestive tract and support a simple dif fusion mechanism for carotenoid absorption by the intestinal epithelium.