Lysophosphatidylcholine Enhances Carotenoid Uptake from Mixed Micelles by Caco-2 Human Intestinal Cells
2001
Sugawara, Tatsuya | Kushiro, Masayo | Zhang, Hong | Nara, Eiichi | Ono, Hiroshi | Nagao, Akihiko
Despite the interest in the beneficial roles of dietary carotenoids in human health, little is known about their solubilization from foods to mixed bile micelles during digestion and the intestinal uptake from the micelles. We investigated the absorption of carotenoids solubilized in mixed micelles by differentiated Caco-2 human intestinal cells, which is a useful model for studying the absorption of dietary compounds by intestinal cells. The micelles were composed of 1 μmol/L carotenoids, 2 mmol/L sodium taurocholate, 100 μmol/L monoacylglycerol, 33.3 μmol/L fatty acid and phospholipid (0-200 μmol/L). The phospholipid content of micelles had profound effects on the cellular uptake of carotenoids. Uptake of micellar β-carotene and lutein was greatly suppressed by phosphatidylcholine (PC) in a dose-dependent manner, whereas lysophosphatidylcholine (lysoPC), the lipolysis product of PC by phospholipase A2 (PLA(2)), markedly enhanced both β-carotene and lutein uptake. The addition of PLA(2) from porcine pancreas to the medium also enhanced the uptake of carotenoids from micelles containing PC. Caco-2 cells could take up 15 dietary carotenoids, including epoxy carotenoids, such as violaxanthin, neoxanthin and fucoxanthin, from micellar carotenoids, and the uptakes showed a linear correlation with their lipophilicity, defined as the distribution coefficient in 1-octanol/water (log P(ow)). These results suggest that pancreatic PLA(2) and lysoPC are important in regulating the absorption of carotenoids in the digestive tract and support a simple diffusion mechanism for carotenoid absorption by the intestinal epithelium.
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