Acyl moieties modulate the effects of phospholipids on β-carotene uptake by Caco-2 cells

Abstract  The intestinal absorption of carotenoids is though to be mediated by the carotenoid assembly in mixed micelles, followed by its transfer into the enterocytes and subsequent secretion to the lymph as chylomicron particles. In the present study we investigated the effects of phospholipids and lysophospholipids with diverse fatty acyl moieties on the uptake of β-carotene solubilized in mixed micelles by Caco-2 cells. Compared with phospholipid-free mixed micelles (NoPL), those containing long-chain PC inhibited β-carotene uptake (16∶0, 18∶1-PC≅16∶0, 18∶2-PC<14∶0, 14∶0-PC≅16∶0, 14∶0-PC <16∶0, 16∶0-PC<NoPL). However, mixed micelles containing medium-chain PC enhanced β-carotene uptake (NoPL<8∶0, 8∶0-PC<12∶0, 12∶0-PC<10∶0, 10∶0-PC), and short-chain PC did not affect the uptake. Among the lysophosphatidylcholine (LysoPC) class, a marked increase of β-carotene uptake by medium-to-long-chain LysoPC was observed (NoPL<12∶0-LysoPC<14∶0-LysoPC<18∶1-LysoPC<16∶0-LysoPC), although short-to-medium-chain LysoPC (6∶0-LysoPC to 10∶0-LysoPC) did not affect β-carotene uptake. The long-chain 16∶0,18∶1-PC increased the β-carotene efflux from cells and drastically changed the β-carotene UV-visible absorbance spectrum, compared with those of NoPL micelles. The acyl moieties of long-chain PC may interact with the carotenoid in the micelle interior, shifting the β-carotene partition toward the micellar phase. Medium-chain PC and long-chain LysoPC, which have nearly equivalent hydrophobicities, may enhance β-carotene uptake through their interaction with the cell membrane.