Novel milk casein–derived peptides decrease cholesterol micellar solubility and cholesterol intestinal absorption in Caco-2 cells

摘要

This study sought to assess the cholesterol-loweringactivity of peptides obtained from milk casein hydrolyzedwith neutrase. The bioactive peptides were separatedusing a Sephadex G-10 chromatographic column(Amersham Pharmacia Biotech, Uppsala, Sweden) afterultrafiltration using a 1-kDa molecular mass cutoffmembrane. Via ultra-performance liquid chromatography-electrospray ionization-tandem mass spectrometry,we determined that peptides Thr-Asp-Val-Glu-Asn[TDVEN; β-casein f(143–147)], Leu-Gln-Pro-Glu[LQPE; β-casein f(103–106)], Val-Ala-Pro-Phe-Pro-Glu[VAPFPE; αS1-casein f(40–45)], and Val-Leu-Pro-Val-Pro-Gln [VLPVPQ β-casein f(185–190)] reduced micellarcholesterol solubility. After Caco-2 cells were treatedwith LQPE, VLPVPQ, and VAPFPE, the Niemann-Pick C1-Like 1 (NPC1L1) protein levels decreased by(means ± SEM) 19.33 ± 2.47%, 52.1 ± 3.77%, and23.09 ± 8.52%, respectively, compared with the controlgroup. Treatment with each peptide induced significantupregulation of ATP binding cassette subfamilyG member 8 antibody (ABCG8) mRNA expression by398.1 ± 23.27%, 86.4 ± 27.07%, and 92.8 ± 8.49%. Wefound that VLPVPQ and LQPE significantly upregulatedATP-binding cassette transporter A1 (ABCA1)transcription by 203.9 ± 8.44% and 220.8 ± 36.42%respectively, whereas VLPVPQ significantly decreasedmRNA expression of acetyl-CoA-acetyltransferase 2(ACAT2) and microsomal triacylglycerols (MTP). Thecholesterol-lowering action of milk-derived peptidesmay be induced by suppression of micellar cholesterolsolubility and affects the expression of cholesterol absorption–related proteins and enzymes in intestinal epithelialcells. This research discovers new milk-derivedpeptides with decreasing cholesterol micellar solubilityand provides a theoretical basis of in vitro cholesterolloweringeffects of peptides.