Three Newly Isolated Calcium-Chelating Peptides from Tilapia Bone Collagen Hydrolysate Enhance Calcium Absorption Activity in Intestinal Caco-2 Cells

In this study, we used reversed-phase high performance liquid chromatography (LC) to isolate three novel peptides with calcium-chelating capacity from tilapia bone collagen hydrolysate. Using LC-tandem mass spectrometry, we determined the amino acid sequences to be GPAGPHGPVG, FDHIVY, and YQEPVIAPKL. We then synthesized the three peptides and verified their calcium-chelating activity. Results showed that the calcium-chelating activity of GPAGPHGPVG, FDHIVY, and YQEPVIAPKL reached 18.80 ± 0.49, 35.73 ± 0.74, and 28.4 ± 0.94 mg/g, respectively. We next investigated how each peptide enhanced intestinal calcium absorption using Caco-2 cell monolayers. Compared with the control group, GPAGPHGPVG, FDHIVY, and YQEPVIAPKL potently enhanced calcium transport within 30 min by 89 ± 9, 202 ± 12, and 130 ± 7%, respectively. Results suggest that these peptides isolated from tilapia bone hydrolysate can be used as dietary supplements to increase calcium absorption.