Moringa oleifera Lam. Leaf Peptide-Calcium Chelate (KTFQGPPHG-Ca): Screening, In Vitro Digestive Stability, Cellular Transport, and Potential Calcium Absorption Mechanisms

Abstract This study aimed to address the poor bioavailability of traditional calcium supplements by investigating the Moringa oleifera Lam. leaf-derived peptide KTFQGPPHG and its peptide-calcium chelate. Virtual screening predicted potential interactions of KTFQGPPHG with Ca2+ and calcium transport-related proteins, including TRPV6, Cav1.3, and PepT1. During simulated digestion, KTFQGPPHG-Ca showed high intestinal-phase stability, with a calcium retention rate of 94.13 ± 1.47%, while its major digestive fragment, TFQGPPHG, retained substantial calcium-binding activity. In Caco-2 cell monolayers, both KTFQGPPHG-Ca and TFQGPPHG-Ca significantly enhanced calcium transport compared with CaCl2, with Cav1.3 and TRPV6 being major pathways involved in this process. Proteomic analysis suggested that these chelates may regulate calcium absorption-associated epithelial pathways, including “cell adhesion molecules” and “ECM–receptor interaction,” which may contribute to epithelial barrier integrity and cell-matrix signaling associated with Ca2+ transport. In conclusion, KTFQGPPHG-Ca exhibits high gastrointestinal stability and enhances calcium transport through multiple pathways, supporting its potential development as a novel calcium supplement.