Egg Yolk Enzymatic Hydrolysate Enriched with Phospho-Peptides Have the Potential to Lower Bone Turnover

Phosphorylated proteins from food sources have been investigated as regulators of bone formation with potential benefits in subsiding osteoporosis. Eggs are a rich source of proteins and bioactive peptides. Phosvitin is a major protein in Egg yolk and the most phosphorylated protein in nature that has been reported to benefit bone health. This study focused on extracting egg yolk hydrolysates containing phosvitin and phosvitin-derived phospho-peptides, showing osteogenic potential and inhibition of bone degradation. The hydrolysates were prepared following an industry-feasible method, allowing for the optimization of industrial production and scalability. Three egg yolk extracts were prepared with and without enzymes and NaCl. Compared to the other extracts, extract C, which includes hydrolyzed phosvitin and water-soluble egg yolk proteins as confirmed through SDS-PAGE and mass spectrometry, exhibited promising effects on bone health. In vitro experiments using MC3T3 E1 pre-osteoblasts and RANKL-stimulated RAW 264.7 cells showed that extract C has the potential to lower bone turnover. Extract C dose-dependently activated the RUNX2 pathway in pre-osteoblasts and increased the OPG/RANKL ratio and bone mineralization while increasing osteoblast proliferation. Alternatively, it inhibited RANKL-induced osteoclastogenesis in RAW 264.7 cells by significantly attenuating TRAF6, c-Fos, NFATc1, cathepsin K, reduced bone resorption, and induced apoptosis. Further investigations are nearing completion to evaluate the effects of said egg yolk hydrolysate in the ovariectomized rat model of osteoporosis. With additional investigation, egg yolk hydrolysates prepared by the specified method could be used to develop bone health-promoting functional foods.