Structural modification of lactoferrin by epigallocatechin gallate: elucidation of its structure and exploration of its potential in promoting osteoblast proliferation.

Lactoferrin (LF) and epigallocatechin gallate (EGCG) are recognized for their potent osteogenic properties. However, the osteogenic activity of LF-EGCG complexes is not fully understood. In this study, both non-covalent and covalent LF-EGCG complexes with different LF : EGCG ratios were prepared, and their effects on the LF structure and thermal stability were investigated using circular dichroism, Fourier transform infrared spectroscopy, fluorescence spectroscopy, Raman spectroscopy, and differential scanning calorimetry. The results indicated that covalent binding had a more pronounced effect on protein structure modification. The covalent complex with an LF : EGCG ratio of 5 : 1 demonstrated maximum hydrophilicity; the particle size reduced to 19.31 nm; and the denaturation temperature increased to 56.96 °C. This complex at a 100 μg mL concentration significantly enhanced osteoblast proliferation, increasing the rate to 1.34-fold. The proliferation rate of osteoblasts was significantly correlated with the tyrosine residue microenvironment and hydrophobicity of the complexes. This study provides valuable insights and strategies for enhancing the nutritional efficacy of LF.