Role of the Maillard reaction products of oyster peptides and chitosan oligosaccharide in chelation with zinc: restoring testicular injury and the testosterone synthesis pathway

Abstract

In this study, an oyster peptide–chitosan oligosaccharide complex (MOC) was prepared via the Maillard reaction (1.2 : 1, 90 °C, 5 h), followed by zinc chelation (30 °C, 30 min) to form MOCZn, achieving 84.5% zinc-binding capacity. Characterization revealed that MOCZn had a compact secondary structure, increased particle size (1338–1971 nm), improved thermal stability, and attenuated zinc crystal peaks. In vitro digestion showed high stability (soluble zinc: 2.17 mg L⁻¹). In zinc-deficient mice, MOCZn increased body weight, restored organ indices, and elevated serum zinc. A medium dose normalized oxidative stress markers (AKP: 0.16 King units per gprot; CAT: 1.79 U per mgprot; GSH: 43.07 μmol L⁻¹; MDA: 0.72 nmol per mgprot; NO: 9.12 μmol L⁻¹; SOD: 105.60 U per mgprot) and reduced inflammatory gene expression (IL-1β, IL-6, TNF-α). MOCZn also reversed zinc deficiency-induced dysregulation of testosterone synthesis genes (downregulated P450SCC, StARD7, HSD17B3; upregulated StAR), mitigating testicular damage (testosterone levels).