Extraction, identification and anti-photoaging activity evaluation of collagen peptides from silver carp (Hypophthalmichthys molitrix) skin

Biologically active peptides are particularly important for anti-photoaging studies. In this study, silver carp (Hypophthalmichthys molitrix) skin collagen polypeptide (SCSCP) with collagenase inhibition activity was obtained by optimizing the enzymatic hydrolysis process. Fourier-transform infrared spectroscopy, matrix-assisted laser desorption ionization time-of-flight mass spectrometry, and liquid-liquid mass spectrometry were used to analyze the secondary structure, molecular weight distribution and characteristics of peptides, respectively. The effects of SCSCP on the proliferation of mouse fibroblasts (L929) and secretion of matrix metalloproteinase-1 (MMP-1) after UVB irradiation were also detected. Process-optimized SCSCP inhibited collagenase activity up to 54.47%. In SCSCP, α-helical and β-folded structures accounted for 17.70% and 22.65%, respectively. The relative molecular weights of SCSCP were more widely distributed below 1600 Da, with higher response values at 665.93 and 980.95 Da. The molecular weights of the characteristic peptides were 358.68–863.89 Da, and the peptide sequences with anti-photoaging activity were GPPGPPGTPGPQ, SGLPGPIGPPGPR, and GLPGPIGPPGPR. SCSCP at 10 mg/mL concentration had high DPPH and hydroxyl radical scavenging activity, while 0.1 mg/mL SCSCP significantly restored UVB-induced L929 cell viability and inhibited MMP-1 secretion in L929 cells after UVB irradiation. These results indicate that SCSCP achieves anti-photoaging effects by scavenging DPPH and hydroxyl radicals and inhibiting MMP-1 secretion.