Antioxidant properties of chicken feather hydrolysates

The goal of the research was to study the antioxidant properties of peptides obtained during microbiological fermentation of feather waste with keratinolytic strains of Bacillus licheniformis BAL-1 and BAL-2. The methods. The major 17 peptide sequences identified by LC-MS/MS with a relative content of >1% were analyzed in the BIOPEP-UWM database to predict bioactive profiles. The interaction of promising peptides with the Kelch domain of the Keap1 protein (PDB ID: 2FLU) was assessed using molecular docking (HPEPDOCK 2.0) and calculation of the thermodynamic parameters of the complexes (PRODIGY). Experimental assessment of the total antioxidant capacity (TAC) of the hydrolysates was performed using the FRAP, DPPH, and ORAC methods. The results. According to the in silico -analysis, most of the studied peptides contained fragments with the predicted antioxidant activity and formed stable complexes with Keap1. The highest affinity was demonstrated by the GGGDIPRQPLYPPLPPRPG peptide, for which ΔG = -9.8 kcal mol⁻¹ and Kd = 6.6×10⁻⁸ M were calculated; this peptide interacted with the key residues of the binding site (GLU216, ARG146, GLN239), competing with the endogenous ligand Nrf2. In the FRAP and DPPH tests, the activity of the samples was below the detection limit, which was due to the deficiency of reactive amino acids (Cys, Trp) in the peptide fractions. Whereas, according to the ORAC method, the BAL-1 and BAL-2 hydrolysates exceeded the original feather by 25.5 and 31.3 times, reaching values of 812.68±32.62 and 997.46±66.04 μmol-eq. quercetin/L, respectively. Conclusion. The obtained results confirm the potential of fermented chicken feather hydrolysates as a source of bioactive peptides with a dual mechanism of antioxidant action (direct radical scavenging and Nrf2 pathway activation) for the further development of functional feed additives. The practical significance of the research lies in substantiating the possibility of using the obtained hydrolysates as a component of functional feed additives to enhance the resistance of poultry to oxidative stress factors, thereby reducing the dependence of the industry on synthetic antioxidants.

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