Isolation, Purification, Identification and Activity of Antioxidant Peptides from Tea Residue

To achieve high value-added utilization of tea residue, we carried out an in-depth study on the activity and mechanism of action of tea residue proteins and peptides derived from their enzymatic hydrolysis using a protease mixture. Antioxidant activity-guided fractionation of the hydrolysate was performed, and the structure of the purified peptides was identified using liquid chromatography-mass spectrometry (LC-MS). Molecular docking was utilized for simulated analysis of the matched peptides to select peptides with high antioxidant activity. The synthesized peptides were used for in vitro activity validation. The results showed that the purity of the purified antioxidant peptide was (90.06 ± 0.23)%. Totally 25 matched peptides were identified from fraction I, which exhibited high antioxidant activity. Two potent antioxidant peptides, CsTP4 SFDPLG and CsTP10 PLYPGG, were selected from the 25 peptides. The molecular docking results showed that the peptides bound to their target proteins with antioxidant activity mainly through hydrogen bonds and hydrophobic interactions, with binding energy of −3.92 and −7.12 kcal/mol for CsTP4 SFDPLG and CsTP10 PLYPGG, respectively. The synthesized peptides were confirmed to have high in vitro antioxidant activity. This study contributes to understanding the mechanism underlying the interaction between active peptides from tea residues and their target proteins, which will promote the development and utilization of these active peptides in the pharmaceutical and health food fields.