Preparation, Identification, and Digestive Stability of Antioxidant Peptides From Chlorella vulgaris

Chlorella , a single-celled green algae rich in proteins, holds promise as a source of bioactive peptides. This research aimed to isolate an antioxidant peptide from Chlorella , examining its stability through digestion. Using Response Surface Methodology (RSM), we identified optimal hydrolysis conditions for Chlorella Protein Hydrolysate (CPH): 55°C, pH 8.75, and an enzyme-to-substrate ratio of 2.15%. These conditions led to CPH with notable radical scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) (53.19 ± 0.99%), 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) (76.86 ± 0.28%), hydroxyl radical (53.39 ± 1.74%), and Fe 2+ chelating rates of 22.56 ± 2.97%. Subsequently, peptides under 3 kDa isolated by ultrafication proved particularly stable and antioxidative after in vitro digestion. In addition, further purify to obtain component C1 with DPPH radical scavenging ability of 59.62 ± 1.29% and an Fe 2+ chelating ability of 49.78 ± 1.55%. Subsequent LC-MS/MS identification and virtual screening led to the discovery of a stable and antioxidative peptide, Ser-Gly-His-His-Lys-Pro-Leu (SGHHKPL). The study provides the theoretical basis for the development and utilization of chlorella .