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

Abstract

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 Fe²⁺ 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 Fe²⁺ 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.