Preparation and identification of antioxidant peptides from protein hydrolysate of marine alga Gracilariopsis lemaneiformis

• Published in: Journal of applied phycology Vol. 31; no. 4; pp. 2585 - 2596
• Main Authors: Zhang, Xiaoqian, Cao, Dequn, Sun, Xue, Sun, Siqi, Xu, Nianjun
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.08.2019; Springer Nature B.V
• Subjects: 2,2-diphenyl-1-picrylhydrazyl; algae; Amino acids; antioxidant activity; Antioxidants; Aromatic compounds; Biomedical and Life Sciences; Chromatography; Chymotrypsin; Ecology; Fractionation; Free radicals; Freshwater & Marine Ecology; gel chromatography; Gels; Gracilariopsis lemaneiformis; High performance liquid chromatography; HPLC; Hydrolysates; hydrolysis; Hydrophobicity; Life Sciences; Liquid chromatography; mass spectrometry; median effective concentration; molecular weight; Nucleotide sequence; Papain; Pepsin; Peptides; Plant Physiology; Plant Sciences; protein hydrolysates; Proteins; Reaction time; Response surface methodology; reversed-phase high performance liquid chromatography; Substrates; Subtilisin; temperature; Trypsin; ultra-performance liquid chromatography; Ultrafiltration; Rhodophyta; Antioxidant peptides; DPPH; Optimization
• ISSN: 0921-8971; 1573-5176
• DOI: 10.1007/s10811-019-1746-9

In this experiment, Gracilariopsis lemaneiformis proteins were hydrolyzed by different proteases (trypsin, pepsin, papain, α-chymotrypsin, alcalase) to prepare antioxidant peptides. Comparing with other hydrolysates, α-chymotrypsin hydrolysates displayed the highest antioxidant activity. The hydrolysis conditions of α-chymotrypsin were further optimized using response surface methodology (RSM), and the optimal conditions were as follows: substrate concentration 10 mg/mL, reaction time 2.0 h, enzyme/substrate ratio ( E / S ) 1.9%, temperature 46.4 °C, and pH 9.2. After fractionation and separation by ultrafiltration, gel exclusion chromatography, and reversed-phase high-performance liquid chromatography, an antioxidant peptide was purified and identified as Glu-Leu-Trp-Lys-Thr-Phe by UPLC-MS/MS. The results also confirmed that Glu-Leu-Trp-Lys-Thr-Phe could significantly scavenge DPPH free radicals with an EC 50 value of 1.514 mg mL −1 . It seems that the smaller molecular size and hydrophobic and/or aromatic amino acids in its sequence contributed to its antioxidant activity. Thus, G. lemaneiformis protein hydrolysate may be a good source of natural antioxidants.