Antioxidant Activity of Selenium‐Enriched Peptides from the Protein Hydrolysate of Cardamine violifolia
2019
Zhu, Song | Du, Chaodong | Yu, Tian | Cong, Xin | Liu, Yuanfa | Chen, Shangwei | Li, Yue
Cardamine violifolia is a selenium (Se)‐enriched plant found in China. In this study, the Se‐enriched peptides of C. violifolia (CP) were isolated using a 1 kDa ultrafiltration membrane after enzymatic hydrolysis by alkaline and neutral proteases. The peptides were separated by DEAE‐Sepharose FF anion‐exchange chromatography and purified using preparative high‐performance liquid chromatography (prep‐HPLC). The component with the highest antioxidant activity, CPR13, was identified by comparing the 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH•), hydroxyl (•OH), 2,2′‐azino‐bis (3‐ethylbenzothiazoline‐6‐sulfonic acid) (ABTS⁺•), and superoxide (O2−·) radical scavenging ability of each fraction. At a concentration of 0.1 mg/mL, the DPPH•, •OH, O2−·, and ABTS⁺• scavenging activities of CPR13 were 89.2%, 26.3%, 40.6%, and 42.9%, respectively. Amino acid sequences were obtained by liquid chromatography combined with mass spectrometry as follows: GRVGSSSC, GRAGGSYM, GHPNFKLNCSGG, GTKSCKA, ASSNARDMI, TAGGCYIPI, and KNCALQ. The seleno‐amino acids were identified as selenomethionine, methylselenocysteine, and selenocysteine. Correlation analysis among organic Se content, peptide content, and antioxidant activity revealed that organic Se plays a greater role in free radical scavenging than peptides, and that the organic Se content of the Se‐enriched peptides was positively correlated with their antioxidant ability (P < 0.05). It indicated that CP has a great potential as natural functional materials for dietary supplement.
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