Physico‐chemical properties, antioxidant activity, and ACE inhibitory activity of protein hydrolysates from wild jujube seed

• Published in: Journal of food science Vol. 87; no. 6; pp. 2484 - 2503
• Main Authors: Han, Rongxin, Shao, Shuai, Zhang, Hongyin, Qi, Hongyu, Xiao, Fengqin, Shen, Yingxin, Fan, Lin, Wang, Haidong, Zhao, Daqing, Li, Guangzhe, Yan, Mingming
• Format: Journal Article
• Language: English
• Published: United States Wiley Subscription Services, Inc 01.06.2022; John Wiley and Sons Inc
• Subjects: ACE inhibitory activity; Angiotensin; antioxidant activity; Antioxidants; Bioavailability; Chemical activity; Chemical properties; Circular dichroism; Coils; Dichroism; Electrophoresis; Food; Food Chemistry; Fourier transforms; Free radicals; Functional foods & nutraceuticals; Glutathione; Glutathione peroxidase; HepG2 cells; Hydrolysates; Hydroxyl radicals; Immunomodulation; Inflammation; Infrared spectroscopy; Molecular structure; Molecular weight; Molecular weight distribution; Peptides; Peptidyl-dipeptidase A; Peroxidase; physico‐chemical properties; Protein structure; Proteins; Random coil; Reactive oxygen species; Scavenging; Secondary structure; Spectrum analysis; Superoxide dismutase; wild jujube seed protein; Ziziphus jujuba; wild jujube seed protein; HepG2 cells; hydrolysates; ACE inhibitory activity; physico-chemical properties; antioxidant activity
• ISSN: 0022-1147; 1750-3841
• DOI: 10.1111/1750-3841.16157

Wild jujube seed protein (WJSP) as one kind of functional food material has attracted much attention due to its highly nutritive and medicinal value in anti‐inflammatory and improving immunomodulatory ability. However, owing to its large molecular weight and complex structure, biological activities of WJSP were greatly limited and cannot be fully utilized by the human body. Therefore, how to improve the bioavailability of WJSP and develop promising WJSP nutritious materials is a great challenge. In this work, wild jujube seed protein hydrolysates (WJSPHs) were prepared from WJSP via enzymatic hydrolysis method, and their physico‐chemical properties, antioxidant activity, and angiotensin converting enzyme (ACE) inhibitory activity in vitro have been investigated for the first time. SDS–PAGE electrophoresis and size–exclusion chromatographic results indicate that WJSPHs have lower molecular weight distribution (< 5,000 Da) than WJSP. Circular dichroism (CD) spectroscopy and Fourier transform infrared spectroscopy (FTIR) results illustrated that random coil is the main secondary structure of WJSPHs. Antioxidant experiments indicate that WJSPHs exhibit high radicals‐scavenging ability of 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radicals (94.60%), 2,2′‐azinobis‐(3‐ethylbenzthiazoline‐6‐sulfonate) (ABTS+) radicals (90.84%), superoxide radicals (44.77%), and hydroxyl radicals (47.77%). In vitro, WJSPHs can significantly decrease the accumulation of reactive oxygen species (ROS) and malondialdehyde (MDA), and increase the activity of superoxide dismutase (SOD) and glutathione peroxidase (GSH‐Px) in HepG2 cells. Moreover, ACE activity was found that can be significantly inhibited by WJSPHs (73.02%). Therefore, all previously mentioned results suggest that WJSPHs may be a promising antioxidant food to prevent oxidative‐related diseases in future. Practical Application This study shows that WJSPHs exhibit high antioxidant activity and ACE inhibitory activity in vitro, which provide potential application value as antioxidant peptides to prevent oxidative‐related diseases.