Preparation, identification, and activity evaluation of antioxidant peptides from protein hydrolysate of corn germ meal

Plant Protein-Derived Active Peptides: A Comprehensive Review

Active peptides are a class of physiologically active protein fragments, which can be prepared from different sources. In the past few decades, the production of peptides with various effects from different plant proteins continues to receive academic attention. With advances in extraction, purification, and characterization techniques, plant protein-derived active peptides continue to be discovered. They have been proven to have various functional activities such as antioxidant, antihypertensive, immunomodulatory, antimicrobial, anti-inflammatory, antidiabetic, antithrombotic, and so on. In this review, we searched Web of Science and China National Knowledge Infrastructure for relevant articles published in recent years. There are 184 articles included in this manuscript. The current status of plant protein-derived active peptides is systematically introduced, including their sources, preparation, purification and identification methods, physiological activities, and applications in the food industry. Special emphasis has been placed on the problems of active peptide exploration and the future trend. Based on these, it is expected to provide theoretical reference for the further exploitation of plant protein-derived active peptides, and promote the healthy and rapid development of active peptide industry.

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

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.

Biological Approaches for Extraction of Bioactive Compounds From Agro-industrial By-products: A Review

Bioactive compounds can provide health benefits beyond the nutritional value and are originally present or added to food matrices. However, because they are part of the food matrices, most bioactive compounds remain in agroindustrial by-products. Agro-industrial by-products are generated in large quantities throughout the food production chain and can—when not properly treated—affect the environment, the profit, and the proper and nutritional distribution of food to people. Thus, it is important to adopt processes that increase the use of these agroindustrial by-products, including biological approaches, which can enhance the extraction and obtention of bioactive compounds, which enables their application in food and pharmaceutical industries. Biological processes have several advantages compared to nonbiological processes, including the provision of extracts with high quality and bioactivity, as well as extracts that present low toxicity and environmental impact. Among biological approaches, extraction from enzymes and fermentation stand out as tools for obtaining bioactive compounds from various agro-industrial wastes. In this sense, this article provides an overview of the main bioactive components found in agroindustrial by-products and the biological strategies for their extraction. We also provide information to enhance the use of these bioactive compounds, especially for the food and pharmaceutical industries.

Exploring Molecular Insights of Cereal Peptidic Antioxidants in Metabolic Syndrome Prevention

The prevalence of metabolic syndrome (MetS) is presently an alarming public health problem globally. Oxidative stress has been postulated to be strongly correlated with MetS, such as type 2 diabetes, obesity, hypertension, cardiovascular diseases, and certain cancers. Cereals are important staple foods which account for a huge proportion of the human diet. However, owing to recent growing demand and the search for natural antioxidants for the prevention and management of MetS, cereal peptides have gained increasing attention for developing functional ingredients or foods with substantial antioxidant properties. This review explores the current production techniques for cereal peptidic antioxidants and their potential mechanism of action in the prevention and management of MetS.

Prospects of cereal protein-derived bioactive peptides: Sources, bioactivities diversity, and production

Cereals account for a large proportion of the human diet and are an important source of protein. The preparation of cereal protein peptides is a good way to utilize these proteins. Cereal protein peptides have good application potential as antioxidant, antibacterial, anti-inflammatory and anticancer compounds, in lowering blood pressure, controlling blood sugar, and inhibiting thrombosis. This article reviews the literature on the functional properties, mechanisms of action, and applications of cereal protein peptides in the food industry with two perspectives, and summarizes the methods for their preparation and identification. The biologically active peptides derived from different grain proteins have varied main functional properties, which may be related to the differences in the amino acid composition and protein types of different grains. On this basis, the structure-activity relationship of cereal protein peptides was discussed. The advancement of identification technology makes the integration of bioinformatics and bioactive peptide research closer. Bioinformatics by combination of online database, computer simulation and experimental verification is helpful to in-deep study the structure-activity relationship of biologically active peptides, and improve efficiency in the process of obtaining target peptides with less cost. In addition, the application of cereal protein peptides in the food industry is also discussed.

Extraction of antioxidant peptides from rice dreg protein hydrolysate via an angling method

Selective enrichment of the highly active antioxidant peptides is required as the lack of an efficient method leads to long screening processes, hampering the research of antioxidant peptides. A simple synthetic metal-organic framework MIL-53 (Cr) was initially applied to extract specific antioxidant peptides from rice dreg protein hydrolysate. The highest active fraction was further purified by reversed-phase high-performance liquid chromatography. The antioxidant peptides with the highest antioxidant activities were identified as Gly-Asp-Met-Asn-Pro and Leu-Leu-Leu-Arg-Trp by LC-MS. These two peptides were synthesized and also exhibited good scavenging activity on the DPPH free radical, superoxide anion free radical and hydroxyl radical, and good chelating ability on Fe²⁺. The results confirmed that the angling method was effective for antioxidant peptide enrichment from protein hydrolysates.