Anti-oxidative capacity of enzymatically released peptides from soybean protein isolate

Hydrophobicity of whey protein hydrolysates enhances the protective effect against oxidative damage on PC 12 cells

The relationship between hydrophobicity and the protective effect of whey protein hydrolysates (WPHs) against oxidative stress was studied. Whey protein was first hydrolysed by pepsin and trypsin to obtain WPHs. After absorbed by macroporous adsorption resin DA201-C, three fractions named as M20, M40, and M60 were eluted by various concentrations of ethanol. The hydrophobicity showed a trend of increase from M20 to M60. Antioxidant ability test in vitro indicated that all the three components of WPHs displayed reasonably good antioxidant ability. Moreover, with the increase of hydrophobicity, antioxidant ability of WPHs improved significantly. Then rat pheochromocytoma line 12 (PC12) cells oxidative model was built to evaluate the suppression of oxidative stress of three components on PC12 cells induced by H2O2. Morphological alterations, cell viability, apoptosis rate, and intracellular antioxidase system tests all indicated that WPHs exert significant protection on PC cells against H2O2-induced damage. Among them, M60 had the highest protective effect by increasing 19·3% cell survival and reducing 28·6% cell apoptosis. These results suggested hydrophobicity of WPHs was contributing to the antioxidant ability and the protective effect against oxidative damage.

Use of phytochemomics to evaluate the bioavailability and bioactivity of antioxidant peptides of soybean β-conglycinin

This research investigates how in vitro digestion contributes to the release of antioxidant peptides crypted in soybean β-conglycinin (7S) and its deglycosylated form (D7S). It also investigates the uptake of the bioactive peptides by human intestinal Caco-2 cells using a bicameral system, and their effect on the antioxidant cell defense. Phytochemomics is used as a tool for achieving this goal. The peptides are obtained by mimicking human physiological gastrointestinal digestion conditions. The antioxidant capacity of the peptides is tested by ABTS•(+) radical cation decolorization (2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS)) and oxygen radical absorbance capacity assays. The antioxidant power of the peptides recovered from the basolateral chamber is also evaluated by an analysis of biomarkers of cellular oxidative stress such as cell proliferation, alkaline phosphatase, and secretion of nitric oxide, lipid peroxidation, superoxide dismutase and catalase. Peptides from D7S were more active than those of 7S in the modulation of the cell proliferation, oxidative status and differentiation of Caco-2 cells treated with H2 O2 . Differences in the bioactivity of the peptides of both proteins can be explained by analysis of the structural data obtained by mass spectrophotometry. Our findings support the bioavailability of antioxidant peptides of 7S. The antioxidant properties of 7S soy protein were influenced by events such as glycosylation, digestion, and absorption. Deglycosylation seems to be an innovative strategy for improving the properties of 7S. Deglycosylation might enhance 7S antioxidant power and reduce its immunoreactivity. The combined use of advanced analytical techniques and biochemical analyses (phytochemomics) has been a key part of this study.

Functional significance of bioactive peptides derived from soybean

Biologically active peptides play an important role in metabolic regulation and modulation. Several studies have shown that during gastrointestinal digestion, food processing and microbial proteolysis of various animals and plant proteins, small peptides can be released which possess biofunctional properties. These peptides are to prove potential health-enhancing nutraceutical for food and pharmaceutical applications. The beneficial health effects of bioactive peptides may be several like antihypertensive, antioxidative, antiobesity, immunomodulatory, antidiabetic, hypocholesterolemic and anticancer. Soybeans, one of the most abundant plant sources of dietary protein, contain 36-56% of protein. Recent studies showed that soy milk, an aqueous extract of soybean, and its fermented product have great biological properties and are a good source of bioactive peptides. This review focuses on bioactive peptides derived from soybean; we illustrate their production and biofunctional attributes.

Partial characterization of ultrafiltrated soy protein hydrolysates with antioxidant and free radical scavenging activities

Soy protein isolate (SPI) was hydrolyzed with Flavourzyme® (SHF) or chymotrypsin (SHC). Hydrolysates were sequencially fractionated by ultrafiltration using different membrane pore sizes (50, 10, and 3 kDa). The antioxidant ability of each hydrolysate protein fraction was tested in a liposome oxidizing system and their free radical scavenging activity (FRSA) was evaluated with the DPPH method (diphenylpicrilhydrazine radical). Molecular weight (MW) distribution, solubility, surface hydrophobicity, and amino acid composition of each SPI hydrolysate fraction were measured and their effect on antioxidant and scavenging activities was established by multivariate correlation. The most active ultrafiltrated peptide fractions (P < 0.05), from SHF and SHC, had of MW of <3 kDa (F3 and C3, respectively). These fractions decreased liposome oxidation by 83.2% and 84.5%, respectively, and also showed the highest FRSA (F3: 21.3% and C3: 24.4%). In addition to molecular size, the antioxidant activity and FRSA of soy protein fractions were related to their amino acid composition, especially to an increased content of Phe and a lowered content of Lys. Also, hydrophobicity of ultrafiltrated peptide fractions was an important characteristic (P < 0.001) associated with their ability to trap free radicals. Ultrafiltered peptide fractions with low MW have a high potential to be used as natural alternatives to prevent lipid oxidation in foods.

Free radical scavenging activity of peptide fractions from defatted soybean meal hydrolysates evaluated by electron spin resonance

Defatted soybean meal, a by-product of soybean oil extraction, was pretreated by ultrasonic and hydrolyzed with neutrase. The DSMH pretreated at 400 W of ultrasonic power, identified to possess the strongest antioxidant activity, was fractionated according to molecular weight into three fractions of DSMH-I (>10 kDa), DSMH-II (5-10 kDa), and DSMH-III (<5 kDa) using ultrafiltration. The fraction, DSMH-III (<5 kDa), exhibited the highest antioxidative activity and was further purified using ion-exchange chromatography. The DSMH-III was separated into five fractions (A, B, C, D, and E). Fraction C with molecular weight of 2434 Da exhibited the strongest free radical scavenging, which was evidenced by the electron spin resonance of 1,1-diphenyl-2-pycryl hydrazyl and hydroxyl radicals. Fraction C was subjected to reverse-phase high performance liquid chromatography and the sequences of the highest activity peptide were determined by liquid chromatography tandem mass spectrometry. The strongest antioxidant activity peptide had the amino acid sequence of Glu-Glu-Gln-Glu-Trp-Pro-Arg-Lys-Glu-Glu-Lys. In conclusion, ultrasonic treatment and ultrafiltration could enhanced antioxidant activity of DSMH.

Biomarker discovery and applications for foods and beverages: proteomics to nanoproteomics

Foods and beverages have been at the heart of our society for centuries, sustaining humankind - health, life, and the pleasures that go with it. The more we grow and develop as a civilization, the more we feel the need to know about the food we eat and beverages we drink. Moreover, with an ever increasing demand for food due to the growing human population food security remains a major concern. Food safety is another growing concern as the consumers prefer varied foods and beverages that are not only traded nationally but also globally. The 21st century science and technology is at a new high, especially in the field of biological sciences. The availability of genome sequences and associated high-throughput sensitive technologies means that foods are being analyzed at various levels. For example and in particular, high-throughput omics approaches are being applied to develop suitable biomarkers for foods and beverages and their applications in addressing quality, technology, authenticity, and safety issues. Proteomics are one of those technologies that are increasingly being utilized to profile expressed proteins in different foods and beverages. Acquired knowledge and protein information have now been translated to address safety of foods and beverages. Very recently, the power of proteomic technology has been integrated with another highly sensitive and miniaturized technology called nanotechnology, yielding a new term nanoproteomics. Nanoproteomics offer a real-time multiplexed analysis performed in a miniaturized assay, with low-sample consumption and high sensitivity. To name a few, nanomaterials - quantum dots, gold nanoparticles, carbon nanotubes, and nanowires - have demonstrated potential to overcome the challenges of sensitivity faced by proteomics for biomarker detection, discovery, and application. In this review, we will discuss the importance of biomarker discovery and applications for foods and beverages, the contribution of proteomic technology in this process, and a shift towards nanoproteomics to suitably address associated issues. This article is part of a Special Issue entitled: Translational plant proteomics.

Proteomics in nutrition: status quo and outlook for biomarkers and bioactives

Food and beverages are the only physical matter we take into our body, if we disregard the air we inhale and the drugs we may have to apply. While traditional nutrition research has aimed at providing nutrients to nourish populations and preventing specific nutrient deficiencies, it more recently explores health-related aspects of individual bioactive components as well as entire diets and this at group rather than population level. The new era of nutrition research translates empirical knowledge to evidence-based molecular science. Modern nutrition research focuses on promoting health, preventing or delaying the onset of disease, optimizing performance, and assessing risk. Personalized nutrition is a conceptual analogue to personalized medicine and means adapting food to individual needs. Nutrigenomics and nutrigenetics build the science foundation for understanding human variability in preferences, requirements, and responses to diet and may become the future tools for consumer assessment motivated by personalized nutritional counseling for health maintenance and disease prevention. The scope of this paper is to review the current and future aspects of nutritional proteomics, focusing on the two main outputs: identification of health biomarkers and analysis of food bioactives.

Antioxidant capacity of alcalase hydrolysates and protein profiles of two conventional and seven low glycinin soybean cultivars

Soy protein hydrolysates are considered a potential dietary source of natural antioxidants with important biological activities. This study was conducted to compare the effect of two conventional and seven low glycinin soybean cultivars on the antioxidant capacity (AC) of soy hydrolysates. Nine cultivars were grown in Bloomington, IL, Findlay, OH and Huxley, IA. The hydrolysates were produced enzymatically using alcalase and analyzed for AC using oxygen radical absorbance capacity (ORAC) assay and soluble protein. Statistical differences were observed in the protein profiles and AC among the different cultivars tested (P < 0.05). The hydrolysate from low glycinin cultivar 3 enriched in β-conglycinin, grown in Bloomington, exhibited the highest AC, compared to the other cultivars across all locations. On average, soy cultivars rich in BC and purified BC hydrolysates (36.2 and 31.8 μM Trolox equivalents (TE)/μg soluble protein, respectively) (P > 0.05) had higher AC than purified glycinin (GL) hydrolysate (28.5 μM TE/μg soluble protein) (P < 0.05). It was possible to select a soybean cultivar that produced a higher antioxidant capacity upon alcalase hydrolysis.