In this study, the effect of limited hydrolysis of soy I2-conglycinin (7S) on the oxidative stability of 7S hydrolysate (7SH)-stabilized emulsions was investigated under different conditions of pH, ...ionic strength, degrees of hydrolysis (DH), and protein concentration in the continuous phase. The hydrolysis was performed using trypsinization and acid hydrolysis. Interfacial protein conformations were studied by thioflavin T fluorescence, scanning and transmission electron microscopy techniques, and Raman spectroscopy at oil-mimicking, functionalized silver surfaces. The antioxidant property was tested by the Trolox equivalent antioxidant capacity (TEAC) assay. At DH 0.7%, trypsinization improved emulsion oxidative stability at pH 7 under low ionic strength, as a result of an increase in protein antioxidant property and enhanced interfacial barrier property due to substantial increment of intermolecular I2-sheets. The loose coil/helix to intermolecular I2-sheet transition was deemed essential in the building of an effective interfacial barrier. At pH 3, however, the tryptic 7SH turned pro-oxidant, and interfacial coverage by the protein became uneven. As such, the emulsion oxidative stability was not better than that based on the native 7S at pH 7. The modification of the surface charge of the oil from non-polar to anionic led to increased formation of intermolecular I2-sheet, but it did not improve the emulsion oxidative stability. Lastly, acid hydrolysis of 7S at a similar DH led to flocculation-induced destabilization of the emulsion at pH 3, which exacerbated the intrinsic oxidation of the encapsulated oil even further. Depletion flocculation and bridging were a result of fibril formation during acid hydrolysis.
Inflammation is a natural protective mechanism that occurs when the body's tissue homeostatic mechanisms are disrupted by biotic, physical, or chemical agents. The immune response generates ...pro-inflammatory mediators, but excessive output, such as chronic inflammation, contributes to many persistent diseases. Some phenolic compounds work in tandem with nonsteroidal anti-inflammatory drugs (NSAIDs) to inhibit pro-inflammatory mediators' activity or gene expression, including cyclooxygenase (COX). Various phenolic compounds can also act on transcription factors, such as nuclear factor-κB (NF-κB) or nuclear factor-erythroid factor 2-related factor 2 (Nrf-2), to up-or downregulate elements within the antioxidant response pathways. Phenolic compounds can inhibit enzymes associated with the development of human diseases and have been used to treat various common human ailments, including hypertension, metabolic problems, incendiary infections, and neurodegenerative diseases. The inhibition of the angiotensin-converting enzyme (ACE) by phenolic compounds has been used to treat hypertension. The inhibition of carbohydrate hydrolyzing enzyme represents a type 2 diabetes mellitus therapy, and cholinesterase inhibition has been applied to treat Alzheimer's disease (AD). Phenolic compounds have also demonstrated anti-inflammatory properties to treat skin diseases, rheumatoid arthritis, and inflammatory bowel disease. Plant extracts and phenolic compounds exert protective effects against oxidative stress and inflammation caused by airborne particulate matter, in addition to a range of anti-inflammatory, anticancer, anti-aging, antibacterial, and antiviral activities. Dietary polyphenols have been used to prevent and treat allergy-related diseases. The chemical and biological contributions of phenolic compounds to cardiovascular disease have also been described. This review summarizes the recent progress delineating the multifunctional roles of phenolic compounds, including their anti-inflammatory properties and the molecular pathways through which they exert anti-inflammatory effects on metabolic disorders. This study also discusses current issues and potential prospects for the therapeutic application of phenolic compounds to various human diseases.
A complex antioxidant system has been developed in mammals to relieve oxidative stress. However, excessive reactive species derived from oxygen and nitrogen may still lead to oxidative damage to ...tissue and organs. Oxidative stress has been considered as a conjoint pathological mechanism, and it contributes to initiation and progression of liver injury. A lot of risk factors, including alcohol, drugs, environmental pollutants and irradiation, may induce oxidative stress in liver, which in turn results in severe liver diseases, such as alcoholic liver disease and non-alcoholic steatohepatitis. Application of antioxidants signifies a rational curative strategy to prevent and cure liver diseases involving oxidative stress. Although conclusions drawn from clinical studies remain uncertain, animal studies have revealed the promising in vivo therapeutic effect of antioxidants on liver diseases. Natural antioxidants contained in edible or medicinal plants often possess strong antioxidant and free radical scavenging abilities as well as anti-inflammatory action, which are also supposed to be the basis of other bioactivities and health benefits. In this review, PubMed was extensively searched for literature research. The keywords for searching oxidative stress were free radicals, reactive oxygen, nitrogen species, anti-oxidative therapy, Chinese medicines, natural products, antioxidants and liver diseases. The literature, including ours, with studies on oxidative stress and anti-oxidative therapy in liver diseases were the focus. Various factors that cause oxidative stress in liver and effects of antioxidants in the prevention and treatment of liver diseases were summarized, questioned, and discussed.
Spirulina is a species of filamentous cyanobacteria that has long been used as a food supplement. In particular,
Spirulina platensis
and
Spirulina maxima
are the most important. Thanks to a high ...protein and vitamin content, Spirulina is used as a nutraceutical food supplement, although its other potential health benefits have attracted much attention. Oxidative stress and dysfunctional immunity cause many diseases in humans, including atherosclerosis, cardiac hypertrophy, heart failure, and hypertension. Thus, the antioxidant, immunomodulatory, and anti-inflammatory activities of these microalgae may play an important role in human health. Here, we discuss the antioxidant, immunomodulatory, and anti-inflammatory activities of Spirulina in both animals and humans, along with the underlying mechanisms. In addition, its commercial and regulatory status in different countries is discussed as well. Spirulina activates cellular antioxidant enzymes, inhibits lipid peroxidation and DNA damage, scavenges free radicals, and increases the activity of superoxide dismutase and catalase. Notably, there appears to be a threshold level above which Spirulina will taper off the antioxidant activity. Clinical trials show that Spirulina prevents skeletal muscle damage under conditions of exercise-induced oxidative stress and can stimulate the production of antibodies and up- or downregulate the expression of cytokine-encoding genes to induce immunomodulatory and anti-inflammatory responses. The molecular mechanism(s) by which Spirulina induces these activities is unclear, but phycocyanin and β-carotene are important molecules. Moreover, Spirulina effectively regulates the ERK1/2, JNK, p38, and IκB pathways. This review provides new insight into the potential therapeutic applications of Spirulina and may provide new ideas for future studies.
Ultraviolet-B (UV-B) radiation has long been perceived as a stressor. However, a conceptual U-turn has taken place, and UV-B damage is now considered rare. We question whether UV-stress and ...UV-B-induced reactive oxygen species (ROS) are still relevant concepts, and if ROS-mediated signaling contributes to UV-B acclimation. Measurements of antioxidants and of antioxidant genes show that both low and high UV-B doses alter ROS metabolism. Yet, there is no evidence that ROS control gene expression under low UV-B. Instead, expression of antioxidant genes is linked to the UV RESISTANCE LOCUS 8 pathway. We hypothesize that low UV-B doses cause ‘eustress’ (good stress) and that stimuli-specific signaling pathways pre-dispose plants to a state of low alert that includes activation of antioxidant defenses.
Flavonoids are plant phenolic secondary metabolites that are widely distributed in the human diet. These antioxidants have received much attention because of their neuroprotective, cardioprotective, ...and chemopreventive actions. While a major focus has been on the flavonoidsa antioxidant properties, there is an emerging view that many of the potential health benefits of flavonoids and their in vivo metabolites are due to modulatory actions in cells through direct interactions with proteins, and not necessarily due to their antioxidant function. This view relies on the observations that flavonoids are present in the circulation at very low concentrations, which are not sufficient to exert effective antioxidant effects. The enzyme paraoxonase 1 (PON1) is associated with high-density lipoprotein (HDL), and is responsible for many of HDLsa antiatherogenic properties. We previously showed that the flavonoid glabridin binds to rePON1 and affects the enzymeas 3D structure. This interaction protects the enzyme from inhibition by an atherogenic component of the human carotid plaque. Here, we broadened our study to an investigation of the structure-activity relationships (SARs) of 12 flavonoids from different subclasses with rePON1 using Trp-fluorescence quenching, modeling calculations and Cu2+-induced low-density lipoprotein (LDL) oxidation methods. Our findings emphasize the aprotein-bindinga mechanism by which flavonoids exert their beneficial biological role toward rePON1. Flavonoidsa capacity to interact with the enzymeas rePON1 hydrophobic groove mostly dictates their pro/antioxidant behavior.
Phenolic compounds play an important role in health benefits because of their highly antioxidant capacity. In this review, total phenolic contents (TPCs), phenolic acid profile and antioxidant ...capacity of the extracted from wheat, corn, rice, barley, sorghum, rye, oat, and millet, which have been recently reported, are summarized. The review shows clearly that cereals contain a number of phytochemicals including phenolics, flavonoids, anthocyanins, etc. The phytochemicals of cereals significantly exhibit antioxidant activity as measured by trolox equivalent antioxidant capacity (TEAC), 2,2-diphenyl-1-picrylhydrazyl radical scavenging, reducing power, oxygen radical absorbance capacity (ORAC), inhibition of oxidation of human low-density lipoprotein (LDL) cholesterol and DNA, Rancimat, inhibition of photochemilumenescence (PCL), and iron(II) chelation activity. Thus, the consumption of whole grains is considered to have significantly health benefits in prevention from chronic diseases such as cardiovascular disease, diabetes, and cancer because of the contribution of phenolic compounds existed. In addition, the extracts from cereal brans are considered to be used as a source of natural antioxidants.
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