Identification of procyanidins as α-glucosidase inhibitors, pancreatic lipase inhibitors, and antioxidants from the bark of Cinnamomum cassia by multi-bioactivity-labeled molecular networking

This study examined the suppressive effects of 16 selected plant-based foods on α-glucosidase and pancreatic lipase and their antioxidant properties. Among these, the bark of Cinnamomum cassia (Cinnamon, WLN-FM 15) showed the highest inhibitory activity against α-glucosidase and the highest antioxidant activity. Additionally, WLN-FM 15 showed promising results in the other tests. To further identify the bioactive constituents of WLN-FM 15, a multi-bioactivity-labeled molecular networking approach was used through a combination of GNPS-based molecular networking, DPPH-HPLC, and affinity-based ultrafiltration-HPLC. A total of nine procyanidins were identified as antioxidants and inhibitors of α-glucosidase and pancreatic lipase in WLN-FM 15. Subsequently, procyanidins A1, A2, B1, and C1 were isolated, and their efficacy was confirmed through functional assays. In summary, WLN-FM 15 has the potential to serve as a functional food ingredient with the procyanidins as its bioactive constituents. These results also suggest that the multi-bioactivity-labeled molecular networking approach is reliable for identifying bioactive constituents in plant-based foods.

Identification and molecular mechanisms of novel antioxidant peptides from fermented broad bean paste: A combined in silico and in vitro study

This study aimed to investigate the antioxidative and cytoprotective activity of antioxidant peptides from fermented broad bean paste (FBBP) and explore their potential molecular mechanisms using a combined in silico and in vitro approach. Seven novel antioxidant peptides (VSRRFIYYL, SPAIPLP, PVPPPGG, KKDGYWWAKFK, LAWY, LGFMQF, and LPGCP) identified by integrated approaches of peptidomics and in silico bioinformatic analysis were synthesized, exhibiting strong antioxidant potential against in vitro radicals. Molecular docking results suggested that these peptides could form stable hydrogen bonds and solvent-accessible surface with key amino acid residues of Keap1, thus potentially regulating the Keap1-Nrf2 pathway by occupying the Nrf2-binding site on Keap1. Additionally, they exhibited strong cellular antioxidant activity and could protect HepG2 cells from AAPH-induced oxidative injury by reducing reactive oxygen species and MDA accumulation. This study firstly unraveled the molecular mechanisms of antioxidant peptides from FBBP, and provided a new theoretical basis for the high-value utilization of FBBP.

Environmentally Friendly UV Absorbers: Synthetic Characterization and Biosecurity Studies of the Host-Guest Supramolecular Complex

Isoamyl 4-methoxycinnamate (IMC) is widely used in various fields because of its exceptional UV-filter properties. However, due to its cytotoxicity and anti-microbial degradability, the potential eco-environmental toxicity of IMC has become a focus of attention. In this study, we propose a host-guest supramolecule approach to enhance the functionality of IMC, resulting in a more environmentally friendly and high-performance materials. Sulfobutyl-β-cyclodextrin sodium salt (SBE-β-CD) was used as the host molecule. IMC-SBE-β-CD supramolecular substances were prepared through the "saturated solution method", and their properties and biosecurity were evaluated. Meanwhile, we conducted the AOS tree evaluation system that surpasses existing evaluation approaches based on apoptosis, oxidative stress system, and signaling pathways to investigate the toxicological mechanisms of IMC-SBE-β-CD within human hepatoma SMMC-7721 cells as model organisms. The AOS tree evaluation system aims to offer the comprehensive analysis of the cytotoxic effects of IMC-SBE-β-CD. Our findings showed that IMC-SBE-β-CD had an encapsulation rate of 84.45% and optimal stability at 30 °C. Further, IMC-SBE-β-CD promoted cell growth and reproduction without compromising the integrity of mitochondria and nucleus or disrupting oxidative stress and apoptosis-related pathways. Compared to IMC, IMC-SBE-β-CD is biologically safe and has improved water solubility with the UV absorption property maintained. Our study provides the foundation for the encapsulation of hydrophobic, low-toxicity organic compounds using cyclodextrins and offers valuable insights for future research in this field.

Targeting Nrf2 by bioactive peptides alleviate inflammation: expanding the role of gut microbiota and metabolites

Inflammation is a complex process that usually refers to the general response of the body to the harmful stimuli of various pathogens, tissue damage, or exogenous pollutants. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a transcription factor that regulates cellular defense against oxidative damage and toxicity by expressing genes related to oxidative stress response and drug detoxification. In addition to its antioxidant properties, Nrf2 is involved in many other important physiological processes, including inflammation and metabolism. Nrf2 can bind the promoters of antioxidant genes and upregulates their expressions, which alleviate oxidation-induced inflammation. Nrf2 has been shown to upregulate heme oxygenase-1 expression, which promotes NF-κB activation and is closely related with inflammation. Nrf2, as a key factor in antioxidant response, is closely related to the expressions of pro-inflammatory factors, NF-κB pathway and cell metabolism. Bioactive peptides come from a wide range of sources and have many biological functions. Increasing evidence indicates that bioactive peptides have potential anti-inflammatory activities. This article summarized the sources, absorption and utilization of bioactive peptides and their role in alleviating inflammation via Nrf2 pathway. Bioactive peptides can also regulate gut microbiota and alter metabolites, which regulates the Nrf2 pathway through novel pathway and supplement the anti-inflammatory mechanisms of bioactive peptides. This review provides a reference for further study on the anti-inflammatory effect of bioactive peptides and the development and utilization of functional foods.

Comparison of the effects of chlorogenic acid isomers and their compounds on alleviating oxidative stress injury in broilers

The development of large-scale and intensive breeding models has led to increasingly prominent oxidative stress issues in animal husbandry production. Chlorogenic acid (CGA) is an important extract with a variety of biological activities. It is an effective antioxidant drug and shows different antioxidant capacities due to its different chemical structures. Therefore, it is a new research target to determine the proportion of chlorogenic acid isomers with high antioxidant activity to resist the damage caused by oxidative stress. In this experiment, the antioxidant activities of the chlorogenic acid monomer and its compounds were compared by a series of in vitro antioxidant indexes. Based on the above experiments, it was found that LB and LC have superior antioxidant abilities (P < 0.05). Subsequently, 300 healthy 1-day-old Arbor Acres (AA) male broilers with no significant difference in body weight (about 44 g) were randomly selected and randomly divided into 5 groups with 6 replicates in each group and 10 chickens in each replicate. One group was the control group, 1 group was the model group, and the remaining 3 groups were the experimental groups. At 37 d of age, animals in the control group were injected with normal saline, and animals in the other 4 groups were injected with 1 mL/kg 5% hydrogen peroxide (H2O2) through the chest muscle before the supplementation. The control group (control) and the model group (PC) were fed a standard diet. The remaining 3 groups included the CGA group, LB group (CIB), and LC group (CIC). In these groups, 50 g/t chlorogenic acid, LB compound, or LC compound were added to the basal diet, respectively, and the other feeding conditions remained consistent. The addition of the LB complex to the diet could significantly improve the growth performance and antioxidant performance of broilers (P < 0.05), upregulate the expression of Nuclear factor erythroid 2-related factor 2 (Nrf2) pathway-related genes in liver and jejunum (P < 0.05), regulate the disordered intestinal flora, and alleviate the damage caused by oxidative stress. These results suggested for the first time that the LB complex exhibited superior effects in vitro and vivo.

Novel antioxidant peptides identified from coix seed by molecular docking, quantum chemical calculations and invitro study in HepG2 cells

The aim of the study was to identify potent antioxidant peptides sourced from coix seed, analyze the structure-activity relationship through molecular docking and quantum chemical calculation. Molecular docking results showed that among thirteen peptides selected in silico, eight had favourable binding interaction with the Keap1-Kelch domain (2FLU). Promising peptides with significant binding scores were further evaluated using quantum calculation. It was shown that peptide FFDR exhibited exceptional stability, with a high energy gap of 5.24 eV and low Highest Occupied Molecular Orbitals (HOMO) and Lowest Unoccupied Molecular Orbitals (LUMO) values. Furthermore, FFDR displayed the capacity to enhance the expression of Nrf2-Keap1 antioxidant genes (CAT, SOD, GSH-Px) and improved cellular redox balance by increasing reduced glutathione (GSH) while reducing oxidized glutathione (GSSG) and malonaldehyde (MDA) levels. These findings highlight the potential of coix seed peptides in developing novel, effective and stable antioxidant-based functional foods.

Unlocking the Therapeutic Potential of a Manila Clam-Derived Antioxidant Peptide: Insights into Mechanisms of Action and Cytoprotective Effects against Oxidative Stress

Reactive oxygen species (ROS) are implicated in various pathological conditions due to their ability to induce oxidative damage to cellular components. In this study, we investigated the antioxidant properties of a peptide isolated from the hydrolysate of Manila clam (Ruditapes philippinarum) muscle. Purification steps yielded RPTE2-2-4, exhibiting potent scavenging activities against DPPH•, HO•, and O2•-, akin to Vitamin C. Structural analysis showed that the isolated peptide, LFKKNLLTL, exhibited characteristics associated with antioxidant activity, including a short peptide length and the presence of aromatic and hydrophobic amino acid residues. Moreover, our study demonstrated the cytoprotective effects of the peptide against H2O2-induced oxidative stress in HepG2 cells. Pretreatment with the peptide resulted in a dose-dependent reduction in intracellular ROS levels and elevation of glutathione (GSH) levels, indicating its ability to modulate cellular defense mechanisms against oxidative damage. Furthermore, the peptide stimulated the expression of the cytoprotective enzyme heme oxygenase-1 (HO-1), further reinforcing its antioxidant properties. Overall, our findings highlight the potential of the Manila clam-derived peptide as a natural antioxidant agent with therapeutic implications for oxidative stress-related diseases. Further investigation into its mechanisms of action and in vivo efficacy is warranted to validate its therapeutic potential.

Identification of mulberry leaf flavonoids and evaluating their protective effects on H2O2-induced oxidative damage in equine skeletal muscle satellite cells

Introduction: Horses are susceptible to oxidative stress during strenuous endurance exercise, leading to muscle fatigue and damage. Mulberry leaf flavonoids (MLFs) possess significant antioxidant properties. However, the antioxidant efficacy of MLFs can be influenced by the extraction process, and their impact on H2O2-induced oxidative stress in equine skeletal muscle satellite cells (ESMCs) remains unexplored. Methods: Our study employed three extraction methods to obtain MLFs: ultrasound-assisted extraction (CEP), purification with AB-8 macroporous resin (RP), and n-butanol extraction (NB-EP). We assessed the protective effects of these MLFs on H2O2-induced oxidative stress in ESMCs and analyzed the MLF components using metabolomics. Results: The results revealed that pre-treatment with MLFs dose-dependently protected ESMCs against H2O2-induced oxidative stress. The most effective concentrations were 0.8 mg/mL of CEP, 0.6 mg/mL of RP, and 0.6 mg/mL of NB-EP, significantly enhancing EMSC viability (p < 0.05). These optimized MLF concentrations promoted the GSH-Px, SOD and T-AOC activities (p < 0.05), while reducing MDA production (p < 0.05) in H2O2-induced ESMCs. Furthermore, these MLFs enhanced the gene expression, including Nrf2 and its downstream regulatory genes (TrxR1, GPX1, GPX3, SOD1, and SOD2) (p < 0.05). In terms of mitochondrial function, ESMCs pre-treated with MLFs exhibited higher basal respiration, spare respiratory capacity, maximal respiration, ATP-linked respiration compared to H2O2-induced ESMCs (p < 0.05). Additionally, MLFs enhanced cellular basal glycolysis, glycolytic reserve, and maximal glycolytic capacity (p < 0.05). Metabolomics analysis results revealed significant differences in mulberrin, kaempferol 3-O-glucoside [X-Mal], neohesperidin, dihydrokaempferol, and isobavachalcone among the three extraction processes (p < 0.05). Discussion: Our study revealed that MLFs enhance antioxidant enzyme activity, alleviate oxidative damage in ESMCs through the activation of the Nrf2 pathway, and improve mitochondrial respiration and cell energy metabolism. Additionally, we identified five potential antioxidant flavonoid compounds, suggesting their potential incorporation into the equine diet as a strategy to alleviate exercise-induced oxidative stress.

Investigation of the effects of catharanthine and Q10 on Nrf2 and its association with MMP-9, MRP1, and Bcl-2 and apoptosis in a model of hepatocellular carcinoma

Since the role of Nrf2 in cancer cell survival has been highlighted, the pharmacological modulation of the Nrf2-Keap1 pathway may provide new opportunities for cancer treatment. This study purposed to use ubiquinone (Q10) as an antioxidant and catharanthine alkaloid as a cAMP inducer suppressing HepG2 cells by reducing Nrf2 level. The effects of Q10 and catharanthine on HepG2 cells in terms of viability were analyzed by MTT test. MTT results were used to determine the effective concentration of both drugs for the subsequent treatment and analysis. Subsequently, the effects of Q10 and catharanthine in a single and combined manner on oxidant/antioxidant status, apoptosis, metastasis, and drug resistance of HepG2 cells were investigated by related methods. Both Q10 and catharanthine decreased the level of oxidative stress products and increased antioxidant capacity in HepG2 cells. Nrf2 gene expression decreased by Q10, but catharanthine unexpectedly increased it. Following Nrf2 alterations, the expression levels of MMP-9 and MRP1 involved in metastasis and drug resistance were significantly and dose-dependently decreased by Q10, while catharanthine slightly increased both. However, both drugs increased caspase 3/7 activity and apoptosis rate, and the effect of Q10 on apoptosis was stronger than that of catharanthine. Most of the effects of the combination treatments were similar to those of the Q10 single treatment and indicated the dominant effect over the catharanthine component. Despite the antioxidant and apoptotic properties of both agents, Q10 was better than catharanthine in inducing apoptosis, counteracting drug resistance, and metastasis in HepG2 cells.

Promotion of improved intestinal barrier health by soybean-derived bioactive peptides in Chinese mitten crab (Eriocheir sinensis) fed a low fishmeal diet

To alleviate the growth inhibition, and intestinal damage of Chinese mitten crab (Eriocheir sinensis) induced by low fishmeal diets (LF), an 8-week feeding trial was conducted to evaluate the addition of dietary soybean-derived bioactive peptides (SBP) in LF diets on the regulation of growth, digestion and intestinal health. The crabs were fed isonitrogenous and isoenergetic conventional diet and LF diets (10 % fishmeal replaced by soybean meal, LF) supplemented with 0, 1 %, 2 %, 4 % and 6 % SBP, respectively. The results showed that LF diet inhibited growth while inclusion of SBP quadratically remitted the growth inhibition induced by LF. For digestive function, increasing addition level of SBP quadratically improved the α-amylase and trypsin activities. For antioxidant function, LF group significantly increased the malondialdehyde content, while SBP linearly decreased the malondialdehyde level and cubically increased the anti-superoxide anion activity and total antioxidant capacity level. For intestinal health, the peritrophic membrane (PM) almost completely separated from the inner wall of the intestinal lumen, the epithelial cells reduced, the muscularis became thinner and the apoptotic signals increased in LF group; with SBP addition, the intestinal morphology was improved, with the PM adhering to the inner wall of the intestinal lumen, an increase in the number of epithelial cells and an increase in the thickness of the muscularis. Additionally, there was a decrease in apoptotic signals. Dietary SBP also increased the expression of PT and Crustin1 quadratically and decreased the expression of ALF1 linearly, ALF3 and ILF2 quadratically.

Purification and Identification of Peptides from Hydrilla verticillata (Linn. f.) Royle with Cytoprotective and Antioxidative Effect against H2O2-Treated HepG2 Cells

Antioxidant peptides were purified from Hydrilla verticillata (Linn. f.) Royle (HVR) protein hydrolysate by ultrafiltration, gel filtration chromatography, and semipreparative reversed-phase HPLC and identified by UPLC-ESI-MS/MS. Therein, TCLGPK and TCLGER were selected to be synthesized, and they displayed desirable radical-scavenging activity to ABTS (99.20 ± 0.56-99.20 ± 0.43%), DPPH (97.32 ± 0.59-97.56 ± 0.97%), hydroxyl radical (54.32 ± 1.27-70.42 ± 2.01%), and superoxide anion (42.93 ± 1.46-52.62 ± 1.11%) at a concentration of 0.96 μmol/mL. They possessed a cytoprotective effect against H2O2-induced oxidative stress in HepG2 cells in a dose-dependent manner. 1.6 μmol/mL of the two peptides could perfectly protect HepG2 cells from H2O2-induced injury. The TCLGPK exhibited higher antioxidant activity and cytoprotective effect than TCLGER. Western blot and molecular docking results indicated that the two peptides achieved antioxidant ability and cytoprotective effect by combining with Kelch-like ECH-associated protein 1 (Keap1) to activate the Keap1-nuclear factor erythroid 2-related factor 2 (Nrf2)-antioxidant response elements signaling pathway, leading to the activity and expression of the related antioxidases in the pathway significantly up-regulating and the intracellular reactive oxygen species level, lipid peroxidation, and cell apoptosis rate significantly down-regulating.

Resveratrol prevents age-related heart impairment through inhibiting the Notch/NF-κB pathway

Resveratrol (RSV) is a natural polyphenol compound found in various plants that has been shown to have potential benefits for preventing aging and supporting cardiovascular health. However, the specific signal pathway by which RSV protects the aging heart is not yet well understood. This study aimed to explore the protective effects of RSV against age-related heart injury and investigate the underlying mechanisms using a D-galactose-induced aging model. The results of the study indicated that RSV provided protection against age-related heart impairment in mice. This was evidenced by the reduction of cardiac histopathological changes as well as the attenuation of apoptosis. RSV-induced cardioprotection was linked to a significant increase in antioxidant activity and mitochondrial transmembrane potential, as well as a reduction in oxidative damage. Additionally, RSV inhibited the production of pro-inflammatory cytokines such as interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α). Furthermore, the expression of toll-like receptor 4 (TLR4), nuclear factor kappa-B p65 (NF-κB p65), and notch 1 protein were inhibited by RSV, indicating that inhibiting the Notch/NF-κB pathway played a critical role in RSV-triggered heart protection in aging mice. Moreover, further data on intestinal function demonstrated that RSV significantly increased short-chain fatty acids (SCFAs) in intestinal contents and reduced the pH value in the feces of aging mice. RSV alleviated aging-induced cardiac dysfunction through the suppression of oxidative stress and inflammation via the Notch/NF-κB pathway in heart tissue. Furthermore, this therapeutic effect was found to be associated with its protective roles in the intestine.

Selenium-Enriched Soybean Peptides as Novel Organic Selenium Compound Supplements: Inhibition of Occupational Air Pollution Exposure-Induced Apoptosis in Lung Epithelial Cells

The occupational groups exposed to air pollutants, particularly PM2.5, are closely linked to the initiation and advancement of respiratory disorders. The aim of this study is to investigate the potential protective properties of selenium-enriched soybean peptides (Se-SPeps), a novel Se supplement, in mitigating apoptosis triggered by PM2.5 in A549 lung epithelial cells. The results indicate a concentration-dependent reduction in the viability of A549 cells caused by PM2.5, while Se-SPeps at concentrations of 62.5-500 µg/mL showed no significant effect. Additionally, the Se-SPeps reduced the production of ROS, proinflammatory cytokines, and apoptosis in response to PM2.5 exposure. The Se-SPeps suppressed the PM2.5-induced upregulation of Bax/Bcl-2 and caspase-3, while also restoring reductions in p-Akt in A549 cells. The antiapoptotic effects of Se-SPeps have been found to be more effective compared to SPeps, SeMet, and Na2SeO3 when evaluated at an equivalent protein or Se concentration. Our study results furnish evidence that supports the role of Se-SPeps in reducing the harmful effects of PM2.5, particularly in relation to its effect on apoptosis, oxidative stress, and inflammation.

A Review of the Potential of Nuclear Factor [Erythroid-Derived 2]-like 2 Activation in Autoimmune Diseases

An autoimmune disease is the consequence of the immune system attacking healthy cells, tissues, and organs by mistake instead of protecting them. Inflammation and oxidative stress (OS) are well-recognized processes occurring in association with acute or chronic impairment of cell homeostasis. The transcription factor Nrf2 (nuclear factor [erythroid-derived 2]-like 2) is of major importance as the defense instrument against OS and alters anti-inflammatory activities related to different pathological states. Researchers have described Nrf2 as a significant regulator of innate immunity. Growing indications suggest that the Nrf2 signaling pathway is deregulated in numerous diseases, including autoimmune disorders. The advantageous outcome of the pharmacological activation of Nrf2 is an essential part of Nrf2-based chemoprevention and intervention in other chronic illnesses, such as neurodegeneration, cardiovascular disease, autoimmune diseases, and chronic kidney and liver disease. Nevertheless, a growing number of investigations have indicated that Nrf2 is already elevated in specific cancer and disease steps, suggesting that the pharmacological agents developed to mitigate the potentially destructive or transformative results associated with the protracted activation of Nrf2 should also be evaluated. The activators of Nrf2 have revealed an improvement in the progress of OS-associated diseases, resulting in immunoregulatory and anti-inflammatory activities; by contrast, the depletion of Nrf2 worsens disease progression. These data strengthen the growing attention to the biological properties of Nrf2 and its possible healing power on diseases. The evidence supporting a correlation between Nrf2 signaling and the most common autoimmune diseases is reviewed here. We focus on the aspects related to the possible effect of Nrf2 activation in ameliorating pathologic conditions based on the role of this regulator of antioxidant genes in the control of inflammation and OS, which are processes related to the progression of autoimmune diseases. Finally, the possibility of Nrf2 activation as a new drug development strategy to target pathogenesis is proposed.

Structural properties of Kudzu protein enzymatic hydrolysate and its repair effect on HepG2 cells damaged by H2O2 oxidation

We investigated the structural properties, foaming capacity and foaming stability, antioxidant activity, and amino acid composition of Kudzu protein (KP) and Kudzu protein hydrolysate (KPH). The peptide sequence of KPH was analyzed using ultra performance liquid chromatography/tandem mass spectrometry (UPLC-MS/MS), and the binding ability of the peptide sequence to Keap1 was predicted through molecular docking simulations. The electrophoresis and molecular weight distribution analysis results showed that the molecular weight of KPH was significantly lower than that of KP, with a mean molecular weight of approximately 2000-5000 Da. The structures and properties were characterized using Fourier transform infrared spectroscopy, relative fluorescence, and circular dichroism. The results showed that KP exposed a large number of hydrophobic groups after enzymatic hydrolysis, and its structure changed from α-helical to random coils. KPH has a higher foaming capacity (200%) and foaming stability (97.5%) than KP, which may be related to the change in structure. These results indicate that moderate hydrolysis can improve the functional properties of KP, providing a new opportunity for its application as a food ingredient. The antioxidant assay results showed that KP and KPH had a good hydroxyl radical, superoxide anion, 1,1-diphenyl-2-picrylhydrazyl (DPPH), and 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) scavenging capacity and a high reducing capacity. KPH exerted better antioxidant effects than KP. The scavenging rates for DPPH, ABTS, hydroxyl radicals, and superoxide anions were 89.31%, 93.14%, 85.74%, and 58.29%, respectively, and its reducing capacity was 2.191, which may be related to the increase in amino acids with antioxidant activity after enzymolysis. In vitro, KP and KPH could significantly repair H2O2-induced oxidative damage in HepG2 cells, reduce the apoptosis rate, activate the Nrf2-Keap1 signaling pathway, reduce the accumulation of reactive oxygen species and malondialdehyde after oxidative damage, increase the activities of superoxide dismutase and glutathione (GSH) peroxidase, and increase the content of GSH and the total antioxidant capacity. Twenty-one peptide components were identified in KPH using UPLC-MS/MS, and the binding ability of 21 peptide components to Keap1 was analyzed through molecular docking technology. The results showed that all 21 peptides in KPH had good antioxidant activity, and real-time quantitative PCR (qRT-PCR) analysis was conducted to further explain the high antioxidant activity of KPH at the genetic level. These results show that KP and KPH are suitable for preparing antioxidant foods and related health foods to prevent oxidation-related diseases. KPH has more beneficial effects than KP.

Modulation of carcinogenesis with selected GRAS nutraceuticals via Keap1-Nrf2 signaling pathway

Keap1-Nrf2 is a fundamental signaling cascade known to promote or prevent carcinogenesis. Extensive studies identify the key target of modulatory aspects of Keap1-Nrf2 signaling against cancer. Nutraceuticals are those dietary agents with many health benefits that have immense potential for cancer chemoprevention. The nutritional supplements known as nutraceuticals are found to be one of the most promising chemoprevention agents. Upon investigating the dual nature of Nrf2, it became clear that, in addition to shielding normal cells from numerous stresses, Nrf2 may also promote the growth of tumors. In the present review, we performed a systematic analysis of the role of 12 different nutraceuticals like curcumin, sulforaphane, resveratrol, polyunsaturated fatty acids (PUFA) from fish oil, lycopene, soybean, kaempferol, allicin, thymoquinone, quercetin, gingerol, and piperine in modulating the Nrf2/Keap1 signaling mechanism. Among these, 12 Generally Recognized As Safe (GRAS) certified nutraceuticals, sulforaphane is the most extensively studied compound in modulating Keap1-Nrf signaling. Even though there is much evidence at preclinical levels, further high-quality research is still required to validate the potential role of these nutraceuticals in Keap1-Nrf2 modulation.

Selenium-enriched peptides identified from selenium-enriched soybean protein hydrolysate: protective effects against heat damage in Caco-2 cells

Our previous study evaluated the antioxidant and anti-inflammatory activities of selenium-enriched soybean peptides (SePPs) in vivo. In this study, we purified SePPs via gel filtration chromatography and obtained five fractions (F1, F2, F3, F4 and F5), among which F3 displayed the highest antioxidant and anti-inflammatory activities. Nineteen selenium-enriched peptides were identified in F3 by mass spectrometry. Two selenium-enriched peptides with sequences ESeCQIQKL (Sep-1) and SELRSPKSeC (Sep-2) were selected for synthesis based on their score and the number of hydrophobic amino acids, acidic and basic amino acids. Both Sep-1 and Sep-2 exhibited preventive effects on the heat stress-induced impairment of intestinal epithelial cell integrity, oxidative stress and inflammatory responses in a Caco-2 cell model. Pretreatment of the cells with Sep-1 or Sep-2 for 24 h reduced intracellular reactive oxygen species (ROS) generation, prevented the disruption of tight junction (TJ) proteins, and decreased paracellular permeability. Western blot results showed that Sep-1 and Sep-2 could improve the abnormal expressions of Nrf2, Keap1, NLRP3, caspase-1 and ASC/TMS1, thereby enhancing the glutathione (GSH) redox system and reducing IL-1β and IL-18 concentrations. Sep-1 activated the Nrf2-Keap1 signaling pathway significantly more than Sep-2. Molecular docking results indicated that Sep-1 and Sep-2 are both bound to Keap1 and NLRP3 in the form of hydrogen bonds, hydrophobic interactions and salt bridges, which interferes with Nrf2 and NLRP3 signaling. Molecular dynamics simulations suggested that more hydrogen bonds were formed during the resultant process of Sep-1 with Keap1, and the compactness and stability of the complex structure were better than those of Sep-2. These findings confirm the value of both Sep-1 and Sep-2 in the development of dietary supplements as potential alternatives for heat damage and related disease prevention.

Auricularia auricula Peptides Nutritional Supplementation Delays H2O2-Induced Senescence of HepG2 Cells by Modulation of MAPK/NF-κB Signaling Pathways

Auricularia auricula is a traditional medicinal and edible mushroom with anti-aging effects. Many studies focused on polysaccharides and melanin. However, the anti-aging effects and mechanism of the nutritional supplementation of Auricularia auricula peptides (AAPs) were not elucidated. In this study, AAPs were prepared by enzymolysis of flavor protease and the protective effects on H2O2-induced senescence of HepG2 cells were explored for the first time. The potential mechanism was also investigated. AAPs were mostly composed of low molecular weights with less than 1000 Da accounting for about 79.17%, and contained comprehensive amino acids nutritionally, including seven essential amino acids, aromatic, acidic, and basic amino acids. AAPs nutritional supplementation could significantly decrease the levels of intracellular reactive oxygen species (ROS) and malondialdehyde (MDA), and increase the activities of antioxidant enzymes (SOD, CAT, and GSH-Px). In addition, the senescence-associated-β-galactosidase (SA-β-gal) activity was restrained, and the expression levels of senescence-associated secretory phenotype (SASP) (IL-6, IL-8, IL-1β, and CXCL2) were also decreased. Ribonucleic acid sequencing (RNA-Seq) was carried out to screen the differentially expressed genes (DEGs) between different groups. GO and KEGG enrichment analysis showed that the mechanism was related to the MAPK/NF-κB signaling pathways. Quantitative real-time PCR (qRT-PCR) analysis and Western blot were carried out to verify the key genes and proteins in the pathways, respectively. AAPs nutritional supplementation resulted a significant down-regulation in key the genes c-fos and c-jun and up-regulation in DUSP1 of the MAPK signaling pathway, and down-regulation in the key genes CXCL2 and IL-8 of the NF-κB signaling pathway. The results of Western blot demonstrate that AAPs nutritional supplementation could inhibit MAPK/NF-κB pathways by reducing the expression levels of IKK, IκB, P65, and phosphorylation of ERK, thus decreasing the inflammatory reaction and delaying cell senescence. It is the first time that AAPs nutritional supplementation was proved to have protective effects on H2O2-induced oxidative damage in HepG2 cells. These results implicate that dietary AAPs could be used as nutrients to reduce the development or severity of aging.

The Role of Heat Shock Proteins and Autophagy in Mechanisms Underlying Effects of Sulforaphane on Doxorubicin-Induced Toxicity in HEK293 Cells

Doxorubicin (DOX) is a cytostatic agent belonging to anthracycline group. Important role in mechanism associated with negative effects of DOX plays an oxidative stress. Heat shock proteins (HSPs) are part of mechanisms initiated in response to stressful stimuli and play an important role in cellular responses to oxidative stress through interaction with components of redox signaling. The present work was aimed to study the role of HSPs and autophagy in mechanisms underlying effects of sulforaphane (SFN), a potential activator of Nrf-2, on doxorubicin-induced toxicity in human kidney HEK293 cells. We investigated effects of SFN and DOX on proteins associated with regulation of heat shock response, redox signaling, and autophagy. Results show that SFN significantly reduced cytotoxic effects of DOX. The positive effects of SFN on DOX-induced changes were associated with up-regulation of Nrf-2 and HSP60 protein levels. In the case of another heat shock protein HSP40, SFN increased its levels when was administered alone but not in conditions when cells were exposed to the effects of DOX. Sulforaphane also reversed negative effects of DOX on activities of superoxide dismutases (SODs) and up-regulation of autophagy markers (LC3A/B-II, Atg5, and Atg12). In conclusion, the changes observed in HSP60 are of particular importance in terms of protecting cells from the effects of DOX. Finding that under conditions where SFN reduced cytotoxic effects of DOX were significantly increased protein levels of both Nrf-2 and HSP60 point to the role of HSP60 in mechanisms of redox signaling underlying effects of SFN on DOX-induced toxicity in HEK293 cells. Moreover, data confirmed an important role of autophagy in effects of SFN on DOX-induced toxicity.

The SWGEDWGEIW from Soybean Peptides Reduces Insulin Resistance in 3T3-L1 Adipocytes by Activating p-Akt/GLUT4 Signaling Pathway

Diabetes mellitus, a group of metabolic disorders characterized by persistent hyperglycemia, affects millions of people worldwide and is on the rise. Dietary proteins, from a wide range of food sources, are rich in bioactive peptides with anti-diabetic properties. Notably, the protective mechanism of the single peptide SWGEDWGEIW (TSP) from soybean peptides (SBPs) on insulin resistance of adipocytes in an inflammatory state was investigated by detecting the lipolysis and glucose absorption and utilization of adipocytes. The results showed that different concentrations of TSP (5, 10, 20 µg/mL) intervention can reduce 3T3-L1 adipocytes’ insulin resistance induced by inflammatory factors in a dose-dependent manner and increase glucose utilization by 34.2 ± 4.6%, 74.5 ± 5.2%, and 86.7 ± 6.1%, respectively. Thus, TSP can significantly alleviate the lipolysis of adipocytes caused by inflammatory factors. Further mechanism analysis found that inflammatory factors significantly reduced the phosphorylation (p-Akt) of Akt, two critical proteins of glucose metabolism in adipocytes, and the expression of GLUT4 protein downstream, resulting in impaired glucose utilization, while TSP intervention significantly increased the expression of these two proteins. After pretreatment of adipocytes with PI3K inhibitor (LY294002), TSP failed to reduce the inhibition of p-Akt and GLUT4 expression in adipocytes. Meanwhile, the corresponding significant decrease in glucose absorption and the increase in the fat decomposition of adipocytes indicated that TSP reduced 3T3-L1 adipocytes’ insulin resistance by specifically activating the p-Akt/GLUT4 signal pathway. Therefore, TSP has the potential to prevent obesity-induced adipose inflammation and insulin resistance.

Purification, Identification, and Mechanistic Investigation of Novel Selenium-Enriched Antioxidant Peptides from Moringa oleifera Seeds

In this study, five novel Se-enriched antioxidant peptides (FLSeML, LSeMAAL, LASeMMVL, SeMLLAA, and LSeMAL) were purified and identified from Se-enriched Moringa oleifera (M. oleifera) seed protein hydrolysate. The five peptides showed excellent cellular antioxidant activity, with respective EC₅₀ values of 0.291, 0.383, 0.662, 0.1, and 0.123 μg/mL. The five peptides (0.025 mg/mL) increased the cell viability from 78.72 to 90.71, 89.16, 93.92, 83.68, and 98.29%, respectively, effectively reducing reactive oxygen species accumulation and significantly increasing superoxide dismutase and catalase activities in damaged cells. Molecular docking results revealed that the five novel Se-enriched peptides interacted with the key amino acid of Keap1, thus directly blocking the interaction of Keap1-Nrf2 and activating the antioxidant stress response to enhance the ability of scavenging free radicals in vitro. In conclusion, Se-enriched M. oleifera seed peptides exhibited significant antioxidant activity and can be expected to find widespread use as a highly active natural functional food additive and ingredient.

Hangover-Relieving Effect of Ginseng Berry Kombucha Fermented by Saccharomyces cerevisiae and Gluconobacter oxydans in Ethanol-Treated Cells and Mice Model

This study aimed to evaluate the hangover relieving effect of ginseng berry kombucha (GBK) fermented with Saccharomyces cerevisiae and Gluconobacter oxydans in in vitro and in vivo models. The antioxidant activity and oxidative stress inhibitory effect of GBK were evaluated in ethanol-treated human liver HepG2 cells. In addition, biochemical and behavioral analyses of ethanol treated male ICR mice were performed to confirm the anti-hangover effect of GBK. The radical scavenging activity of GBK was increased by fermentation, and the total ginsenoside content of GBK was 70.24 μg/mL. In HepG2 cells, in which oxidative stress was induced using ethanol, GBK significantly increased the expression of antioxidant enzymes by upregulating the Nrf2/Keap1 pathway. Moreover, GBK (15 and 30 mg/kg) significantly reduced blood ethanol and acetaldehyde concentrations in ethanol-treated mice. GBK significantly increased the levels of alcohol-metabolizing enzymes, including alcohol dehydrogenase and acetaldehyde dehydrogenase. The balance beam test and elevated plus maze test revealed that high-dose GBK significantly ameliorated ethanol-induced behavioral changes. Collectively, GBK exerted a protective effect against ethanol-induced liver damage by regulating the Nrf2/Keap1 pathway.

Effects of dietary supplementation with bioactive peptides derived from rapeseed protein on the growth performance, serum biochemistry and faecal micro‐organism composition of weaned piglets

The present study investigated the effects of supplementing bioactive peptides derived from rapeseed protein (rapeseed peptide, Rsp) on the growth performance, serum biochemistry and faecal micro-organism composition of weaned piglets. Sixty Duroc × Landrace × Yorkshire weaned piglets of similar weights were randomly divided into three groups. The control group (NC) was fed a basal diet, and the two treatment groups, Rsp-1 and Rsp-2, were fed a basal diet supplemented with 1% or 2% Rsp, respectively, for 28 days. Each treatment consisted of five replicates with four piglets per replicate. The results showed that Rsp treatment significantly improved the average daily gain and had a better feed-to-gain ratio (p < 0.05). The diarrhoea incidence and indices of Rsp-1 and Rsp-2 groups were significantly lower than the NC group (p < 0.05), and the effect of Rsp-2 on reducing the incidence of diarrhoea was significantly higher than that of Rsp-1 (p < 0.05). The serum albumin, serum immunoglobulin A and catalase levels of the Rsp-1 and Rsp-2 groups were significantly better than the NC group (p < 0.05). Additionally, Rsp treatment significantly gained the relative abundance of faecal Lactobacillaceae and decreased the relative abundance of faecal Eubacterium_coprostanoligenes_group, Treponema and Coprococcus (p < 0.05). In summary, Rsp supplementation improved the growth performance, ameliorated the diarrhoea, enhanced the immune and antioxidant functions and changed the composition of faecal micro-organisms in piglets. These findings indicate that Rsp positively affected the health of weaned piglets.

Preparation of antioxidant peptides from Moringa oleifera leaves and their protection against oxidative damage in HepG2 cells

Moringa oleifera leaves are a kind of new food raw materials, rich in functional factors, M. oleifera leaves aqueous extract have antioxidant activity and M. oleifera leave protein is an important active ingredient in the aqueous extract. Numerous studies have shown that peptides have strong antioxidant activity. To reveal the antioxidant effects of M. oleifera (MO) leaves peptides, MO leave antioxidant peptides were isolated and prepared to clarify their antioxidant activity. MLPH1 (<1 kDa), MLPH3 (1~3 kDa), MLPH5 (3~5 kDa), and MLPH10 (5~10 kDa) fractions were obtained by the membrane ultrafiltration classification of MO leaves proteolytic hydrolysate (MLPH). MLPH1 was further separated by centrifugal filters, and the fraction separated by <1 kDa (MLPH1-1) was identified and analyzed by LC-MS/MS. The purpose of this study was to investigate the effect of MO leaves antioxidant peptide pretreatment on H2O2-treated HepG2 cells and to refine the antioxidant activity. The results showed that MLPH1 had the strongest antioxidant activity, and three MO leaves antioxidant peptides (LALPVYN, LHIAALVFQ, and FHEEDDAKLF) were obtained. The peptide with the sequence LALPVYN and a molecular weight of 788.44 Da had the strongest antioxidant activity. After 24 h of LALPVYN pretreatment, the cell viability and the CAT, GSH-Px, and SOD enzyme activity were significantly increased, and the MDA, ROS, and apoptosis rates were significantly decreased. These results provide a theoretical basis for further research on the antioxidant mechanism of MO leaves peptides.

The SWGEDWGEIW from Soybean Peptides Reduce Oxidative Damage-Mediated Apoptosis in PC-12 Cells by Activating SIRT3/FOXO3a Signaling Pathway

The goal of the investigation was to study the protective effects of the SWGEDWGEIW (the single peptide, TSP) from soybean peptides (SBP) on hydrogen peroxide (H2O2)-induced apoptosis together with mitochondrial dysfunction in PC-12 cells and their possible implications to protection mechanism. Meanwhile, the SBP was used as a control experiment. The results suggested that SBP and TSP significantly (p < 0.05) inhibited cellular oxidative damage and ROS-mediated apoptosis. In addition, SBP and TSP also enhanced multiple mitochondrial biological activities, decreased mitochondrial ROS levels, amplified mitochondrial respiration, increased cellular maximal respiration, spare respiration capacity, and ATP production. In addition, SBP and TSP significantly (p < 0.05) raised the SIRT3 protein expression and the downstream functional gene FOXO3a. In the above activity tests, the activity of TSP was slightly higher than that of SBP. Taken together, our findings suggested that SBP and TSP can be used as promising nutrients for oxidative damage reduction in neurons, and TSP is more effective than SBP. Therefore, TSP has the potential to replace SBP and reduce neuronal oxidative damage.

Co-Encapsulation of Tannic Acid and Resveratrol in Zein/Pectin Nanoparticles: Stability, Antioxidant Activity, and Bioaccessibility

Hydrophilic tannic acid and hydrophobic resveratrol were successfully co-encapsulated in zein nanoparticles prepared using antisolvent precipitation and then coated with pectin by electrostatic deposition. The encapsulation efficiencies of the tannic acid and resveratrol were 51.5 ± 1.9% and 77.2 ± 3.2%, respectively. The co-encapsulated nanoparticles were stable against aggregation at the investigated pH range of 2.0 to 8.0 when heated at 80 °C for 2 h and when the NaCl concentration was below 50 mM. The co-encapsulated tannic acid and resveratrol exhibited stronger in vitro antioxidant activity than ascorbic acid, as determined by 1,1-diphenyl-2-picrylhydrazyl free radical (DPPH·) and 2,2'-azinobis (3-ethylberizothiazoline-6-sulfonic acid) radical cation (ABTS+·) scavenging assays. The polyphenols-loaded nanoparticles significantly decreased the malondialdehyde (MDA) concentration and increased the superoxide dismutase (SOD) and catalase (CAT) activities in peroxide-treated human hepatoma cells (HepG2). An in vitro digestion model was used to study the gastrointestinal fate of the nanoparticles. In the stomach, encapsulation inhibited tannic acid release, but promoted resveratrol release. However, in the small intestine, it led to a relatively high bioaccessibility of 76% and 100% for resveratrol and tannic acid, respectively. These results suggest that pectin-coated zein nanoparticles have the potential for the co-encapsulation of both polar and nonpolar nutraceuticals or drugs.

Transepithelial transport and cellular mechanisms of food-derived antioxidant peptides

Considering the involvement of oxidative stress in the etiology of many non-communicable diseases, food-derived antioxidant peptides (FDAPs) are strong candidates for nutraceutical development for disease prevention and management. This paper reviews current evidence on the transepithelial transport and cellular mechanisms of antioxidant activities of FDAPs. Several FDAPs have multiple health benefits such as anti-inflammatory and anti-photoaging activities, in addition to antioxidant properties through which they protect cellular components from oxidative damage. Some FDAPs have been shown to permeate the intestinal epithelium, which could facilitate their bioavailability and physiological bioactivities. Molecular mechanisms of FDAPs include suppression of oxidative stress as evidenced by reduction in intracellular reactive oxygen species production, lipid peroxidation and apoptotic protein activation as well as increase in antioxidant defense mechanisms (enzymatic and non-enzymatic). Since many FDAPs have demonstrated promising antioxidant activity, future investigation should focus on further elucidation of molecular mechanisms and human studies to explore their practical application for the prevention and management of oxidative stress-related diseases.

Taurine inhibits hydrogen peroxide-induced oxidative stress, inflammatory response and apoptosis in liver of Monopterus albus

Fish are extremely vulnerable to environmental stimulation and produce oxidative stress. Among them, hydrogen peroxide is an oxidative stress source that cannot be ignored in fish, which can cause physical disorders, inflammation and even death. Taurine was revealed to reduce oxidative damage and inflammation caused by toxic substances, but whether it can reduce toxicity of rice field eel caused by H₂O₂ has not been determined. Thus, the intervention effects of taurine on H₂O₂-induced oxidative stress, inflammation, apoptosis, and autophagy in rice field eel. The results showed that oxidative injury in the liver was determined after H₂O₂ injection, as indicated by enhanced serum AST and ALT activities, inhibited the antioxidant function (increased MDA and ROS contents, decreased antioxidant enzymes, inhibited nrf2 transcription level), and induced inflammatory response (upregulated il-1β, il-6, il-8, and il-12β gene expression, downregulated tgf-β1 gene expression, activated the transcription level of nf-κb, tlr-3, and tlr-7). In addition, bax, caspase3, beclin1, and Lc3B gene expression were significantly upregulated after H₂O₂ injection, while bcl2 and p62 gene expression were downregulated, leading to the occurrence of apoptosis and autophagy. In contrast, adding 0.2 and 0.5% taurine to feed significantly alleviated this damage, as indicated by the recovery of the aforementioned bioindicators, and the effect of 0.5% taurine addition is better than 0.2%. Overall, these results suggested that taurine can relieve the liver toxicity induced by H₂O₂, which enriched the toxic mechanism of H₂O₂ on fish and provided evidence for the protective effect of taurine on liver.

Clinical Research Progress of Small Molecule Compounds Targeting Nrf2 for Treating Inflammation-Related Diseases

Studies have found that inflammation is a symptom of various diseases, such as coronavirus disease 2019 (COVID-19) and rheumatoid arthritis (RA); it is also the source of other diseases, such as Alzheimer's disease (AD), Parkinson's disease (PD), lupus erythematosus (LE), and liver damage. Nrf2 (nuclear factor erythroid 2-related factor 2) is an important multifunctional transcription factor in cells and plays a central regulatory role in cellular defense mechanisms. In recent years, several studies have found a strong association between the activation of Nrf2 and the fight against inflammation-related diseases. A number of small molecule compounds targeting Nrf2 have entered clinical research. This article reviews the research status of small molecule compounds that are in clinical trials for the treatment of COVID-19, rheumatoid arthritis, Alzheimer's disease, Parkinson's disease, lupus erythematosus, and liver injury.

In vitro and in vivo Studies of Soybean Peptides on Milk Production, Rumen Fermentation, Ruminal Bacterial Community, and Blood Parameters in Lactating Dairy Cows

Soybean peptides (SPs), a feed additive derived from soybean, exhibit nutritional function and biological activity in monogastric animals, but limited studies have been conducted in dairy cows. Our experiments were conducted to evaluate the effects of SPs on the nutrient degradability of dry matter (DM), crude protein (CP), neutral detergent fiber (NDF), and acid detergent fiber (ADF) in vitro and milk production, rumen fermentation and bacterial community, and blood parameters of dairy cows. For in vitro experiment, ruminal fluids were collected from three ruminal cannulated Holstein dairy cows. A total of three levels of SPs (0, 0.38, and 1.92 g/kg DM of SPs) were added to the total mixed ration (TMR). Nutrient degradability and fermentation fluid pH were determined at 24 and 48 h using 3.0 g samples of the substrate. Gas production after 48 h was recorded by an automated trace gas recording system using 0.5 g samples of the substrate. The results showed that DM, NDF, ADF (p < 0.01), and CP (p < 0.05) degradabilities were significantly increased at 1.92 g/kg DM of SPs at 24 h, and asymptotic gas production (p = 0.05) was increased at 48 h. For in vivo experiment, 110 lactating Holstein cows (209.7 ± 65.2 DIM; 37.2 ± 6.4 kg/d milk yield) were randomly assigned to 0 (control group, CON) or 50 g/head/day SPs (SP-supplemented group). Yields of milk (p < 0.05), milk protein (p < 0.05), and milk lactose (0.05 < p < 0.10) increased on SPs supplementation; however, the milk fat percentage decreased (p < 0.05). The concentrations of individual volatile fatty acids (VFAs) (p < 0.05) and superoxide dismutase (SOD) (p < 0.01) were also increased. Rumen bacterial diversity in SP-supplemented cows was higher (p < 0.05). The relative abundances of Rikenellaceae_RC9_gut_group, Butyrivibrio, Selenomonas, and Shuttleworthia were significantly increased and that of Coprococcus was decreased (p < 0.05). Our results showed that supplementing 1.92 g/kg DM of SPs could improve the nutrient degradability in vitro and 50 g/head/day of SPs could improve milk production and antioxidant ability of dairy cows. The rumen bacterial diversity was also enhanced by SP supplementation.

Alleviating Effects of Black Soybean Peptide on Oxidative Stress Injury Induced by Lead in PC12 Cells via Keap1/Nrf2/TXNIP Signaling Pathway

Many researchers have found that Pb exposure can cause oxidative stress damage to the body’s tissue. Black soybean peptide (BSP) has a variety of physiological functions, especially in terms of oxidative stress. Nevertheless, the mitigation function of BSPs on Pb-induced oxidative stress damage in PC12 cells has not been clearly defined. In this study, cell viability was detected by CCK8. Oxidative stress indicators, such as ROS, GSH/GSSG, MDA, SOD, CAT, GPx, and GR, were tested with biochemical kit. Protein expression of Keap1, Nrf2, and TXNIP was measured by Western blot. Compared with the control group, Pb reduced the cell viability of PC12 cells. However, BSP treatment significantly increased the viability of PC12 cells induced by lead exposure (p < 0.05). Lead can enrich the contents of MDA and ROS, but decrease the amount of CAT, SOD, GR, GPx, and GSH/GSSG in PC12 cells, while BSP can alleviate it (p < 0.05). Lead can enhance the expression of Keap1 and TXNIP proteins, but reduce Nrf2 expression. In contrast, BSPs reversed this phenomenon (p < 0.05). BSPs can alleviate oxidative stress injury induced by lead in PC12 cells through the Keap1/Nrf2/TXNIP signaling pathway.

The deubiquitinase USP7 regulates oxidative stress through stabilization of HO-1

Heme oxygenase-1 (HO-1) is an inducible heme degradation enzyme that plays a cytoprotective role against various oxidative and inflammatory stresses. However, it has also been shown to exert an important role in cancer progression through a variety of mechanisms. Although transcription factors such as Nrf2 are involved in HO-1 regulation, the posttranslational modifications of HO-1 after oxidative insults and the underlying mechanisms remain unexplored. Here, we screened and identified that the deubiquitinase USP7 plays a key role in the control of redox homeostasis through promoting HO-1 deubiquitination and stabilization in hepatocytes. We used low-dose arsenic as a stress model which does not affect the transcriptional level of HO-1, and found that the interaction between USP7 and HO-1 is increased after arsenic exposure, leading to enhanced HO-1 expression and attenuated oxidative damages. Furthermore, HO-1 protein is ubiquitinated at K243 and subjected to degradation under resting conditions; whereas when after arsenic exposure, USP7 itself can be ubiquitinated at K476, thereafter promoting the binding between USP7 and HO-1, finally leading to enhanced HO-1 deubiquitination and protein accumulation. Moreover, depletion of USP7 and HO-1 inhibit liver tumor growth in vivo, and USP7 positively correlates with HO-1 protein level in clinical human hepatocellular carcinoma (HCC) specimens. In summary, our findings reveal a critical role of USP7 as a HO-1 deubiquitinating enzyme in the regulation of oxidative stresses, and suggest that USP7 inhibitor might be a potential therapeutic agent for treating HO-1 overexpressed liver cancers.

Sanguinarine attenuates hydrogen peroxide-induced toxicity in liver of Monopterus albus: Role of oxidative stress, inflammation and apoptosis

In aquatic animals, hydrogen peroxide (H₂O₂), which is a source of oxidative stress, can cause physiological dysfunction, inflammation, and death. Sanguinarine (SAN) is a plant extract known to improve antioxidant and immune capacity. However, the roles of SAN in H₂O₂-induced liver tissue toxicity is unclear. The effects on hepatic oxidative damage, inflammatory response, and apoptosis were investigated by feeding rice field eel with 0, 375, and 750 μg/kg of SAN for eight weeks and then intraperitoneally injected with H₂O₂. The results showed that after 24 h of H₂O₂ injection, the activities of ALT and AST in serum were significantly increased, oxidative damage and inflammatory response occurred in the liver, and apoptosis was induced, which indicated that H₂O₂ induced liver damage in rice field eel. However, dietary supplemented with 375 or 750 μg/kg SAN significantly decreased the activities of ALT and AST in serum, and significantly increased the antioxidant function (decreased ROS, MDA, and antioxidant enzymes levels, downregulated antioxidant-related gene expression, and inhibited the transcription level of nrf2). The addition of SAN at 375 or 750 μg/kg ameliorated H₂O₂-induced inflammatory response of liver (upregulated tgf-β1 mRNA expression, downregulated il-1β, il-6, il-8, and il-12β mRNA expression, and inhibited the transcription levels of tlr-3 tlr-7, and nf-κb). In addition, dietary supplemented with 375 or 750 μg/kg SAN alleviated the apoptosis of liver induced by H₂O₂ (downregulated bax mRNA expression, upregulated caspase3 mRNA expression, and reduced the number of apoptotic cells by TUNEL staining). Overall, these results suggested that SAN could alleviate the liver injury in rice field eel induced by H₂O₂, mainly by improving antioxidant capacity, alleviating inflammatory response and inhibiting apoptosis, and the effect of 750 μg/kg SAN addition is better than 375 μg/kg.

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.

The Interplay between Autophagy and Redox Signaling in Cardiovascular Diseases

Reactive oxygen and nitrogen species produced at low levels under normal cellular metabolism act as important signal molecules. However, at increased production, they cause damage associated with oxidative stress, which can lead to the development of many diseases, such as cardiovascular, metabolic, neurodegenerative, diabetes, and cancer. The defense systems used to maintain normal redox homeostasis plays an important role in cellular responses to oxidative stress. The key players here are Nrf2-regulated redox signaling and autophagy. A tight interface has been described between these two processes under stress conditions and their role in oxidative stress-induced diseases progression. In this review, we focus on the role of Nrf2 as a key player in redox regulation in cell response to oxidative stress. We also summarize the current knowledge about the autophagy regulation and the role of redox signaling in this process. In line with the focus of our review, we describe in more detail information about the interplay between Nrf2 and autophagy pathways in myocardium and the role of these processes in cardiovascular disease development.

Chicken muscle hydrolysate reduces blood pressure in spontaneously hypertensive rats, upregulates ACE2, and ameliorates vascular inflammation, fibrosis, and oxidative stress

Spent hens are egg-laying chicken reaching the end of their egg-laying cycle and are seen as a by-product to the egg industry. A spent hen muscle protein hydrolysate prepared by food-grade thermoase PC10F (SPH-T) has previously shown antihypertensive potential. In the present work, we further investigated its antihypertensive effect and underlying mechanisms in spontaneously hypertensive rats. There are three groups: untreated, low dose (250 mg SPH-T/kg/day body weight), and high dose (1,000 mg SPH-T/kg/day body weight). Oral administration of SPH-T over a period of 20 days reduced systolic blood pressure by 25.7 mm Hg (p < 0.001) and 11.9 mm Hg (p < 0.05), respectively, for the high- and low-dose groups. The high-dose treatment decreased the circulating level of angiotensin II (from 25.0 to 5.7 pg/ml) while increased angiotensin-converting enzyme 2 (ACE2) (from 1.3 to 3.3 IU/ml) and angiotensin (1-7) (from 37.0 to 70.1 pg/ml) significantly (p < 0.05). Furthermore, the high-dose group doubled the aortic expression of ACE2 while reduced the expression of angiotensin (Ang) II type 1 receptor (by 35%). Circulating inflammatory cytokines including tumor necrosis factor alpha and monocyte chemoattractant protein-1 as well as vascular inflammatory proteins including inducible nitric oxide synthase and vascular cell adhesion molecule-1 were attenuated by ∼15%-50% by the treatment; nitrosative stress (35%) and type I collagen synthesis (50%) in the aorta were also attenuated significantly (p < 0.05). Moreover, SPH-T possessed an umami taste (no obvious bitter taste) as analyzed by electronic tongue. PRACTICAL APPLICATION: Hypertension is a global health concern, afflicting more than 20% of adults worldwide. Uncovering the antihypertensive effect of spent hen protein hydrolysate underpinned its functional food nutraceutical applications for the prevention and treatment of hypertension.

Antioxidant activity of SSeCAHK in HepG2 cells: a selenopeptide identified from selenium-enriched soybean protein hydrolysates

This paper is aimed at purifying and identifying selenium (Se)-containing antioxidative peptides from Se-enriched soybean peptides (SSP). In this work, the SSP was separated into five fractions (F1 to F5). Fraction F4, displaying the highest antioxidative activity, was further separated, and sub-fractions F4-1 to F4-5 were selected for antioxidative activity evaluation using 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2-azino-bis-(3-ethylbenzo-thiazoline-6-sulphonic acid)diammonium salt (ABTS), and OH- radical scavenging assays. The Se-containing antioxidative peptides with sequence Ser-SeC-Ala-His-Lys (SSeCAHK) were identified in sub-fraction F4-1 and chemically synthesized. This Se-containing pentapeptide showed a preventive effect against hydrogen peroxide (H2O2)-induced oxidative stress in HepG2 cells. Pretreating the cells for 2 h with SSeCAHK (0.13-0.50 mg mL-1) induced strong intracellular, reactive oxygen species (ROS) scavenging activity while preventing a decrease in reduced glutathione (GSH) and an increase in malondialdehyde (MDA). Therefore, SSeCAHK treatment improved H2O2-induced oxidative stress in HepG2 cells, demonstrating the significant potential of SSeCAHK as a natural antioxidative functional material for dietary supplementation.

Antioxidant Effect of Lactobacillus fermentum CQPC04-Fermented Soy Milk on D-Galactose-Induced Oxidative Aging Mice

The aim of this study is to evaluate the changes in soy isoflavones and peptides in soy milk after lactic acid bacterial fermentation, and explore the positive effects of fermented soy milk on an oxidative aging mouse model induced with D-galactose. We found that free soybean isoflavones and peptides increased after soy milk was fermented by Lactobacillus fermentum CQPC04. The in vivo results indicated that L. fermentum CQPC04-fermented soy milk enhanced the organ index of the liver and spleen, and improved the pathological morphology of the liver, spleen, and skin. L. fermentum CQPC04-fermented soy milk increased the enzymatic activity of glutathione peroxidase (GSH-Px), total superoxide dismutase (T-SOD), and catalase (CAT), increased glutathione (GSH), but decreased the levels of nitric oxide (NO) and malondialdehyde (MDA) in serum, liver, and brain tissues of oxidative aging mice. The above mentioned fermented soy milk also increased the levels of collagen I (Col I), hyaluronic acid (HA), and collagen III (Col III), and decreased the levels of advanced glycation End products (AGEs) and hydrogen peroxide (H₂O₂). The RT-qPCR results showed that L. fermentum CQPC04-fermented soy milk upregulated the mRNA expression of nuclear factor erythroid 2?related factor (Nrf2), heme oxygenase-1 (HMOX1), quinone oxido-reductase 1 (Nqo1), neuronal nitric oxide synthase (NOS1), endothelial nitric oxide synthase (NOS3), Cu/Zn–superoxide dismutase (Cu/Zn-SOD), Mn–superoxide dismutase (Mn-SOD), and CAT, but downregulated the expression of inducible nitric oxide synthase (NOS2) and glutamate cysteine ligase modifier subunit (Gclm) in liver and spleen tissues. Lastly, the fermented soy milk also increased the gene expression of Cu/Zn-SOD, Mn-SOD, CAT, GSH-Px, matrix metalloproteinases 1 (TIMP1), and matrix metalloproteinases 2 (TIMP2), and decreased the expression of matrix metalloproteinase 2 (MMP2) and matrix metalloproteinase 9 (MMP9) in skin tissue. In conclusion, L. fermentum CQPC04-fermented soy milk was able to satisfactorily delay oxidative aging effects, and its mechanism may be related to the increase in free soy isoflavones and peptides.

Anwulignan alleviates d-galactose induced renal damage by regulating Nrf2/ARE signaling pathway in mice

Free radical accumulation in the body will cause oxidative stress damages including the renal damage. Schisandrae Sphenantherae Fructus (Schisandra), a traditional Chinese herbal medicine, has been used throughout the world. Anwulignan, a monomer extracted from Schisandra, has been shown in our previous studies to possess antioxidant and protective effects on the liver, brain and spleen damages in the aging mice. However, its effect on the renal damage caused by aging is not clear. This study showed that anwulignan could significantly increase the kidney index, the creatinine clearance, the activities of superoxide dismutase, catalase and glutathione peroxidase; reduce the urinary protein concentration, the serum urea nitrogen and creatinine content, the content of malondialdehyde and 8-hydroxylated deoxyguanosine in the renal tissue; and improve the renal tissue damage. Moreover, anwulignan increased the production of Nrf2, HO-1 and NQO1 proteins and decreased the production level of Keap1 protein in the renal tissue in the d-galactose induced aging mice. These results suggest that anwulignan significantly alleviates the renal damage by its antioxidant effect through regulating the production of Nrf2/ARE pathway-related proteins in the renal tissue in the d-galactose induced aging mice.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-021-00951-7.

Antioxidant Activity of Novel Casein-Derived Peptides with Microbial Proteases as Characterized via Keap1-Nrf2 Pathway in HepG2 Cells

Casein-derived antioxidant peptides by using microbial proteases have gained increasing attention. Combination of two microbial proteases, Protin SD-NY10 and Protease A "Amano" 2SD, was employed to hydrolyze casein to obtain potential antioxidant peptides that were identified by LCMS/ MS, chemically synthesized and characterized in a oxidatively damaged HepG2 cell model. Four peptides, YQLD, FSDIPNPIGSEN, FSDIPNPIGSE, YFYP were found to possess high 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging ability. Evaluation with HepG2 cells showed that the 4 peptides at low concentrations (< 1.0 mg/ml) protected the cells against oxidative damage. The 4 peptides exhibited different levels of antioxidant activity by stimulating mRNA and protein expression of the antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px), as well as nuclear factor erythroid-2-related factor 2 (Nrf2), but decreasing the mRNA expression of Kelch-like ECH-associated protein 1 (Keap1). Furthermore, these peptides decreased production of reactive oxygen species (ROS) and malondialdehyde (MDA), but increased glutathione (GSH) production in HepG2 cells. Therefore, the 4 casein-derived peptides obtained by using microbial proteases exhibited different antioxidant activity by activating the Keap1-Nrf2 signaling pathway, and they could serve as potential antioxidant agents in functional foods or pharmaceutic preparation.

Synthesis and pharmacological evaluation of a novel synthetic peptide CWHTH based on the Styela clava-derived natural peptide LWHTH with improved antioxidant, hepatoprotective and angiotensin converting enzyme inhibitory activities

LWHTH (Leu-Trp-His-Thr-His) is an antioxidant pentapeptide isolated from Styela clava tissue. Based on LWHTH, we designed and synthesized a series of novel peptides using the alanine scanning technique and determined the pharmacological activities of these derivatives. Among the ten newly synthesized LWHTH analogs, peptide CWHTH was identified as the most potent compound with prominent antioxidant activity. CWHTH not only showed the ability to scavenge several biologically important radicals, protected cells from H₂O₂ or APAP-induced damage by activating the PI3K/Akt and suppressing the JNK/c-Jun pathways, but also exerted strong in vivo hepatoprotective effects in an APAP-induced liver injury model in mice. Moreover, it was demonstrated that CWHTH possesses potent angiotensin converting enzyme (ACE) inhibitory activity and high stability against gastrointestinal proteases. In summary, CWHTH is a promising antioxidant peptide worthy of further investigation as a potential hepatoprotective and antihypertensive agent.

Production and Characterization of Medium-Sized and Short Antioxidant Peptides from Soy Flour-Simulated Gastrointestinal Hydrolysate

Soybeans (Glycine max) are an excellent source of dietary proteins and peptides with potential biological activities, such as antihypertensive, anti-cholesterol, and antioxidant activity; moreover, they could prevent cancer. Also, soy contains all the essential amino acids for nutrition; therefore, it represents an alternative to animal proteins. The goal of this paper was the comprehensive characterization of medium-sized and short peptides (two to four amino acids) obtained from simulated gastrointestinal digestion. Two different analytical approaches were employed for peptide characterization, namely a common peptidomic analysis for medium-sized peptides and a suspect screening analysis for short peptides, employing an inclusion list of exact m/z values of all possible amino acid combinations. Moreover, fractionation by preparative reversed-phase liquid chromatography was employed to simplify the starting protein hydrolysate. Six fractions were collected and tested for antioxidative activity by an innovative antioxidant assay on human gastric adenocarcinoma AGS cell lines. The two most active fractions (2 and 3) were then characterized by a peptidomic approach and database search, as well as by a suspect screening approach, in order to identify potential antioxidant amino acid sequences. Some of the peptides identified in these two fractions have been already reported in the literature for their antioxidant activity.