Neuroprotective effects of N-acetylglucosamine against hydrogen peroxide-induced apoptosis in human neuronal SK-N-SH cells by inhibiting the activation of caspase-3, PARP, and p38

Neuroprotective effects of N-acetylglucosamine (GlcNAc), a monosaccharide derivative of glucose, against H₂O₂-induced neurotoxicity and its underlying mechanism in human SK-N-SH neuroblastoma cells were investigated. Pretreatment of GlcNAc prior to exposure of cells to H₂O₂ stress significantly reduced the H₂O₂-mediated neuronal cell death and apoptosis. The GlcNAc dose-dependently decreased the level of intracellular reactive oxygen species (ROS) in H₂O₂-treated cells and also effectively inhibited H₂O₂-induced apoptotic features such as DNA fragmentation, caspase-3, and poly ADP-ribose polymerase (PARP) cleavages, and p38 phosphorylation. These results suggested that GlcNAc might potentially serve as agents for prevention of neurodegenerative diseases caused by oxidative stresses and this effect may be associated with the suppression of caspase-3, PARP, and p38 activation.     

Molecular mechanism underlying anti-apoptotic and anti-inflammatory effects of Mamao (Antidesma thwaitesianum Müll. Arg.) polyphenolics in human breast epithelial cells

There has been increasing interest in finding natural antioxidants to prevent free radical damage and retard the progress of chronic inflammatory diseases. Our previous data demonstrated the strong antioxidant properties of polyphenolics in Mamao seed (MS) and Mamao marc (MM) extracts. In this study we further investigated the effect of MS and MM polyphenolics on hydrogen peroxide (H₂O₂)-induced apoptosis and tumour promoter 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced inflammation, using human breast epithelial (MCF10A) cells. MS and MM extracts conferred dose-dependent protection against H₂O₂-induced apoptosis by inhibiting PARP/caspase-3 cleavage, inducing anti-apoptotic Bcl-2 expression, and down-regulating pro-apoptotic Bax. Moreover, MS and MM polyphenolics inhibited TPA-induced COX-2 and NF-κB activation by blocking the degradation of cytoplasmic IκBα, as well as subsequent nuclear translocation of p65 and attenuation of the activation of ERK, but not JNK and p38. These data establish the molecular mechanism for the anti-apoptotic and anti-inflammatory effects of MS and MM polyphenolics.     

Quercitrin protects against oxidative stress-induced injury in lung fibroblast cells via up-regulation of Bcl-xL

The cytoprotective effect of quercitrin (QR) against oxidative stress induced cell damage by hydrogen peroxide (H₂O₂) in Chinese hamster lung fibroblast (V79-4) cells was investigated. QR evidenced a scavenging effect of 1,1-diphenyl-2-picrylhydrazyl (DPPH), superoxide, hydroxyl radicals and on intracellular ROS, and thus prevented lipid peroxidation. As a result, QR reduced H₂O₂-induced cell death and apoptosis in V79-4 cells. Moreover, H₂O₂ induced the cleavage of caspase-3, -9, and poly-ADP-ribose polymerase (PARP) and a reduction in Bcl-xL levels, whereas pretreatment with QR significantly inhibited caspase-3, -9, and PARP cleavage and the reduction in Bcl-xL levels, and ultimately ameliorated H₂O₂-induced apoptosis. Taken together, these results indicate that the treatment of V79-4 cells with QR can block H₂O₂-induced apoptosis via the regulation of Bcl-xL. QR may be exploited as a biopreservative in food applications or as a health supplement to alleviate oxidative stress.     

Oryzadine,a new alkaloid of Oryza sativa cv. Heugjinjubyeo, attenuates oxidative stress-induced cell damage via a radical scavenging effect

The antioxidant properties of oryzadine, a new alkaloid, obtained from Oryza sativa cv. Heugjinjubyeo was investigated by applying various methods based on cell-free and cell experiments. Oryzadine showed scavenging effects on the hydroxyl radical, superoxide radical, and intracellular reactive oxygen species (ROS). Oryzadine inhibited H₂O₂-induced DNA damage, which was demonstrated by DNA tail formation, lipid peroxidation which was demonstrated by the formation of thiobarbituric acid reactive substance (TBARS), and protein oxidation which was demonstrated by protein carbonyl formation. Therefore, oryzadine protected H₂O₂-induced cell damage. Our results show that the cytoprotective effects of oryzadine stem from its ability to inhibit H₂O₂-induced apoptosis, as demonstrated by a decrease in apoptotic body formation and the inhibition of mitochondrial membrane potential (ΔΨ) loss. Taken together, these findings suggest that oryzadine protected cells against H₂O₂-induced cell damage via ROS scavenging effect. Therefore, oryzadine could be considered a significant natural source of antioxidant.     

s‐Ethyl Cysteine and s‐Methyl Cysteine Protect Human Bronchial Epithelial Cells Against Hydrogen Peroxide Induced Injury

Protective effects and actions from s‐ethyl cysteine (SEC) and s‐methyl cysteine (SMC) for BEAS‐2B cells were examined. BEAS‐2B cells were pretreated with SEC or SMC at 4, 8, or 16 μmol/L, and followed by hydrogen peroxide (H₂O₂) treatment. Data showed that H₂O₂ enhanced Bax, caspase‐3 and caspase‐8 expression, and declined Bcl‐2 expression. However, SEC or SMC dose‐dependently decreased caspase‐3 expression and reserved Bcl‐2 expression. H₂O₂ increased reactive oxygen species (ROS) production, and lowered glutathione level, glutathione peroxide, and glutathione reductase activities in BEAS‐2B cells. SEC or SMC pretreatments reduced ROS generation, and maintained glutathione redox cycle in those cells. H₂O₂ upregulated the expression of both p47^phox and gp91^phox. SEC and SMC downregulated p47^phox expression. SEC or SMC at 8 and 16 μmol/L decreased H₂O₂‐induced release of inflammatory cytokines. H₂O₂ stimulated the activation of nuclear factor‐κB (NF‐κB) and mitogen‐activated protein kinase. SEC and SMC pretreatments dose‐dependently downregulated NF‐κB p65 and p‐p38 expression. Pyrrolidine dithiocarbamate or SB203580 inhibited NF‐κB activation and p38 phosphorylation; thus, SEC or SMC pretreatments failed to affect protein expression of these factors. These novel findings suggest that SEC or SMC could protect bronchial cells and benefit respiratory epithelia stability and functions.     

Catechin-7-O-β-d-glucopyranoside scavenges free radicals and protects human B lymphoma BJAB cells on H2O2-mediated oxidative stress

Catechin-7-O-β-d-glucopyranoside (CA-G) was previously isolated from red bean (the seed of Phaseolus calcaratus cv. Roxburgh). This study examined the ability of CA-G to scavenge reactive oxygen species generated by cell-free systems and to protect cells from oxidative stress caused by hydrogen peroxide (H₂O₂). The mechanism by which CA-G exerts its antioxidant and anti-apoptotic action on H₂O₂-exposed cells was also investigated. CA-G treatment prevented H₂O₂-mediated apoptosis and inhibited the formation of single stand breaks in DNA in H₂O₂-exposed BJAB cells. CA-G suppressed mitochondrial stress and caspase activation caused by H₂O₂. Mechanistic experiments revealed that the antioxidant mechanism of CA-G on H₂O₂-mediated oxidative damage was due to the direct scavenging of hydroxyl radicals and/or to the chelation of metal ions that were used to produce hydroxyl radicals from H₂O₂ via the Fenton reaction. Collectively, these findings suggest beneficial roles of CA-G or CA-G-rich red bean on the protection from oxidative damage.     

Nuclear factor erythroid 2-related factor 2 antioxidant response element pathways protect bovine mammary epithelial cells against H2O2-induced oxidative damage in vitro

The experiment was conducted to determine the role of nuclear factor (erythroid-derived 2)-like factor 2 (NFE2L2, formerly Nrf2) antioxidant response element (ARE) pathway in protecting bovine mammary epithelial cells (BMEC) against H₂O₂-induced oxidative stress injury. An NFE2L2 small interfering RNA (siRNA) interference or a pCMV6-XL5-NFE2L2 plasmid fragment was transfected to independently downregulate or upregulate expression of NFE2L2. Isolated BMEC in triplicate were exposed to H₂O₂ (600 μM) for 6 h to induce oxidative stress before transient transfection with scrambled siRNA, NFE2L2-siRNA, pCMV6-XL5, and pCMV6-XL5-NFE2L2. Cell proliferation, apoptosis and necrosis rates, antioxidant enzyme activities, reactive oxygen species (ROS) and malondialdehyde (MDA) production, protein and mRNA expression of NFE2L2 and downstream target genes, and fluorescence activity of ARE were measured. The results revealed that compared with the control, BMEC transfected with NFE2L2-siRNA3 had proliferation rates that were 9 or 65% lower without or with H₂O₂, respectively. These cells also had apoptosis and necrosis rates that were 27 and 3.5 times greater with H₂O₂ compared with the control group, respectively. In contrast, transfected pCMV6-XL5-NFE2L2 had proliferation rates that were 64.3% greater or 17% lower without or with H₂O₂ compared with the control group, respectively. Apoptosis rates were 1.8 times lower with H₂O₂ compared with the control. In addition, compared with the control, production of ROS and MDA and activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), catalase (CAT), and glutathione-S-transferase (GST) increased markedly in cells transfected with pCMV6-XL5-NFE2L2 and without H₂O₂. However, compared with the control, production of ROS and MDA and activity of CAT and GSH-Px increased markedly, whereas activities of SOD and GST decreased in cells transfected with pCMV6-XL5-NFE2L2 and incubated with H₂O₂. Compared with the control, cells transfected with NFE2L2-siRNA3 with or without H₂O₂ had lower production of ROS and MDA and activity of SOD, CAT, GSH-Px, and GST. Cells transfected with pCMV6-XL5-NFE2L2 with or without H₂O₂ had markedly higher protein and mRNA expression of NFE2L2, heme oxygenase-1 (HMOX-1), NADH quinone oxidoreductase 1, glutamate cysteine ligase catalytic subunit, and glutamyl cystine ligase modulatory subunit compared with the control incubations. Cells transfected with NFE2L2-siRNA3 without or with H₂O₂ had markedly lower protein and mRNA expression of NFE2L2, HMOX-1, NADH quinone oxidoreductase 1, glutamyl cystine ligase modulatory subunit, and glutamate-cysteine ligase catalytic subunit compared with the control incubations. In addition, expression of HMOX-1 was 5.3-fold greater with H₂O₂ compared with the control. Overall, results indicate that NFE2L2 plays an important role in the NFE2L2-ARE pathway via the control of HMOX-1. The relevant mechanisms in vivo merit further study.     

Effect of heat-shock protein B7 on oxidative stress in adipocytes from preruminant calves

Dairy cows with ketosis display excessive lipolysis in adipose tissue. Heat-shock protein B7 (HSPB7), a small heat-shock protein, plays important roles in mediating cytoprotective responses to oxidative stress in rodent adipose tissue. Accordingly, it is assumed that HSPB7 may also play important roles in the antioxidant response in adipose tissue of ketotic cows. Therefore, the aim of this study is to investigate (1) the redox state of adipose tissue in ketotic cows and (2) the role and mechanism of HSPB7 on the regulation of oxidative stress in adipocytes from preruminant calves. An in vivo study consisting of 15 healthy and 15 clinically ketotic cows was performed to harvest subcutaneous adipose tissue and blood samples. In addition, adipocytes isolated from calves were treated with different concentrations of H₂O₂ (0, 12.5, 25, 50, 100, or 200 μM) for 2 h, transfected with adenovirus-mediated overexpression of HSPB7 for 48 h, or transfected with small interfering RNA of HSPB7 for 48 h followed by exposure to H₂O₂ (200 μM) for 2 h. Serum concentrations of nonesterified fatty acids and β-hydroxybutyrate were greater in cows with clinical ketosis, whereas serum concentration of glucose was lower. Compared with healthy cows, the malondialdehyde content was greater but the activity of glutathione peroxidase and superoxide dismutase was lower in adipose tissue of clinically ketotic cows. The abundance of HSPB7 and nuclear factor, erythroid 2 like 2 (NFE2L2) was greater in adipose tissue of clinically ketotic cows. In vitro, H₂O₂ treatment induced the overproduction of reactive oxygen species and malondialdehyde, and inhibited the activity of antioxidant enzymes glutathione peroxidase and superoxide dismutase in adipocytes from preruminant calves. The low concentration of H₂O₂ (12.5, 25, and 50 μM) increased the abundance of HSPB7 and NFE2L2, but high concentrations of H₂O₂ (100 or 200 μM) reduced the abundance of HSPB7 and NFE2L2. The overexpression of HSPB7 improved the H₂O₂-induced oxidative stress in adipocytes via increasing the abundance of NFE2L2 and its downstream target genes heme oxygenase-1 (HMOX1) and NADH quinone oxidoreductase 1 (NQO1). Knockdown of HSPB7 markedly inhibited the expression of NFE2L2, HMOX1, and NQO1 and further exacerbated H₂O₂-induced oxidative stress. Overall, these results indicate that activation of the HSPB7-NFE2L2 pathway increases cellular antioxidant capacity, thereby alleviating oxidative stress in bovine adipocytes.     

Curcumin protects mouse neuroblastoma Neuro-2A cells against hydrogen-peroxide-induced oxidative stress

Curcumin has been traditionally used in China and India for food and medicinal purposes. It has been shown to possess potent antioxidative activity both in vitro and in vivo. In the present study, the neuroprotective effects and the potential mechanisms of curcumin against H₂O₂-induced oxidative stress in mouse neuroblastoma Neuro-2A cells were investigated. Treatment with curcumin at 20 and 25 μg/mL for 1 h prior to H₂O₂ exposure significantly attenuated cell viability loss, reduced apoptosis, suppressed the elevation of intracellular reactive oxygen species (ROS) and calcium levels, and stabilised mitochondrial membrane potential. Furthermore, curcumin could block H₂O₂-mediated degradation of the protein IκBα and subsequent activation of nuclear factor κB, thus inhibiting the expression of its target gene cyclooxygenase 2. These results indicate that curcumin has potential protective effects against H₂O₂-induced oxidative stress in neuron cells, which might make curcumin a suitable therapeutic agent for prevention and treatment of neurodegenerative diseases associated with oxidative stress.     

Cytoprotective effect of white tea against H2O2-induced oxidative stress in vitro

The protective effect of water extracts of white tea (WEWT) on oxidative stress in vitro is investigated. WEWT, like water extracts of green tea (WEGT) and water extracts of Pu-erh tea (WEPT), demonstrates a marked inhibition of the oxidation of liposome, albumin and LDLmodel systems. WEWT protects against H₂O₂-induced cytotoxicity, in a dose-dependent manner. The inhibition of ROS generation and MDA formation by WEWT in H₂O₂-induced Clone 9 cells parallels the effects on cell viability. Moreover, GSH and antioxidant enzymes may play an important role in the protective effect that is associated with H₂O₂-induced oxidative stress. The HPLC-DAD and HPLC–MS/MS analysis, shows that sixteen bioactive compounds are present in WEWT, which may partially account for its protective effect against oxidative insult. These results suggest that the mechanism of the protective actions of WEWT is related to its antioxidant potential and the maintenance of the normal redox status of the cell.     

Effects of hydrogen peroxide and l-tryptophan on antioxidative potential,apoptosis, and mammalian target of rapamycin signaling in bovine intestinal epithelial cells

Amino acids are primarily absorbed in the ruminant small intestine, and the small intestine is a target organ prone to oxidative stress, causing intestinal disfunction. Previous study suggested that l-Trp could benefit intestinal function and production performance. This study aimed to explore the effects of l-Trp on hydrogen peroxide (H₂O₂)-induced oxidative injury in bovine intestinal epithelial cells (BIEC) and the potential mechanism. The effects of l-Trp on cell apoptosis, antioxidative capacity, AA transporters, and the mammalian target of rapamycin (mTOR) signaling pathway were evaluated in BIEC treated with 0.8 mM l-Trp for 2 hours combined with or without H₂O₂ induction. In addition, to explore whether the effects of 0.8 mM l-Trp on oxidative stress were related to mTOR, an mTOR-specific inhibitor was used. The percentage of apoptosis was measured using flow cytometry. The relative gene abundance and protein expression in BIEC were determined using real-time PCR and Western blot assay, respectively. Results showed l-Trp at 0.4 and 0.8 mM enhanced the cell viability, and it was inhibited by l-Trp at 6.4 mM. l-Tryptophan at 0.4, 0.8, and 1.6 mM remarkably decreased the percentage of apoptosis and enhanced antioxidative capacity in H₂O₂-mediated BIEC. Moreover, l-Trp at 0.8 mM increased the relative gene abundance and protein expression of antioxidative enzymes and AA transporters, and the mTOR signaling pathway. The mTOR inhibitor lowered the protein expression of large neutral amino acid transporter 1, but the inhibition of mTOR did not alter the activities of catalase and superoxide dismutase or protein expression of alanine-serine-cysteine transporter 2 with or without H₂O₂ induction. l-Tryptophan increased catalase and superoxide dismutase activities in H₂O₂-mediated BIEC, although not with a present mTOR inhibitor. l-Tryptophan increased the protein expression of large neutral amino acid transporter 1 and alanine-serine-cysteine transporter 2 in H₂O₂-mediated BIEC with or without the presence of an mTOR inhibitor. The present work suggested that l-Trp supplementation could alleviate oxidative injury in BIEC by promoting antioxidative capacity and inhibiting apoptosis, and the mTOR signal played vital roles in the alleviation.     

The production of hydrogen peroxide is not a common mechanism by which olive oil phenols induce apoptosis on HL60 cells

We have recently demonstrated that hydroxytyrosol (3,4-DHPEA), the most representative olive oil phenol, induces apoptosis on HL60 cells through the production of considerable amount of extracellular hydrogen peroxide (H₂O₂). The aims of the present investigation were first to assess the ability of different phenolic compounds to both produce extracellular H₂O₂ and induce apoptosis on HL60 cells, and second to elucidate whether the pro-apoptotic activity was mediated by the production of H₂O₂ in the cell culture medium. Based on the results phenols can be classified as follows: (1) those which were not able to induce both apoptosis and H₂O₂ accumulation (tyrosol, homovanillic alcohol and protocatechuic, o-coumaric, vanillic, homovanillic, ferulic and syringic acids); (2) those which showed a pro-apoptotic activity mediated, at least in part, by the production of H₂O₂, as evidenced by the ability of catalase to inhibit apoptosis (3,4-DHPEA, dopamine, 3,4-dihydroxyphenylacetic, 3,4-dihydroxy-hydrocinnamic, caffeic and gallic acids); and (3) those which induced apoptosis without the involvement of H₂O₂ (the secoiridoid derivatives of both hydroxytyrosol and tyrosol). Oleuropein showed a peculiar behaviour since, and although it caused an abundant production of H₂O₂ in the cell culture medium, it exerted a weak pro-apoptotic effect. From these results we may conclude that the cathecol moiety of the phenol molecule is necessary for the H₂O₂ producing activity, and that the 3,4-DHPEA metabolism to homovanillic alcohol and homovanillic acid may significantly reduce its pro-apoptotic potential. The real in vivo meaning of the phenol-induced H₂O₂ production remains to be investigated.     

Antioxidant activity and antiproliferative action of methanol extracts of 4 different colored bell peppers (Capsicum annuum l.)

Methanol extracts of 4 different colored (red, orange, yellow, and green) bell peppers (Capsicum annuum L.) were examined to (1) determine the total phenolic content (TPC), (2) compare the antioxidant activities, (3) assess the protective effects of extracts on H₂O₂-induced and 4-hydroxy-2-nonenal (HNE)-induced DNA damage using the Comet assay, and (4) examine the antiproliferative action of their extracts on HT-29 cells. Red and orange bell peppers had significantly higher levels of TPC than yellow or green bell peppers. Orange bell pepper exhibited the highest level of radical scavenging activity and total antioxidant activity, while green bell pepper exhibited the highest superoxide dismutase-like activity. These results suggest that the difference in antioxidant activities may depend on the kinds of antioxidant compounds related to the color of the pepper. It was found a significant negative correlation between TPC and radical scavenging activity inhibiting capacity (IC)₅₀, and a significant positive corretation between TPC and total antioxidant activity. All extracts of bell pepper inhibited H₂O₂-induced and 4-hydroxy-2-nonenal-induced DNA damage in human leukocytes and showed potential toxicity on HT-29 cells. These findings suggest that the 4 different colored bell peppers may be useful as antioxidants and cancer prevention in food.     

Antioxidant activity of Fragilariopsis pseudonana and protective effect against hydrogen peroxide-induced inhibition of gap junctional intercellular communication

This study was aimed to evaluate antioxidant activities of a methanol extract from the polar microalgae Fragilariopsis pseudonana (FP) and to investigate the protective effect for gap junctional intercellular communication (GJIC) in WB-F344 normal rat liver epithelial cells. The results indicated that the methanol extract of FP (FPM) scavenged ABTS free radicals and inhibited copper-induced low density lipoprotein oxidation in a dose-dependent manner. Exposing HepG2 cells to FeSO₄ increased intracellular reactive oxygen species formation and lipid peroxides, which was significantly reduced by treatment with FPM. Furthermore, FPM increased the activities of superoxide dismutase and glutathione peroxidase in cells. FPM recovered the hydrogen peroxide (H₂O₂)-induced inhibition of GJIC and attenuated the phosphorylation of connexin 43 (Cx43) and extracellular signal-regulated kinase1/2 (ERK1/2). Taken together, these results demonstrated that FPM has antioxidant activity and protects against H₂O₂-induced inhibition of GJIC by blocking phosphorylation of Cx43 via activation of ERK1/2.     

Selenomethionine increases proliferation and reduces apoptosis in bovine mammary epithelial cells under oxidative stress

The decline in mammary epithelial cell number as lactation progresses may be due, in part, to oxidative stress. Selenium is an integral component of several antioxidant enzymes. The present study was conducted to examine the effect of oxidative stress and selenomethionine (SeMet) on morphology, viability, apoptosis, and proliferation of bovine mammary epithelial cells (BMEC) in primary culture. Cells were isolated from mammary glands of lactating dairy cows and grown for 3 d in a low-serum gel system containing lactogenic hormones and 0 or 100 μM H₂O₂ with 0, 10, 20, or 50 nM SeMet. Hydrogen peroxide stress increased intracellular H₂O₂ to 3 times control concentrations and induced a loss of cuboidal morphology, cell-cell contact, and viability of BMEC by 25%. Apoptotic cell number more than doubled during oxidative stress, but proliferating cell number was not affected. Supplementation with SeMet increased glutathione peroxidase activity 2-fold and restored intracellular H₂O₂ to control levels with a concomitant return of morphology and viability to normal. Apoptotic BMEC number was decreased 76% below control levels by SeMet and proliferating cell number was increased 4.2-fold. These findings suggest that SeMet modulated apoptosis and proliferation independently of a selenoprotein-mediated reduction of H₂O₂. In conclusion, SeMet supplementation protects BMEC from H₂O₂-induced apoptosis and increased proliferation and cell viability under conditions of oxidative stress.     

Collagen peptides from Acaudina molpadioides prevent CCl4-induced liver injury via Keap1/Nrf2-ARE,PI3K/AKT,and MAPKs pathways

Collagen peptide from Acaudina molpadioides (AMP) showed antioxidative activity in H₂O₂-induced RAW264.7 cells in our pervious study. In this study, it was observed that AMP could effectively improve the morphology and function of liver in CCl₄-induced mice. After 200 mg/kg AMP treatment, the content of MDA in liver decreased by 62.3%, and the level of antioxidant enzymes (SOD, GSH-Px, and CAT) increased by more than 65%. Western blot results disclosed that AMP (200 mg/kg) upregulated the Nrf2 level by 73.8% and downregulated Keap1 by 41.0% in CCl₄-induced mice liver. The levels of p-ERK, p-JNK, and p-p38 in 200 mg/kg AMP treatment groups decreased by 57.3%, 40.9%, and 40.6%, but the levels of p-PI3K and p-AKT increased by 162.6% and 60.3%, respectively. Furthermore, the trends of Nrf2, Keap1, p-ERK, p-JNK, p-p38, p-PI3K, and p-AKT levels in H₂O₂-induced RAW264.7 cells after AMP treatment were similar to the results in CCl₄-induced mice liver. These findings provided evidence that AMP exerted antioxidant activity via Keap1/Nrf2-ARE, PI3K/AKT, and MAPKs pathways in vivo and in vitro. Therefore, the collagen peptide from A. molpadioides might represent a novel functional food to prevent acute liver injury via attenuation of oxidative stress.     

Identification of antioxidative peptides from defatted walnut meal hydrolysate with potential for improving learning and memory

Defatted walnut meal (DWM), a main byproduct of walnut oil production, is rich in proteins with a high essential amino acid content. Our research was focused on the functional activities of defatted walnut meal hydrolysate (DWMH). DWMH exhibited relatively strong hydroxyl scavenging and oxygen radical absorbance capacities, protective effect on H₂O₂-injured PC12 cells compared with GSH and cerebrolysin. Besides, DWMH could combat d-galactose induced learning and memory impairments in the Morris water maze test and in the Dark/light avoidance test of mice. Seventy-seven peptides were identified by UPLC-ESI-MS/MS in the most potent antioxidative fraction of DWMH. WSREEQEREE and ADIYTEEAGR were the peptides that most likely accounted for the suppression of H₂O₂-induced apoptosis in PC12 cells. The mixture of the commercially available amino acids did not offer any protection on H₂O₂-injured PC12 cells, suggesting that amino acid sequence rather than amino acid composition was the dominant influencing factor. DWMH could be recommended as natural antioxidants for the development of functional foods targeting memory impairments.     

Cytoprotective activity of lotus (Nelumbo nucifera Gaertner) leaf extracts on the mouse embryonic fibroblast cell

This study was conducted to evaluate the cytoprotective activity of lotus (Nelumbo nucifera Gaertner) leaf extract (LLE) on mouse embryonic fibroblast (MEF) cells. The 2-diphenyl-1-picrylhydrazyl hydrate (DPPH) free radical scavenging activities of LLE increased in a concentration dependent manner. The cells, damaged by oxidative stress, decreased their viability following increasing concentration of H₂O₂, but the co-treatment of n-butanol fraction of LLE and H₂O₂ resulted in an increase in cell growth, by about 25%, compared to the cells treated with H₂O₂. The n-butanol fraction of LLE inhibited the cytotoxicity induced by H₂O₂ in a concentration dependent manner. The oxidative damage to the cells, measured by apoptotic and necrotic cell accumulation, was similar with the addition of the n-butanol fraction of LLE to H₂O₂. Taken together, these results suggest that LLE inhibited the cytotoxicity which is induced by H₂O₂, and has a protective effect on MEF cell against oxidative stress.