Fucoxanthin enhances HO-1 and NQO1 expression in murine hepatic BNL CL.2 cells through activation of the Nrf2/ARE system partially by its pro-oxidant activity

To determine whether fucoxanthin, a major carotenoid in brown sea algae, may activate cellular antioxidant enzymes via up-regulation of the Nrf2/antioxidant-response element (ARE) pathway, we incubated mouse hepatic BNL CL.2 cells with fucoxanthin (0.5-20 μM) for 0-24 h. We found that fucoxanthin (≥5 μM) significantly increased cellular reactive oxygen species (ROS) at 6 h of incubation, whereas preincubation with α-d-tocopherol (30 μM) significantly attenuated the increase of ROS, indicating the pro-oxidant nature of fucoxanthin. Fucoxanthin significantly increased the phosphorylation of ERK and p38 and markedly increased nuclear Nrf2 protein accumulation after incubation for 12 h. Moreover, fucoxanthin significantly enhanced binding activities of nuclear Nrf2 with ARE and increased mRNA and protein expression of HO-1 and NQO1 after incubation for 12 h. siRNA inhibition of Nrf2 led to markedly decreased HO-1 and NQO1 protein expression. Thus, fucoxanthin may exert its antioxidant activity, at least partly, through its pro-oxidant actions.     

Juice and phenolic fractions of the berry Aristotelia chilensis inhibit LDL oxidation in vitro and protect human endothelial cells against oxidative stress

Oxidative modification of low-density lipoprotein (LDL) particles is a key event in the development of atherosclerosis. Oxidized LDL induces oxidative stress and modifies gene expression in endothelial cells. Berries constitute a rich dietary source of phenolic antioxidants. We found that the endemic Chilean berry Aristotelia chilensis (ach) has higher phenol content and scores better for total radical-trapping potential and total antioxidant reactivity in in vitro antioxidant capacity tests, when compared to different commercial berries. The juice of ach is also effective in inhibiting copper-induced LDL oxidation. In human endothelial cell cultures, the addition of ach juice significantly protects from hydrogen peroxide-induced intracellular oxidative stress and is dose-dependent. The aqueous, anthocyanin-rich fraction of ach juice accounts for most of ach's antioxidant properties. These results show that ach is a rich source of phenolics with high antioxidant capacity and suggest that it may have antiatherogenic properties.     

Oligophosphopeptides derived from egg yolk phosvitin up-regulate gamma-glutamylcysteine synthetase and antioxidant enzymes against oxidative stress in Caco-2 cells

Previously, we have found phosphopeptides (PPPs) from hen egg yolk phosvitin possess a potent antioxidative activity against oxidative stress in human intestinal epithelial cells, Caco-2. However, their biological activity at the cellular level has not yet fully understood. The objective of this study is to evaluate the regulation of glutathione (GSH) biosynthesis-associated and antioxidant enzymes against oxidative stress in Caco-2 cells using an in vitro model. Treatment of 1 mM H2O2-induced Caco-2 cells with PPPs increased cellular GSH levels, concomitant with a significant increase in gamma-glutamylcysteine synthetase (gamma-GCS) activity and the expression of gamma-GCS heavy subunit mRNA. Furthermore, intracellular glutathione reductase, glutathione S-transferase, and catalase activities were elevated by PPPs. In addition, PPPs with high content of phosphorus showed higher induction of these enzyme activities than PPPs without phosphorus. These data indicate that oligophosphopeptides from hen egg yolk phosvitin can up-regulate cellular GSH biosynthesis-associated enzymes activity and antioxidative activities, which play key roles against tissue oxidative stress in the human intestinal epithelial cells.     

Effect of hesperetin against oxidative stress via ER- and TrkA-mediated actions in PC12 cells

Hesperetin is known to activate estrogen receptors (ERs). Estrogen-mediated neuroprotection could be via both ER and tyrosine kinase receptor (Trk) signaling. This study tested whether hesperetin protected PC12 cells from hydrogen peroxide induced oxidative damage via ER- and/or TrkA-mediated actions. Hesperetin (0.1, 1, and 50 μM) inhibited cell viability decreases and reactive oxygen species, intracellular calcium level, and caspase-3 activity increases in H(2)O(2)-induced PC12 cells. Such actions were significantly (p < 0.05) suppressed by ICI 182,780 (an ER antagonist) or K252a (a TrkA antagonist) at low concentrations (0.1 or 1 μM) only. Hesperetin also stimulated the activation of Akt, ERK, and CREB as well as induced brain-derived neurotrophic factor, PPARγ coactivator 1α (PGC-1α), and seladin-1 (selective Alzheimer's disease indicator-1) via both ER and TrkA in the cells. This study demonstrates that the neuroprotective effects of hesperetin, at low concentrations, are attributed to its stimulation on receptor signaling. Moreover, ER and TrkA are known to be expressed in most Alzheimer's disease (AD) vulnerable brain regions. This study thus suggests that hesperetin might have potential for intervention in neurodegenerative disorders, particularly for AD.     

Influence of delphinidin-3-glucoside on oxidized low-density lipoprotein-induced oxidative stress and apoptosis in cultured endothelial cells

Increased oxidative stress and apoptosis were detected in atherosclerotic lesions. Oxidized low-density lipoprotein (oLDL) may induce oxidative stress and apoptosis via multiple pathways in vascular endothelial cells (EC). Delphinidin-3-glucoside (D3G), an anthocyanidin glycan enriched in dark-skin berries, may neutralize those effects of oLDL in EC. The present study demonstrated that oLDL increased the generation of intracellular NADPH-dependent superoxide and impaired redox status in cultured porcine aortic EC (PAEC). The activities of mitochondrial respiratory chain complex I-IV and the contents of NADH dehydrogenase (ND)1, ND6 (complex I enzyme subunits), or cytochrome b (complex III enzyme subunit) were significantly reduced in PAEC treated with oLDL compared to controls. Treatment with oLDL significantly increased the abundances of NADPH oxidase (NOX)2, NOX4, and p22phox in PAEC. oLDL reduced cell viability and the protein content of B-cell lymphoma (Bcl)-2, but increased the content of caspase 3 in PAEC. Co-treatment with D3G prevented oLDL-induced increases in intracellular superoxide or in the protein content of NOX2, NOX4, p22phox, or caspase 3, inhibited the impairment of redox statues or cell viability, and prevented the attenuation of mitochondrial enzyme activities and the reductions of Bcl-2, ND1, or cytochrome b contents in PAEC. The findings suggest that oLDL induced oxidative stress and apoptosis in EC, which was associated with the activation of NOX, the impairment of mitochondrial respiration chain enzymes, and the disorder of key regulators for apoptosis. D3G neutralized the harmful effects of oLDL on oxidative stress, mitochondrial dysfunction, and apoptosis in cultured vascular EC.     

Identification of hen egg yolk-derived phosvitin phosphopeptides and their effects on gene expression profiling against oxidative stress-induced Caco-2 cells

Oxidative stress is involved in the initiation and propagation of chronic intestinal pathologies. Bioactive peptides such as egg yolk-derived phosvitin phosphopeptides (PPP3) have been previously shown to reduce in vitro oxidative stress by up-regulating glutathione synthesis and antioxidant enzyme activities. Peptide and gene expression profile analysis of the PPP3 peptides can provide insight into structures involved in signal transduction mechanisms in the antioxidative stress response. The objectives of this research were to identify the PPP3 amino acid sequences before and after simulated gastrointestinal digestion and to assess the genes influenced by PPP3. Peptide sequences were analyzed using ESI Q-TOF-MS/MS, and the expression profile of 84 human oxidative stress and antioxidant defense genes were analyzed. Undigested PPP3 was composed of three main peptides: GTEPDAKTSSSSSSASSTATSSSSSSASSPNRKKPMDE (phosvitin-PV residues 4-41), NSKSSSSSSKSSSSSSRSRSSSKSSSSSSSSSSSSSSKSSSSR (PV residues 155-197), and EDDSSSSSSSSVLSKIWGRHEIYQ (PV residues 244-257) and their fragments. There was limited degradation of PPP3 after gastrointestinal digestion as deduced from the fragment sizes of digested PPP3, which ranged from 5 to 32 amino acids. These fragments were rich in contiguous serines and, in some cases, monoesterified with phosphate. Both undigested and digested PPP3 significantly reduced IL-8 secretion in H(2)O(2)-induced Caco-2 cells, indicating that antioxidative stress bioactivity is retained upon digestion. After PPP3 pretreatment, antioxidant genes associated with oxygen and reactive oxygen species (ROS) metabolism and cellular responses to chemical stimulus, oxidative stress, and ROS are up-regulated in the presence and absence of oxidative stress, thereby contributing to the prevention of intestinal oxidative stress and the promotion of gut health.     

Acacetin induces apoptosis in human gastric carcinoma cells accompanied by activation of caspase cascades and production of reactive oxygen species

Acacetin (5,7-dihydrocy-4'-methoxy flavone), which is a flavonoid compound, possesses anti-peroxidative and anti-inflammatory effects. The effects of acacetin on cell viability in human gastric carcinoma AGS cells were investigated. This study demonstrated that acacetin was able to inhibit cell proliferation and induce apoptosis in a concentration- and time-dependent manner. Acacetin-induced cell death was characterized with changes in nuclear morphology, DNA fragmentation, and cell morphology. The molecular mechanism of acacetin-induced apoptosis was also investigated. Treatment with acacetin caused induction of caspase-3 activity in a time-dependent manner, but not caspase-1 activity, and induced the degradation of DNA fragmentation factor (DFF-45) and poly(ADP-riobse) polymerase. Cell death was completely prevented by a pancaspase inhibitor, Z-Val-Ala-Asp-fluoromethyl ketone. Furthermore, treatment with acacetin caused a rapid loss of mitochondrial transmembrane potential, stimulation of reactive oxygen species (ROS), release of mitochondrial cytochrome c into cytosol, and subsequent induction of procaspase-9 processing. Antioxidants such as N-acetylcysteine and catalase, but not superoxide dismutase, allopurinol, or pyrrolidine dithiocarbamate, significantly inhibited acacetin-induced cell death. In addition, it was found that acacetin promoted the up-regulation of Fas and FasL prior to the processing and activation of pro-caspase-8 and cleavage of Bid, suggesting the involvement of a Fas-mediated pathway in acacetin-induced apoptosis. On the other hand, the results showed that acacetin-induced apoptosis was accompanied by up-regulation of Bax and p53, down-regulation of Bcl-2, and cleavage of Bad. Taken together, these results suggest that ROS production and a certain intimate link might exist between receptor- and mitochondria-mediated death signalings that committed to acacetin-induced apoptosis in AGS cells. The induction of apoptosis by acacetin may provide a pivotal mechanism for its cancer chemopreventive action.     

Effect of diallyl sulfide on in vitro and in vivo Nrf2-mediated pulmonic antioxidant enzyme expression via activation ERK/p38 signaling pathway

Increasing oxidative stress is intimately involved in the pathogenesis of lung failure. Nuclear factor-erythroid 2 related factor 2 (Nrf2) is a key element in redox homeostasis. Nrf2 regulates antioxidant-associated genes that are often the target of phytochemicals in chemoprevention. This study evaluated the effect of diallyl sulfide (DAS), which is present in garlic, on the expression of antioxidant enzymes in the rat lung and the Nrf2 modulation in MRC-5 lung cells. DAS increased the activities of glutathione S-transferase, glutathione reductase, and catalase as well as the GSH/GSSG ratio compared with the lung of untreated control rats (p < 0.05). The pulmonic superoxide dismutase, glutathione peroxidase, NAD(P)H:quinone oxidoreductase 1, and catalase mRNA levels were also significantly increased (p < 0.05) after DAS treatment. Following DAS treatment, DAS level was measured in the plasma after 7 days of oral administration, and the C(max) value was 15 ± 4.2 μM. The total amount of pulmonic Nrf2 and the nuclear translocation of Nrf2 were elevated in DAS-treated rats, clarifying the effect of DAS on the modulation of antioxidant enzymes. Furthermore, DAS could induce nuclear translocation of Nrf2 via ERK/p38 signaling pathway in lung MRC-5 cells. This study demonstrates that DAS administration can significantly induce the activity of antioxidant enzymes in rat lungs and suggests a possible use for DAS as a dietary preventive agent against oxidative stress-induced lung injury.     

Effects of capsaicin on induction of apoptosis and inhibition of adipogenesis in 3T3-L1 cells

Currently, at the beginning of the 21st century, obesity has become the leading metabolic disease in the world. It is a serious health problem in industrialized countries. Previous research has suggested that decreased preadipocyte differentiation and proliferation and decreased lipogenesis are mechanisms to reduce obesity. In the present study, the effects of capsaicin on the induction of apoptosis and inhibition of lipid accumulation in 3T3-L1 preadipocytes and adipocytes were investigated. The results demonstrated that capsaicin decreased cell population growth of 3T3-L1 preadipocytes, assessed with the MTT assay. Flow cytometric analysis of 3T3-L1 preadipocytes exposed to capsaicin showed that apoptotic cells increased in a time- and dose-dependent manner. Treatment with capsaicin decreased the number of normal cells and increased the number of early apoptotic and late apoptotic cells in a dose-dependent manner. The treatment of cells with capsaicin caused the loss of mitochondria membrane potential (delta psi m). The induction of apoptosis in 3T3-L1 preadipocytes by capsaicin was mediated through the activation of caspase-3, Bax, and Bak, and then through the cleavage of PARP and the down-regulation of Bcl-2. Moreover, capsaicin significantly decreased the amount of intracellular triglycerides and glycerol-3-phosphate dehydrogenase (GPDH) activity in 3T3-L1 adipocytes. Capsaicin also inhibited the expression of PPARgamma, C/EBPalpha, and leptin, but induced up-regulation of adiponectin at the protein level. These results demonstrate that capsaicin efficiently induces apoptosis and inhibits adipogenesis in 3T3-L1 preadipocytes and adipocytes.     

Direct in vivo evidence of protective effects of grape seed procyanidin fractions and other antioxidants against ethanol-induced oxidative DNA damage in mouse brain cells

Ethanol is a principle ingredient of alcoholic beverages with potential neurotoxicity and carcinogenicity, and the ethanol-associated oxidative DNA damage in the central nervous system is well documented. The present work studied the possible protective effects of grape seed oligomer and polymer procyanidin fractions against ethanol-induced toxicity and compared these with resveratrol and other well-known antioxidants (ascorbic acid and vitamin E). By using the single cell gel electrophoresis (comet assay), a simple and sensitive technique for genotoxicity studies, the potential genotoxicity of acute and chronic ethanol administration in the different brain regions was investigated. Acute ethanol administration, at the dose of 2.5 or 5.0 g kg(-1) i.p., could induce significant DNA damage in cerebellum and hippocampus. Chronic administration of ethanol at the dose of 2.5 or 5.0 g kg-1 p.o. for 30 days could induce significant DNA damage in cerebellum, hippocampus, hypothalamus, and cortex, which could be auto-repaired at least 3 days after ethanol withdrawal. Oral administration of grape seed oligomer and polymer procyanidins and resveratrol (25, 50, and 100 mg kg(-1)) for 3 days before acute ethanol (5.0 g kg(-1), i.p.) or repeated administration of these substances together with ethanol (5.0 g kg(-1), p.o.) for 30 consecutive days could significantly inhibit DNA damage in brain cells induced by ethanol. As compared, ascorbic acid (50, 100, and 200 mg kg(-1)) and vitamin E (100, 200, and 400 mg kg(-1)) could also present protective effects on ethanol-induced DNA damage. Furthermore, the concentrations of ethanol and acetaldehyde in brain regions of the mice were detected by gas chromatography after administration of ethanol plus antioxidants. All of the results indicated that ethanol could induce region-specific oxidative DNA damage in which the cerebellum and hippocampus were more vulnerable, but intake of grape seed procyanidins or other natural antioxidants could protect the brain against ethanol-induced genotoxicity.     

Cyanidin and Malvidin from Oryza sativa cv. Heugjinjubyeo mediate cytotoxicity against human monocytic leukemia cells by arrest of G(2)/M phase and induction of apoptosis

Oryza sativa cv. Heugjinjubyeo (Gramineae), anthocyanin-pigmented rice, having dark purple grains, is known broadly as enriched rice with an improved taste. Two bioactive compounds were isolated from the 0.5% HCl-ethyl alcohol soluble fraction of the aleurone layer of O. sativa cv. Heugjinjubyeo through an activity-monitored fractionation and isolation method. From spectral analysis, the cytotoxic components were the anthocyanidins cyanidin (1) and malvidin (2) The 50% growth inhibitory concentrations (IC(50)) of cyanidin and malvidin on U937, human monocytic leukemia cells, were 60 and 40 microg/mL, respectively. These compounds showed cytotoxicity through the arrest of the G(2)/M phase of cell cycle and induction of apoptosis.     

Antcin B and its ester derivative from Antrodia camphorata induce apoptosis in hepatocellular carcinoma cells involves enhancing oxidative stress coincident with activation of intrinsic and extrinsic apoptotic pathway

The triterpenoids methylantcinate B (MAB) and antcin B (AB), isolated from the medicinal mushroom Antrodia camphorata , have been identified as strong cytotoxic agents against various type of cancer cells; however, the mechanisms of MAB- and AB-induced cytotoxicity have not been adequately explored. This study investigated the roles of caspase cascades, reactive oxygen species (ROS), DNA damage, mitochondrial disruption, and Bax and Bcl-2 proteins in MAB- and AB-induced apoptosis of hepatocellular carcinoma (HCC) HepG2 cells. Here, we showed that MAB and AB induced apoptosis in HepG2 cells, as characterized by increased DNA fragmentation, cleavage of PARP, sub-G1 population, chromatin condensation, loss of mitochondrial membrane potential, and release of cytochrome c. Increasing the levels of caspase-2, -3, -8, and -9 activities was involved in MAB- and AB-induced apoptosis, and they could be attenuated by inhibitors of specific caspases, indicating that MAB and AB triggered the caspase-dependent apoptotic pathway. Additionally, the enhanced apoptotic effect correlates with high expression of Fas, Fas ligand, as well as Bax and decreased protein levels of Bcl-(XL) and Bcl-2, suggesting that both the extrinsic and intrinsic apoptosis pathways were involved in the apoptotic processes. Incubation of HepG2 cells with antioxidant enzymes superoxide dismutase and catalase and antioxidants N-acetylcysteine and ascorbic acid attenuated the ROS generation and apoptosis induced by MAB and AB, which indicate that ROS plays a pivotal role in cell death. NADPH oxidase activation was observed in MAB- and AB-stimulated HepG2 cells; however, inhibition of such activation by diphenylamine significantly blocked MAB- and AB-induced ROS production and increased cell viability. Taken together, our results provide the first evidence that triterpenoids MAB and AB induced a NADPH oxidase-provoked oxidative stress and extrinsic and intrinsic apoptosis as a critical mechanism of cause cell death in HCC cells.     

2︰1和1︰1型黏土矿物胶体凝聚中Hofmeister效应的比较研究

土壤胶体是土壤具备肥力与生态功能的物质基础,土壤胶体凝聚与分散影响着土壤中一系列微观过程和宏观现象。采用动态光散射技术比较研究三种碱金属阳离子(Li+、Na+、K+)引发不同类型黏土矿物(2︰1型蒙脱石和1︰1型高岭石)胶体凝聚中的Hofmeister效应。研究发现,Li+、Na+、K+作用下蒙脱石、高岭石胶体的凝聚速率、临界聚沉浓度及活化能都存在明显差异,表现出强烈的Hofmeister效应。当电解质浓度为20 mmol·L–1时,K+引发蒙脱石胶体凝聚的速率为66.61 nm·min–1,远高于Na+、Li+引发蒙脱石胶体凝聚速率(5.93、4.41 nm·min–1);而与之对应的临界聚沉浓度则呈现K+(蒙脱石21.8 mmol·L–1、高岭石34.6 mmol·L–1)低于Na+(蒙脱石57.6 mmol·L–1、高岭石85.8 mmol·L–1)低于Li+(蒙脱石81.8 mmol·L–1、高岭石113.9 mmol·L–1)规律,胶体凝聚中活化能可合理解释此现象。电解质浓度为25 mmol·L–1时,Li+、Na+、K+引发蒙脱石、高岭石胶体凝聚的活化能分别为1.97 kT、1.43 kT、0 kT和2.94 kT、1.71 kT、0.49 kT,说明蒙脱石、高岭石胶体凝聚过程中Hofmeister效应序列均为Li+相似文献