Protective effect of ebselen against hydrogen peroxide-induced cytotoxicity and DNA damage in HepG2 cells

A novel diselenide attenuates the carrageenan-induced inflammation by reducing neutrophil infiltration and the resulting tissue damage in mice

Selenium-containing compounds have emerged as promising treatment for redox-based and inflammatory diseases. This study aimed to investigate the in vitro and in vivo anti-inflammatory activity of a novel diselenide named as dibenzyl[diselanediyIbis(propane-3-1diyl)] dicarbamate (DD). DD reacted with HOCl (k = 9.2 x 107 M-1s-1), like glutathione (k = 1.2 x 108 M-1s-1), yielding seleninic and selenonic acid derivatives, and it also decreased HOCl formation by activated human neutrophils (IC50=4.6 μM) and purified myeloperoxidase (MPO) (IC50=3.8 μM). However, tyrosine, MPO-I and MPO-II substrates, did not restore HOCl formation in presence of DD. DD inhibited the oxidative burst in dHL-60 cells with no toxicity up to 25 µM for 48h. Next, an intraperitoneal administration of 25, 50, and 75 mg/kg DD decreased total leukocyte, neutrophil chemotaxis, and inflammation markers (MPO activity, lipid peroxidation, albumin exudation, nitrite, TNF-α, IL-1β, CXCL1/KC, and CXCL2/MIP-2) on a murine model of carrageenan-induced peritonitis. Likewise, 50 mg/kg DD (i.p.) decreased carrageenan-induced paw edema over 5h. Histological and immunohistochemistry analyses of the paw tissue showed decreased neutrophil count, edema area, and MPO, carbonylated, and nitrated protein staining. Furthermore, DD treatment decreased the fMLP-induced chemotaxis of human neutrophils (IC50=3.7 μM) in vitro with no toxicity. Lastly, DD presented no toxicity in a single-dose model using mice (50 mg/kg, i.p.) over 15 days and in Artemia salina bioassay (50 to 2000 µM), corroborating findings from in silico toxicological study. Altogether, these results demonstrate that DD attenuates carrageenan-induced inflammation mainly by reducing neutrophil migration and the resulting damage from MPO-mediated oxidative burst.

Ebselen: A Review on its Synthesis, Derivatives, Anticancer Efficacy and Utility in Combating SARS-COV-2

Ebselen is a selenoorganic chiral compound with antioxidant properties comparable to glutathione peroxidase. It is also known as 2-phenyl-1,2-benzisoselenazol-3(2H)-one. In studies examining its numerous pharmacological activities, including antioxidant, anticancer, antiviral, and anti- Alzheimer's, ebselen has demonstrated promising results. This review's primary objective was to emphasize the numerous synthesis pathways of ebselen and their efficacy in fighting cancer. The data were collected from multiple sources, including Scopus, PubMed, Google Scholar, Web of Science, and Publons. The starting reagents for the synthesis of ebselen are 2-aminobenzoic acid and N-phenyl benzamide. It was discovered that ebselen has the ability to initiate apoptosis in malignant cells and prevent the formation of new cancer cells by scavenging free radicals. In addition, ebselen increases tumor cell susceptibility to apoptosis by inhibiting TNF-α mediated NF-kB activation. Ebselen can inhibit both doxorubicin and daunorubicin-induced cardiotoxicity. Allopurinol and ebselen administered orally can be used to suppress renal ototoxicity and nephrotoxicity. Due to excessive administration, diclofenac can induce malignancy of the gastrointestinal tract, which ebselen can effectively suppress. Recent research has demonstrated ebselen to inhibit viral function by binding to cysteinecontaining catalytic domains of various viral proteases. It was discovered that ebselen could inhibit the catalytic dyad function of Mpro by forming an irreversible covalent bond between Se and Cys145, thereby altering protease function and inhibiting SARS-CoV-2. Ebselen may also inhibit the activation of endosomal NADPH oxidase of vascular endothelial cells, which is believed to be required for thrombotic complications in COVID-19. In this review, we have included various studies conducted on the anticancer effect of ebselen as well as its inhibition of SARS-CoV-2.

Iron Chelation Property, Antioxidant Activity, and Hepatoprotective Effect of 6-Gingerol-Rich Ginger (Zingiber officinale) Extract in Iron-Loaded Huh7 Cells

Iron is essential for numerous biological processes; however, an iron imbalance can contribute to a number of diseases. An excess of iron can accumulate in the body and subsequently induce the production of reactive oxygen species (ROS), leading to oxidative tissue damage and organ dysfunction. The liver, a major iron storage site, is vulnerable to this iron-induced oxidative damage; however, this issue can be overcome by the chelation of excess iron. This study aimed to investigate the effect of 6-gingerol-rich ginger (Zingiber officinale) extract on iron chelation, antioxidation, and hepatoprotective function in protecting against iron-induced oxidative liver cell injury. In experiments, 6-gingerol was confirmed to be a main bioactive component of the ginger extract and possessed free radical scavenging activity, decreasing ABTS•+ and DPPH• radical levels, and inhibiting AAPH-induced red blood cell hemolysis. Interestingly, the extract significantly reduced the levels of labile cellular iron (LCI), intracellular ROS, and lipid peroxidation products (TBARS) in iron-loaded human hepatoma (Huh7) cells. In conclusion, this work highlights the iron chelation property of 6-gingerol-rich ginger extract and its antioxidant activity, which could potentially protect the liver from iron-induced oxidative tissue damage.

A Study of Phytochemistry, Genoprotective Activity, and Antitumor Effects of Extracts of the Selected Lamiaceae Species

This study was designed to evaluate the genoprotective, antigenotoxic, as well as antitumor potential of methanolic, ethanolic, and aqueous extracts of Melissa officinalis, Mentha × piperita, Ocimum basilicum, Rosmarinus officinalis, Salvia officinalis, and Satureja montana (Lamiaceae), in different model systems. The polyphenols in these extracts were quantified both spectrophotometrically and using HPLC-DAD technique, while DPPH assay was used to assess the antioxidant activity. The genoprotective potential was tested on pUC19 Escherichia coli XL1-blue, and the antigenotoxicity on Salmonella typhimurium TA1535/pSK1002 and human lung fibroblasts, while the antitumor activity was assessed on colorectal cancer cells. Rosmarinic acid, quercetin, rutin, and luteolin-7-O-glucoside were among the identified compounds. Methanolic extracts had the best DPPH-scavenging and SOS-inducing activities, while ethanolic extracts exhibited the highest antigenotoxicity. Additionally, all extracts exhibited genoprotective potential on plasmid DNA. The antitumor effect was mediated by modulation of reactive oxygen species (ROS), nitric oxide (NO) production, and exhibition of genotoxic effects on tumor cells, especially with O. basilicum ethanolic extract. Generally, the investigated extracts were able to provide antioxidant protection for the acellular, prokaryotic, and normal human DNA, while also modulating the production of ROS and NO in tumor cells, leading to genotoxicity toward these cells and their decrease in proliferation.

A comprehensive assessment of the chemical composition, antioxidant, genoprotective and antigenotoxic activities of Lamiaceae species using different experimental models in vitro

This research was aimed to assess the potential of Glechoma hederacea, Hyssopus officinalis, Lavandula angustifolia, Leonurus cardiaca, Marrubium vulgare and Sideritis scardica (Lamiaceae) methanolic, ethanolic and aqueous extracts against the damaging effects of oxidative stress using different experimental models. The chemical characterization was done spectrophotometrically by quantifying total phenolics, phenolic acids, flavonoids and flavonols in the extracts, as well as by employing HPLC-DAD technique. Moreover, DPPH assay was used to assess the extracts' radical scavenging potential. Genoprotective properties of the extracts were evaluated using plasmid pUC19 Escherichia coli XL1-Blue, whereas their antigenotoxic potential was determined using Salmonella typhimurium TA1535/pSK1002 and normal human lung fibroblasts. All of the extracts showed antioxidant activity in DPPH assay. Furthermore, the results have shown that aqueous extracts provided the best protection for plasmid DNA, while alcoholic extracts most effectively contributed to the preservation of prokaryotic DNA. Additionally, each of the tested samples significantly protected the eukaryotic cells against genomic damages. Finally, despite not showing exceptional results in DPPH assay, S. scardica extracts are regarded as the most favorable in maintaining the integrity of DNA, which might be due to high quantities of phenolics such as quercetin (up to 17.95 mg g^-1), naringin (up to 5.07 mg g^-1) and luteolin-7-O-glucoside (up to 3.54 mg g^-1). Overall, this comprehensive concept highlights the ability of these Lamiaceae species to safeguard the DNA from reactive oxygen species, to curtail the inflicted damage and also improve the efficiency of the DNA repair mechanisms, while emphasizing the importance of polyphenols as their active principles.

Utilizing systems biology to reveal cellular responses to peroxisome proliferator-activated receptor γ ligand exposure

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Human (HepG2) cells were exposed to PPARγ ligands to induce systems-level effects.

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Ciglitazone decreases HepG2 cell viability while GW 9662 had no effect.

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Ciglitazone and GW 9662 increase neutral lipids as a function of concentration.

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Cholesterol biosynthesis transcripts are affected by ciglitazone and GW 9662.

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Ciglitazone alters lipid profiles but GW 9662 was similar to vehicle-exposed cells.

Peroxisome proliferator-activated receptor γ (PPARγ) is a nuclear receptor that, upon activation by ligands, heterodimerizes with retinoid X receptor (RXR), binds to PPAR response elements (PPREs), and activates transcription of downstream genes. As PPARγ plays a central role in adipogenesis, fatty acid storage, and glucose metabolism, PPARγ-specific pharmaceuticals (e.g., thiazolidinediones) have been developed to treat Type II diabetes and obesity within human populations. However, to our knowledge, no prior studies have concurrently assessed the effects of PPARγ ligand exposure on genome-wide PPARγ binding as well as effects on the transcriptome and lipidome within human cells at biologically active, non-cytotoxic concentrations. In addition to quantifying concentration-dependent effects of ciglitazone (a reference PPARγ agonist) and GW 9662 (a reference PPARγ antagonist) on human hepatocarcinoma (HepG2) cell viability, PPARγ abundance in situ, and neutral lipids, HepG2 cells were exposed to either vehicle (0.1% DMSO), ciglitazone, or GW 9662 for up to 24 h, and then harvested for 1) chromatin immunoprecipitation-sequencing (ChIP-seq) to identify PPARγ-bound regions across the entire genome, 2) mRNA-sequencing (mRNA-seq) to identify potential impacts on the transcriptome, and 3) lipidomics to identify potential alterations in lipid profiles. Following exposure to ciglitazone and GW 9662, we found that PPARγ levels were not significantly different after 2–8 h of exposure. While ciglitazone and GW 9662 resulted in a concentration-dependent increase in neutral lipids, the magnitude and localization of PPARγ-bound regions across the genome (as identified by ChIP-seq) did not vary by treatment. However, mRNA-seq and lipidomics revealed that exposure of HepG2 cells to ciglitazone and GW 9662 resulted in significant, treatment-specific effects on the transcriptome and lipidome. Overall, our findings suggest that exposure of human cells to PPARγ ligands at biologically active, non-cytotoxic concentrations results in toxicity that may be driven by a combination of both PPARγ-dependent and PPARγ-independent mechanisms.

Selenium Compounds as Novel Potential Anticancer Agents

The high number of new cancer incidences and the associated mortality continue to be alarming, leading to the search for new therapies that would be more effective and less burdensome for patients. As there is evidence that Se compounds can have chemopreventive activity, studies have begun to establish whether these compounds can also affect already existing cancers. This review aims to discuss the different classes of Se-containing compounds, both organic and inorganic, natural and synthetic, and the mechanisms and molecular targets of their anticancer activity. The chemical classes discussed in this paper include inorganic (selenite, selenate) and organic compounds, such as diselenides, selenides, selenoesters, methylseleninic acid, 1,2-benzisoselenazole-3[2H]-one and selenophene-based derivatives, as well as selenoamino acids and Selol.

The impact of different extracts of six Lamiaceae species on deleterious effects of oxidative stress assessed in acellular, prokaryotic and eukaryotic models in vitro

The main objective of this research was to evaluate the impact of methanolic, ethanolic and aqueous extracts of Origanum majorana L., Origanum vulgare L., Teucrium chamaedrys L., Teucrium montanum L., Thymus serpyllum L. and Thymus vulgaris L. (Lamiaceae) on the effects of free radicals using different model systems. The extracts were characterized on the basis of the contents of total phenolics, phenolic acids, flavonoids and flavonols, and also using high-performance liquid chromatography with diode-array detection. Antioxidant activity in vitro was assessed using DPPH assay. The genoprotective properties were tested using plasmid relaxation assay on pUC19 E. coli XL1-Blue, while SOS/umuC assay on Salmonella typhimurium TA1535/pSK1002 and Comet assay on human lung fibroblasts were used to assess the antigenotoxicity of the extracts. Ethanolic extracts had the most phenolics (up to 236.20 mg GAE/g at 0.5 mg/mL), flavonoids (up to 42.47 mg QE/g at 0.5 mg/mL) and flavonols (up to 16.56 mg QE/g at 0.5 mg/mL), and they exhibited the highest DPPH activity (up to 92.16% at 0.25 mg/mL). Interestingly enough, aqueous extracts provided the best protection of plasmid DNA (the lowest IC₅₀ value was 0.17 mg/mL). Methanolic extracts, on the other hand, most efficiently protected the prokaryotic DNA, while all the extracts had a significant impact against genomic damages inflicted on human fibroblasts. O. vulgare extracts are considered to be the most promising in preserving the overall DNA integrity against oxidative genomic damages. Moreover, HPLC-DAD analysis highlighted rosmarinic acid as the most abundant in the investigated samples (551.45 mg/mL in total in all the extracts), followed by luteolin-7-O-glucoside (150.19 mg/mL in total), while their presence correlates with most of the displayed activities. The novelty of this study is reflected in the application of a prokaryotic model for testing the antigenotoxic effects of Lamiaceae species, as no previous reports have yet been published on the genoprotective potential of these species.

Aflatoxin B1 Induces Neurotoxicity through Reactive Oxygen Species Generation, DNA Damage, Apoptosis, and S-Phase Cell Cycle Arrest

Aflatoxin B1 (AFB₁) is a mycotoxin widely distributed in a variety of food commodities and exhibits strong toxicity toward multiple tissues and organs. However, little is known about its neurotoxicity and the associated mechanism. In this study, we observed that brain integrity was markedly damaged in mice after intragastric administration of AFB₁ (300 μg/kg/day for 30 days). The toxicity of AFB₁ on neuronal cells and the underlying mechanisms were then investigated in the neuroblastoma cell line IMR-32. A cell viability assay showed that the IC50 values of AFB₁ on IMR-32 cells were 6.18 μg/mL and 5.87 μg/mL after treatment for 24 h and 48 h, respectively. ROS levels in IMR-32 cells increased significantly in a time- and AFB₁ concentration-dependent manner, which was associated with the upregulation of NOX2, and downregulation of OXR1, SOD1, and SOD2. Substantial DNA damage associated with the downregulation of PARP1, BRCA2, and RAD51 was also observed. Furthermore, AFB₁ significantly induced S-phase arrest, which is associated with the upregulation of CDKN1A, CDKN2C, and CDKN2D. Finally, AFB₁ induced apoptosis involving CASP3 and BAX. Taken together, AFB₁ manifests a wide range of cytotoxicity on neuronal cells including ROS accumulation, DNA damage, S-phase arrest, and apoptosis-all of which are key factors for understanding the neurotoxicology of AFB₁.

Scavenging of reactive dicarbonyls with 2-hydroxybenzylamine reduces atherosclerosis in hypercholesterolemic Ldlr-/- mice

Lipid peroxidation generates reactive dicarbonyls including isolevuglandins (IsoLGs) and malondialdehyde (MDA) that covalently modify proteins. Humans with familial hypercholesterolemia (FH) have increased lipoprotein dicarbonyl adducts and dysfunctional HDL. We investigate the impact of the dicarbonyl scavenger, 2-hydroxybenzylamine (2-HOBA) on HDL function and atherosclerosis in Ldlr^−/− mice, a model of FH. Compared to hypercholesterolemic Ldlr^−/− mice treated with vehicle or 4-HOBA, a nonreactive analogue, 2-HOBA decreases atherosclerosis by 60% in en face aortas, without changing plasma cholesterol. Ldlr^−/− mice treated with 2-HOBA have reduced MDA-LDL and MDA-HDL levels, and their HDL display increased capacity to reduce macrophage cholesterol. Importantly, 2-HOBA reduces the MDA- and IsoLG-lysyl content in atherosclerotic aortas versus 4-HOBA. Furthermore, 2-HOBA reduces inflammation and plaque apoptotic cells and promotes efferocytosis and features of stable plaques. Dicarbonyl scavenging with 2-HOBA has multiple atheroprotective effects in a murine FH model, supporting its potential as a therapeutic approach for atherosclerotic cardiovascular disease.

Hypercholesterolemia is associated with lipid peroxidation induced reactive dicarbonyl adducts. Here the authors show that the dicarbonyl scavenger, 2-hydroxybenzylamine(2-HOBA), decreases reactive dicarbonyl modifications of LDL and HDL, improves HDL function, reduces atherosclerosis and promotes features of stable plaques in a mouse model of hypercholestrolemia.

Azulene-Derived Fluorescent Probe for Bioimaging: Detection of Reactive Oxygen and Nitrogen Species by Two-Photon Microscopy

Two-photon fluorescence microscopy has become an indispensable technique for cellular imaging. Whereas most two-photon fluorescent probes rely on well-known fluorophores, here we report a new fluorophore for bioimaging, namely azulene. A chemodosimeter, comprising a boronate ester receptor motif conjugated to an appropriately substituted azulene, is shown to be an effective two-photon fluorescent probe for reactive oxygen species, showing good cell penetration, high selectivity for peroxynitrite, no cytotoxicity, and excellent photostability.

Hepatoprotective effects of an Acer tegmentosum Maxim extract through antioxidant activity and the regulation of autophagy

ETHNOPHARMACOLOGICAL RELEVANCE

Acer tegmentosum Maxim (AT), the East Asian stripe maple, is an herb used to treat liver disease and is approved as a functional food in Korea. AT protects against hepatic disorders, atopic dermatitis, and diabetes mellitus.

AIM OF THE STUDY

We explored the mechanism of the hepatoprotective effects of AT extract in in vitro and in vivo levels.

MATERIALS AND METHODS

AT extract from Acer tegmentosum Maxim was extracted by hot water. Hepatoprotective effects of AT extract were confirmed using carbon tetrachloride (CCl₄)- or alcohol-induced mouse model, and H₂O₂- or alcohol-induced HepG2 (liver hepatocellular carcinoma cell line) cells by measuring GOT, GPT, TG, and MDA levels. Hematoxylin and eosin (H&E) staining was used to observe the pathological analysis. Cytotoxicity or protective effect of AT extract was confirmed using MTT assay in HepG2 cells. Antioxidant effect of AT extract was measured using DPPH or H₂DCFDA assay. Mechanism study of antioxidant and autophagy was carried out using western blotting and immunofluorescence analysis.

RESULTS

AT extract increased the viability of HepG2 cells treated with H₂O₂ and ethanol, and protected the liver against damage induced by CCl₄ and alcohol. The AT extract increased the levels of nuclear respiratory factor 2 (Nrf2) and heme oxygenase-1 (HO-1). The level of microtubule-associated protein light chain 3 (LC3)-Ⅱ, beclin-1, autophagy-related genes (Atg) such as Atg3 and Atg12-5 as markers of autophagy activation was also increased. Moreover, the AT extract increased activation of mitogen-activated protein kinase (MAPK), which regulated autophagy and HO-1.

CONCLUSION

Therefore, these results indicate that the AT extract has a hepatoprotective effect by increasing antioxidant activity and inducing autophagy.

Short-term exposure of Balb/c mice to buprofezin insecticide induces biochemical, enzymatic, histopathologic and genotoxic damage in liver and kidney tissues

Buprofezin is a type-1 chitin synthesis inhibitor insecticide used to control hemipteran insects. It is generally considered safe for humans, but its persistent nature may become a health hazard if long-term exposure takes place. Adverse effects on mammals are remaining to be explored. The present study investigated buprofezin toxicity on liver and kidney tissues of Balb/c mice treated intraperitoneally with 4.0, 6.0 and 8.0 µg/kg b.w doses respectively for 24 h. Statistical analyses demonstrated increased activities (p < 0.05) of serum alanine aminotransferase, aspartate aminotransferase, creatinine and urea, ROS and TBARS (thiobarbutaric acid) in liver and kidney tissues. Concomitant significant decrease occurred in tissue total protein, antioxidants enzymes, the superoxide dismutase, catalase and peroxidase and non-enzymatic reduced glutathione. Significantly altered histomorphology of liver and kidney tissues revealed excessive tissue damage. Congestion, hepatocyte necrosis, decreases sinusoidal damage in liver, while in kidneys, glomerular shrinkage, capillary damage, widened Bowman's space and lumens of tubules and collecting ducts and necrosis of tubular epithelial cells were evident. TUNEL assay confirmed apoptosis, the Comet assay demonstrated DNA damage by an increase in the head length, tail length, comet length, tail moment and olive tail moment. The study concludes that buprofezin is highly toxic for mammalian tissues and warrants further biochemical, molecular and cellular studies.

A chemically characterized ethanolic extract of Thai Perilla frutescens (L.) Britton fruits (nutlets) reduces oxidative stress and lipid peroxidation in human hepatoma (HuH7) cells

Perilla frutescens is cultivated in East Asian countries including Thailand, and the nutlets (single-seeded fruits) are used as traditional and medicinal food. Perilla nutlets extracted by ethyl acetate (EA), 80% ethanol (Eth), and hot water (HW) sequentially were chemically characterized using high-resolution accurate liquid chromatography-mass spectrometry with the main compounds detected assigned as rosmarinic acid and derivatives of the flavones apigenin and luteolin, with the more diverse chemical composition observed with the Eth extract. All extracts showed dose-dependent free-radical scavenging activity, with the Eth extract the most potent (IC₅₀  = 3.43 mg/ml for ABTS^• scavenging and 0.27 mg/ml for DPPH^• scavenging). The Eth extract also inhibited AAPH-induced hemolysis (IC₅₀  = 0.07 mg/ml) more potently than did the HW (IC₅₀  = 0.38 mg/ml) and EA extracts (IC₅₀  = 1.63 mg/ml). An MTT test revealed all the extracts were noncytotoxic at concentrations up to 200 μg/ml. Only the Eth and EA extracts showed protective effects against the generation of reactive oxygen species and lipid peroxidation in FeCl₃ -induced HuH7 cells in a dose-dependent manner. Our findings suggest the Eth extract of Thai perilla nutlets, containing rosmarinic acid and flavones and their derivatives, may have potential to provide protection against oxidative stress in hepatic disorders.

Influence of Ellagic Acid and Ebselen on Sperm and Oxidative Stress Parameters during Liquid Preservation of Ram Semen

Objective

The purpose of the present study was to assess the effects of ellagic acid and ebselen on sperm and oxidative stress parameters during liquid preservation of ram semen.

Materials and Methods

In this experimental study, sixty ejaculates from six mature Merino rams were used. In experiment 1, the ejaculates were diluted in base extender contained ellagic acid at 0 (control), 0.5, 1, and 2 mM. In experiment 2, ebselen at 0 (control), 10, 20, and 40 μM were added to the extender. Sperm motility, viability, mitochondrial membrane potential, DNA integrity, lipid peroxidation (LPO), the antioxidant potential (AOP), and total glutathione (tGSH) were evaluated at 0, 24, 48, and 72 hours of preservation.

Results

Supplementation of ellagic acid at 1 and 2 mM resulted in higher sperm motility and viability at 0 hours of storage. Ellagic acid at 2 mM led to higher motility and viability compared to controls after 0, 24, and 48 hours of preservation and increased AOP after 24 and 72 hours. Higher tGSH was at 1 mM ellagic acid, compared to control after 72 hours. Addition of ebselen at a concentration of 40 μM increased motility at 24 and 48 hours and 10 μM produced the same effect after 48 and 72 hours of storage as well as higher viability, compared to the controls after 0 hours of storage. Sperm DNA integrity was significantly improved after 24, 48, and 72 hours with the addition of ebselen at 10 μM, and after 72 hours at 40 μM. Addition of 40 mM ebselen also reduced the LPO levels after 24 hours of storage compared to the controls.

Conclusion

The results showed that supplementation of ellagic acid and ebselen in semen extender has a potential effect on sperm and oxidative stress parameters during liquid preservation of ram semen.

miR449a/SIRT1/PGC-1α Is Necessary for Mitochondrial Biogenesis Induced by T-2 Toxin

T-2 toxin is one of the type A trichothecenes produced mainly by the Fusarium genus. Due to its broad distribution and highly toxic nature, it is of great concern as a threat to human health and animal breeding. In addition to its ribotoxic effects, T-2 toxin exposure leads to mitochondrial dysfunction, reactive oxygen species (ROS) accumulation and eventually cell apoptosis. We observed that mitochondrial biogenesis is highly activated in animal cells exposed to T-2 toxin, probably in response to the short-term toxic effects of T-2 toxin. However, the molecular mechanisms of T-2 toxin-induced mitochondrial biogenesis remain unclear. In this study, we investigated the regulatory mechanism of key factors in the ROS production and mitochondrial biogenesis that were elicited by T-2 toxin in HepG2 and HEK293T cells. Low dosages of T-2 toxin significantly increased the levels of both mitochondrial biogenesis and ROS. This increase was linked to the upregulation of SIRT1, which is controlled by miR-449a, whose expression was strongly inhibited by T-2 toxin treatment. In addition, we found that T-2 toxin-induced mitochondrial biogenesis resulted from SIRT1-dependent PGC-1α deacetylation. The accumulation of PGC-1α deacetylation, mediated by high SIRT1 levels in T-2 toxin-treated cells, activated the expression of many genes involved in mitochondrial biogenesis. Together, these data indicated that the miR449a/SIRT1/deacetylated PGC-1α axis plays an essential role in the ability of moderate concentrations of T-2 toxin to stimulate mitochondrial biogenesis and ROS production.

Hydrogen peroxide produced by superoxide dismutase SOD-2 activates sperm in Caenorhabditis elegans

Superoxide dismutase (SOD) is a ubiquitous antioxidant enzyme that catalytically converts the superoxide radical to hydrogen peroxide (H₂O₂). In mammals, high SOD activity is detectable in sperm and seminal plasma, and loss of SOD activity has been correlated with male infertility; however, the underlying mechanisms of sperm infertility remain to be clarified. Here we report that the deletion of two major SOD genes in Caenorhabditis elegans, sod-1 and sod-2, causes sperm activation defects, leading to a significant reduction in brood size. By examining the reactivity to the sperm activation signals Pronase and triethanolamine, we found that sod-1;sod-2 double mutant sperm cells display defects in pseudopod extension. Neither the content nor oxidative modification of major sperm protein, an essential cytoskeletal component for crawling movement, were significantly affected in sod-1;sod-2 mutant sperm. Surprisingly, H₂O₂, the dismutation product of SOD, could activate sod-1;sod-2 mutant sperm treated with Pronase. Moreover, the H₂O₂ scavenger ebselen completely inhibited pseudopod extension in wild-type sperm treated with Pronase, and H₂O₂ could directly induce pseudopod extension in wild-type sperm. Analysis of Pronase-triggered sperm activation in sod-1 and sod-2 single mutants revealed that sod-2 is required for pseudopod extension. These results suggest that SOD-2 plays an important role in the sperm activation of C. elegans by producing H₂O₂ as an activator of pseudopod extension.

Protective role of selenium in the activities of antioxidant enzymes in piglet splenic lymphocytes exposed to deoxynivalenol

We evaluated the effects of selenium (Se) on antioxidant enzymes of piglet splenic lymphocytes exposed to deoxynivalenol (DON). We measured cell viability, the activities of several antioxidant enzymes, and lactate dehydrogenase (LDH), as well as total antioxidant capacity (T-AOC) and the levels of malonaldehyde (MDA) and hydrogen peroxide (H₂O₂). We found that DON exposure increased the concentrations of LDH, MDA, and H₂O₂ in all experimental groups in a dose-dependent manner, while the concentrations of other antioxidant enzymes were decreased. In Se-pretreated DON-exposed cells, damage to antioxidant enzymes was reduced, especially in the lower-dose DON groups over longer exposure times. These results may indicate that in piglet splenic lymphocytes, Se can alleviate DON-induced damage to antioxidant enzymes by improving glutathione peroxidase activity. Se may function as a potential antioxidative agent to alleviate DON-induced oxidative stress.

Charge properties of peptides derived from casein affect their bioavailability and cytoprotection against H2O2-induced oxidative stress

The effects of charge properties of casein peptides on absorption stability, antioxidant activity, and cytoprotection were evaluated. Alcalase hydrolysates of casein were separated into 4 fractions by cation-exchange chromatography according to charge properties. After simulated digestion and Caco-2 cell transmembrane transport, we determined the total antioxidant capacity (Trolox equivalent antioxidative capacity and oxygen radical antioxidant activity) and nitrogen content of peptide fractions to estimate available antioxidant efficacy and bioavailability (BA) of peptides. Results showed that negatively charged peptide fractions had greater BA and antioxidant activities after digestion and absorption. The peptide permeates were used to test the cytoprotective effect against H2O2-induced oxidative damage in HepG-2 cells. All peptide permeates increased cell viability, elevated catalase activity, and decreased superoxide dismutase activity. However, negatively charged peptide fractions preserved cell viability to a greater degree. Therefore, the negatively charged peptides from casein may be potential antioxidants and could be used as ingredients in functional foods and dietary supplements.

Hair growth promoting potential of phospholipids purified from porcine lung tissues

BP201, porcine lung tissue-derived phospholipids, consists of phosphatidylcholine as a major phospholipid species. BP201 promoted hair growth after application onto the shaved backs of BALB/c and C3H mice. Its effect was enhanced when applied together with minoxidil (MNX) in C3H mice. When the tissue specimens prepared from the shaved skins of BP201-treated and control mice were microscopically examined, the total numbers of hair follicles in both anagen and telogen phases of BP201-treated mice were significantly higher than those of control mice. The numbers of hair follicles in the anagen phase of BP201-treated mice were also higher than those of control mice. In combination with MNX, BP201 further increased the total number of hair follicles, but did not alter the percentage of hair follicles in the anagenic phase. BP201 also increased the proliferation of human hair follicle dermal papilla cells. Collectively, BP201 possesses hair growth promoting potential, which would suggest its use singly or in combination for hair growth products.

SENIEUR status of the originating cell donor negates certain 'anti-immunosenescence' effects of ebselen and N-acetyl cysteine in human T cell clone cultures

Background

Damage to T cells of the immune system by reactive oxygen species may result in altered cell function or cell death and thereby potentially impact upon the efficacy of a subsequent immune response. Here, we assess the impact of the antioxidants Ebselen and N-acetyl cysteine on a range of biological markers in human T cells derived from a SENIEUR status donor. In addition, the impact of these antioxidants on different MAP kinase pathways in T cells from donors of different ages was also examined.

Methods

T cell clones were derived from healthy 26, 45 and SENIEUR status 80 year old people and the impact of titrated concentrations of Ebselen or N-acetyl cysteine on their proliferation and in vitro lifespan, GSH:GSSG ratio as well as levels of oxidative DNA damage and on MAP kinase signaling pathways was examined.

Results

In this investigation neither Ebselen nor N-acetyl cysteine supplementation had any impact on the biological endpoints examined in the T cells derived from the SENIEUR status 80 year old donor. This is in contrast to the anti-immunosenescent effects of these antioxidants on T cells from donors of 26 or 45 years of age. The analysis of MAP kinases showed that pro-apoptotic pathways become activated in T cells with increasing in vitro age and that Ebselen or N-acetyl cysteine could decrease activation (phosphorylation) in T cells from 26 or 45 year old donors, but not from the SENIEUR status 80 year old donor.

Conclusions

The results of this investigation demonstrate that the biological phenotype of SENIEUR status derived human T cells negates the anti-immunosenescence effects of Ebselen and also N-acetyl cysteine. The results highlight the importance of pre-antioxidant intervention evaluation to determine risk-benefit.

Electronic supplementary material

The online version of this article (doi:10.1186/s12979-014-0017-5) contains supplementary material, which is available to authorized users.

Protective effect of the edible brown alga Ecklonia stolonifera on doxorubicin-induced hepatotoxicity in primary rat hepatocytes

OBJECTIVES

As part of our efforts to isolate anti-hepatotoxic agents from marine natural products, we screened the ability of 14 edible varieties of Korean seaweed to protect against doxorubicin-induced hepatotoxicity in primary rat hepatocytes.

METHODS

Among the crude extracts of two Chlorophyta (Codium fragile and Capsosiphon fulvescens), seven Phaeophyta (Undaria pinnatifida, Sargassum thunbergii, Pelvetia siliquosa, Ishige okamurae, Ecklonia cava, Ecklonia stolonifera and Eisenia bicyclis), five Rhodophyta (Chondrus ocellatus, Gelidium amansii, Gracilaria verrucosa, Symphycladia latiuscula and Porphyra tenera), and the extracts of Ecklonia stolonifera, Ecklonia cava, Eisenia bicyclis and Pelvetia siliquosa exhibited significant protective effects on doxorubicin-induced hepatotoxicity, with half maximal effective concentration (EC50) values of 2.0, 2.5, 3.0 and 15.0 μg/ml, respectively.

KEY FINDINGS

Since Ecklonia stolonifera exhibits a significant protective potential and is frequently used as foodstuff, we isolated six phlorotannins, including phloroglucinol (1), dioxinodehydroeckol (2), eckol (3), phlorofucofuroeckol A (4), dieckol (5) and triphloroethol-A (6). Phlorotannins 2 ∼ 6 exhibited potential protective effects on doxorubicin-induced hepatotoxicity, with corresponding EC50 values of 3.4, 8.3, 4.4, 5.5 and 11.5 μg/ml, respectively.

CONCLUSION

The results clearly demonstrated that the anti-hepatotoxic effects of Ecklonia stolonifera and its isolated phlorotannins are useful for further exploration and development of therapeutic modalities for treatment of hepatotoxicity.

Ebselen induces reactive oxygen species (ROS)-mediated cytotoxicity in Saccharomyces cerevisiae with inhibition of glutamate dehydrogenase being a target

Ebselen is a synthetic, lipid-soluble seleno-organic compound. The high electrophilicity of ebselen enables it to react with multiple cysteine residues of various proteins. Despite extensive research on ebselen, its target molecules and mechanism of action remains less understood. We performed biochemical as well as in vivo experiments employing budding yeast as a model organism to understand the mode of action of ebselen. The growth curve analysis and FACS (florescence activated cell sorting) assays revealed that ebselen exerts growth inhibitory effects on yeast cells by causing a delay in cell cycle progression. We observed that ebselen exposure causes an increase in intracellular ROS levels and mitochondrial membrane potential, and that these effects were reversed by addition of antioxidants such as reduced glutathione (GSH) or N-acetyl-l-cysteine (NAC). Interestingly, a significant increase in ROS levels was noticed in gdh3-deleted cells compared to wild-type cells. Furthermore, we showed that ebselen inhibits GDH function by interacting with its cysteine residues, leading to the formation of inactive hexameric GDH. Two-dimensional gel electrophoresis revealed protein targets of ebselen including CPR1, the yeast homolog of Cyclophilin A. Additionally, ebselen treatment leads to the inhibition of yeast sporulation. These results indicate a novel direct connection between ebselen and redox homeostasis.

Oxidative stress in freshwater fish, Labeo rohita as a biomarker of malathion exposure

This study examined the effect of lethal (4.5 μg/l) and sublethal (0.45 μg/l) malathion levels on oxidative stress responses of the freshwater edible fish, Labeo rohita. Fish were exposed to lethal (1-4 days) and sublethal (1, 5, 10, and 15 days) periods. In the present study, catalase and protease activity, hydrogen peroxide, malondialdehyde, protein carbonyls, and free amino acids levels increased in the gill, liver, and kidney tissues of fish exposed to lethal and sublethal concentrations of malathion except protein content. Time- and concentration-dependent induction/reduction of the above parameters by lethal and sublethal concentrations of malathion was observed in the tissues (the gill, liver, and kidney) of L. rohita. Thus, the results clearly infer oxidative damage and decline in antioxidant defense due to malathion-induced oxidative stress.

An investigation of the effects of the antioxidants, ebselen or N-acetyl cysteine on human peripheral blood mononuclear cells and T cells

BACKGROUND

The research literature has documented age-related increases in genetic damage, including oxidative DNA damage, in human T lymphocytes, in vitro and ex vivo. Such damage has the potential to interfere with the ability of the T cells to proliferate at times when they need to, such as when antigen challenged. The consequence of this could be a sub-optimal immune response in vivo.

CONTEXT AND PURPOSE

The purpose of the research reported in this paper was to investigate the impact of two antioxidants, which can be administered in vivo, Ebselen and N-acetyl L-cysteine, on the age-related increase in genetic damage, and on T cell proliferation and lifespan. In vitro human T cell clones, ex vivo peripheral blood mononuclear cells or T cells were supplemented with different concentrations of antioxidants, under standard conditions and for different periods of time. A range of assays were then applied in order to determine any impact of the antioxidants.

RESULTS

30 μM ebselen or 7.5 mM N-acetyl L-cysteine supplementation resulted in a significantly higher intracellular GSH: GSSG ratio. This increased ratio was accompanied by reduced levels of oxidative DNA damage in established CD4+ human T cell clones, from a young or a middle-aged donor. Additionally, cultures of primary human peripheral blood mononuclear cells and CD4+ T cells from donors aged 25-30 or 55-60 years were also supplemented with these agents. Cells from all sources exhibited increased proliferation, and in the case of the T cell clones, an increase in cumulative population doublings. Neither ebselen nor N-acetyl L-cysteine had such effects on clones supplemented from the midpoint of their in vitro lifespan.

CONCLUSIONS

Ebselen and N-acetyl L-cysteine, under certain conditions, may have anti-immunosenescent potential in T cells in in vitro clonal and ex vivo polyclonal culture models.

Protective and antioxidant role of selenium on arsenic trioxide-induced oxidative stress and genotoxicity in the fish hepatoma cell line PLHC-1

In vitro models are useful tools for rapid screening for toxicity, elucidation of mechanisms of toxicity, and understanding complex interactions among environmental toxicants. These evaluations may provide useful information for ecological evaluations if the relationship between in vitro and in vivo effects is established. The present study was undertaken to evaluate the protective effect of selenium on arsenic trioxide (As(2) O(3) )-induced cytotoxicity, DNA damage, and apoptosis. N-acetylcysteine (NAC), a free radical scavenger, was used to determine the involvement of reactive oxygen species (ROS) in As(2) O(3) -induced DNA damage and apoptosis. Poeciliopsis lucida hepatocellular carcinoma line 1 (PLHC-1) cells were pretreated with selenium (1, 5, and 10 µM) and NAC (50 and 100 µM) for 2 h. After pretreatment, cells were exposed to 100 µM of As(2) O(3) for 10-, 20-, and 40-h intervals. The As(2) O(3) exposure promoted extensive DNA damage and apoptosis compared to control, while selenium- and NAC-pretreated cells improved cell survival rate against As(2) O(3) -induced cell death. Improved survival likely resulted from increasing glutathione peroxidase activity and reduction of ROS formation, reduction of mitochondrial membrane potential damage, DNA damage, and caspase-3 activity. During As(2) O(3) exposure, selenium played the same role as NAC. The authors conclude that As(2) O(3) -induced DNA damage and apoptosis are mediated by oxidative stress and selenium and that, although toxic at higher concentrations, selenium provides significant protection against As(2) O(3) effects in PLHC-1 cells.

Antioxidative, anti-inflammatory, and matrix metalloproteinase inhibitory activities of 20(S)-ginsenoside Rg3 in cultured mammalian cell lines

Ginsenoside Rg3 is one of ginsenosides that are the well-known bioactive principles of Panax ginseng. Among the two stereoisomeric forms of Rg3, 20(S)-ginsenoside Rg3 [20(S)-Rg3] is predominant. 20(S)-Rg3 is capable of suppressing the nitric oxide (NO), reactive oxygen species (ROS) and prostaglandin E2 (PGE2) productions induced by lipopolysaccharide (LPS) in RAW264.7 macrophage cells in a concentration-dependent manner. In the same stimulated macrophages, 20(S)-Rg3 was able to suppress matrix metalloproteinase-9 (MMP-9) activity and suppress cyclooxygenase-2 (COX-2) expression. It suppressed the production of some proinflammatory cytokines, such as TNF-α, IL-1β and IL-6, and the cell mobility enhanced by LPS in the macrophage cells. 20(S)-Rg3 displayed suppressive effect on the ROS level but not on the NO level, and down-regulating effect on MMP-9 but not on MMP-2 in non-stimulated HaCat keratinocytes. 20(S)-Rg3 also exhibited suppressive effect on the MMP-9 gelatinolytic activity enhanced in the HaCat keratinocytes stimulated with tumor necrosis factor-α (TNF-α), one of the major proinflammatory cytokines. However, 20(S)-Rg3 was not able to modulate the NO level even in the presence of TNF-α. Taken together, anti-inflammatory and related antioxidative and MMP-9 inhibitory activities of 20(S)-Rg3, the major stereoisomeric form of ginsenoside Rg3, are confirmed in macrophage and keratinocyte cell lines.

Effects of White Radish (Raphanus sativus) Enzyme Extract on Hepatotoxicity

Raphanus sativus (Cruciferaceae), commonly known as radish is widely available throughout the world. From antiquity it has been used in folk medicine as a natural drug against many toxicants. The present study was designed to evaluate the hepatoprotective activity of radish (Raphanus sativus) enzyme extract (REE) in vitro and in vivo test. The IC50 values of REE in human liver derived HepG2 cells was over 5,000 μg/ml in tested maximum concentration. The effect of REE to protect tacrine-induced cytotoxicity in HepG2 cells was evaluated by MTT assay. REE showed their hepatoprotective activities on tacrineinduced cytotoxicity and the EC50 value was 1,250 μg/ml. Silymarin, an antihepatotoxic agent used as a positive control exhibited 59.7% hepatoprotective activitiy at 100 μg/ml. Moreover, we tested the effect of REE on carbon tetrachloride (CCl4)-induced liver toxicity in rats. REE at dose of 50 and 100 mg/kg and silymarin at dose of 50 mg/kg were orally administered to CCl4-treated rats. The results showed that REE and silymarin significantly reduced the elevated levels of serum enzyme markers induced by CCl4. The biochemical data were supported by evaluation with liver histopathology. These findings suggest that REE, can significantly diminish hepatic damage by toxic agent such as tacrine or CCl4.

Glutaredoxin 2a, a mitochondrial isoform, plays a protective role in a human cell line under serum deprivation

The roles of mitochondrial glutaredoxin (Grx2a) under serum deprivation were assessed using the human stable HepG2 cell lines overexpressing or down-regulating Grx2a. The Grx2a-overexpressing stable cells displayed enhanced proliferation, decreased reactive oxygen species (ROS) and caspase-3 activity levels, and increased total GSH level, compared to the vector control cells. These characteristics of the overexpressing stable cells were reversed by down-regulating Grx2a in the same cell line. In the limited serum conditions, the Grx2a-overexpressing stable pcDNA3.0/HA-Grx2a cells exhibited higher cellular viabilities and total GSH level, and showed much lower enhancement in ROS and caspase-3 activity levels than the vector control pcDNA3.0/HA cells. However, the Grx2a-down-regulating stable cells gave rise to diminished cellular viabilities and further decreased total GSH level, and contained significantly higher ROS and caspase-3 activity levels, under serum deprivation than the vector control cells. These results suggest that Grx2a plays proliferative and anti-apoptotic roles under serum deprivation.

Disruption of redox homeostasis and induction of apoptosis by suppression of glutathione synthetase expression in a mammalian cell line

The stable HepG2 transfectants anti-sensing expression of the glutathione synthetase (GS) gene exhibited delayed cell growth and increased reactive oxygen species (ROS) level. After the treatment with hydrogen peroxide, the intracellular ROS level was much higher in the stable transfectants than in the vector control cells. However, the GSH levels decreased more significantly in the stable transfectants than in the vector control cells, in the presence of hydrogen peroxide. Hydrogen peroxide-induced apoptosis of the stable transfectants was notably higher than that of the vector control cells. The GS anti-sense RNAs rendered the HepG2 cells more sensitive to growth arrest caused by glucose deprivation. They also sensitized the HepG2 cells to cadmium chloride (Cd) and nitric oxide (NO)-generating sodium nitroprusside (SNP). In brief, the results confirm that GS plays an important role in the defense of the human hepatoma cells against oxidative stress by reducing apoptosis and maintaining redox homeostasis.

Methylmercury-induced alterations in astrocyte functions are attenuated by ebselen

Methylmercury (MeHg) preferentially accumulates in glia of the central nervous system (CNS), but its toxic mechanisms have yet to be fully recognized. In the present study, we tested the hypothesis that MeHg induces neurotoxicity via oxidative stress mechanisms, and that these effects are attenuated by the antioxidant, ebselen. Rat neonatal primary cortical astrocytes were pretreated with or without 10 μM ebselen for 2h followed by MeHg (0, 1, 5, and 10 μM) treatments. MeHg-induced changes in astrocytic [(3)H]-glutamine uptake were assessed along with changes in mitochondrial membrane potential (ΔΨ(m)), using the potentiometric dye tetramethylrhodamine ethyl ester (TMRE). Western blot analysis was used to detect MeHg-induced ERK (extracellular-signal related kinase) phosphorylation and caspase-3 activation. MeHg treatment significantly decreased (p<0.05) astrocytic [(3)H]-glutamine uptake at all time points and concentrations. Ebselen fully reversed MeHg's (1 μM) effect on [(3)H]-glutamine uptake at 1 min. At higher MeHg concentrations, ebselen partially reversed the MeHg-induced astrocytic inhibition of [(3)H]-glutamine uptake [at 1 min (5 and 10 μM) (p<0.05); 5 min (1, 5 and 10 μM) (p<0.05)]. MeHg treatment (1h) significantly (p<0.05) dissipated the ΔΨ(m) in astrocytes as evidenced by a decrease in mitochondrial TMRE fluorescence. Ebselen fully reversed the effect of 1 μM MeHg treatment for 1h on astrocytic ΔΨ(m) and partially reversed the effect of 5 and 10 μM MeHg treatments for 1h on ΔΨ(m). In addition, ebselen inhibited MeHg-induced phosphorylation of ERK (p<0.05) and blocked MeHg-induced activation of caspase-3 (p<0.05-0.01). These results are consistent with the hypothesis that MeHg exerts its toxic effects via oxidative stress and that the phosphorylation of ERK and the dissipation of the astrocytic mitochondrial membrane potential are involved in MeHg toxicity. In addition, the protective effects elicited by ebselen reinforce the idea that organic selenocompounds represent promising strategies to counteract MeHg-induced neurotoxicity.

Glutathione reductase plays an anti-apoptotic role against oxidative stress in human hepatoma cells

The cellular roles of glutathione reductase (GR) in the reactive oxygen species (ROS)-induced apoptosis were studied using the HepG2 cells transfected with GR. The overexpression of GR caused a marked enhancement in reduced and oxidized glutathione (GSH/GSSG) ratio, and significantly decreased ROS levels in the stable transfectants. Hydrogen peroxide (H(2)O(2)), under the optimal condition for apoptosis, significantly decreased cellular viability and total GSH content, and rather increased ROS level, apoptotic percentage and caspase-3 activity in the mock-transfected cells. However, hydrogen peroxide could not largely generate these apoptotic changes in cellular viability, ROS level, apoptotic percentage, caspase-3 activity and total GSH content in the cells overexpressing GR. Taken together, GR may play a protective role against oxidative stress.

Inhibition of the JAK-STAT3 pathway by andrographolide enhances chemosensitivity of cancer cells to doxorubicin

Andrographolide (Andro), a diterpenoid lactone isolated from a traditional herbal medicine Andrographis paniculata, is known to possess potent anti-inflammatory and anticancer properties. In this study, we sought to examine the effect of Andro on signal transducer and activator of transcription 3 (STAT3) pathway and evaluate whether suppression of STAT3 activity by Andro could sensitize cancer cells to a chemotherapeutic drug doxorubicin. First, we demonstrated that Andro is able to significantly suppress both constitutively activated and IL-6-induced STAT3 phosphorylation and subsequent nuclear translocation in cancer cells. Such inhibition is found to be achieved through suppression of Janus-activated kinase (JAK)1/2 and interaction between STAT3 and gp130. For understanding the biological significance of the inhibitory effect of Andro on STAT3, we next investigated the effect of Andro on doxorubicin-induced apoptosis in human cancer cells. In our study the constitutive activation level of STAT3 was found to be correlated to the resistance of cancer cells to doxorubicin-induced apoptosis. Both the short-term MTT assay and the long-term colony formation assay showed that Andro dramatically promoted doxorubicin-induced cell death in cancer cells, indicating that Andro enhances the sensitivity of cancer cells to doxorubicin mainly via STAT3 suppression. These observations thus reveal a novel anticancer function of Andro and suggest a potential therapeutic strategy of using Andro in combination with chemotherapeutic agents for treatment of cancer.

In vitro toxicity of silver nanoparticles at noncytotoxic doses to HepG2 human hepatoma cells

Although it has been reported that silver nanoparticles (Ag-NPs) have strong acute toxic effects to various cultured cells, the toxic effects at noncytotoxic doses are still unknown. We, therefore, evaluated in vitro toxicity of Ag-NPs at noncytotoxic doses in human hepatoma cell line, HepG2, based on cell viability assay, micronucleus test, and DNA microarray analysis. We also used polystyrene nanoparticles (PS-NPs) and silver carbonate (Ag2CO3) as test materials to compare the toxic effects with respect to different raw chemical composition and form of silver. The cell viability assay demonstrated that Ag-NPs accelerated cell proliferation at low doses (< 0.5 mg/L), which was supported by the DNA microarray analysis showing significant induction of genes associated with cell cycle progression. However, only Ag-NPs exposure exhibited a significant cytotoxicity at higher doses (> 1.0 mg/L) and induced abnormal cellular morphology, displaying cellular shrinkage and acquisition of an irregular shape. In addition, only Ag-NPs exposure increased the frequency of micronucleus formation up to 47.9 +/- 3.2% of binucleated cells, suggesting that Ag-NPs appear to cause much stronger damages to chromosome than PS-NPs and ionic Ag+. Cysteine, a strong ionic Ag+ ligand, only partially abolished the formation of micronuclei mediated by Ag-NPs and changed the gene expression, indicating that ionic Ag+ derived from Ag-NPs could not fully explain these biological actions. Based on these discussions, it is concluded that both "nanosized particle of Ag" as well as "ionic Ag+" contribute to the toxic effects of Ag-NPs.

Overexpression of manganese superoxide dismutase in human dermal fibroblasts enhances the contraction of free floating collagen lattice: implications for ageing and hyperplastic scar formation

Cell-matrix interactions are of significant importance for tissue homeostasis of the skin and, if disturbed, may lead to ageing and hyperplastic scar formation. We have studied fibroblasts stably overexpressing manganese superoxide dismutase (MnSOD) with a defined capacity for the removal of superoxide anions and concomitant accumulation of hydrogen peroxide to evaluate the role of enhanced MnSOD activity on the dynamics of cell-matrix interactions in the three-dimensional collagen lattice contraction assay. MnSOD overexpressing fibroblast populated collagen lattices revealed a significantly enhanced contraction compared to collagen lattices populated with vector control cells. The enhanced collagen lattice contraction was in part due to an increase in active TGF-beta1 and the accumulation of H2O2 in MnSOD overexpressing fibroblasts populated collagen lattices. Inhibition of TGF-beta1 signalling by the ALK4,5,7 kinases' inhibitor SB431542 at least partly inhibited the enhanced collagen lattice contraction of MnSOD overexpressing fibroblasts populated lattices. In addition, supplementation of vector control fibroblast populated collagen lattices with recombinant TGF-beta1 concentration dependently enhanced the collagen lattice contraction. In the presence of the antioxidant Ebselen, a mimic of H2O2 and other hydroperoxides/peroxynitrite-detoxifying glutathione peroxidase, collagen lattice contraction and the activation of TGF-beta1 were significantly reduced in collagen lattices populated with MnSOD overexpressing fibroblasts. Collectively, these data suggest that H2O2 or other hydroperoxides or peroxynitrite or a combination thereof may function as important second messengers in collagen lattice contraction and act at least in part via TGF-beta1 activation.

Cellular protection of morin against the oxidative stress induced by hydrogen peroxide

Flavonoids are a class of secondary metabolites abundantly found in fruits and vegetables. In addition, flavonoids have been reported as potent antioxidants with beneficial effects against oxidative stress-related diseases such as cancer, aging, and diabetes. The present study was carried out to investigate the cytoprotective effects of morin (2',3,4',5,7-pentahydroxyflavone), a member of the flavonoid group, against hydrogen peroxide (H(2)O(2))-induced DNA and lipid damage. Morin was found to prevent the cellular DNA damage induced by H(2)O(2) treatment, which is shown by the inhibition of 8-hydroxy-2'-deoxyguanosine (8-OHdG) formation (a modified form of DNA base), inhibition of comet tail (a form of DNA strand breakage), and decrease of nuclear phospho histone H2A.X expression (a marker for DNA strand breakage). In addition, morin inhibited membrane lipid peroxidation, which is detected by inhibition of thiobarbituric acid reactive substance (TBARS) formation. Morin was found to scavenge the intracellular reactive oxygen species (ROS) generated by H(2)O(2) treatment in cells, which is detected by a spectrofluorometer, flow cytometry, and confocal microscopy after staining of 2',7'-dichlorodihydrofluorescein diacetate (DCF-DA). Morin also induces an increase in the activity of catalase and protein expression. The results of this study suggest that morin protects cells from H(2)O(2)-induced damage by inhibiting ROS generation and by inducing catalase activation.

Signaling pathways from membrane lipid rafts to JNK1 activation in reactive nitrogen species-induced non-apoptotic cell death

At present, the signaling pathways controlling reactive nitrogen species (RNS)-induced non-apoptotic cell death are relatively less understood. In this work, various RNS donors are found to induce caspase-independent non-apoptotic cell death in mouse embryonic fibroblasts (MEF). In search of the molecular mechanisms, we first established the role of c-Jun N-terminal kinase (JNK) in RNS-induced non-apoptotic cell death. RNS readily activate JNK, and the jnk1-/- MEF are resistant to RNS-induced cell death. Moreover, the reconstitution of JNK1 effectively restores the sensitivity to RNS. Next, we identified tumor necrosis factor receptor-associated factor 2 (TRAF2) and apoptosis signal-regulating kinase 1 (ASK1) as the essential upstream molecules for RNS-induced JNK activation and cell death. RNS fail to activate JNK and induce cell death in traf2-/- MEF; and reconstitution of TRAF2 effectively restores the responsiveness of traf2-/- MEF to RNS. Moreover, RNS-induced ASK1 activation is impaired in traf2-/- cells and overexpression of a mutant ASK1 protein suppresses RNS-induced cell death in wild-type MEF cells. Last, we explored the signaling events upstream of TRAF2 and found that translocation of TRAF2 and JNK1 onto membrane lipid rafts is required for RNS-mediated JNK1 activation and cell death. Taken together, data from our study reveal a novel signaling pathway regulating RNS-induced JNK1 activation and non-apoptotic cell death.

Antioxidant activity of diphenyl diselenide prevents the genotoxicity of several mutagens in Chinese hamster V79 cells

Diphenyl diselenide (DPDS) is an electrophilic reagent used in the synthesis of a variety of pharmacologically active organic selenium compounds. Studies have shown its antioxidant, hepatoprotective, neuroprotective, anti-inflammatory, and antinociceptive effects. We recently showed the antioxidant effect of DPDS in V79 cells, and established the beneficial and toxic doses of this compound in this cell line. Here, we report the antigenotoxic and antimutagenic properties of DPDS, investigated by using a permanent lung fibroblast cell line derived from Chinese hamsters. We determined the cytotoxicity by clonal survival assay, and evaluated DNA damage in response to several mutagens by comet assay and micronucleus test in binucleated cells. In the clonal survival assay, at concentrations ranging from 1.62 to 12.5microM, DPDS was not cytotoxic, while at concentrations up to 25microM, it significantly decreased survival. The treatment with this organoselenium compound at non-cytotoxic dose range increased cell survival after challenge with hydrogen peroxide, methyl-methanesulphonate, and UVC radiation, but did not protect against 8-methoxypsoralen plus UVA-induced cytotoxicity. In addition, the treatment prevented induced DNA damage, as verified in the comet assay. The mutagenic effect of these genotoxins, as measured by the micronucleus test, similarly attenuated or prevented cytotoxicity and DNA damage. Treatment with DPDS also decreased lipid peroxidation levels after exposure to hydrogen peroxide MMS, and UVC radiation, and increased glutathione peroxidase activity in the extracts. Our results clearly demonstrate that DPDS at low concentrations presents antimutagenic properties, which are most probably due to its antioxidant properties.

Andrographolide induces cell cycle arrest at G2/M phase and cell death in HepG2 cells via alteration of reactive oxygen species

The cytotoxicity of andrographolide to HepG2 human hepatoma cells was investigated in the present study. Growth of HepG2 cells was affected in the presence of andrographolide with an IC(50) of 40.2 microM after 48 h treatment. Flow cytometric analysis and DNA fragmentation assay revealed that andrographolide induced cell cycle arrest at G2/M phase and a late apoptosis of the cells. The occurrence of cell cycle arrest was accompanied by the collapse of mitochondrial membrane potential (MMP) and an intracellular increase of hydrogen peroxide (H(2)O(2)) but a decrease of superoxide radicals (O(2)(-)) and reduced glutathione. In the treated cells, expression of Bax as well as the transcriptional controller of this pro-apoptotic gene, p53, was upregulated but not other apoptotic proteins such as Bad, Bcl-2 and Bcl-X(L). Although the activity of caspase-3, which has direct effect on apoptosis, was also enhanced by the presence of andrographolide, cell death of HepG2 could neither be prevented by a specific inhibitor of capsase-3 nor the pan-caspase inhibitor-zVAD (Val-Ala-Asp), indicating that it was a caspase-independent cell death. Since the overall percentage of apoptotic cells was relatively small throughout the experimental studies, we conclude that the cytotoxic effect of andrographolide on HepG2 cells is primary attributed to the induction of cell cycle arrest via the alteration of cellular redox status.

Methyl-3-indolylacetate inhibits cancer cell invasion by targeting the MEK1/2-ERK1/2 signaling pathway

Epidemiologic studies have suggested an inverse correlation between dietary intake of cruciferous vegetables and cancer risk. It is thus of interest to investigate the anticancer potential of phytochemicals presented in cruciferous vegetables. In this study, methyl-3-indolylacetate (MIA), a cruciferous indole for which the bioactivity has not been previously reported, was found to significantly suppress the invasion of cancer cells stimulated by the 12-O-tetradecanoyl-phorbol-13-acetate (TPA). Our data show that MIA pretreatments inhibited matrix metalloproteinase 9 (MMP-9) expression in a concentration-dependent manner, resulting in decreased MMP-9 activity. By using real-time reverse transcription-PCR, luciferase reporter gene assay, and electrophoretic mobility shift assay, we provided convincing evidence that MIA suppresses MMP-9 gene transcription via targeting the activator protein-1 signaling but not the nuclear factor-kappaB pathway. The TPA-induced mitogen-activated protein kinase (MAPK) activation cascade was also analyzed. Despite extensive activation of major MAPKs [c-Jun NH2-terminal kinase, p38, and extracellular signal-regulated kinase-1/2 (ERK1/2)] under TPA stimulation, only the ERK1/2 activation and its consequent nuclear translocation were found to be diminished by MIA. Interestingly, MIA did not affect the TPA-induced phosphorylation of either c-Raf or MAPK/ERK kinase-1/2 (MEK1/2), two upstream kinases of ERK. Moreover, using the in vitro kinase assay, MIA was shown to inhibit the kinase activity of MEK1/2, the upstream kinases of ERK, suggesting that MEK is the major molecular target of MIA. In conclusion, data from this study provided new insight into the anticancer potential of MIA, a cruciferous vegetable-derived indole compound.

Pyridoxamine analogues scavenge lipid-derived gamma-ketoaldehydes and protect against H2O2-mediated cytotoxicity

Isoketals and levuglandins are highly reactive gamma-ketoaldehydes formed by oxygenation of arachidonic acid in settings of oxidative injury and cyclooxygenase activation, respectively. These compounds rapidly adduct to proteins via lysyl residues, which can alter protein structure/function. We examined whether pyridoxamine, which has been shown to scavenge alpha-ketoaldehydes formed by carbohydrate or lipid peroxidation, could also effectively protect proteins from the more reactive gamma-ketoaldehydes. Pyridoxamine prevented adduction of ovalbumin and also prevented inhibition of RNase A and glutathione reductase activity by the synthetic gamma-ketoaldehyde, 15-E2-isoketal. We identified the major products of the reaction of pyridoxamine with the 15-E2-isoketal, including a stable lactam adduct. Two lipophilic analogues of pyridoxamine, salicylamine and 5'-O-pentylpyridoxamine, also formed lactam adducts when reacted with 15-E2-isoketal. When we oxidized arachidonic acid in the presence of pyridoxamine or its analogues, pyridoxamine-isoketal adducts were found in significantly greater abundance than the pyridoxamine-N-acyl adducts formed by alpha-ketoaldehyde scavenging. Therefore, pyridoxamine and its analogues appear to preferentially scavenge gamma-ketoaldehydes. Both pyridoxamine and its lipophilic analogues inhibited the formation of lysyl-levuglandin adducts in platelets activated ex vivo with arachidonic acid. The two lipophilic pyridoxamine analogues provided significant protection against H2O2-mediated cytotoxicity in HepG2 cells. These results demonstrate the utility of pyridoxamine and lipophilic pyridoxamine analogues to assess the potential contributions of isoketals and levuglandins in oxidant injury and inflammation and suggest their potential utility as pharmaceutical agents in these conditions.

Horseradish peroxidase inhibition and antioxidant activity of ebselen and related organoselenium compounds

Horseradish peroxidase (HRP) inhibition and glutathione peroxidase (GPx) activities of ebselen and some related derivatives are described. These studies show that ebselen and ebselen ditelluride (EbTe(2)) with significant antioxidant activity, inhibit the HRP-catalyzed oxidation reactions. In addition, inhibition of lipid peroxidation and singlet oxygen quenching studies were carried out. Although the inhibition of HRP by ebselen is comparable with that of EbTe(2), the inhibitory effect on gamma-radiation induced lipid peroxidation and the GPx activity of ebselen is found to be much higher than that of EbTe(2).

Neuroprotective effects of ebselen are associated with the regulation of Bcl-2 and Bax proteins in cultured mouse cortical neurons

There is little information available on the mechanisms underlying the neuroprotective actions of the organoselenium compound ebselen. In this study, we sought to determine the relationship between alterations in the expression of Bcl-2 and Bax proteins and intracellular levels of calcium and the protective effects of ebselen with a concentration range of 0.01-20 microM against glutamate toxicity in cultured mouse cortical neurons. Pretreatment with ebselen at moderate doses (4-12 microM), but not at lower or higher doses, significantly improved glutamate-induced suppression of cell viability. Pretreatment with ebselen (8 microM) also prevented apoptotic alterations, completely reversed the suppression of Bcl-2 expression, and significantly inhibited Bax overexpression, but did not alter elevated intracellular concentrations of calcium induced by glutamate. Pre-, co-, and post-treatment with ebselen (8 microM) had similar potency in improving the decreased viability of glutamate-exposed cells. These results indicate that the neuroprotective effects of ebselen at low doses are associated with the regulation of Bcl-2 and Bax proteins but appear to be independent of glutamate-mediated elevation of intracellular calcium, suggesting that different mechanisms are involved in the actions of low and high dose regimens. Ebselen may be an effective agent used for early treatment of acute brain injuries.