Quercetin protects HCT116 cells from Dichlorvos-induced oxidative stress and apoptosis

The present study was designed to assess the possible protective effects of Quercetin (QUER), a flavonoid with well-known pharmacological effects, against Dichlorvos (DDVP)-induced toxicity in vitro using HCT116 cells. The cytotoxicity was monitored by cell viability, reactive oxygen species (ROS) generation, anti-oxidant enzyme activities, malondialdehyde (MDA) production, and DNA fragmentation. The apoptosis was assessed through the measurement of the mitochondrial transmembrane potential (ΔΨm) and caspase activation. The results indicated that pretreatment of HCT116 cells with QUER, 2 h prior to DDVP exposure, significantly decreased the DDVP-induced cell death, inhibited the ROS generation, modulated the activities of catalase (CAT) and superoxide dismutase (SOD), and reduced the MDA level. The reductions in mitochondrial membrane potential, DNA fragmentation, and caspase activation were also attenuated by QUER. These findings suggest that dietary QUER can protect HCT116 cells against DDVP-induced oxidative stress and apoptosis.     

Possible use of quercetin, an antioxidant, for protection of cells suffering from overload of intracellular Ca2+: a model experiment

Quercetin is known to protect the cells suffering from oxidative stress. The oxidative stress elevates intracellular Ca(2+) concentration, one of the phenomena responsible for cell death. Therefore, we hypothesized that quercetin would protect the cells suffering from overload of intracellular Ca(2+). To test the hypothesis, the effects of quercetin on the cells suffering from oxidative stress and intracellular Ca(2+) overload were examined by using a flow cytometer with appropriate fluorescence probes (propidium iodide, fluo-3-AM, and annexin V-FITC) and rat thymocytes. The concentrations (1-30 microM) of quercetin to protect the cells suffering from intracellular Ca(2+) overload by A23187, a calcium ionophore, were similar to those for the cells suffering from oxidative stress by H(2)O(2). The cell death respectively induced by H(2)O(2) and A23187 was significantly suppressed by removal of external Ca(2+). Furthermore, quercetin greatly delayed the process of Ca(2+)-dependent cell death although it did not significantly affect the elevation of intracellular Ca(2+) concentration by H(2)O(2) and A23187, respectively. It is concluded that quercetin can protect the cells from oxidative injury in spite of increased concentration of intracellular Ca(2+). Results suggest that quercetin is also used for protection of cells suffering from overload of intracellular Ca(2+).     

Crocin and Quercetin protect HCT116 and HEK293 cells from Zearalenone-induced apoptosis by reducing endoplasmic reticulum stress

Mycotoxins are considered to be significant contaminants of food and animal feed. Zearalenone (ZEN) is a non-steroidal estrogenic mycotoxin produced by several species of Fusarium in cereals and agricultural products. ZEN has been shown to be cytotoxic, genotoxic, and mutagenic in different cell types. In the present study, we investigated the involvement of endoplasmic reticulum (ER) stress in ZEN-mediated toxicity in human intestine (HCT116) and kidney (HEK293) cells and evaluated the effects of the two common dietary compounds Quercetin (QUER) and Crocin (CRO). We show that ZEN treatment induces ER stress and activates the unfolded protein response (UPR) as evidenced by XBP1 mRNA splicing and upregulation of GRP78, ATF4, GADD34, PDIA6, and CHOP. Activation of the ER stress response is associated with activation of the mitochondrial pathway of apoptosis. This apoptotic process is characterized by an increase in ROS generation and lipid peroxidation, a loss of mitochondrial transmembrane potential (ΔΨm), and an activation of caspases and DNA damages. We also demonstrate that the antioxidant properties of QUER and CRO help to prevent ER stress and reduce ZEN-induced apoptosis in HCT116 and HEK293 cells. Our results suggest that antioxidant molecule might be helpful to prevent ZEN-induced ER stress and toxicity.     

Effects of naringin on cytosine arabinoside (Ara-C)-induced cytotoxicity and apoptosis in P388 cells

Naringin (NG), a flavonoid in grapefruit and citrus, has been reported to exhibit antioxidant effects and pharmacological actions. Recently, we have reported that NG suppressed the cytotoxicity and apoptosis induced by H(2)O(2), a typical pro-oxidant, in mouse leukemia P388 cells. Cytosine arabinoside (1-beta-d-arabinofuranosylcytosine; Ara-C) is the most important antimetabolite chemotherapeutic drug used for acute leukemia. It has been suggested that Ara-C-induced cytotoxicity is caused by apoptosis, which is mediated by reactive oxygen species (ROS). In this study, we examined the effect of NG on the cytotoxicity and apoptosis in mouse leukemia P388 cells treated with Ara-C. Ara-C caused cytotoxicity in a concentration and time-dependent manner in the cells. N-Acetyl-L-cysteine (NAC), cystamine (CysA) or a reduced form of glutathione (GSH), typical antioxidants significantly blocked Ara-C-induced cytotoxicity. Similarly, Ara-C-induced cell death was completely prevented by NG. NG strongly reduced ROS production caused by Ara-C in the cells. NG slightly increased the activities of antioxidant enzymes, catalase and glutathione peroxidase. Ara-C caused apoptosis with nuclear morphological change and DNA fragmentation. NG remarkably attenuated the Ara-C-induced apoptosis. NG completely blocked the DNA damage caused by Ara-C treatment at 6 h using the Comet assay. Our data suggest that NG reduces Ara-C-induced oxidative stress through both an inhibition of the generation of ROS production and an increase in antioxidant enzyme activities. Consequently, NG blocked apoptosis caused by Ara-C-induced oxidative stress, resulting in the inhibition of the cytotoxicity of Ara-C.     

Micropropagation of gerbera: lipid peroxidation and antioxidant enzyme activities during acclimatization process

Gerbera jamesonii H. Bolus ex Hook (Family: Asteraceae) has been successfully acclimatized from temperate to subtropical North Indian plains of Lucknow through in vitro propagation. Flower heads were collected from greenhouse, segmented into 4–16 pieces and cultured in Murashige and Skoog’s medium (MS) (Physiol Plant 15:472–497, 1962) supplemented with 2.87 μM indole-3-acetic acid (IAA) and 8.88 μM N⁶-benzyladenine (BA) for shoot regeneration. Shoots were subcultured on growth regulator free MS medium. Apical shoot meristems from in vitro plantlets of gerbera were tested in MS medium with different combination of cytokinins [BA, kinetin, and thidiazuron (TDZ)] alongwith 2.68 μM 1-naphthaleneacetic acid (NAA) for shoot multiplication. The optimum results were obtained with 8.88 μM BA. Regenerated plants with well-established root system were transferred to pots containing soil and sand (1:1 v/v) and were kept in humidity chamber with 80–90% relative humidity for 0, 5, 10, 15, 20, and 25 days before they were transferred to field (during October, 2005 to February, 2006). Survival percentage was higher when regenerated plantlets were kept under humidity chamber for 15 days. An attempt was made to obtain basic information on different biochemical changes during acclimatization process of in vitro raised plantlets. Increased lipid peroxidation and high H₂O₂ content in early stages of acclimatization process reflected a similar process of oxidative stress. Our work suggests that tissue-cultured plants develop antioxidant enzymatic protective system which determine the ability to survive in oxidative stress and up regulation of these enzymes would help to reduce the built up of reactive oxygen species (ROS).     

Vitamin D2 protects acute and repeated noise stress induced behavioral,biochemical, and histopathological alterations: Possible antioxidant effect

Noise is an environmental stressor which causes distress and hearing loss in individuals residing in urban areas. Psychological deficits such as anxiety, depression, impaired memory and cognitive decline are caused by noise stress. Different vitamins have been used as a potential antioxidant for neuronal protection. In this study we investigate the anxiolytic, antidepressant and memory enhancing effect of vitamin D2 (Vit D2) following noise stress. Thirty-six albino rats were randomly divided into six groups. (i) Unstressed + corn oil (ii) Unstressed + Vit D2 (iii) Acute noise stress + corn oil (iv) Acute noise stress + Vit D2 (v) Repeated noise stress + corn oil (vi) Repeated noise stress + Vit D2. 600 IU/kg body weight of Vit D2 dosage was prepared in corn oil. Corn oil is used as vehicle and all the drugs administered via oral gavage till end of the experiment (day 16). Recorded sound of generator which was amplified by speakers and had 100 dB intensity was used as noise stress. Repeated stressed animals were exposed to noise (4-hrs) daily for 14 days, while acute stressed animals were exposed to noise (4-hrs) once after 14 days. Behavioral tests (elevated plus maze, light dark box, tail suspension test and Morris water maze) of all groups were performed after15 days treatment period. After behavioral tests rats received their last dosage and decapitated after 1-hr. Brain of all animals was removed and used for biochemical (oxidative stress biomarker, antioxidant enzymes and acetylcholinesterase) and histopathological estimations. Results show that Vit D2 decreased time spent in light box and open arm of light dark activity box and elevated plus maze test respectively (used for anxiety evaluation), decreased immobility time in tail suspension test (for depression) and improved cognitive ability evaluated by Morris water maze test in acute and repeated noise stressed rats. Furthermore, increased antioxidant enzymes activity, decreased lipid peroxidation and acetylcholinesterase activity were also observed in Vit D2 treated animals following acute and repeated noise stress. Normalization in histopathological studies was also observed in Vit D2 treated following acute and repeated noise stress. It is concluded that Vit D2 protects from noise stress induced behavioral, biochemical and histopathological impairment through its antioxidant potential.     

Effect of 4-hydroxynonenal on antioxidant capacity and apoptosis induction in Jurkat T cells

4-Hydroxynonenal (HNE) is one of the major end products of lipid peroxidation and may have either physiological or pathological significance regulating cell proliferation. We studied some biochemical effects of HNE, at various concentrations (0.1-100 μM), on Jurkat T cells incubated thereafter for 24, 48 and 72 h. HNE at low concentrations significantly enhanced the proliferation index, whereas at higher concentrations progressively blocked cell proliferation. Caspase 3 activity increased significantly at HNE concentrations between 1 and 10 μM and decreased at higher concentrations. Superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and glutathione reductase (GSH-Rd) increased progressively with HNE concentrations, particularly GSH-Px. Glucose-6-phosphate dehydrogenase (G6PDH) showed a different pattern, increasing at low HNE (1-5 μM) concentrations and rapidly declined thereafter. These results show that HNE may induce growth inhibition of Jurkat T cells and regulate the activity of typical antioxidant enzymes. Furthermore, the protective effect of doubling the foetal calf serum still points out the risk that cultured cells undergo oxidative stress during incubation.     

Contribution of inducible nitric oxide synthase and cyclooxygenase-2 to apoptosis induction in smooth chorion trophoblast cells of human fetal membrane tissues

We examined the contribution of apoptosis- and oxidative stress-associated genes to apoptosis induction in trophoblast cells of human fetal membrane tissues undergoing apoptosis during in vitro incubation. RT-PCR analyses demonstrated an increased level of HO-1, Mn-SOD, Cox-2, iNOS, TNFalpha, TNFR1, IL-1beta, IL-6, Bax, Bak, and Bad gene expression, while Bcl-2 mRNA expression level decreased. Western blot analyses demonstrated an increase in iNOS, Cox-2, and HO-1 protein levels; a decrease in pro-caspase-3 and 9, proform-PARP, and Apaf-1 protein levels; a leakage of cytochrome c from the mitochondria. An antioxidative reagent, general and selective Cox-2 inhibitors, and an iNOS inhibitor suppressed in vitro progression of the apoptosis. Furthermore, an NO donor reagent induced apoptosis in primary cultured trophoblast cells. Therefore, we concluded that the induction of apoptosis in the smooth chorion trophoblasts is mediated through oxidative stress induction followed by mitochondria damage, suggesting that iNOS and Cox-2 play an important role in the apoptosis induction in trophoblasts of human fetal membrane tissues.     

Proliferating effects of the flavonoids daidzein and quercetin on cultured chicken primordial germ cells through antioxidant action

Primordial germ cells (PGCs) are undifferentiated pluripotent stem cells, whose proliferation is influenced by many internal and external factors. In the present study, a PGC-somatic cell co-culture model was established to evaluate effects of the flavonoids daidzein (DAI) and quercetin (QUE) on proliferation of PGCs from embryonic chickens. PGCs were isolated from the germinal ridge of 3.5-4day embryos and cultured in 5% fetal calf serum (FCS)-supplemented Medium 199. PGC subculture was carried out on chicken embryonic fibroblast feeder (CEF) or follicular granulosa cell feeder (GCF) layers. The subcultured PGCs were challenged with flavonoids alone or in combination with a reactive oxygen substance (ROS)-producing system on CEF for 48h. The results showed a better supporting effect of CEF than GCF. Flavonoids (1microg/ml) significantly promoted PGC proliferation, which could be markedly inhibited by ROS. The oxidative damage by ROS was further manifest by decreased superoxide dismutase activity and glutathione levels. In addition, activation of protein kinase A (PKA) by forskolin significantly stimulated PGC proliferation, but PKA inhibitor H89 inhibited the proliferating effects induced by DAI and QUE. These results indicated that cultured PGCs respond to exogenous agents on proliferation and that antioxidant flavonoids could restore the intracellular antioxidant system and promote PGC proliferation via their antioxidant action involving the PKA signaling pathway.     

Mild thermotolerance induced at 40 °C increases antioxidants and protects HeLa cells against mitochondrial apoptosis induced by hydrogen peroxide: Role of p53

Exposure of cells to mild temperatures (40 °C) induces thermotolerance, which renders cells resistant to subsequent toxic insults. Thermotolerance is usually associated with accumulation of heat shock proteins. This study determines whether mild thermotolerance (40 °C, 3 h) can induce other defense proteins (e.g. antioxidants, anti-apoptosis proteins), and protect HeLa cells against apoptosis triggered by H₂O₂. Protein expression and enzymatic activity of MnSOD and catalase were increased in thermotolerant cells, as well as intracellular glutathione levels and γ-glutamylcysteine synthetase expression. Furthermore, levels of reactive oxygen species (ROS) were increased in thermotolerant cells, which caused mitochondrial membrane hyperpolarisation. Mild thermotolerance inhibited activation of the mitochondrial cascade of apoptosis by H₂O₂. This entailed inhibition of mitochondrial Bax translocation, mitochondrial membrane depolarisation, cytochrome c release, activation of caspases-9/-3 and chromatin condensation. Thermotolerance inhibited H₂O₂-induced caspase-independent apoptosis involving apoptosis-inducing factor, and activation of p53 and increased expression of its target protein PUMA. Thermotolerance induced at mild physiological temperatures protects cells against both caspase-dependent and caspase-independent apoptosis triggered by oxidative stress.     

Tricyclic diterpenes from the resin of Daemonorops draco and their activities on oxidative stress-induced mesenchymal stromal cells

A bioassay-guided chemical investigation of the resin exudates from Daemonorops draco (dragon’s blood, Palmaceae) has resulted in the isolation of two new trinorditerpenes, 7β-13-dihydroxypodocarpa-8,11,13-trien-15-oic acid (1) and 7α-13-dihydroxypodocarpa-8,11,13-trien-15-oic acid (2), along with ten previously described abietane diterpenes, 7β-15-dihydroxydehydroabietic acid (3), 7α-15-dihydroxydehydroabietic acid (4), 15-hydroxydehydroabietic acid (5), 7-oxodehydroabietic acid (6), dehydroabietic acid (7), 15-hydroxyabietic acid (8), 12α-hydroxyabietic acid (9), abietic acid (10), 7,13,15-abietatrien-18-oic acid (11), and cephasinene B (12). The structures of 1 and 2 were elucidated using spectroscopic techniques, including HR-ESIMS and 1D/2D NMR. The absolute configurations were determined by comparing the experimental electronic circular dichroism (ECD) spectra with the calculated ECD data based on time-dependent density functional theory. The bioactivity of the extracts, fractions, and isolated compounds was assessed in oxidative stress-induced mesenchymal stromal cells (MSCs). The crude extract and the hexanes, ethyl acetate, and aqueous fractions exhibited high potency against oxidative stress-induced apoptosis of MSCs. Among the isolated compounds, compounds 1 (3 μM) and 10 (100 μM) demonstrated good recovery of MSCs against oxidative stress.     

The effect of menadione-induced oxidative stress on the in vivo reactive oxygen species and antioxidant response system of Phanerochaete chrysosporium

The antioxidant response system of Phanerochaete chrysosporium against menadione-induced oxidative stress was investigated in this study. The superoxide anion radical levels in tested menadione-supplemented conditions generally decreased over the incubation period. The level of hydrogen peroxide and the activities of NAD(P)H oxidase, superoxide dismutase (SOD) and catalase (CAT) were higher than those in the controls at all incubation times. The highest NADH and NADPH oxidase activities were determined to be 4.9- and 5.0-fold higher than those in the control, respectively in cells exposed to 0.75 mM menadione. The SOD and CAT activities increased with increasing menadione, and their highest activities were 5.4- and 5.1-fold higher than those in the control, respectively. In 0.1–0.5 mM menadione exposed cells, the lipid peroxidation levels did not change significantly when compared to each other, except 8th hour of incubation (p > 0.01). Our result shows that although menadione induces the formation of reactive oxygen species, the antioxidant response system of P. Chrysosporium is able to negate menadione-induced oxidative stress up to relatively high menadione concentrations, as 0.75 mM. These results are important to determine the effects of menadione, as a medicine, on the antioxidant response system of eukaryotic models and the resulting level of damage.     

Oxidative stress, osmotic stress and apoptosis: impacts on sperm function and preservation in the horse

Oxidative stress is an important component of the cytopathology of equine spermatozoa undergoing storage as liquid or frozen semen. Damage to chromatin, membranes and proteins of sperm are important components of oxidative damage to sperm. Similarly, sperm are exposed to a variety of osmotic stresses during storage that result from exposure to hypertonic media or result as a consequence of osmotic changes induced during freezing. A number of changes induced during processing and storage of equine sperm also appear to induce apoptotic-like changes which may adversely affect sperm survival and function. These processes appear in many cases to be interrelated, and this review will examine current understanding of these processes on the equine sperm function.     

The protective effects of nutritional antioxidant therapy on Ehrlich solid tumor-bearing mice depend on the type of antioxidant therapy chosen: histology, genotoxicity and hematology evaluations

Strong evidence indicates that reactive oxygen species (ROS) play an important role in the initiation as well as the promotion phase of carcinogenesis. Studies support the role of ROS in cancer, in part, by showing that dietary antioxidants act as cancer-preventive agents. Although results are promising, the research on this topic is still controversial. Thus, the aim of this study was to investigate whether vitamins C, E and pequi oil can, individually, provide prevention and/or be used afterward as an adjuvant in cancer therapy. Ehrlich solid tumor-bearing mice received antioxidant as follows: before tumor inoculation, before and after tumor inoculation (continuous administration), and after tumor inoculation; morphometric analyses of tumor, genotoxicity and hematology were then carried out. Antioxidant administrations before tumor inoculation effectively inhibited its growth in the three experimental protocols, but administrations after the tumor's appearance accelerated tumor growth and favored metastases. Continuous administration of pequi oil inhibited the tumor's growth, while the same protocol with vitamins E and C accelerated it, favoring metastasis and increasing oxidative stress on erythrocytes. Except for continuous administration with vitamin E, the development of ascites tumor metastases was linked with increased inflammation. Results suggest that the efficiency and applicability of antioxidants in the medical clinic can depend not only on the nature of the antioxidant, the type and stage of cancer being treated and the prevailing oxygen partial pressure in the tissues, but also on the type of antioxidant therapy chosen.     

The effects of NaCl on antioxidant enzyme activities in callus tissue of salt-tolerant and salt-sensitive cotton cultivars (Gossypium hirsutum L.)

Summary To determine NaCl effects on callus growth and antioxidant activity, callus of a salt-tolerant and a salt-sensitive cultivar of cotton was grown on media amended with 0, 75, and 150 mM NaCl. Callus of the salt-tolerant cultivar, Acala 1517-8 8, grown at 150 mM NaCl, showed significant increases in superoxide dismutase, catalase, ascorbate peroxidase, peroxidase and glutathione reductase activities compared to callus tissue grown at 0 mM NaCl. In contrast, callus tissue of the salt-sensitive cultivar, Deltapine 50, grown at 0, 75, and 150 mM NaCl, showed no difference in the activities of these enzymes. At the 150 mM NaCl treatment, peroxidase was the only antioxidant enzyme from Deltapine 50 with an activity as high as that observed in Acala 1517-88. The NaCl-induced increase in the activity of these enzymes in Acala 1517-88 indicates that callus tissue from the more salt-tolerant cultivar has a higher capacity for scavenging and dismutating superoxide, an increased ability to decompose H₂O₂, and a more active ascorbate-glutathione cycle when grown on media amended with NaCl.     

Hyperglycemia differentially affects proliferation,apoptosis, and BNIP3 and p53 mRNA expression of human umbilical cord Wharton's jelly cells from non-diabetic and diabetic pregnancies

Diabetes in pregnancy constitutes an unfavorable environment for embryonic and fetal development, where the child has a higher risk of perinatal morbidity and mortality, with high incidence of congenital malformations and predisposition to long-term metabolic diseases that increase with a hypercaloric diet. To analyze whether hyperglycemia differentially affects proliferation, apoptosis, and mRNA expression in cells from children of normoglycemic pregnancies (NGPs) and diabetes mellitus pregnancies (DMPs), we used umbilical cord Wharton jelly cells as a research model. Proliferation assays were performed to analyze growth and determine the doubling time, and the rate of apoptosis was determined by flow cytometry-annexin-V assays. AMPK, BNIP3, HIF1α, and p53 mRNA gene expression was assessed by semi-quantitative RT-PCR. We found that hyperglycemia decreased proliferation in a statistically significant manner in NGP cells treated with 40?mM D-glucose and in DMP cells treated with 30 and 40?mM D-glucose. Apoptosis increased in hyperglycemic conditions in NGP and DMP cells. mRNA expression of BNIP3 and p53 was significantly increased in cells from DMPs but not in cells from NGPs. We found evidence that maternal irregular metabolic conditions, like diabetes with hyperglycemia in culture, affect biological properties of fetal cells. These observations could be a constituent of fetal programming.     

Effects of dietary antioxidants on DNA damage in lysed cells using a modified comet assay procedure

A modified version of the comet assay was employed to investigate the effect in vitro of dietary antioxidants in the subcellular environment. Human lymphocytes were isolated, embedded in agarose gel, lysed in high ionic strength solution with Triton X-100, and then incubated for 30 min with antioxidants at different concentrations. Gels were washed, and the comet assay performed on cells stressed by 5 min incubation with 45 microM hydrogen peroxide and on unstressed cells in parallel. Results showed that alpha-tocopherol was protective against oxidant stress, whereas caffeic acid did not protect, and at high concentration (100 microM) caused increased DNA damage. Results for quercetin suggested a direct damaging effect, but this did not reach statistical significance. However, at low concentration (3.1 microM), quercetin appeared protective. Thus some dietary antioxidants that have been shown previously to have a protective effect in the 'standard', whole-cell, comet assay cause DNA damage in this lysed-cell version. The cell membrane may have an important role in limiting cellular access of these 'double-edged' antioxidants. Furthermore, the absolute concentration and the presence of complementary or synergistic intracellular antioxidants may delineate the type of action of a putative antioxidant. We suggest that, used in conjunction with the standard comet assay, this lysed-cell version is useful for assessing the effect of the cell membrane and intracellular systems on susceptibility of DNA to oxidative damage, and will help determine the mechanism of protection or damage by phytochemicals.     

Effects of boric acid on cell death and oxidative stress of mouse TM3 Leydig cells in vitro

BackgroundBoron (B) is an abundant element on earth and presents at physiological pH in the form of boric acid (BA). It has both positive and negative effects on biological systems. BA and sodium borates have been considered as being toxic to the reproduction system in animal experiments. Unfortunately, the molecular mechanism underlying the toxic effects of BA is not fully understood.MethodsHere, we demonstrate the influence of BA on mouse TM3 Leydig cells which are male reproductive system cells targeted by BA exposure. The cytotoxicity was evaluated by MTT and NRU assays. Annexin V-FITC/PI double staining kit, mitochondria membrane potential (ΔΨm) assay kit with JC-1 and caspase-3 colorimetric assay kit were used to indicate the cell death pathway. To estimate the role of oxidative stress in BA induced toxicity, glutathione (GSH) level, catalase (CAT) and superoxide dismutase (SOD) activities were measured manually.ResultsThe cell viability assays showed that BA was not cytotoxic within the tested concentrations up to 1000 μM. Sub-toxic concentrations were used for detecting oxidative stress status. BA exposure was significantly reduced GSH level at 1000 μM and CAT activity in a concentration-dependent manner. However, SOD activity was increased at the tested concentrations (100–1000 μM). Moreover, ΔΨm was significantly decreased at 500 and 1000 μM of BA, while caspase-3 activity was not changed apparently.ConclusionThese findings demonstrated that BA is not cytotoxic and apoptotic but may slightly induces oxidative stress in TM3 Leydig cells at higher concentrations.     

Interactions of nitric oxide and oxygen in cytotoxicity: Proliferation and antioxidant enzyme activities of endothelial cells in culture

Nitric oxide (NO) shows cytotoxicity, and its reaction products with reactive oxygen species, such as peroxynitrite, are potentially more toxic. To examine the role of O₂ in the NO toxicity, we have examined the proliferation of cultured human umbilical vein endothelial cells in the presence or absence of NO donor, ((Z)-1-[N-(2-aminoethyl)-N-(2-ammonioethyl)-amino]diazen-1-ium-1,2-diolate) (DETA-NONOate) (100–500 μM), under normoxia (air), hypoxia (< 0.04% O₂) or hyperoxia (88–94% O₂). It was found that the dose dependency on NONOate was little affected by the ambient O₂ concentration, showing no apparent synergism between the two treatments. We have also examined the effects of exogenous NO under normoxia and hyperoxia on the cellular activities of antioxidant enzymes involved in the H₂O₂ elimination, since many of them are known to be inhibited by NO or peroxynitrite in vitro. Under normoxia DETA-NONOate (500 μM) caused 25% decrease in catalase activity and 30% increases in glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase activities in 24 h. Under hyperoxia NO caused about 25% decreases in activities of catalase, glutathione reductase and glucose-6-phosphate dehydrogenase. The H₂O₂ removal rate by NO-treated cells was computed on the mathematical model for the enzyme system. It was concluded that the cellular antioxidant function is little affected by NO under normoxia but that it is partially impaired when the cells are exposed to NO under hyperoxia.