Inhibition of cellular antioxidants: a possible mechanism of toxic cell injury

GUCY2C signaling limits dopaminergic neuron vulnerability to toxic insults

Mitochondrial dysfunction and reactive oxygen species (ROS) accumulation within the substantia nigra pars compacta (SNpc) are central drivers of dopaminergic (DA) neuron death in Parkinson's disease (PD). Guanylyl cyclases, and their second messengers cyclic (c)GMP, support mitochondrial function, protecting against ROS and promoting cell survival in a number of tissues. However, the role of the guanylyl cyclase-cGMP axis in defining the vulnerability of DA neurons in the SNpc in PD remains unclear, in part due to the challenge of manipulating cGMP levels selectively in midbrain DA neurons. In that context, guanylyl cyclase C (GUCY2C), a receptor primarily expressed by intestinal epithelial cells, was discovered recently in midbrain DA neurons. Here, we demonstrate that GUCY2C promotes mitochondrial function, reducing oxidative stress and protecting DA neurons from degeneration in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of neurodegeneration. GUCY2C is overexpressed in the SNpc in PD patients and in mice treated with MPTP, possibly reflecting a protective response to oxidative stress. Moreover, cGMP signaling protects against oxidative stress, mitochondrial impairment, and cell death in cultured DA neurons. These observations reveal a previously unexpected role for the GUCY2C-cGMP signaling axis in controlling mitochondrial dysfunction and toxicity in nigral DA neurons, highlighting the therapeutic potential of targeting DA neuron GUCY2C to prevent neurodegeneration in PD.

Interactions of Bisphenol A with Artemia franciscana and the ameliorative effect of probiotics

In the present study, the bidirectional interactions of Artemia franciscana with BPA, administered either alone or following treatment with the probiotics Bacillus subtilis, Lactococcus lactis or Lactobacillus plantarum, were evaluated. A 24 h exposure to BPA below LC₅₀ induced oxidative stress to Artemia, indicated by diminished activity of superoxide dismutase, glutathione reductase, glutathione transferase and phenoloxidase, increased lipid peroxidation and decreased survival. Probiotic treatment prior to BPA exposure, led to increased survival, reduced lipid peroxidation and increased enzyme activities. BPA quantification in Artemia and its culture medium, showed a time dependent reduction in its levels, more evident in probiotic series, indicating its biotransformation. ESI-MS analysis confirmed the presence of the tentative BPA metabolites hydroquinone and BPA-sulfate, while BPA-disulfate formation was confirmed in only in the probiotic series. Our results provide evidence that probiotics alleviate the oxidative stress response induced by BPA, by enhancing the BPA biotransformation ability of Artemia.

Molecular Insights of Plant Phytochemicals Against Diabetic Neuropathy

Diabetes and its associated complications including diabetic neuropathy have become a menacing headache for health workers and scientists all over the world. The number of diabetic individuals has been growing exponentially every day while the entire medical fraternity feels crippled and unable to handle such an enormous and anarchical scenario. The disease also demonstrates itself in the patients in numerous ways ranging from a little discomfort to death. Diabetic neuropathy has a poor prognosis since it might go unnoticed for years after the onset of diabetes. The etiology of the disease has been linked to oxidative stress caused by increased free radical production. Hyperglycemia causes multiple metabolic pathways to be activated, as well as significant oxidative stress, which becomes the major cause of cell death, culminating in Diabetic Neuropathy. So, it is the need of the hour to find out permanent treatment for this life-threatening disease. The primary goal of this study is to emphasize the potential importance of numerous processes and pathways in the development of diabetic neuropathy as well as the possible role of plant metabolites to control the disease at a molecular level. A possible mechanism was also summarized in the study about scavenging the reactive oxygen species by a flavonoid component. The study also covered the in vivo data of various plants and some of the flavonoid compounds actively studied against Diabetic Neuropathy by inhibiting or reducing the contributing factors such as proinflammatory cytokines, ROS, RNS inhibition, and upregulating the various cellular antioxidants such as GSH, SOD, and CAT.

Synbiotics and Their Antioxidant Properties, Mechanisms, and Benefits on Human and Animal Health: A Narrative Review

Antioxidants are often associated with a variety of anti-aging compounds that can ensure human and animal health longevity. Foods and diet supplements from animals and plants are the common exogenous sources of antioxidants. However, microbial-based products, including probiotics and their derivatives, have been recognized for their antioxidant properties through numerous studies and clinical trials. While the number of publications on probiotic antioxidant capacities and action mechanisms is expanding, that of synbiotics combining probiotics with prebiotics is still emerging. Here, the antioxidant metabolites and properties of synbiotics, their modes of action, and their different effects on human and animal health are reviewed and discussed. Synbiotics can generate almost unlimited possibilities of antioxidant compounds, which may have superior performance compared to those of their components through additive or complementary effects, and especially by synergistic actions. Either combined with antioxidant prebiotics or not, probiotics can convert these substrates to generate antioxidant compounds with superior activities. Such synbiotic-based new routes for supplying natural antioxidants appear relevant and promising in human and animal health prevention and treatment. A better understanding of various component interactions within synbiotics is key to generating a higher quality, quantity, and bioavailability of antioxidants from these biotic sources.

Microplastics cause neurotoxicity and decline of enzymatic activities in important bioturbator Hediste diversicolor

Microplastics (MPs) tend to accumulate in marine sediments thus benthic fauna is particularly vulnerable to microplastic pollution. Hediste diversicolor is a widespread species in coastal marine sediments. It plays key ecological functions mostly related to bioturbation process which means sediment reworking due to the worm burrowing activity and building a network of galleries. Herein, we show that commercial plastic microspheres of two sizes (63-75 and 300-355 μm) have the potential to cause neurotoxicity in H. diversicolor. The whole-body acetylcholinesterase (AChE) activity - a common indicator of neurotoxic effect - was on average 60% lower in polychaetes exposed for 28 days to MPs served at environmentally relevant concentrations (0.08% sediment d. wt.), than in unexposed ones. Significantly reduced activities of antioxidant enzymes (SOD, CAT, GST) indicated suppression of the cellular antioxidative system in worms exposed to MPs. No changes were, however, observed in tGSH, lipid or protein oxidation measures (CBO, MDA), and in the energetic value of these polychaetes. The response was generally similar with no regard to MPs size. Only very few microspheres were found in polychaetes exposed to MPs spiked sediment. The potential role of MPs-associated pollutants as a factor responsible for observed biochemical effects, is discussed.

Oxidation of catalytic cysteine of human deubiquitinase BAP1 triggers misfolding and aggregation in addition to functional loss

Deubiquitinating enzymes (DUBs) form a large protease family involved in a myriad of biological and pathological processes, including ROS sensors. ROS-mediated inhibition of their DUB activities is critical for fine-tuning the stress-activated signaling pathways. Here, we demonstrate that the ubiquitin C-terminal hydrolase (UCH) domain of BAP1 (BAP1-UCH) is highly sensitive to moderate oxidative stress. Oxidation of the catalytic C91 significantly destabilizes BAP1-UCH and increases the population of partially unfolded form, which is prone to aggregation. Unlike other DUBs, the oxidation-induced structural and functional loss of BAP1-UCH cannot be fully reversed by reducing agents. The oligomerization of oxidized BAP1-UCH is attributed to inter-molecular disulfide bond formation. Hydrogen-deuterium mass exchange spectrometry (HDX-MS) reveals increased fluctuations of the central β-sheet upon oxidation. Our findings suggest that oxidation-mediated functional loss and increased aggregation propensity may contribute to oncogenesis associated with BAP1.

A Comparative Study of Antioxidative Activity of Saliva in Children and Young Teenagers with and without Gingivitis

Objectives: The aim of this study was to compare the values of total antioxidant capacity (TAC), catalase (CAT) and glutathione peroxidase (GPX) in the saliva of children and young teenagers with and without gingivitis. Materials and Methods: A total of 120 children and young teenagers of the mean age of 12.2 participated in the research. Gingival condition was assessed using the Löe and Silness Gingival Index. The subjects were divided into groups of those without gingivitis and those with gingivitis. Samples of unstimulated saliva were collected, and TAC, CAT and GPX were determined spectrophotometrically. Results: By comparing the values of TAC, CAT and GPX in subjects with and without gingivitis, significantly lower values of TAC (p < 0.001) and CAT (p < 0.001) were observed in the group of subjects with gingivitis. The correlation analysis of these values showed a positive correlation in groups of subjects not suffering from gingival inflammation and those with gingival inflammation. Conclusions: The study showed significantly lower values of TAC and CAT in the saliva of subjects with gingivitis. This indicates their possible role as a potential biomarker in the early diagnosis and expression of periodontal disease in children and young teenagers.

Age differences in brain structural and metabolic responses to binge ethanol exposure in fisher 344 rats

An overarching goal of our research has been to develop a valid animal model of alcoholism with similar imaging phenotypes as those observed in humans with the ultimate objective of assessing the effectiveness of pharmacological agents. In contrast to our findings in humans with alcohol use disorders (AUD), our animal model experiments have not demonstrated enduring brain pathology despite chronic, high ethanol (EtOH) exposure protocols. Relative to healthy controls, older individuals with AUD demonstrate accelerating brain tissue loss with advanced age. Thus, this longitudinally controlled study was conducted in 4-month old (equivalent to ~16-year-old humans) and 17-month old (equivalent to ~45-year-old humans) male and female Fisher 344 rats to test the hypothesis that following equivalent alcohol exposure protocols, older relative to younger animals would exhibit more brain changes as evaluated using in vivo structural magnetic resonance imaging (MRI) and MR spectroscopy (MRS). At baseline, total brain volume as well as the volumes of each of the three constituent tissue types (i.e., cerebral spinal fluid (CSF), gray matter, white matter) were greater in old relative to young rats. Baseline metabolite levels (except for glutathione) were higher in older than younger animals. Effects of binge EtOH exposure on brain volumes and neurometabolites replicated our previous findings in Wistar rats and included ventricular enlargement and reduced MRS-derived creatine levels. Brain changes in response to binge EtOH treatment were more pronounced in young relative to older animals, negating our hypothesis. Higher baseline glutathione levels in female than male rats suggest that female rats are perhaps protected against the more pronounced changes in CSF and gray matter volumes observed in male rats due to superior metabolic homeostasis mechanisms. Additional metabolite changes including low inositol levels in response to high blood alcohol levels support a mechanism of reversible osmolarity disturbances due to temporarily altered brain energy metabolism.

Vitamin E as an Antioxidant in Female Reproductive Health

Vitamin E was first discovered in 1922 as a substance necessary for reproduction. Following this discovery, vitamin E was extensively studied, and it has become widely known as a powerful lipid-soluble antioxidant. There has been increasing interest in the role of vitamin E as an antioxidant, as it has been discovered to lower body cholesterol levels and act as an anticancer agent. Numerous studies have reported that vitamin E exhibits anti-proliferative, anti-survival, pro-apoptotic, and anti-angiogenic effects in cancer, as well as anti-inflammatory activities. There are various reports on the benefits of vitamin E on health in general. However, despite it being initially discovered as a vitamin necessary for reproduction, to date, studies relating to its effects in this area are lacking. Hence, this paper was written with the intention of providing a review of the known roles of vitamin E as an antioxidant in female reproductive health.

In silico genotoxicity of coumarins: application of the Phenol-Explorer food database to functional food science

Coumarins are a group of phytochemicals that may be beneficial or harmful to health depending on their type and dosage and the matrix that contains them. Some of these compounds have been proven to display pro-oxidant and clastogenic activities. Therefore, in the current work, we have studied the coumarins that are present in food sources extracted from the Phenol-Explorer database in order to predict their clastogenic activity and identify the structure-activity relationships and genotoxic structural alerts using alternative methods in the field of computational toxicology. It was necessary to compile information on the type and amount of coumarins in different food sources through the analysis of databases of food composition available online. A virtual screening using a clastogenic model and different software, such as MODESLAB, ChemDraw and STATISTIC, was performed. As a result, a table of food composition was prepared and qualitative information from this data was extracted. The virtual screening showed that the esterified substituents inactivate molecules, while the methoxyl and hydroxyl substituents contribute to their activity and constitute, together with the basic structures of the studied subclasses, clastogenic structural alerts. Chemical subclasses of simple coumarins and furocoumarins were classified as active (xanthotoxin, isopimpinellin, esculin, scopoletin, scopolin and bergapten). In silico genotoxicity was mainly predicted for coumarins found in beer, sherry, dried parsley, fresh parsley and raw celery stalks. The results obtained can be interesting for the future design of functional foods and dietary supplements. These studies constitute a reference for the genotoxic chemoinformatic analysis of bioactive compounds present in databases of food composition.

Cryptosporidium-contaminated water disinfection by a novel Fenton process

Three novel modified advanced oxidation process systems including ascorbic acid-, pro-oxidants- and ascorbic acid-pro-oxidants-modified Fenton system were utilized to study the disinfection efficiency on Cryptosporidium-contaminated drinking water samples. Different concentrations of divalent and trivalent iron ions, hydrogen peroxide, ascorbic acid and pro-oxidants at different exposure times were investigated. These novel systems were also compared to the classic Fenton system and to the control system which comprised of only hydrogen peroxide. The complete in vitro mechanism of the mentioned modified Fenton systems are also provided. The results pointed out that by considering the optimal parameter limitations, the ascorbic acid-modified Fenton system decreased the Cryptosporidium oocytes viability to 3.91%, while the pro-oxidant-modified and ascorbic acid-pro-oxidant-modified Fenton system achieved an oocytes viability equal to 1.66% and 0%, respectively. The efficiency of the classic Fenton at optimal condition was observed to be 20.12% of oocytes viability. The control system achieved 86.14% of oocytes viability. The optimum values of the operational parameters during this study are found to be 80mgL^-1 for the divalent iron, 30mgL^-1 for ascorbic acid, 30mmol for hydrogen peroxide, 25mgL^-1 for pro-oxidants and an exposure time equal to 5min. The ascorbic acid-pro-oxidants-modified Fenton system achieved a promising complete water disinfection (0% viability) at the optimal conditions, leaving this method a feasible process for water disinfection or decontamination, even at industrial scales.

Food Antioxidants and Their Anti-Inflammatory Properties: A Potential Role in Cardiovascular Diseases and Cancer Prevention

Mediterranean-style diets caused a significant decline in cardiovascular diseases (CVDs) in early landmark studies. The effect of a traditional Mediterranean diet on lipoprotein oxidation showed that there was a significant reduction in oxidative stress in the intervention group (Mediterranean diet + Virgin Olive Oil) compared to the low-fat diet group. Conversely, the increase in oxidative stress causing inflammation is a unifying hypothesis for predisposing people to atherosclerosis, carcinogenesis, and osteoporosis. The impact of antioxidants and anti-inflammatory agents on cancer and cardiovascular disease, and the interventive mechanisms for the inhibition of proliferation, inflammation, invasion, metastasis, and activation of apoptosis were explored. Following the Great Oxygen Event some 2.3 billion years ago, organisms have needed antioxidants to survive. Natural products in food preservatives are preferable to synthetic compounds due to their lower volatility and stability and generally higher antioxidant potential. Free radicals, reactive oxygen species, antioxidants, pro-oxidants and inflammation are described with examples of free radical damage based on the hydroxyl, nitric oxide and superoxide radicals. Flavonoid antioxidants with 2- or 3-phenylchroman structures such as quercetin, kaempferol, myricetin, apigenin, and luteolin, constituents of fruits, vegetables, tea, and wine, which may reduce coronary disease and cancer, are described. The protective effect of flavonoids on the DNA damage caused by hydroxyl radicals through chelation is an important mechanism, though the converse may be possible, e.g., quercetin. The antioxidant properties of carotenoids, which are dietary natural pigments, have been studied in relation to breast cancer risk and an inverse association was found with plasma concentrations: higher levels mean lower risk. The manipulation of primary and secondary human metabolomes derived especially from existing or transformed gut microbiota was explored as a possible alternative to single-agent dietary interventions for cancer and cardiovascular disease. Sustained oxidative stress leading to inflammation and thence to possibly to cancer and cardiovascular disease is described for spices and herbs, using curcumin as an example of an intervention, based on activation of transcription factors which suggest that oxidative stress, chronic inflammation, and cancer are closely linked.

Chlorogenic acid content, essential oil compositions, and in vitro antioxidant activities of Chromolaena odorata leaves

Chromolaena odorata (L.) R. M. King and H. Rob. is a Thai medicinal plant used for the treatment of wounds, rashes, diabetes, and insect repellent. The leaves of C. odorata were collected from 10 different sources throughout Thailand. The chemical constituents of essential oils were hydro-distilled from the leaves and were analyzed by gas chromatography-mass spectrometry. Chlorogenic acid contents were determined by thin-layer chromatography (TLC) - densitometry with winCATS software and TLC image analysis with ImageJ software. The TLC plate was developed in the mobile phase that consisted of ethyl acetate:water:formic acid (17:3:2). Antioxidant activities were examined by 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical scavenging and β-carotene bleaching assays. C. odorata essential oil has shown the major components of pregeijerene, dauca-5, 8-diene, (E)-caryophyllene, β-pinene, and α-pinene. The chlorogenic acid content of C. odorata leaves was determined by TLC-densitometry and TLC image analysis. Results have shown that TLC-densitometry and TLC image analysis method were not statistically significantly different. DPPH radical scavenging and β-carotene bleaching assays of ethanolic extract of C. odorata leaves showed its antioxidant potential.

The role of CAPE in PI3K/AKT/mTOR activation and oxidative stress on testis torsion

Ischemia reperfusion injury arises from testicular torsion resulting in a loss of spermatogenesis and significant germ cell apoptosis. This study evaluates the prooxidant/antioxidant effects of caffeic acid phenethyl ester (CAPE) through PI3K/AKT/mTOR signal pathways on testis torsion. A total of (28) male Wistar rats were divided randomly into 4 groups (n=7 for each group):group A (sham) group,group B torsion/detorsion group, group C (saturation group, during four days of CAPE, one dose (10 μmol/kg, i.p)) and group D (a single dose of CAPE 2h after torsion and before detorsion). At the end of the study, unilateral orchiectomies were performed for measurements of MDA and 8OHdG levels, histopathologic and immunohistochemical and TUNEL apoptotic cell examination. Testicular torsion-detorsion led to a significant decrease in the mean values of the Johnsen's scores and a significant increase in the apoptotic cell values of group B. There were no significant differences between group D and group A. In addition, the MDA and 8OHdG levels increased significantly in group B. The MDA and 8OHdG values were lower in group D. However, the 8OHdG levels were higher in group C than the groups A and D. On the other hand, CAPE suppresses mTOR activation and reduces the apoptosis on ischemia/reperfusion damage in rat testis. These results demonstrate that CAPE suppresses mTOR activation and reduces the apoptosis on ischemia/reperfusion damage in rat testis.

A metabolomic perspective of griseofulvin-induced liver injury in mice

Griseofulvin (GSF) causes hepatic porphyria in mice, which mimics the liver injury associated with erythropoietic protoporphyria (EPP) in humans. The current study investigated the biochemical basis of GSF-induced liver injury in mice using a metabolimic approach. GSF treatment in mice resulted in significant accumulations of protoporphyrin IX (PPIX), N-methyl PPIX, bile acids, and glutathione (GSH) in the liver. Metabolomic analysis also revealed bioactivation pathways of GSF that contributed to the formation of GSF-PPIX, GSF-GSH and GSF-proline adducts. GSF-PPIX is the precursor of N-methyl PPIX. A six-fold increase of N-methyl PPIX was observed in the liver of mice after GSF treatment. N-methyl PPIX strongly inhibits ferrochelatase, the enzyme that converts PPIX to heme, and leads to PPIX accumulation. Excessive PPIX in the liver results in bile duct blockage and disturbs bile acid homeostasis. The accumulation of GSH in the liver was likely due to Nrf2-mediated upregulation of GSH synthesis. In summary, this study provides the biochemical basis of GSF-induced liver injury that can be used to understand the pathophysiology of EPP-associated liver injury in humans.

Heat stress and sudden infant death syndrome--stress gene expression after exposure to moderate heat stress

The aim of the present study was to investigate stress gene expression in cultured primary fibroblasts established from Achilles tendons collected during autopsies from sudden infant death syndrome (SIDS) cases, and age-matched controls (infants dying in a traumatic event). Expression of 4 stress responsive genes, HSPA1B, HSPD1, HMOX1, and SOD2, was studied by quantitative reverse transcriptase PCR analysis of RNA purified from cells cultured under standard or various thermal stress conditions. The expression of all 4 genes was highly influenced by thermal stress in both SIDS and control cells. High interpersonal variance found in the SIDS group indicated that they represented a more heterogeneous group than controls. The SIDS group responded to thermal stress with a higher expression of the HSPA1B and HSPD1 genes compared to the control group, whereas no significant difference was observed in the expression of SOD2 and HMOX1 between the two groups. The differences were related to the heat shock treatment as none of the genes were expressed significantly different in SIDS at base levels at 37 °C. SOD2 and HMOX1 were up regulated in both groups, for SOD2 though the expression was lower in SIDS at all time points measured, and may be less related to heat stress. Being found dead in the prone position (a known risk factor for SIDS) was related to a lower HSPA1B up-regulation in SIDS compared to SIDS found on their side or back. The study demonstrates the potential usefulness of gene expression studies using cultured fibroblasts established from deceased individuals as a tool for molecular and pathological investigations in forensic and biomedical sciences.

A review on antioxidants, prooxidants and related controversy: natural and synthetic compounds, screening and analysis methodologies and future perspectives

Many studies have been conducted with regard to free radicals, oxidative stress and antioxidant activity of food, giving antioxidants a prominent beneficial role, but, recently many authors have questioned their importance, whilst trying to understand the mechanisms behind oxidative stress. Many scientists defend that regardless of the quantity of ingested antioxidants, the absorption is very limited, and that in some cases prooxidants are beneficial to human health. The detection of antioxidant activity as well as specific antioxidant compounds can be carried out with a large number of different assays, all of them with advantages and disadvantages. The controversy around antioxidant in vivo benefits has become intense in the past few decades and the present review tries to shed some light on research on antioxidants (natural and synthetic) and prooxidants, showing the potential benefits and adverse effects of these opposing events, as well as their mechanisms of action and detection methodologies. It also identifies the limitations of antioxidants and provides a perspective on the likely future trends in this field.

Growth hormone reduces tissue damage in rat ovaries subjected to torsion and detorsion: biochemical and histopathologic evaluation

OBJECTIVE

To evaluate the effects of growth hormone (GH) as an antioxidant and tissue-protective agent and analyse the biochemical and histopathological changes in rat ovaries due to experimental ischemia and ischemia/reperfusion injury.

STUDY DESIGN

Forty-eight adult female rats were randomly divided into eight groups. In Group 1, a period of bilateral ovarian ischemia was applied. In Groups 2 and 3, 1 and 2 mg/kg of GH was administered, and 30 min later, bilateral ovarian ischemia was applied (after a 3-h period of ischemia, both ovaries were surgically removed). Group 4 received a 3-h period of ischemia followed by 3h of reperfusion. Groups 5 and 6 received 1 and 2 mg/kg of GH, respectively, 2.5 h after the induction of ischemia. At the end of a 3-h period of ischemia, bilateral vascular clips were removed, and 3h of reperfusion continued. Group 7 received a sham operation plus 2mg/kg of GH. Group 8 received a sham operation only. After the experiments, superoxide dismutase and myeloperoxidase activity and levels of glutathione and lipid peroxidation were determined, and histopathological changes were examined in all rat ovarian tissue.

RESULTS

Ischemia and ischemia/reperfusion decreased superoxide dismutase activity and glutathione levels in ovarian tissue, but increased lipid peroxidation levels and myeloperoxidase activity significantly in comparison to the sham group. The 1 and 2 mg/kg doses of GH before ischemia and ischemia/reperfusion decreased lipid peroxidation levels and myeloperoxidase activity in the experimental groups. The administration of GH before ischemia and ischemia/reperfusion treatments also increased superoxide dismutase and glutathione levels. The histopathological findings also suggested a protective role of GH in ischemia/reperfusion injury. That is, ovarian tissues in the ischemia groups showed histopathological changes, such as haemorrhage, cell degeneration, and necrotic and apoptotic cells, but these changes in the GH groups were lesser. Moreover, in the ischemia/reperfusion groups, acute inflammatory processes--such as neutrophil adhesion and migration, apoptotic and degenerative cells, stromal oedema and haemorrhage--were present. However, the ovarian tissues of the IR+GH (1 mg) group had minimal apoptotic cells, and the IR+GH (2 mg) group had no apoptotic cells. In addition, the general ovarian histological structures of these groups were similar to those of the healthy control group.

CONCLUSIONS

The administration of GH is protective against ischemia and/or ischemia/reperfusion-induced ovarian damage. This protective effect can be attributed to the antioxidant properties of GH.

The effects of fucoidan extracts on CCl(4)-induced liver injury

The aim of this study was to elucidate the antioxidant properties of fucoidan extracts (FE) against CCl(4)-induced oxidative stress by monitoring the levels of glutamate oxaloacetate transaminase (GOT), glutamate pyruvate transaminase (GPT), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx). Female, Sparague-Dowley rats were administered with FE (100 mg/kg daily) for 14 days and CCl(4) on the 15'th day, 12 h before they were sacrificed. The levels of GOT, GPT, ALP and LDH in serum of rats, as well as the levels of MDA, SOD, CAT and GPx in total liver homogenate were analyzed. CCl(4)-treatment was found to increase the levels of GOT, GPT, ALP, LDH and MDA, as well as decrease levels of SOD, CAT and GPx significantly. The pre-treatment of rats with FE, however, suppressed the increment of levels of GOT, GPT, ALP, LDH and MDA, as well as recovered the levels of SOD, CAT and GPx in CCl(4)-treated rats. Moreover there was a significant decrease in incidences of necrosis and cirrhosis in the liver tissue of FE-treated rats. These results implied that FE possessed antioxidant properties against CCl(4)-induced oxidative stress.

Protective effects of amlodipine on ischemia-reperfusion injury of rat ovary: biochemical and histopathologic evaluation

OBJECTIVE

To evaluate the effects of amlodipine as an antioxidant and analyze the histopathologic changes in experimental ischemic and ischemic-reperfusion (I/R) injury in rat ovaries.

DESIGN

Experimental study.

SETTING

Experimental surgery laboratory.

ANIMAL(S)

Forty-two rats with experimentally induced ovarian torsion.

INTERVENTION(S)

Group 1: sham operation; group 2: bilateral ovarian ischemia; group 3: 3-hour period of ischemia plus 3 hours of reperfusion; groups 4 and 5: amlodipine administration at 3 and 5 mg/kg respectively before one half hour of ischemia, and then bilateral ovarian ischemia. The ovaries were removed at the third hour of ischemia. Groups 6 and 7: 3-hour period of bilateral ovarian ischemia. Two and a half hours after the induction of ischemia, the rats received amlodipine. At the end of a 3-hour period of ischemia, 3 hours of reperfusion was continued; then the ovaries were removed.

MAIN OUTCOME MEASURE(S)

Ovarian tissue superoxide dismutase and nitric oxide activity; histopathologic examination of all ovarian rat tissue.

RESULT(S)

Ischemia and I/R increased the inducible nitric oxide synthase activity while decreasing the superoxide dismutase activity significantly in comparison with the sham group. Both doses of amlodipine before ischemia and I/R reversed the trend in nitric oxide synthase activities and reversed the trend in the rat's ovary.

CONCLUSION(S)

Conservative treatment with amlodipine is effective in reducing tissue damage induced by ischemia, I/R, or both in ovaries.

The inhibition kinetics of yeast glutathione reductase by some metal ions

Glutathione reductase (GR, type IV, Baker's yeast, E.C 1.6.4.2) is a flavoprotein that catalyzes the NADPH-dependent reduction of oxidized glutathione (GSSG) to reduced glutathione (GSH). In this study some metal ions have been tested on GR; lithium, manganese, molybdate, aluminium, barium, zinc, calcium, cadmium and nickel. Cadmium, nickel and calcium showed a good to moderate inhibitory effect on yeast GR. GR is inhibited non-competitively by Zn2+ (up to 2 mM) and activated above this concentration. Ca2+ inhibition was non-competitive with respect to GSSG and uncompetitive with respect to NADPH. Nickel inhibition was competitive with respect to GSSG and uncompetitive with respect to NADPH. The inhibition constants for these metals on GR were determined. The chelating agent EDTA recovered 90% of the GR activity inhibited by these metals.

Validation of a high-throughput in vitro alkaline elution/rat hepatocyte assay for DNA damage

In vitro alkaline elution is a sensitive and specific short term assay which measures DNA strand breakage in a mammalian test system (primary rat hepatocytes). This lab has previously demonstrated the performance of the assay with known genotoxic and non-genotoxic compounds. The methodology employed has relatively low sample throughput and is labor-intensive, requiring a great deal of manual processing of samples in a format that is not amenable to automation. Here, we present an automated version of the assay. This high-throughput alkaline elution assay (HT-AE) was made possible through 3 key developments: (1) DNA quantitation using PicoGreen and OliGreen fluorescent DNA binding dyes; (2) design and implementation of a custom automation system; and (3) reducing the assay to a 96-well plate format. The assay can now be run with 5-50mg of test compound. HT-AE was validated in a similar manner as the original assay, including assessment of non-genotoxic and non-carcinogenic compounds and evaluation of cytotoxicity to avoid confounding effects of toxicity-associated DNA degradation. The validation test results from compounds of known genotoxic potential were used to set appropriate criteria to classify alkaline elution results for genotoxicity.

The Role of Salicornia herbacea in Ovariectomy-Induced Oxidative Stress

Ovarian hormone deficiency increases the generation of reactive oxygen species. Their excess induces oxidative stress, which results in the cell damage or death. It causes the aging diseases-atherosclerosis, rheumatoid arthritis, osteoporosis, etc. Ovariectomized rats are used as oxidative stress models. We verified the effects of ovariectomy-induced oxidative stress on free radical production as evaluated by DPPH elimination, lipoperoxidation evaluated by malondialdehyde levels, and antioxidant activation of superoxide dismutase, catalase, glutathione peroxidase, and estradiol in the liver and sera. Ovariectomized rats were given Salicornia herbacea (SH) intraperitoneally at the dose of 100 mg/kg daily for 2 months. Free radical-scavenging activity of SH was measured in comparison with that of L-ascorbic acid. The histopathology of liver tissue was also investigated. Antioxidative values in the ovariectomized group decreased, but those in the SH-treated group increased due to the free radical-scavenging activity of SH. Moreover, inflammation and cirrhosis in the liver tissue of SH-treated rats decreased significantly. These results suggest that SH may be a potential candidate for an antioxidative reagent.

The preventive inhibition of chondroitin sulfate against the CCl4-induced oxidative stress of subcellular level

Our work in this study was made in the microsomal fraction to evaluate the lipid peroxidation by measuring superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and malondialdehyde (MDA) and to elucidate the preventive role of CS in the CCl4-induced oxidative stress. The excessive lipid peroxidation by free radicals derived from CCl4 leads to the condition of oxidative stress which results in the accumulation of MDA. MDA is one of the end-products in the lipid peroxidation process and oxidative stress. MDA, lipid peroxide, produced in this oxidative stress causes various diseases related to aging and hepatotoxicity, etc. Normal cells have a number of enzymatic and nonenzymatic endogenous defense systems to protect themselves from reactive species. The enzymes in the defense systems, for example, are SOD, CAT, and GPx. They quickly eliminate reactive oxygen species (ROS) such as superoxide anion free radical *O2(-), hydrogen peroxide H2O2 and hydroxyl free radical *OH. CS inhibited the accumulation of MDA and the deactivation of SOD, CAT and GPx in the dose-dependent and preventive manner. Our study suggests that CS might be a potential scavenger of free radicals in the oxidative stress originated from the lipid peroxidation of the liver cells of CCl4-treated rats.

The effect of chondroitin sulfate against CCl4-induced hepatotoxicity

This study was conducted to develop a new biomaterial to be used for an antioxidative drug. In this study, the hepatoprotective effect of chondroitin sulfate (CS) (100 mg/kg and 200 mg/kg body weight) was investigated at the antioxidative enzyme levels of liver total homogenate and mitochondria fraction. And the carbone tetrachloride (CCl(4))-induced rats were used as hepatotoxic models. The CCl(4) induced rat has been widely used as a hepatotoxic model due to its practicality, convenience and cost effectiveness since the generation of free oxygen radicals by CCl(4) injection was proposed as an important causative agent of hepatotoxicity. Malondialdehyde (MDA) levels were determined as well as the activities of superoxide dismutase (SOD), catalase (CAT), reduced-glutathione (GSH), oxidized-glutathione (GSSG) and glutathione peroxidase (GPx) in the liver. In addition, histopathology of liver tissue was investigated. Liver antioxidative enzyme activity was elevated while MDA concentration was decreased in all CS treated animals. The results demonstrated that CS protected oxidative stress in a dose dependent manner. Moreover, inflammation and cirrhosis in liver tissue of CS treated group were significantly decreased. It gave us an impression that CS might be a radical scavenger.

Postnatal efficacy of Momordica charantia peel, pulp, seed and whole fruit extract in the detoxication pathway of suckling neonates and lactating mice

The present study evaluates the postnatal efficacy of Momordica charantia peel, pulp, seed and whole fruit extract via assessing the modulation in the biotransformation system enzymes of suckling neonates and lactating mice. The peel, seed or whole fruit extract of Momordica (100 microl/animal/day) independently induced a significant increase in the hepatic levels of glutathione S-transferase (GST) and acid soluble sulfhydryl (-SH) after 14 or 21 days treatment in lactating dams (P < 0.01) and translactationally exposed neonates (P < 0.05). However, the elevation (P < 0.05) in hepatic cytochrome b5 (Cyt. b5) and cytochrome P-450 (Cyt. P-450) levels was observed only in the lactating dams treated with the respective extracts of peel, seed or whole fruit of Momordica. In lactating dams and suckling neonates the modulated levels of biotransformation system enzymes suggest the potential for the translactational passage of active principle(s) and/or metabolites of Momordica.

Effect of superoxide dismutase(SOD) on pronucleus formation of porcine oocytes fertilized in vitro

This study was undertaken to evaluate the effects of superoxide dismutase (SOD) on pronucleus formation in porcine oocytes fertilized in vitro by frozen-thawed spermatozoa. No differences were found in penetration rates when SOD was added to maturation or fertilization medium at any level tested in first and second experiments. Pronucleus formation rates were higher (P < 0.05) when SOD at 10 and 100 units was added to the maturation medium (46 and 53%, respectively) compared with the controls (26%). On the other hand, when the fertilization medium was supplemented with SOD at different concentrations (1, 10 and 100 units/ml), pronucleus formation rates (55, 52 and 50%) were significantly higher (P < 0.05) than in the control group. In third experiment, the oocytes were cultured in medium with (1 unit/ml) or without SOD for 8, 16, 24 and 32 h after insemination. The penetration rates had a tendency to increase as time of sperm-oocyte culture was prolonged. No significant differences, however, were observed in penetration rates between groups with and without SOD. On the other hand, the pronucleus formation rates were higher in medium with than without SOD at 8 (7 vs 0%), 16 (14 vs 3%), 24 (48 vs 16%; P < 0.01) and 32 h (49 vs 22%; P < 0.05). These findings demonstrate the advantage of culture with SOD on pronucleus formation in porcine oocytes penetrated by spermatozoa. However, SOD does not affect penetration rates and polyspermy.

In vitro inactivation of yeast glutathione reductase by tetramethylthiuram disulphide

Previous in vivo investigations have shown that glutathione reductase is one of the sites of action of the dithiocarbamate fungicide tetramethylthiuram disulphide (thiram) in the yeast Saccharomyces cerevisiae. The inactivation of glutathione reductase by thiram has now been demonstrated in vitro. This inactivation was time-dependent and occurred only with the enzyme in the reduced state and in the absence of glutathione. Since the turnover rate of the enzyme with thiram as a substrate was significantly higher than the rate of enzyme inactivation, it was suggested that more than one enzyme-inhibitor complex was involved in the reaction. Arguments supporting a covalent modification of glutathione reductase were further obtained by experiments carried out with [14C]thiram and gel filtration. A kinetic scheme for the inactivation is proposed and the relevance of the in vitro data to previous in vivo studies is discussed taking into consideration current concepts of glutathione reductase inactivation by affinity reagents.

Effects of oxygen toxicity on early development of mouse embryos

To examine the effects of oxygen toxicity on embryonic development, mouse pronuclear embryos were cultured under low oxygen conditions with or without superoxide dismutase (SOD), and the blastulation rate was compared with that of embryos cultured under standard conditions. The blastulation rate of mouse pronuclear embryos cultured under standard conditions was only 1.5% (2/131). This rate was increased significantly, to 28.5% (43/151), when the embryos were cultured under low oxygen conditions; and to 31.0% (35/113) when SOD (500 micrograms/ml) was added to the medium under standard conditions; the rate was increased to 75.2% (115/153) when the embryos were cultured under low oxygen conditions in the presence of SOD. The minimum effective concentration of SOD in the culture medium was 50 micrograms/ml under conditions of 5% O2. The blastulation rate was significantly decreased after 1-hr exposure of pronuclear embryos to room atmospheric oxygen concentration (20% O2), and subsequent culture under 5% O2 with SOD did not result in an improved blastulation rate. Culture with SOD under 5% O2 promoted the development of two-cell stage embryos to the blastocyst stage. When two-cell stage embryos were collected 48 hr after hCG and cultured for 66 hr, their blastulation rate was similar to that of embryos collected from mice 114 hr after hCG. These results suggested that embryonic development in vitro is greatly affected by atmospheric oxygen throughout the early embryonic stages and that this harmful effect can be prevented by culturing embryos under low oxygen conditions and in the presence of SOD.

Modulatory influences of clove (Caryophyllus aromaticus, L) on hepatic detoxification systems and bone marrow genotoxicity in male Swiss albino mice

Modulatory effects observed due to clove administration (0.5%, 1% and 2% w/w in the diet) to Swiss albino mice for 10, 20 and 30 days in the hepatic levels of cytochrome P-450 (Cyt. P-450), cytochrome b5 (Cyt. b5), aryl hydrocarbon hydroxylase (AHH), glutathione S-transferase (GST), DT-diaphorase (DTD), acid soluble sulfhydryl (SH) content and radiation-induced malondialdehyde (MDA) formation were recorded. Enhanced GST, Cyt. b5 and SH levels were observed in all the treatment groups, excepting those maintained on a 0.5% diet for 10 days which did not show significant increase in the GST and SH levels as compared to their respective controls. Significant reduction in Cyt. P-450 and MDA levels was observed in all groups at 30 days duration. While AHH levels remained unaltered by clove administration, DTD activity was elevated by 1% and 2% clove diets at 30 days duration. An in vivo bone marrow micronucleus assay demonstrated that administration of 0.5% and 2% clove diets for 10 days neither significantly induced micronuclei nor could effectively modulate the 7, 12-dimethylbenz[a]anthracene genotoxicity in mice. The results suggest whole cloves as potential chemopreventive agents.

Involvement of superoxide radicals in the mouse two-cell block

The effect of oxygen toxicity on the development of mammalian embryos was assessed by the use of superoxide dismutase (SOD), a potent scavenger of superoxide radicals. Mouse pronuclear embryos recovered 17 h after human chorionic gonadotropin (hCG) were cultured in medium BWW at 37 degrees C under an atmosphere of 5% CO2 in air. Culture of mouse pronuclear embryos in the presence of Cu.Zn-SOD (500 micrograms/ml) significantly increased the blastulation rate (44.6%) when compared with the control culture system (4.2%). Essentially the same effects were observed in SOD containing either Mn or Fe in the catalytic center. Heat treatment of the SOD preparation, and the addition of anti-SOD antibodies to the culture medium, significantly reduced the attenuation of the two-cell block by SOD, indicating that this effect is SOD dependent. SOD activity was detected in rabbit oviduct fluid (3.675 +/- 3.084 mIU/mg protein) by electron spin resonance. These results suggest that active oxygen is involved in the two-cell block phenomenon in mouse embryos exposed to air and that SOD in the oviduct may play an important role in the protection of embryos from superoxide radicals.

Absorption, transport and metabolism of vitamin E

Vitamin E includes eight naturally occurring fat-soluble nutrients called tocopherols and dietary intake of vitamin E activity is essential in many species. alpha-Tocopherol has the highest biological activity and the highest molar concentration of lipid soluble antioxidant in man. Deficiency of vitamin E may cause neurological dysfunction, myopathies and diminished erythrocyte life span. alpha-Tocopherol is absorbed via the lymphatic pathway and transported in association with chylomicrons. In plasma alpha-tocopherol is found in all lipoprotein fractions, but mostly associated with apo B-containing lipoproteins in man. In rats approximately 50% of alpha-tocopherol is bound to high density lipoproteins (HDL). After intestinal absorption and transport with chylomicrons alpha-tocopherol is mostly transferred to parenchymal cells of the liver were most of the fat-soluble vitamin is stored. Little vitamin E is stored in the non-parenchymal cells (endothelial, stellate and Kupffer cells). alpha-Tocopherol is secreted in association with very low density lipoprotein (VLDL) from the liver. In the rat about 90% of total body mass of alpha-tocopherol is recovered in the liver, skeletal muscle and adipose tissue. Most alpha-tocopherol is located in the mitochondrial fractions and in the endoplasmic reticulum, whereas little is found in cytosol and peroxisomes. Clinical evidence from heavy drinkers and from experimental work in rats suggests that alcohol may increase oxidation of alpha-tocopherol, causing reduced tissue concentrations of alpha-tocopherol. Increased demand for vitamin E has also been observed in premature babies and patients with malabsorption, but there is little evidence that the well balanced diet of the healthy population would be improved by supplementation with vitamin E.

Some aspects of antioxidant status in blood from alcoholics

The effect of ethanol consumption on serum concentration of alpha-tocopherol, erythrocyte activities of superoxide dismutase, glutathione peroxidase, and catalase were studied in 34 male alcoholics and 35 age-matched controls. Serum concentration of alpha-tocopherol was 30% lower in the alcoholics as compared to the controls (p less than 0.001). No significant difference was found in erythrocyte activities of Cu-Zn-containing superoxide dismutase, glutathione peroxidase, or catalase between the groups. Of the 12 alcoholics with subnormal serum alpha-tocopherol, 50% had concomitant neurological clinical scores and cerebellar atrophy, and their neurological scores were significantly higher (82%) than for alcoholics with normal alpha-tocopherol levels (p less than 0.03). However, no significant correlation was observed between levels of alpha-tocopherol and neurological clinical scores or cerebellar atrophy. When entering the study, alcoholics and controls were each randomized into two separate groups, receiving vitamin E supplementation (100 mg/day) or placebo capsules for 10 days, respectively. In the four subgroups, alpha-tocopherol levels increased only in alcoholics receiving vitamin E supplementation (23%) (p less than 0.001). The reduced serum levels of alpha-tocopherol in alcoholics may be normalized by vitamin E supplementation.

Tyrosyl-tRNA synthetase from baker's yeast. Order of substrate addition, discrimination of 20 amino acids in aminoacylation of tRNATyr-C-C-A and tRNATyr-C-C-A(3'NH2)

The order of substrate addition to tyrosyl-tRNA synthetase from baker's yeast was investigated by bisubstrate kinetics, product inhibition and inhibition by dead-end inhibitors. The kinetic patterns are consistent with a random bi-uni uni-bi ping-pong mechanism. Substrate specificity with regard to ATP analogs shows that the hydroxyl groups of the ribose moiety and the amino group in position 6 of the base are essential for recognition of ATP as substrate. Specificity with regard to amino acids is characterized by discrimination factors D which are calculated from kcat and Km values obtained in aminoacylation of tRNATyr-C-C-A. The lowest values are observed for Cys, Phe, Trp (D = 28,000-40,000), showing that, at the same amino acid concentrations, tyrosine is 28,000-40,000 times more often attached to tRNATyr-C-C-A than the noncognate amino acids. With Gly, Ala and Ser no misacylation could be detected (D greater than 500,000); D values of the other amino acids are in the range of 100,000-500,000. Lower specificity is observed in aminoacylation of the modified substrate tRNATyr-C-C-A(3'NH2) (D1 = 500-55,000). From kinetic constants and AMP-formation stoichiometry observed in aminoacylation of this tRNA species, as well as in acylating tRNATyr-C-C-A hydrolytic proof-reading factors could be calculated for a pretransfer (II 1) and a post-transfer (II 2) proof-reading step. The observed values of II 1 = 12-280 show that pretransfer proof-reading is the main correction step whereas post-transfer proof-reading is marginal for most amino acids (II 2 = 1-2). Initial discrimination factors caused by differences in Gibbs free energies of binding between tyrosine and noncognate amino acids are calculated from discrimination and proof-reading factors. Assuming a two-step binding process, two factors (I1 and I2) are determined which can be related to hydrophobic interaction forces. The tyrosine side chain is bound by hydrophobic forces and hydrogen bonds formed by its hydroxyl group. A hypothetical model of the amino acid binding site is discussed and compared with results of X-ray analysis of the enzyme from Bacillus stearothermophilus.

Chemoprevention of cancer: phenolic antioxidants (BHT, BHA)

1. The synthetic phenolic antioxidants (e.g. BHT, BHA) added to human and animal food are able to lengthen the life of organisms and lower the incidence of cancer caused by chemical compounds. 2. On the other hand they may not be rendered completely harmless since they can cause lung damage (BHT) or promote the action of some carcinogens (BHA). 3. They could act as compounds preventing cancer either via interception of harmful free radicals, activating the detoxifying enzymes of the body, inhibiting the formation of ultimately carcinogenic metabolites and their binding to DNA, and modifying the immune response of the organism. 4. Their action is influenced by their own chemical structure, the composition of carcinogen, the strain, sex and age of experimental animals, the tissue upon which they are supposed to act and the time of their administration in relation to the time of the carcinogen insult. 5. These compounds are concentrated in adipose tissue, liver and kidney. They are excreted within tens of hours mainly in urine. 6. The acceptable daily intake of BHA is at present considered to be 0.6 mg kg-1 body wt day-1. In spite of their possible tumor-promoting properties they could not be considered overtly toxic. Their pronounced chemoprotective role against some forms of chemical carcinogenesis deserves considerable attention.

Pathogenesis of neurological signs associated with bovine enteric coccidiosis: a prospective study and review

Various hypotheses have been proposed for the pathogenesis of the neurological signs associated with bovine enteric coccidiosis. We undertook a prospective study of cases of bovine enteric coccidiosis with and without nervous signs to test the validity of these hypotheses and explore other possible pathophysiological mechanisms. Clinical, pathological and toxicological data from 12 calves with, and 15 calves without, neurological signs were compared. Calves with neurological signs had a lower liver Cu concentration (p less than 0.01) and a higher plasma glucose concentration (p less than 0.05) than did calves without neurological signs. Hyperglycemia and Cu deficiency may increase the susceptibility to central nervous system damage, but are not likely to account for the onset of neurological signs in calves with enteric coccidiosis. The results of the study suggest that the following are not involved in the pathogenesis of "nervous coccidiosis": disturbance of serum Na, K, Ca, P, or Mg concentration, vitamin A deficiency, thiamine deficiency, anemia, lead intoxication, uremia, Haemophilus somnus meningoencephalitis, severity of coccidial infection, gross alterations in intestinal bacterial flora and hepatopathy.