Syzygium aromaticum aqueous extract inhibits human neutrophils myeloperoxidase and protects mice from LPS-induced lung inflammation

Context: Syzygium aromaticum (L.) Merr. &; Perry (Myrtaceae), commonly known as clove, originally found in the Muluku Islands in East Indonesia, is widely used as a spice and has numerous medicinal properties.

Objective: This study investigated the antioxidant potential of S. aromaticum aqueous extract (SAAE) in vitro and its protective effects on lipopolysaccharide (LPS)-induced lung inflammation in mice.

Material and methods: Neutrophils were isolated from healthy donors and reactive oxygen species (ROS) generation was measured by luminol-amplified chemiluminescence. Superoxide anion generation was detected by cytochrome c reduction assay. H₂O₂ was detected by DCFH fluorescence assay. Myeloperoxidase (MPO) activity was mesured by tetramethyl benzidine oxidation method. To study the anti-inflammatory activity of SAAE, lung inflammation was induced in mice (BALB/c) by intra-tracheal instillation of lypopolysaccharide (5?µg/mouse), and SAAE (200?mg/kg body weight) was injected intraperitoneally prior to LPS administration. Bronchoalveolar lavage and lung tissue were collected to assess inflammatory cells count and total protein content. Metalloproteinases activity was detected by zymography technique.

Results: SAAE inhibited luminol-amplified chemiluminescence of resting neutrophils and N-formyl-methionyl-leucyl-phenylalanine- or phorbol myristate acetate-stimulated neutrophils, with an inhibitory effect starting at a concentration as low as 0.5?µg/mL. Moreover, SAAE reduced significantly MPO activity and it exhibits a dose-dependent action (IC₅₀ = 0.5?µg/mL). In vivo results showed that SAAE decreased markedly neutrophil count (From 61% to 15%) and proteins leakage into bronchoalveolar lavage fluid. Gelatin zymography assay showed that S. aromaticum inhibited MMP-2 (15%) and MMP-9 (18%) activity in lung homogenates.

Discussion and conclusion: Our results suggest that the anti-inflammatory activity of SAAE, in vivo, is due to the inhibition of ROS production and metalloproteinases activity via its action on MPO. According to these findings, SAAE could be a potential source of new compounds with anti-inflammatory activity.     

Fish oil prophylaxis attenuates rotenone-induced oxidative impairments and mitochondrial dysfunctions in rat brain

Studies describing the potential of fish oil (FO) prophylaxis to render neuroprotection in experimental model/s are limited. In the present study, we have examined the propensity of FO supplements to modulate endogenous markers of oxidative stress and attenuate neurotoxicant-induced oxidative stress and mitochondrial dysfunctions in rat brain. Prepubertal male rats given FO supplements (oral, 2 and 4 mL/kg bw/day, for 30 days) showed no alterations in malondialdehyde and reactive oxygen species in brain regions. However, FO supplements significantly enhanced the GSH levels in all brain regions examined, while differential effect was discernible in the activity levels of antioxidant enzymes. Further, we investigated whether FO prophylaxis could offset Rotenone (ROT, a well known neurotoxicant) induced early oxidative stress and mitochondrial dysfunctions. While ROT elicited marked oxidative stress as evidenced by the elevated levels of malondialdehyde, hydroperoxides and protein carbonyls in the cerebellum, FO prophylaxis significantly attenuated the effect. FO prophylaxis offered varying degree of protection against ROT-induced mitochondrial dysfunctions. Collectively, our findings in the ROT model allow us to hypothesize that the prophylactic protection offered by FO may be due to its ability to enhance GSH levels, antioxidant machinery, offset protein oxidation and specific modulatory effects on brain mitochondria.     

Antiplatelet effect of phloroglucinol is related to inhibition of cyclooxygenase, reactive oxygen species, ERK/p38 signaling and thromboxane A(2) production

Platelet dysfunction is a major risk factor of cardiovascular diseases such as atherosclerosis, stroke and myocardial infarction. Many antiplatelet agents are used for prevention and treatment of these diseases. In this study, phloroglucinol (2.5-25 μM) suppressed AA-induced platelet aggregation and thromboxane B₂ (TXB₂) production, but not U46619-induced platelet aggregation. Phloroglucinol (100-250 μM) showed little cytotoxicity to platelets. Phloroglucinol inhibited the COX-1 and COX-2 activities by 45-74% and 49-72% respectively at concentrations of 10-50 μM. At concentrations of 1 and 5 μM, phloroglucinol attenuated the AA-induced ROS production in platelets by 30% and 53%, with an IC₅₀ of 13.8 μM. Phloroglucinol also inhibited the PMA-stimulated ROS production in PMN. Preincubation of platelets by phloroglucinol (10-25 μM) markedly attenuated the AA-induced ERK and p38 phosphorylation. Intravenous administration of phloroglucinol (2.5 and 5 μmol/mouse) suppressed the ex vivo AA-induced platelet aggregation by 57-71%. Phloroglucinol administration also elevated the mice tail bleeding time. Moreover, phloroglucinol inhibited the IL-1β-induced PGE₂ production in pulp fibroblasts. These results indicate that antiplatelet and anti-inflammatory effects of phloroglucinol are related to inhibition of COX, ROS and TXA2 production as well as ERK/p38 phosphorylation in platelets. Phloroglucinol further suppress PMA-induced ROS production in PMN. The antiplatelet effect of phloroglucinol was confirmed by ex vivo study. Clinically, the consumption of phloroglucinol-containing food/natural products as nutritional supplement may be helpful to cardiovascular health. Phloroglucinol has potential pharmacological use.     

Cytotoxic effects of incense particles in relation to oxidative stress,the cell cycle and F-actin assembly

Epidemiological studies have suggested that combustion-derived smoke, such as that produced during incense burning, is a deleterious air pollutant. It is capable of initiating oxidative stress and mutation; however, the related apoptotic processes remain unclear. In order to elucidate the biological mechanisms of reactive oxygen species (ROS)-induced respiratory toxicology, alveolar epithelial A549 cells were exposed to incense particulate matter (PM), with and without antioxidant N-acetyl-l-cysteine (NAC). The cross-linking associations between oxidative capacity, cell cycle events, actin cytoskeletal dynamics and intracellular calcium signals were investigated. An incense PM suspension caused significant oxidative stress in A549 cells, as shown by inhibition of the cell cycle at G1 and G2/M check-points, and the induction of apoptosis at Sub-G1. At the same time, alterations in the F-actin filamentous assemblies were observed. The levels of intracellular Ca²⁺ were increased after incense PM exposure. Antioxidant NAC treatment revealed that oxidative stress and F-actin remodelling was significantly mitigated. This suggests that ROS accumulation could alter cell cycle regulation and anomalous remodelling of the cortical cytoskeleton that allowed impaired cells to enter into apoptosis. This study has elucidated the integral patho-physiological interactions of incense PM and the potential mechanisms for the development of ROS-driven respiratory impairment.     

Protective effect of the extracts from Cnidium officinale against oxidative damage induced by hydrogen peroxide via antioxidant effect

The dried rhizomes of Cnidium officinale are used as herbal drugs in the treatment of pain, inflammation, menstrual disturbance and antivitamin deficiency disease, and also act as a blood pressure depressant. In addition, there are several reports suggesting that they have pharmacological properties to tumor metastasis and angiogenesis, and that they act as an inhibitor of high glucose-induced proliferation of glomerular mesangial cells. However, little has been known about the functional role of the extracts from C. officinale on oxidative DNA damage and apoptosis caused by ROS. In this work, we have investigated the DPPH radical, hydroxyl radical and intracellular ROS scavenging capacity, and Fe²⁺ chelating activity of the extracts from C. officinale. In addition, we evaluated whether the extracts are capable of reducing H₂O₂-induced DNA and cell damage in the human skin fibroblast cell. These extracts showed a dose-dependent free-radical scavenging capacity and a protective effect on DNA damage and the lipid peroxidation causing the cell damage by ROS. These antioxidant activities and inhibitory effects of the extracts on DNA and cell damage may further explain that C. officinale is useful as a herbal medicine for cancer chemoprevention.     

Time course of systemic oxidative stress and inflammatory response induced by an acute exposure to Residual Oil Fly Ash

It is suggested that systemic oxidative stress and inflammation play a central role in the onset and progression of cardiovascular diseases associated with the exposure to particulate matter (PM). The aim of this work was to evaluate the time changes of systemic markers of oxidative stress and inflammation, after an acute exposure to Residual Oil Fly Ash (ROFA). Female Swiss mice were intranasally instilled with a ROFA suspension (1.0 mg/kg body weight) or saline solution, and plasma levels of oxidative damage markers [thiobarbituric acid reactive substances (TBARSs) and protein carbonyls], antioxidant status [reduced (GSH) and oxidized (GSSG) glutathione, ascorbic acid levels, and superoxide dismutase (SOD) activity], cytokines levels, and intravascular leukocyte activation were evaluated after 1, 3 or 5 h of exposure. Oxidative damage to lipids and decreased GSH/GSSG ratio were observed in ROFA-exposed mice as early as 1 h. Afterwards, increased protein oxidation, decreased ascorbic acid content and SOD activity were found in this group at 3 h. The onset of an adaptive response was observed at 5 h after the ROFA exposure, as indicated by decreased TBARS plasma content and increased SOD activity. The observed increase in oxidative damage to plasma macromolecules, together with systemic antioxidants depletion, may be a consequence of a systemic inflammatory response triggered by the ROFA exposure, since increased TNF-α and IL-6 plasma levels and polymorphonuclear leukocytes activation was found at every evaluated time point. These findings contribute to the understanding of the increase in cardiovascular morbidity and mortality, in association with environmental PM inhalation.     

Aspirin attenuates vinorelbine-induced endothelial inflammation via modulating SIRT1/AMPK axis

Vinorelbine (VNR), a semisynthetic vinca alkaloid acquired from vinblastine, is frequently used as the candidate for intervention of solid tumors. Nevertheless, VNR-caused endothelial injuries may lead a mitigative effect of clinical treatment efficiency. A growing body of evidence reveals that aspirin is a potent antioxidant and anti-inflammation drug. We investigated whether aspirin attenuate VNR-induced endothelial dysfunction. Human endothelial cells (EA.hy 926) were treated with VNR to cause endothelial inflammation. Western blotting, ROS assay, ELISA were used to confirm the anti-inflammatory effect of aspirin. We confirmed that VNR supresses SIRT1 expression, reduced LKB1 and AMPK phosphorylation as well as enriched PKC activation in treated endothelial cells. Furthermore, the membrane translocation assay displayed that the levels of NADPH oxidase subunits p47phox and Rac-1 in membrane fractions of endothelial cells were higher in cells that had been treated with VNR for than in untreated cells. We corroborated that treatment of Aspirin significantly diminishes VNR-repressed SIRT1, LKB1 and AMPK phosphorylation and VNR-promoted NADPH oxidase activation, however, those findings were vanished by SIRT1 and AMPK siRNAs. Our data also shown that Aspirin represses VNR-activated TGF-beta-activated kinase-1 (TAK1) activation, inhibited the interaction of TAK1/TAK-binding protein1 (TAB1), suppressed NF-kappa B activation and pro-inflammatory cytokine secretion. We demonstrated a novel connection between VNR-caused oxidative damages and endothelial dysfunction, and provide further insight into the protective effects of aspirin in VNR-caused endothelial dysfunction.     

EGCG-meditated cyto- and genotoxicity in HaCat keratinocytes is impaired by cell-mediated clearance of auto-oxidation-derived H2O2: an algorithm for experimental setting correction

Several lines of evidence suggest that besides antioxidant also prooxidant properties are crucially involved in cytotoxic and protective activities of the major green tea catechin epigallocatechin-3-gallate (EGCG) in vitro (Elbling et al., 2011). Furthermore recent data suggest that EGCG induces oxidative stress also in vivo (Li et al., 2010). Here we set out to identify factors modulating cellular effects of EGCG in vitro. Using the HaCat keratinocytes model, we demonstrate that the cytotoxic, genotoxic and signal-activating effects of EGCG are significantly dependent on the ratio of cell number to working volume. Treatment with identical EGCG concentrations at altered experimental settings resulted in IC₅₀ values differing up to orders of magnitude and could even exert contradictory effects. This effect was based on cell-mediated clearance of autooxidation-derived H₂O₂ from the supernatant. In order to estimate EGCG/H₂O₂ concentrations equally effective under different settings, we have rationally derived and experimentally verified a simple algorithm relating concentration, working volume, cell number and - indirectly - exposure time. Algorithm application resulted in similar H₂O₂ clearance curves from cell supernatants as well as comparable EGCG/H₂O₂ effects at different settings. Our results demonstrate the importance of standardized experimental settings when investigating cytotoxic and/or beneficial effects of autooxidizing compounds.     

Effects of non-steroidal anti-inflammatory agents on human neutrophil functions in vitro and in vivo

Human blood neutrophils exposed to appropriate stimuli aggregate, degranulate and generate superoxide anion (O2-). These responses are anteceded by mobilization of membrane-associated calcium, monitored as a decrease in fluorescence of cells preloaded with chlortetracycline (CTC). We studied the effects, both in vitro and in vivo, of non-steroidal anti-inflammatory agents (aspirin, indomethacin, ibuprofen and piroxicam) on these neutrophil responses to three stimuli: a chemoattractant, N-formyl-methionyl-leucyl-phenylalanine (FMLP); a tumor promotor, phorbol myristate acetate (PMA); and a lectin, concanavalin A (Con A). The effects of these drugs were compared with those of two polyenoic inhibitors of arachidonate metabolism: eicosatrienoic acid (ETI) and eicosatetraynoic acid (ETYA). The pattern of inhibition of neutrophil functions varied both with inhibitor and the nature of the stimulus. Thus, aspirin, piroxicam, ETYA and ETI inhibited neutrophil aggregation, degranulation, and O2- generation in response to FMLP, whereas ibuprofen inhibited only aggregation and degranulation and indomethacin only inhibited aggregation. None of the agents inhibited aggregation or degranulation induced by PMA or Con A: only piroxicam inhibited O2- generation in response to PMA or Con A. ETI and ibuprofen inhibited decrements of CTC fluorescence induced by FMLP, but whereas ETI inhibited the CTC response to PMA or Con A, ibuprofen was without effect. The agents had varying effects on binding of the stimulus [( 3H]FMLP, [3H]Con A), but these did not correlate with neutrophil responses to the ligands. Neutrophils from subjects taking therapeutic doses of ibuprofen, indomethacin, or piroxicam showed profiles of inhibited responses to FMLP similar to those observed with these agents in vitro. These data suggest that, although non-steroidal anti-inflammatory agents may inhibit discrete neutrophil functions both in vitro and in vivo, their effects do not duplicate those of polyenoic inhibitors of arachidonate metabolism. Moreover, since the susceptibility of neutrophils differed not only with respect to each inhibitor, but also to the stimulus, it is unlikely that all neutrophil responses are necessarily linked by a common pathway that is blocked by inhibitors of arachidonic acid metabolism.     

Antimycin A-induced mitochondrial apoptotic cascade is mitigated by phenolic constituents of Phyllanthus amarus aqueous extract in Hep3B cells

Antimycin A (AMA) treatment of cells blocks mitochondrial electron transport chain, and leads to elevated ROS generation, thereby causing damage to mtDNA, proteins and lipids, along with mitochondrial membrane depolarization, release of pro-apoptotic proteins into the cytoplasm, and induction of apoptosis. Prevention of such oxidative cellular damage by the aqueous extract of Phyllanthus amarus has been investigated in this study. The extract demonstrated significant potential in mitigating H₂O₂-induced membrane damage along with considerable recession in AMA-governed mitochondrial protein and lipid degradation in Hep3B cells. 8-OHdG analysis of mtDNA damage revealed substantial protective potential of the extract against mtDNA damage. SQ-PCR of selected mtDNA sequences confirmed the potential of the extract to alleviate levels of mtDNA damage. FACS analysis with JC-1 fluorescent dye established significant escalation of mitochondrial membrane potential by the extract in AMA-treated cells. Extract treatment resulted in a distinct decline in the degrees of AMA-induced release of cytochrome c and AIF into the cytoplasm along with consequent pacification of apoptosis. All protective efficiencies of the extract reported in this study were found to hold strong and significant (P < 0.05) positive correlation to its total phenolic contents, thereby proving that polyphenolic constituents of P. amarus aqueous extract mitigate oxidative stress-induced cellular degeneration and aging.     

Size-dependent cytotoxicity of amorphous silica nanoparticles in human hepatoma HepG2 cells

The purpose of this study is to compare the potential cytotoxicity induced by amorphous silica particles with different sizes. The effects of one fine particle (498 nm) and three nanoparticles (68, 43, and 19 nm) on cultured human hepatoma (HepG2) cells were investigated by detecting morphological changes, cell viability, cytomembrane integrity, DNA damage, cell cycle distribution, and apoptosis after the cells were treated with 100 μg/mL of four silica particles for 24 h. The results indicated that in HepG2 cells, the cytotoxicity generated by silica particles strongly depended on the particle size, and smaller silica particle possessed higher toxic effect. In order to further elucidate the possible mechanisms of cell injuries, intracellular reactive oxygen species (ROS) was measured. Increased ROS level was also observed in a size dependent way. However, the result showed the fine particle did not promote intracellular ROS level significantly, while cell injuries were detected in this treated group. Thus, our data demonstrated that exposure to different sizes of silica particles resulted in a size dependent cytotoxicity in cultured HepG2 cells, and ROS generation should be one possible damage pathway but might not be completely responsible for the toxic effect produced by silica particles.     

Study of cytotoxic and apoptogenic properties of saffron extract in human cancer cell lines

Saffron (dried stigmas of Crocus sativus L.) has been used as a spice, food colorant and medicinal plant for millennia. In this study cytotoxic effect of saffron extract was evaluated in HepG2 and HeLa cell lines. Meanwhile role of apoptosis and ROS were explored. Malignant and non-malignant cells (L929) were cultured in DMEM medium and incubated with different concentrations of ethanolic saffron extract. Cell viability was quantitated by MTT assay. Apoptotic cells were determined using PI staining of DNA fragmentation by flow cytometry (sub-G1 peak). ROS was measured using DCF-DA by flow cytometry analysis. Saffron could decrease cell viability in malignant cells as a concentration and time-dependent manner. The IC50 values against HeLa and HepG2 were determined 800 and 950 μg/ml after 48 h, respectively. Saffron induced a sub-G1 peak in flow cytometry histogram of treated cells compared to control indicating apoptotic cell death is involved in saffron toxicity. This toxicity was also independent of ROS production. It might be concluded that saffron could cause cell death in HeLa and HepG2 cells, in which apoptosis or programmed cell death plays an important role. Saffron could be also considered as a promising chemotherapeutic agent in cancer treatment in future.     

A novel marine compound xyloketal B protects against oxidized LDL-induced cell injury in vitro

Xyloketal B is a novel marine compound with unique chemical structure isolated from mangrove fungus Xylaria sp. (no. 2508). Pretreatment with xyloketal B (0.63-40 μM) significantly improved oxLDL (150 μg/ml)-induced injury in human umbilical vein endothelial cells (HUVECs) without either toxic or proliferative effects. Xyloketal B concentration-dependently attenuated oxLDL-induced ROS generation, peroxynitrite formation and decrease of Bcl-2 expression. In addition, xyloketal B significantly inhibited NADPH oxidase activity, as well as mRNA expression of gp91phox and p47phox. Furthermore, xyloketal B alone augmented the production of nitric oxide (NO). Collectively, these data indicate that xyloketal B protects against oxLDL-induced endothelial oxidative injury probably through inhibiting NADPH oxidase-derived ROS generation, promoting NO production and restoring Bcl-2 expression, making it a promising compound for further evaluation in the treatment of atherosclerosis.     

MiADMSA reverses impaired mitochondrial energy metabolism and neuronal apoptotic cell death after arsenic exposure in rats

Arsenicosis, due to contaminated drinking water, is a serious health hazard in terms of morbidity and mortality. Arsenic induced free radicals generated are known to cause cellular apoptosis through mitochondrial driven pathway. In the present study, we investigated the effect of arsenic interactions with various complexes of the electron transport chain and attempted to evaluate if there was any complex preference of arsenic that could trigger apoptosis. We also evaluated if chelation with monoisoamyl dimercaptosuccinic acid (MiADMSA) could reverse these detrimental effects. Our results indicate that arsenic exposure induced free radical generation in rat neuronal cells, which diminished mitochondrial potential and enzyme activities of all the complexes of the electron transport chain. Moreover, these complexes showed differential responses towards arsenic. These early events along with diminished ATP levels could be co-related with the later events of cytosolic migration of cytochrome c, altered bax/bcl₂ ratio, and increased caspase 3 activity. Although MiADMSA could reverse most of these arsenic-induced altered variables to various extents, DNA damage remained unaffected. Our study for the first time demonstrates the differential effect of arsenic on the complexes leading to deficits in bioenergetics leading to apoptosis in rat brain. However, more in depth studies are warranted for better understanding of arsenic interactions with the mitochondria.     

Effect of extracts from pine needle against oxidative DNA damage and apoptosis induced by hydroxyl radical via antioxidant activity

In this study, the protective effects of water extracts from pine needle (WEPN) against DNA damage and apoptosis induced by hydroxyl radical were investigated in non-cellular and cellular system. WEPN exhibited strong scavenging action on hydroxyl radical and intracellular ROS, and chelating action of Fe²⁺ ion. WEPN inhibited oxidative DNA damage by hydroxyl radical. Also, WEPN prevented the cells from oxidative damage through lowering p21 and BAX protein expression, blocking the cleavage of PARP and increasing Bcl-2 protein, which was confirmed by Hoechst 33342 staining. These data indicate that WEPN possesses a spectrum of antioxidant and DNA-protective properties common to cancer chemopreventive agents.     

Sex-specific differences in hyperoxic lung injury in mice: Implications for acute and chronic lung disease in humans

Sex-specific differences in pulmonary morbidity in humans are well documented. Hyperoxia contributes to lung injury in experimental animals and humans. The mechanisms responsible for sex differences in the susceptibility towards hyperoxic lung injury remain largely unknown. In this investigation, we tested the hypothesis that mice will display sex-specific differences in hyperoxic lung injury. Eight week-old male and female mice (C57BL/6J) were exposed to 72 h of hyperoxia (FiO₂ > 0.95). After exposure to hyperoxia, lung injury, levels of 8-iso-prostaglandin F₂ alpha (8-iso-PGF 2α) (LC–MS/MS), apoptosis (TUNEL) and inflammatory markers (suspension bead array) were determined. Cytochrome P450 (CYP)1A expression in the lung was assessed using immunohistochemistry and western blotting. After exposure to hyperoxia, males showed greater lung injury, neutrophil infiltration and apoptosis, compared to air-breathing controls than females. Pulmonary 8-iso-PGF 2α levels were higher in males than females after hyperoxia exposure. Sexually dimorphic increases in levels of IL-6 (F > M) and VEGF (M > F) in the lungs were also observed. CYP1A1 expression in the lung was higher in female mice compared to males under hyperoxic conditions. Overall, our results support the hypothesis that male mice are more susceptible than females to hyperoxic lung injury and that differences in inflammatory and oxidative stress markers contribute to these sex-specific dimorphic effects. In conclusion, this paper describes the establishment of an animal model that shows sex differences in hyperoxic lung injury in a temporal manner and thus has important implications for lung diseases mediated by hyperoxia in humans.     

Protective role of estrogen receptor-alpha on lower chlorinated PCB congener-induced DNA damage and repair in human tumoral breast cells

Polychlorinated biphenyls (PCBs) are ubiquitous environmental contaminants. Much of the research has focused on the carcinogenic potential of higher chlorinated PCBs, but accumulative evidence has shown that lower chlorinated PCB congeners have initiating and promoting activities. The goal of this study was to examine the potential of lower chlorinated PCBs, including 2,2′,5,5′-tetrachlorobiphenyl (PCB52) and 3,3′,4,4′-tetrachlorobiphenyl (PCB77), to induce DNA damage and apoptosis in human MDA-MB-231 (MDA) and MCF-7 breast cancer cells. Results confirmed that treatment of cells with PCB52 and PCB77 resulted in oxidative stress and caspase-dependent apoptosis in both MDA and MCF-7 cells. We noticed that at non-cytotoxic concentrations PCB52 and PCB77-induced decreases in intracellular NAD(P)H in MDA cells but not in MCF-7 cells. Further investigation confirmed that decreases in intracellular NAD(P)H in PCB-treated MDA cells are primarily due to reduction in intracellular NAD⁺ pool mediated by poly(ADP-ribose)polymerase-1 activation through formation of DNA strand breaks. Antagonism was observed between PCB52 and PCB77 for the effect on induction of DNA strand breaks in MDA cells. Overall, this evidence demonstrates that at non-cytotoxic concentrations, lower chlorinated PCB congeners are capable of inducing oxidative DNA lesions in ERα(−)/MDA cells but not in ERα(+)/MCF-7 cells and that functional ERα plays a protective role in modulating the PCB-induced DNA damage in human breast cancer cells.     

Effects of Epigallocatechin-3-gallate on lead-induced oxidative damage

Recent studies have shown that lead (Pb) could disrupt the prooxidant/antioxidant balance of tissue which leads to biochemical and physiological dysfunction. Epigallocatechin-3-gallate (EGCG), a catechin polyphenols component, is found to be an effective antioxidant. The present study investigated whether EGCG administration could reverse the changes on redox states in rat hippocampus caused by lead exposure. The association between redox status changes and long-term potentiation (LTP) in CA1 area of hippocampus were also examined. Wistar rats exposed to lead from postnatal day 1 were followed by 10 days of EGCG (10, 25 and 50 mg/kg) administration through intraperitoneally (ip), and the rats were sacrificed for experiments at the age of 21–23 days. The experimental results showed that glutathione (GSH) and superoxide dismutase (SOD) activity decreased accompanied with LTP amplitude decrease in CA1 area of hippocampus in the lead-exposed group. EGCG supplementation following lead intoxication resulted in increases in the GSH and SOD levels and increases in the LTP amplitude. Malondialdehyde (MDA) levels, a major lipid peroxidation byproduct, increased following lead exposure and decreased following EGCG treatment. In hippocampal neuron culture model, lead exposure (20 μM) significantly inhibited the viability of neurons which was followed by an accumulation of ROS and a decrease of mitochondrial membrane potential (ΔΨ_m). Treatment by EGCG (10–50 μM) effectively increased cell viability, decreased ROS formation and improved ΔΨ_m in hippocampal neurons exposed to lead. These observations suggest that EGCG is a potential complementary agent in the treatment of chronic lead intoxication through its antioxidative character.