Menadione-induced caspase-dependent programmed cell death in the green chlorophyte Chlamydomonas reinhardtii.

Menadione, a quinone that undergoes redox cycles leading to the formation of superoxide radicals, induces programmed cell death (PCD) in animals and plants. In this study, we investigated whether the unicellular green alga Chlamydomonas reinhardtii P.A.Dangeard is capable of executing PCD upon exposure to menadione stress. We report here, the morphological, molecular, and biochemical changes after menadione exposure of C. reinhardtii cells. The effect of menadione on cell death has been shown to be dose-dependent; 5-100 µM menadione causes 20%-46% cell death, respectively. It appears that growth is inhibited with the concomitant degradation of the photosynthetic pigments and by a decrease in the photosynthetic capacity. Being an oxidative stress, we found an H2 O2 burst within 15 min of menadione exposure, followed by an increase in antioxidant enzyme (superoxide dismutase [SOD], catalase [CAT], and ascorbate peroxidase [APX]) activities. In parallel, RT-PCR was performed for transcript analyses of Mn-SOD, CAT, and APX. Our results clearly revealed that expression of these genes were up-regulated upon menadione exposure. Furthermore, classical hallmarks of PCD such as alteration of mitochondrial membrane potential, significant increase in caspase-3-like DEVDase activity, cleavage of poly (ADP) ribose polymerase (PARP)-1-like enzyme, and DNA fragmentation as detected by terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) assay and oligosomal DNA fragmentation were observed. Moreover, antibodies against a mammalian active caspase-3 shared epitopes with a caspase-3-like protein of ~17 kDa; its pattern of expression and activity correlated with the onset of cell death. To the best of our knowledge, this is the first report on menadione-induced PCD through a mitochondrian-caspase protease pathway in an algal species.

Seabuckthron (Hippophae rhamnoides L.) leaf extract ameliorates the gamma radiation mediated DNA damage and hepatic alterations.

In vitro assessment showed that H. rhamnoides (HrLE) extract possessed free radical scavenging activities and can protect gamma (gamma) radiation induced supercoiled DNA damage. For in vivo study, Swiss albino mice were administered with HrLE (30 mg/kg body weight) for 15 consecutive days before exposing them to a single dose of 5 Gy of beta radiation. HrLE significantly prevented the radiation induced genomic DNA damage indicated as a significant reduction in the comet parameters. The lipid peroxidation, liver function enzymes, expression of phosphorylated NFkappaB (p65) and IkappaBalpha increased whereas the endogenous antioxidants diminished upon radiation exposure compared to control. Pretreatment of HrLE extract ameliorated these changes. Based on the present results it can be concluded that H. rhamnoides possess a potential preventive element in planned and accidental nuclear exposures.

Protective effect of secondary plant metabolites from Ipomoea aquatica Forsk. against carbofuran induced damages.

Plausible interactions between food contaminants and natural constituents in vivo and protective effect of polyphenols present in I. aquatica against carbofuran toxicity in Charles Foster rats were evaluated. Determinations based on antioxidant enzyme activities showed significant alterations in glutathione, glutathione peroxidase, superoxide dismutase and catalase in tissues (liver and brain) and plasma of pesticide treated group while polyphenolic extracts from I. aquatica (IAE) attenuated their activities when given alongwith carbofuran. IAE decreased enhanced lipid peroxidation levels in plasma and erythrocyte membrane and cholesterol levels in brain and plasma. IAE also minimized histopathological degenerative changes produced by carbofuran. While single cell gel electrophoresis showed that secondary metabolites in leafy vegetables produced a combinatorial effect with pesticide at cellular level, DNA fragmentation level in bone marrow cells showed a decline in the IAE treated rats. Food safety adversely affected by various chemical contaminants can be retained by plant polyphenols and secondary plant constituents that can be found together in bolus. Therefore, the present study gives an insight into the protective role of naturally found polyphenols against pesticide toxicity.

Amelioration of ionizing radiation induced lipid peroxidation in mouse liver by Moringa oleifera Lam. leaf extract.

Protective effect of Moringa oleifera leaf extract (MoLE) against radiation-induced lipid peroxidation has been investigated. Swiss albino mice, selected from an inbred colony, were administered with MoLE (300 mg/kg body wt) for 15 days before exposing to a single dose of 5 Gy 60Co-gamma radiation. After treatments, animals were necropsied at different post irradiation intervals (days 1, 7 and 15) and hepatic lipid peroxidation and reduced glutathione (GSH) contents were estimated to observe the relative changes due to irradiation and its possible amelioration by MoLE. It was observed that, MoLE treatment restored GSH in liver and prevented radiation induced augmentation in hepatic lipid peroxidation. Phytochemical analysis showed that MoLE possess various phytochemicals such as ascorbic acid, phenolics (catechin, epicatechin, ferulic acid, ellagic acid, myricetin) etc., which may play the key role in prevention of hepatic lipid peroxidation by scavenging radiation induced free radicals.

Ferulic acid (FA) abrogates γ-radiation induced oxidative stress and DNA damage by up-regulating nuclear translocation of Nrf2 and activation of NHEJ pathway.

The present study was aimed to evaluate the radioprotective effect of ferulic acid (FA), a naturally occurring plant flavonoid in terms of DNA damage and damage related alterations of repair pathways by gamma radiation. FA was administered at a dose of 50 mg/kg body weight for five consecutive days prior to exposing the swiss albino mice to a single dose of 10 Gy gamma radiation. Ionising radiation induces oxidative damage manifested by decreased expression of Cu, Zn-SOD (SOD stands for super oxide dismutase), Mn-SOD and catalase. Gamma radiation promulgated reactive oxygen species (ROS) mediated DNA damage and modified repair pathways. ROS enhanced nuclear translocation of p53, activated ATM (ataxia telangiectasia-mutated protein), increased expression of GADD45a (growth arrest and DNA-damage-inducible protein) gene and inactivated Non homologous end joining (NHEJ) repair pathway. The comet formation in irradiated mice peripheral blood mononuclear cells (PBMC) reiterated the DNA damage in IR exposed groups. FA pretreatment significantly prevented the comet formation and regulated the nuclear translocation of p53, inhibited ATM activation and expression of GADD45a gene. FA promoted the nuclear translocation of nuclear factor (erythroid-derived 2)-like 2 (Nrf2) and activated NHEJ repair pathway to overcome ROS mediated oxidative stress and DNA damage. Therefore, the current study stated that FA can challenge the oxidative stress by (i) inducing nuclear translocation of Nrf2, (ii) scavenging ROS, and (iii) activating NHEJ DNA repair process.

Gossypetin ameliorates ionizing radiation-induced oxidative stress in mice liver--a molecular approach.

Radioprotective action of gossypetin (GTIN) against gamma (γ)-radiation-induced oxidative stress in liver was explored in the present article. Our main aim was to evaluate the protective efficacy of GTIN against radiation-induced alteration of liver in murine system. To evaluate the effect of GTIN, it was orally administered to mice at a dose of 30 mg/kg body weight for three consecutive days prior to γ-radiation at a dose of 5 Gy. Radioprotective efficacy of GTIN were evaluated at physiological, cellular, and molecular level using biochemical analysis, comet assay, flow cytometry, histopathology, immunofluorescence, and immunoblotting techniques. Ionizing radiation was responsible for augmentation of hepatic oxidative stress in terms of lipid peroxidation and depletion of endogenous antioxidant enzymes. Immunoblotting and immunofluorescence studies showed that irradiation enhanced the nuclear translocation of nuclear factor kappa B (NF-κB) level, which leads to hepatic inflammation. To investigate further, we found that radiation induced the activation of stress-activated protein kinase/c-Jun NH2-terminal kinase (SAPK/JNK)-mediated apoptotic pathway and deactivation of the NF-E2-related factor 2 (Nrf2)-mediated redox signaling pathway, whereas GTIN pretreatment ameliorated these radiation-mediated effects. This is the novel report where GTIN rationally validated the molecular mechanism in terms of the modulation of cellular signaling system' instead of ' This is the novel report where GTIN is rationally validated in molecular terms to establish it as promising radioprotective agents. This might be fruitful especially for nuclear workers and defense personnel assuming the possibility of radiation exposure.

Role of ferulic acid in the amelioration of ionizing radiation induced inflammation: a murine model.

Ionizing radiation is responsible for oxidative stress by generating reactive oxygen species (ROS), which alters the cellular redox potential. This change activates several redox sensitive enzymes which are crucial in activating signaling pathways at molecular level and can lead to oxidative stress induced inflammation. Therefore, the present study was intended to assess the anti-inflammatory role of ferulic acid (FA), a plant flavonoid, against radiation-induced oxidative stress with a novel mechanistic viewpoint. FA was administered (50 mg/kg body wt) to Swiss albino mice for five consecutive days prior to exposing them to a single dose of 10 Gy 60Co γ-irradiation. The dose of FA was optimized from the survival experiment and 50 mg/kg body wt dose showed optimum effect. FA significantly ameliorated the radiation induced inflammatory response such as phosphorylation of IKKα/ß and IκBα and consequent nuclear translocation of nuclear factor kappa B (NF-κB). FA also prevented the increase of cycloxygenase-2 (Cox-2) protein, inducible nitric oxide synthase-2 (iNOS-2) gene expression, lipid peroxidation in liver and the increase of tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) in serum. It was observed that exposure to radiation results in decreased activity of superoxide dismutase (SOD), catalase (CAT) and the pool of reduced glutathione (GSH) content. However, FA treatment prior to irradiation increased the activities of the same endogenous antioxidants. Thus, pretreatment with FA offers protection against gamma radiation induced inflammation.

Modulatory role of quercetin against gamma radiation-mediated biochemical and morphological alterations of red blood cells.

PURPOSE: The present work was intended to evaluate the radioprotective effect of quercetin against gamma radiation-induced oxidative stress on red blood cells (RBC). MATERIALS AND METHODS: Swiss albino male mice were treated with quercetin (100 mg/kg body wt) for three consecutive days prior to 5 Gy (60)Co-gamma irradiation. RBC was isolated to estimate the level of intracellular reactive oxygen species (ROS), membrane lipid peroxidation (LPO), intracellular reduced glutathione (GSH), mean corpuscular hemoglobin concentration (MCHC), osmotic fragility and morphological alterations by atomic force microscope (AFM). RESULTS: Irradiation increased intracellular ROS and membrane LPO whereas it decreased the intracellular GSH. Quercetin pretreatment ameliorated these alterations. The MCHC value decreased after irradiation whereas quercetin pretreatment restored it. The average osmotic fragility (H50) and the maximum rate of hemolysis (dH/dC)max increased after irradiation. Quercetin pretreatment decreased the H50 and (dH/dC)max. The AFM study showed that irradiation transformed RBC from biconcave to echinocytes, increased their surface roughness and decreased the vertical distance whereas pretreatment of quercetin significantly prevented both the alterations. CONCLUSIONS: Gamma radiation produced ROS and LPO which rendered oxidative stress and ultimately damaged RBC whereas quercetin ameliorated these changes and protected RBC from radiation-mediated damage.

Gossypetin, a naturally occurring hexahydroxy flavone, ameliorates gamma radiation-mediated DNA damage.

PURPOSE: To evaluate the protective effect of gossypetin (GTIN) against gamma (γ)-radiation-mediated DNA damage. MATERIALS AND METHODS: Increasing concentrations (10-150 µM) of GTIN were incubated with supercoiled DNA 1 h prior exposure to γ-radiation in the range of 5-Gy absorbed dose from Co(60) γ source. To establish the effective protective concentration of GTIN, supercoiled DNA was pre-incubated with 50 µM of GTIN for 1 h followed by exposure of 5, 10 and 20 Gy doses of γ-radiation. Moreover, 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical, hydroxyl radical, nitric oxide (NO) scavenging, metal chelating activity and ferric reducing antioxidant power (FRAP) of GTIN were measured and compared with standards. The flowcytometric analysis and radiation-induced genomic DNA damage by comet assay were employed to estimate the level of intracellular reactive oxygen species (ROS) using isolated murine hepatocytes. RESULTS: GTIN was able to effectively scavenge different free radicals in in vitro situations. It could significantly prevent radiation induced supercoiled and genomic DNA damage with reduced comet parameters. It also acted as a potent scavenger of the radiation induced ROS. CONCLUSIONS: GTIN ameliorated radiation-induced oxidative stress and DNA damage by its free-radical scavenging activity.

Epicatechin ameliorates ionising radiation-induced oxidative stress in mouse liver.

The current study was intended to evaluate the hepatoprotective effect of Epicatechin (EC) against radiation-induced oxidative stress, in terms of inflammation and lipid peroxidation. Swiss albino mice were administered with EC (15 mg/kg body weight) for three consecutive days before exposing them to a single dose of 5-Gy (60)Co gamma (γ) irradiation. Mice were necropsied and livers were taken for immunohistochemistry, western blot analysis and biochemical tests for the detection of markers of hepatic oxidative stress. Nuclear translocation of nuclear factor kappa B (NF-κB) and lipid peroxidation were increased whereas the activities of superoxide dismutase (SOD) and catalase (CAT), reduced glutathione (GSH) content and ferric reducing antioxidant power (FRAP) were diminished upon radiation exposure compared to control. Translocation of NF-κB from cytoplasm to nucleus and lipid peroxidation were found to be inhibited whereas an increase in SOD, CAT, GSH and FRAP was observed in the mice treated with EC prior to irradiation. Thus, pre-treatment with EC offers protection against γ-radiation induced hepatic alterations.

Leaf extract of Moringa oleifera prevents ionizing radiation-induced oxidative stress in mice.

The present study evaluated the hepatoprotective effect of aqueous ethanolic Moringa oleifera leaf extract (MoLE) against radiation-induced oxidative stress, which is assessed in terms of inflammation and lipid peroxidation. Swiss albino mice were administered MoLE (300 mg/kg of body weight) for 15 consecutive days before exposing them to a single dose of 5 Gy of 6°Co γ-irradiation. Mice were sacrificed at 4 hours after irradiation. Liver was collected for immunoblotting and biochemical tests for the detection of markers of hepatic oxidative stress. Nuclear translocation of nuclear factor kappa B (NF-κB) and lipid peroxidation were augmented, whereas the superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GSH), and ferric reducing antioxidant power (FRAP) values were decreased by radiation exposure. Translocation of NF-κB from cytoplasm to nucleus and lipid peroxidation were found to be inhibited, whereas increases in SOD, CAT, GSH, and FRAP were observed in the mice treated with MoLE prior to irradiation. Therefore pretreatment with MoLE protected against γ-radiation-induced liver damage. The protection may be attributed to the free radical scavenging activity of MoLE, through which it can ameliorate radiation-induced oxidative stress.