Radioprotective effect of vitamins C and E

Ascorbic Acid Protects Bone Marrow from Oxidative Stress and Transient Elevation of Corticosterone Caused by X-ray Exposure in Akr1a-Knockout Mice

Bone marrow cells are the most sensitive to exposure to X-rays in the body and are selectively damaged even by doses that are generally considered permissive in other organs. Ascorbic acid (Asc) is a potent antioxidant that is reported to alleviate damages caused by X-ray exposure. However, rodents can synthesize Asc, which creates difficulties in rigorously assessing its effects in such laboratory animals. To address this issue, we employed mice with defects in their ability to synthesize Asc due to a genetic ablation of aldehyde reductase (Akr1a-KO). In this study, concentrations of white blood cells (WBCs) were decreased 3 days after exposure to X-rays at 2 Gy and then gradually recovered. At approximately one month, the recovery rate of WBCs was delayed in the Akr1a-KO mouse group, which was reversed via supplementation with Asc. Following exposure to X-rays, Asc levels decreased in plasma, bone marrow cells, and the liver during an early period, and then started to increase. X-ray exposure stimulated the pituitary gland to release adrenocorticotropic hormone (ACTH), which stimulated corticosterone secretion. Asc released from the liver, which was also stimulated by ACTH, appeared to be recruited to the bone marrow. Since corticosterone in high doses is injurious, these collective results imply that Asc protects bone marrow via its antioxidant capacity against ROS produced via exposure to X-rays and the cytotoxic action of transiently elevated corticosterone.

Brain DNA damaging effects of volatile anesthetics and 1 and 2 Gy gamma irradiation in vivo: Preliminary results

Although both can cause DNA damage, the combined impact of volatile anesthetics halothane/sevoflurane/isoflurane and radiotherapeutic exposure on sensitive brain cells in vivo has not been previously analyzed. Healthy Swiss albino male mice (240 in total, 48 groups) were exposed to either halothane/sevoflurane/isoflurane therapeutic doses alone (2 h); 1 or 2 gray of gamma radiation alone; or combined exposure. Frontal lobe brain samples from five animals were taken immediately and 2, 6, and 24 h after exposure. DNA damage and cellular repair index were analyzed using the alkaline comet assay and the tail intensity parameter. Elevated tail intensity levels for sevoflurane/halothane were the highest at 6 h and returned to baseline within 24 h for sevoflurane, but not for halothane, while isoflurane treatment caused lower tail intensity than control values. Combined exposure demonstrated a slightly halothane/sevoflurane protective and isoflurane protective effect, which was stronger for 2 than for 1 gray. Cellular repair indices and tail intensity histograms indicated different modes of action in DNA damage creation. Isoflurane/sevoflurane/halothane preconditioning demonstrated protective effects in sensitive brain cells in vivo. Owing to the constant increases in the combined use of radiotherapy and volatile anesthetics, further studies should explore the mechanisms behind these effects, including longer and multiple exposure treatments and in vivo brain tumor models.

High-throughput screening strategies for space-based radiation countermeasure discovery

As humanity begins to venture further into space, approaches to better protect astronauts from the hazards found in space need to be developed. One particular hazard of concern is the complex radiation that is ever present in deep space. Currently, it is unlikely enough spacecraft shielding could be launched that would provide adequate protection to astronauts during long-duration missions such as a journey to Mars and back. In an effort to identify other means of protection, prophylactic radioprotective drugs have been proposed as a potential means to reduce the biological damage caused by this radiation. Unfortunately, few radioprotectors have been approved by the FDA for usage and for those that have been developed, they protect normal cells/tissues from acute, high levels of radiation exposure such as that from oncology radiation treatments. To date, essentially no radioprotectors have been developed that specifically counteract the effects of chronic low-dose rate space radiation. This review highlights how high-throughput screening (HTS) methodologies could be implemented to identify such a radioprotective agent. Several potential target, pathway, and phenotypic assays are discussed along with potential challenges towards screening for radioprotectors. Utilizing HTS strategies such as the ones proposed here have the potential to identify new chemical scaffolds that can be developed into efficacious radioprotectors that are specifically designed to protect astronauts during deep space journeys. The overarching goal of this review is to elicit broader interest in applying drug discovery techniques, specifically HTS towards the identification of radiation countermeasures designed to be efficacious towards the biological insults likely to be encountered by astronauts on long duration voyages.

Chemical and biological basis for development of novel radioprotective drugs for cancer therapy

Ionizing radiation (IR) causes chemical changes in biological systems through direct interaction with the macromolecules or by causing radiolysis of water. This property of IR is harnessed in the clinic for radiotherapy in almost 50% of cancers patients. Despite the advent of stereotactic radiotherapy instruments and other advancements in shielding techniques, the inadvertent deposition of radiation dose in the surrounding normal tissue can cause late effects of radiation injury in normal tissues. Radioprotectors, which are chemical or biological agents, can reduce or mitigate these toxic side-effects of radiotherapy in cancer patients and also during radiation accidents. The desired characteristics of an ideal radioprotector include low chemical toxicity, high risk to benefit ratio and specific protection of normal cells against the harmful effects of radiation without compromising the cytotoxic effects of IR on cancer cells. Since reactive oxygen species (ROS) are the major contributors of IR mediated toxicity, plethora of studies have highlighted the potential role of antioxidants to protect against IR induced damage. However, owing to the lack of any clinically approved radioprotector against whole body radiation, researchers have shifted the focus toward finding alternate targets that could be exploited for the development of novel agents. The present review provides a comprehensive insight in to the different strategies, encompassing prime molecular targets, which have been employed to develop radiation protectors/countermeasures. It is anticipated that understanding such factors will lead to the development of novel strategies for increasing the outcome of radiotherapy by minimizing normal tissue toxicity.

Nutrition Can Help DNA Repair in the Case of Aging

Micronutrients such as vitamins and trace elements are crucial for maintaining the health of all organisms. Micronutrients are involved in every cellular/biochemical process. They play roles in proper heart and brain functioning, influence immunological responses, and antioxidant defense systems. Therefore, prolonged deficiency in one or more micronutrients leads to cardiovascular or neurodegenerative disorders. Keeping micronutrients at adequate levels is especially important for seniors. They are prone to deficiencies due to age-associated functional decline and often to a diet poor in nutrients. Moreover, lack of micronutrients has an indirect impact on the genome. Their low levels reduce the activity of antioxidant enzymes, and therefore inhibit the efficiency of defense against free radicals which can lead to the formation of DNA lesions. The more DNA damage in the genetic material, the faster aging at the cellular level and a higher risk of pathological processes (e.g., carcinogenesis). Supplementation of crucial antioxidative micronutrients such as selenium, zinc, vitamin C, and vitamin E seems to have the potential to positively influence the condition of an aging organism, including minimizing inflammation, enhancing antioxidative defense, and limiting the formation of DNA lesions. In consequence, it may lead to lowering the risk and incidence of age-related diseases such as cardiovascular diseases, neurodegenerative diseases, and malnutrition. In this article, we attempt to present the synergistic action of selected antioxidant micronutrients (vitamin C, vitamin E, selenium, and zinc) for inhibiting oxidative stress and DNA damage, which may impede the process of healthy aging.

Space Radiation Biology for "Living in Space"

Space travel has advanced significantly over the last six decades with astronauts spending up to 6 months at the International Space Station. Nonetheless, the living environment while in outer space is extremely challenging to astronauts. In particular, exposure to space radiation represents a serious potential long-term threat to the health of astronauts because the amount of radiation exposure accumulates during their time in space. Therefore, health risks associated with exposure to space radiation are an important topic in space travel, and characterizing space radiation in detail is essential for improving the safety of space missions. In the first part of this review, we provide an overview of the space radiation environment and briefly present current and future endeavors that monitor different space radiation environments. We then present research evaluating adverse biological effects caused by exposure to various space radiation environments and how these can be reduced. We especially consider the deleterious effects on cellular DNA and how cells activate DNA repair mechanisms. The latest technologies being developed, e.g., a fluorescent ubiquitination-based cell cycle indicator, to measure real-time cell cycle progression and DNA damage caused by exposure to ultraviolet radiation are presented. Progress in examining the combined effects of microgravity and radiation to animals and plants are summarized, and our current understanding of the relationship between psychological stress and radiation is presented. Finally, we provide details about protective agents and the study of organisms that are highly resistant to radiation and how their biological mechanisms may aid developing novel technologies that alleviate biological damage caused by radiation. Future research that furthers our understanding of the effects of space radiation on human health will facilitate risk-mitigating strategies to enable long-term space and planetary exploration.

Mutagenic effect of imidacloprid insecticide: The ameliorative effect of pre and post exposure to olive oil

Imidacloprid, a systemic chloro-nicotinyl insecticide belong to neonicotinoid insecticides. In this study 120 rats were divided into four groups, the first group used as a control group, the second group was administered imidacloprid at a dose of 22.5 mg/kg b.w. for 4, 8, and 12 weeks. The third group was treated with olive oil (OLO) in a dose of 10 ml/kg body weight for 2 weeks before the oral dose of imidacloprid for 4, 8, and 12 weeks. The fourth group was given OLO in a dose of 10 ml/kg b.w. for 2 weeks after exposure to imidacloprid for 4, 8, and 12 weeks. Bone marrow was collected for micronucleus and chromosomal aberrations assays. The results revealed that imidacloprid induced a mutagenic effect in the 8^th and 12^th weeks of exposure and OLO decreased the mutagenic effect of imidacloprid in albino rats but not completely revert them to normal. PRACTICAL APPLICATIONS: Using OLO as a protective or therapeutic agent due to it has an ameliorative effect on mutagenicity induced by IMI.

Oral Administration of Vitamin C, Cimetidine and Famotidine on Micronuclei Induced by Low Dose Radiation in Mouse Bone Marrow Cells

BACKGROUND

In many studies, chemicals and natural materials were tested to reduce the harmful effects of radiation. It is known that Famotidine and vitamin C reduce DNA damage.

OBJECTIVE

The aim of this study was to evaluate the radioprotective effect of vitamin C, Cimetidine and Famotidine on gamma-radiation-induced damage on mouse bone marrow.

METHODS

Six-to-seven week male NMRI mice (28 g ±3) were randomly divided into fourteen groups: control, 2Gy irradiation, six group drugs without irradition (Famotidine, Cimetidine, vitaminC, Fam-Cim, Fam-Vit, Cim-Vit), six groups received drugs and 2Gy radiation with a 60Co |γ|-ray source at room temperature 22 ± 2 °C. The mice were killed 48 hours after irradiation by cervical dislocation. Slides were prepared from bone marrow cells and stained in May-Granwald and Giemsa. Finally, the cells were counted with microscope, frequencies of polychromatic erythrocyte (PCE), normochoromatic erythrocyte (NCE) and their micronuclated cell were recorded. PCE / PCE + NCE were calculated.

RESULTS

There were significant differences of MNPCE/1000PCE, MNNCE/1000NCE and PCE/PCE+NCE among different groups with similar radiation doses (p≤0.01). Moreover, there were significant differences of MNPCE/1000PCE and PCE/PCE+NCE among different doses of radiation (p≤0.01). While considering MNNCE/1000NCE, there were no significant differences among silimar groups with radiation dose (p˃0.05).

CONCLUSION

Oral administration of Famotidine, vitamin C and Cimetidine demonstrate reliable and similar radioprotective effects. Additionally, the protective effect of single use of these drugs was similar to the combination form. Thus, the oral use of combination, 48 hours after irradiation cannot induce more radioprotective effect.

Protective effects of vitamin C and vitamin E against hysterosalpingography-induced epithelial degeneration and proliferation in rat endometrium

Aim

The aim of this study was to examine the protective effects of vitamin C (VC) and vitamin E (VE) against hysterosalpingography (HSG)-induced epithelial degeneration and proliferation in rat endometrium.

Materials and methods

A total of 28 female Wistar albino rats were randomized into four groups: G1 (n=7; abdomen was opened and closed), G2 (n=7; 0.1 mL Lipiodol [ethiodized oil] was administered to each uterine horn in conjunction with X-ray irradiation), G3 (n=7; 50 mg/kg of intraperitoneal (ip) VC was administered, followed by the administration of 0.1 mL of ethiodized oil into the uterine horns after 15 minutes), and G4 (n=7; 50 mg/kg of ip VE was administered, followed by the administration of 0.1 mL of ethiodized oil into the uterine horns after 15 minutes). After abdominal closure, rats in G2, G3 and G4 groups were exposed to whole-body X-irradiation three times with 2-minute intervals at a total dose of 15–20 mrad. Three hours after exposure, abdominal cavities of all the rats were reopened and uterine horns were removed. The right uterine horns were embedded into paraffin blocks after fixing in 10% formaldehyde for histopathological and immunohistochemical examination. Uterine horns on the other side were rapidly excised and stored at −80°C for the examination of expression of microRNAs (miRNAs) and oxidant, antioxidant, apoptotic and antiapoptotic gene expression using real-time polymerase chain reaction (RT-PCR) method.

Results

No differences were observed in terms of expression of miRNAs and oxidant, antioxidant, apoptotic and anti-apoptotic gene expression between the study groups. Congestion, epithelial degeneration and malondialdehyde immunoreactivity were significantly lower in G3 and G4 groups than in G2 group; no differences were observed between G1, G3 and G4 groups. Ki-67 immunoreactivity score was significantly higher in G2 group when compared with G1, G3 and G4 groups. Caspase-3 immunoreactivity was not statistically different between the groups.

Conclusion

VC and VE may confer cellular protection against radiation injury induced by HSG in endometrial epithelium.

Iron induced genotoxicity: attenuation by vitamin C and its optimization

Vitamin C (VC) is a well-known antioxidant and strong free radical scavenger. Its antioxidant activity is useful for protection of cellular macromolecules, particularly DNA, from oxidative damage induced by different agents. This study was undertaken to evaluate the optimum level of VC in attenuating the chromosome aberrations (CAs) and DNA damage after iron sulfate (FeSO4) acute administration in Wistar rats. The results exhibited that the increase of CAs and DNA damage induced by FeSO4, 200 mg Fe/kg, could be reduced significantly by VC pretreatment at the dose of 500 mg/kg (p<0.001), but not in the 100 mg/kg group. The findings provide evidence that VC at the dose of 500 mg/kg exerted a possible protective effect against FeSO4 induced CAs and DNA damage. The possible mechanisms of VC may be attributed to its property as a free radical scavenger or to its indirect action in reducing the level of reactive oxygen species (ROS).

Searching for life on Mars: degradation of surfactant solutions used in organic extraction experiments

Life-detection instruments on future Mars missions may use surfactant solutions to extract organic matter from samples of martian rocks. The thermal and radiation environments of space and Mars are capable of degrading these solutions, thereby reducing their ability to dissolve organic species. Successful extraction and detection of biosignatures on Mars requires an understanding of how degradation in extraterrestrial environments can affect surfactant performance. We exposed solutions of the surfactants polysorbate 80 (PS80), Zonyl FS-300, and poly[dimethylsiloxane-co-[3-(2-(2-hydroxyethoxy)ethoxy)propyl]methylsiloxane] (PDMSHEPMS) to elevated radiation and heat levels, combined with prolonged storage. Degradation was investigated by measuring changes in pH and electrical conductivity and by using the degraded solutions to extract a suite of organic compounds spiked onto grains of the martian soil simulant JSC Mars-1. Results indicate that the proton fluences expected during a mission to Mars do not cause significant degradation of surfactant compounds. Solutions of PS80 or PDMSHEPMS stored at -20 °C are able to extract the spiked standards with acceptable recovery efficiencies. Extraction efficiencies for spiked standards decrease progressively with increasing temperature, and prolonged storage at 60°C renders the surfactant solutions ineffective. Neither the presence of ascorbic acid nor the choice of solvent unequivocally alters the efficiency of extraction of the spiked standards. Since degradation of polysorbates has the potential to produce organic compounds that could be mistaken for indigenous martian organic matter, the polysiloxane PDMSHEPMS may be a superior choice of surfactant for the exploration of Mars.

Gamma-tocopherol-N,N-dimethylglycine ester as a potent post-irradiation mitigator against whole body X-irradiation-induced bone marrow death in mice

We examined the radioprotective and mitigative effects of gamma-tocopherol-N,N-dimethylglycine ester (GTDMG), a novel water-soluble gamma-tocopherol derivative, against X-irradiation-induced bone marrow death in mice. Mice (C3H, 10 weeks, male) were injected intraperitoneally with GTDMG suspended in a 0.5% methyl cellulose solution before or after receiving of 7.5-Gy whole body X-irradiation. GTDMG significantly enhanced the 30-day survival rate when given 30 min before or immediately after the irradiation. Its mitigative activity (administered after exposure) was examined further in detail. The optimal concentration of GTDMG given immediately after irradiation was around 100 mg/kg body weight (bw) and the 30-day survival rate was 97.6 ± 2.4%. When GTDMG was administered 1, 10 and 24 h post-irradiation, the survival rate was 85.7 ± 7.6, 75.0 ± 9.7 and 36.7 ± 8.8%, respectively, showing significant mitigation even at 24 h after irradiation (P < 0.05). The value of the dose reduction factor (100 mg/kg bw, given intraperitoneally (i.p.) immediately after irradiation) was 1.25. GTDMG enhanced the recovery of red blood cell-, white blood cell-, and platelet-counts after irradiation and significantly increased the number of endogenous spleen colonies (P < 0.05). Subcutaneous (s.c.) administration also had mitigative effects. In conclusion, GTDMG is a potent radiation mitigator.

Vitamin C Modulation of Cisplatin-Induced Cytogenotoxicity in Bone Marrow, Spermatogonia and its Transmission in the Male Germline of Swiss Mice

Relative modulatory effects of three different doses of vitamin C (VC), 10, 20 and 40 mg/kg, on cytogenotoxicity induced by cisplatin (CP) 5 mg/kg were assessed from the comparison of chromosomal aberrations (CAs) and mitotic index in bone marrow cells, micronucleus test (MNT) in polychromatic erythrocytes from the somatic cell line and spermatogonial chromosome aberrations (SCAs), primary spermatocytic chromosome analysis and sperm morphology assay from the male germline of VC-pretreated and CP-alone treated mice. Each pretreatment dose of VC protected bone marrow cells from the CP-induced cytogenotoxicity by decreasing the aberrant metaphases, CAs and MN significantly, particularly the lower doses. The protection was inversely proportional to the pretreated dose of VC i.e., the higher the dose of VC the less protection was provided. The lower doses of VC also protected the spermatogonial cells by significantly decreasing the CP-induced aberrant metaphases and SCAs, whereas the highest dose potentiated such effects by increasing them significantly. Besides, transmission of CP-induced cytogenotoxicity in the male germline was enhanced significantly in all VC pretreated mice, resulting in an increase in the frequency of aberrant prima ry spermatocytes and abnormal sperm. Since the spermatogonial cells with gross effects were eliminated/died, the tolerable effects stabilized in some of them were transmitted through the male germline with the consequent increase in the manifestation of aberrant primary spermatocytes and abnormal sperm. However, VC failed to decrease in the transmission of such effects. Thus, the protective action of VC was dose dependent and tissue specific. Moreover, the time of VC treatment i.e., its pre- or post-treatment to the exposure of cells to cytogenotoxic substances is important in providing protection from or potentiation of the cytogenotoxic effects.

Hydrogen protects rats from dermatitis caused by local radiation

BACKGROUND

Radiation therapy produced unwanted side effect on normal tissues, such as radiodermatitis. Hydrogen was previously shown capable of radiation protective in both animals and cell cultures. The effect of hydrogen was now to be investigated on radiation-induced cutaneous.

OBJECTIVE

Development of dermatitis is a frequent side effect of radiotherapy of patients with head-and-neck cancer. Here we analyzed the radioprotective efficacy of hydrogen under conditions of local, single-dose or fractionated radiation treatment, and its possible molecular mechanisms.

METHODS

Rats received either single-dose or fractioned irradiation of the head-and-neck area with or without subcutaneous injection of hydrogen solution before irradiation. In vitro, the effect of hydrogen medium on radiation-induced cell viability, apoptosis, and biochemical assays was measured.

RESULT

Hydrogen significantly reduced the severity of dermatitis, accelerated tissue recovery, and reduced the extent of radiation-induced weight loss in rats after a single dose of 15 or 20 Gy but not 25 Gy of radiation. Hydrogen was also protective from cumulative doses of 30 Gy delivered in three fractions, respectively. Hydrogen also protect HaCaT cells from radiation-induced injury, it could significantly inhibit ionizing injury.

CONCLUSION

These results suggest that hydrogen has a positive effect on acute radiodermatitis.

Radio-protective effect of catalpol in cultured cells and mice

Ionizing radiation can induce DNA damage and cell death by generating reactive oxygen species (ROS). The objective of this study was to investigate the radio-protective effect of catalpol (a main bioactive component in the traditional Chinese Rehmannia) on irradiated cells and mice. We found that treating cells with catalpol (25-100 μg/ml) before irradiation could significantly inhibit ionizing radiation (IR)-induced human lymphocyte AHH-1 cells apoptosis and increase cells viability in vitro. At the same time our study also showed that catalpol (25-100 mg/kg) reduced morphological damage of the gastrointestinal tract by 15.6%, 33.3% and 44.4%, respectively compared with the radiation-induced group, decreased plasma malondialdehyde (MDA) intestinal 8-hydroxydeoxyguanosine (8-OHdG) levels and increased plasma endogenous antioxidants and peripheral white blood cells and platelets in vivo. These results suggest that catalpol possesses notable radio-protective activity, which might be related to its effect of reducing ROS.

Toxicity of cadmium and protective effect of bee honey, vitamins C and B complex

The present work aimed to study the toxic effect of cadmium (Cd) on rabbits' blood indices, as well as the therapeutic effect of the antioxidant agents, vitamins C and B complex and bee honey on Cd intoxicated rabbits. Cadmium chloride (CdCl2) was injected subcutaneously at a dose of 3 mg/kg of body weight. The results showed a significant increase in serum glucose, triglycerides, cholesterol, total protein, albumin, globulin, urea and creatinine, compared to the control group. In addition, CdCl2 intoxication increased the levels of uric acid, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase and bilirubin. Concerning haematological parameters, the more obvious changes were an increase in mean corpuscular volume and a decrease in white blood cells count, platelets, lymphocytes, heamatocrit, haemoglobin and red blood cells count. Treatment of CdCl2-intoxicated animals with vitamins C and B complex and bee honey showed a decrease in the harmful effects of Cd by restoring haematological and biochemical changes. Bee honey treatment was the most effective in providing recoveries in the altered blood parameters.

Investigation of cytotoxic and mutagenic effects of Malpighia glabra L. (barbados cherry) fruit pulp and vitamin C on plant and animal test systems

Fruits are important sources of nutrients in human diet, and Barbados Cherry (Malpighia glabra L.) is of particular interest due to its high content of antioxidants. Diets rich in fruits and vegetables protect individuals against diseases and cancer, but excessive intake of vitamins may act as pro-oxidant and generate changes in DNA. To evaluate the effect of different in natura (BAN) and frozen (BAF) Barbados Cherry pulp concentrations and synthetic vitamin C in liquid form (VC) on the chromosome level and the cell cycle division, root meristeme cells of Allium cepa L. and bone marrow cells of Wistar rats Rattus norvegicus, were used as test system. In Allium cepa L., BAN, at the highest concentration (0.4 mg.mL-1) and BAF, at the lowest concentration (0.2 mg.mL-1), inhibited cell division, and there was recovery of cell division after the recovery period in water only for BAN. In the Wistar rats, all treatments with Barbados Cherry, either acute or subchronic, were not cytotoxic or mutagenic; only the highest concentration of VC increased significantly the rate of chromosomal abnormalities. The data obtained are important to reinforce the use of Barbados Cherry fruit in the diet.

Effect of saccharin on albino rats’ blood indices and the therapeutic action of vitamins C and E

The present work aimed to study some blood indices of rats as affected by saccharin and the therapeutic action of vitamins C and E. The used adult female Rattus norvegicus albino rats in the present study were weighing 100—120 g. Administration of saccharin at a dose of 35 mg kg—1body weight (b.wt.) day—1for 35 days significantly decreased serum glucose, triglycerides, cholesterol, total protein and albumin values. These decrements were by 20.16%, 22.76%, 44.92%, 20.16% and 40.44%, respectively, compared to control level (p value < 0.01). But it increased levels of kidney function indices. The effect of saccharin was more pronounced on creatinine. Activities of Alanine aminotranferease (ALT), aspartate aminotransferase (AST) and Alkaline phosphatase (ALP) increased significantly following saccharin treatment to rats. Concerning hematoligical parameters, the more obvious changes were observed in the increment of white blood cell (WBC), mean corpuscular volume (MCV) and platelets (PLT) and the decrease in hematocrit, hemoglobin (Hb) and red blood cells (RBCs) count in response to the administration of saccharin. In general, vitamin C or E (150 mg kg—1b.wt. day—1for 35 days) was able to reduce the effects of saccharin intake. Both vitamins, however, generally have beneficial effects in reducing the changes in the studied parameters.

Radioprotective effect of hydrogen in cultured cells and mice

It has been demonstrated that hydrogen can selectively reduce hydroxyl and peroxynitrite in vitro. Since most of the ionizing radiation-induced cellular damage is caused by hydroxyl radicals, this study was designed to test the hypothesis that hydrogen may be an effective radioprotective agent. This paper demonstrates that treating cells with hydrogen before irradiation could significantly inhibit ionizing irradiation(IR)-induced Human Lymphocyte AHH-1 cells apoptosis and increase cells viability in vitro. This paper also shows that hydrogen can protect gastrointestinal endothelia from radiation-induced injury, decrease plasma malondialdehyde (MDA) intestinal 8-hydroxydeoxyguanosine (8-OHDG) levels and increase plasma endogenous antioxidants in vivo. It is suggested that hydrogen has a potential as an effective and safe radioprotective agent.

The potential cardioprotective effects of hydrogen in irradiated mice

Most ionizing radiation-induced damage is caused by hydroxyl radicals, and the selective reduction of hydroxyl by hydrogen in vitro has been demonstrated previously. Irradiation of the heart can cause chronic cardiac disease. This study was designed to test the hypothesis that hydrogen-rich water (pure water saturated with molecular hydrogen), which is easy to use, induces cardioprotection against ionizing irradiation injury in mice. In this paper, we demonstrate that hydrogen can protect myocardium degeneration from radiation-induced injury, decrease myocardium malondialdehyde (MDA), 8-hydroxydeoxyguanosine (8-OHdG) levels, and increase myocardium endogenous antioxidants in vivo. We suggest that hydrogen has a cardioprotective effect against radiation induced injury.

Pretreatment with ascorbic acid prevents lethal gastrointestinal syndrome in mice receiving a massive amount of radiation

While bone marrow or stem cell transplantation can rescue bone marrow aplasia in patients accidentally exposed to a lethal radiation dose, radiation-induced irreversible gastrointestinal damage (GI syndrome) is fatal. We investigated the effects of ascorbic acid on radiation-induced GI syndrome in mice. Ascorbic acid (150 mg/kg/day) was orally administered to mice for 3 days, and then the mice underwent whole body irradiation (WBI). Bone marrow transplantation (BMT) 24 h after irradiation rescued mice receiving a WBI dose of less than 12 Gy. No mice receiving 14 Gy-WBI survived, because of radiation-induced GI syndrome, even if they received BMT. However, pretreatment with ascorbic acid significantly suppressed radiation-induced DNA damage in the crypt cells and prevented denudation of intestinal mucosa; therefore, ascorbic acid in combination with BMT rescued mice after 14 Gy-WBI. DNA microarray analysis demonstrated that irradiation up-regulated expressions of apoptosis-related genes in the small intestine, including those related to the caspase-9-mediated intrinsic pathway as well as the caspase-8-mediated extrinsic pathway, and down-regulated expressions of these genes in ascorbic acid-pretreated mice. Thus, pretreatment with ascorbic acid may effectively prevent radiation-induced GI syndrome.

Investigation of the radioprotective efficacy of hesperidin against gamma-radiation induced cellular damage in cultured human peripheral blood lymphocytes

The present study was aimed to evaluate the radioprotective efficacy of hesperidin (HN), a flavonone glycoside against gamma-radiation-induced cellular damage in cultured human peripheral blood lymphocytes. Different concentrations of HN (3.27, 6.55, 9.83, 13.10, 16.38 and 19.65 microM) were pre-incubated with lymphocytes for 30 min prior to gamma-irradiation [4 Gy] and the micronuclei (MN) scoring, dicentric aberration and comet assay were performed to fix the effective dose of HN against gamma-irradiation induced cellular damage. The results indicated that among all the concentrations, 16.38 microM concentration of HN showed optimum protection by effectively decreasing the MN frequencies, dicentric aberrations and comet attributes. Based on the above results, 16.38 microM concentration of HN was fixed as the effective dose to further investigate its radioprotective efficacy which was then carried out by pre-incubating lymphocytes with 16.38 microM concentration of HN, exposing the lymphocytes to different doses (1, 2, 3 and 4 Gy) of radiation and investigating radiation induced genetic damage (MN, dicentric aberration, comet assay, DNA fragmentation assay) and biochemical changes (changes in the level of enzymic and non-enzymic antioxidants, lipid peroxidation). The results indicated a dose dependent increase in both genetic damage and thiobarbituric acid reactive substances (TBARS), accompanied by a significant decrease in the antioxidant status compared to HN treated groups which modulated the toxic effects through its antioxidant potential. Thus the current study shows HN to be an effective radioprotector against gamma-radiation induced in-vitro cellular damage in lymphocytes.

Vitamin C protects against ionizing radiation damage to goblet cells of the ileum in rats

The aim of the present study was to evaluate the radioprotective effect of vitamin C on gamma-radiation-induced damage to goblet cells of the ileum. Thirty male Wistar albino rats weighing between 250 and 300 g were randomized into the following study groups: I, control; II, single dose radiation treated; III, two dose radiation treated with a 4-day interval between doses; IV, single dose radiation treated with vitamin C; V, two dose radiation treated with vitamin C. Each group contained six animals. The rats in groups IV and V were given a daily dose of 100 mg/kg of vitamin C for 14 and 18 days, respectively. During the vitamin C administration period, the rats in group IV were exposed in the abdominal area to a gamma-ray dose of 5 Gy on day 10 and group V was exposed to same dose of radiation on days 10 and 14. Irradiation and treatment groups were decapitated 4 days after exposure to single or two dose irradiation and ileum tissues were removed for light and electron microscopic investigation. Single or two dose gamma-irradiation caused a marked intestinal mucosal injury in rats. Radiation produced increases in the number of goblet cells. Using transmission electron microscopy, extensions in the area between the cells, disorders in the microvilli, mitochondrial damage and endoplasmic reticulum (ER) cisternae dilatation were observed. Antioxidant treatment with vitamin C prior to irradiation provided protection against intestinal damage.

Cytogenetic damage in preimplantation mouse embryos generated after paternal and parental gamma-irradiation and the influence of vitamin C

Cytogenetic damage expressed as micronuclei (MN) in 4-8-cell embryos generated after irradiation of male or male and female mice in the absence and presence of vitamin C was investigated. Male NMRI mice were whole body exposed to 4 Gy gamma-rays and mated with non-irradiated superovulated female mice in 6 successive weeks after irradiation in a weekly interval. In experiments involving irradiation of both male and female mice, irradiated male mice for 6 weeks post irradiation were mated with female mice irradiated after induction of superovulation. Effect of 100 mg/kg vitamin C (ascorbic acid) on the frequency of MN was also studied. Pregnant animals were euthanized and embryos flushed from the oviducts and fixed on slides. The rate of MN observed in embryos generated from irradiated male compared with control group dramatically increased (P<0.01). Frequency of MN in this group decreased dramatically after vitamin C treatment (P<0.01). Frequency of MN in embryos generated by mating both male and female irradiated mice was higher than that observed for those embryos generated by irradiated male mice alone. However, a considerable modifying effect of vitamin C was observed for this group too (P<0.05). Results indicate that irradiation of gonads during spermatogenesis and preovulatory stage oocytes may lead to unstable chromosomal aberrations and probably stable chromosomal abnormalities affecting pairing and disjunction of chromosomes in successive preimplantation embryos expressed as MN. The way vitamin C reduces clastogenic effects of radiation on germ cells leading to reduced frequency of MN in pre-embryos might be due to its antioxidation and radical scavenging properties.

Protective effects of vitamin glycosides on gamma-radiation and H2O2-induced decomposition of thymine in aqueous solutions

Effects of ascorbic acid (AA), ascorbic acid glycoside (AAG) and alpha-tocopherol monoglycoside (TMG) on radiation - and H(2)O(2)-induced decomposition of thymine in aqueous solutions were investigated. Of the three compounds studied, AAG was found to possess the most marked protector properties. An explanation of this phenomenon has been given in terms of differences in molecular structures of AA and AAG, as well as properties of radical adducts formed during their interaction with OH radicals.

Frequency of micronuclei in 4-8 cell mouse embryos generated after maternal gamma-irradiation in the presence and in the absence of vitamin C

The objective of this investigation was to evaluate the frequency of chromosomal aberrations expressed as micronuclei (MN) in 4-8 cell embryos generated by gamma-irradiation of female mice in the absence and in the presence of vitamin C. Female NMRI mice were whole body exposed to 4 Gy gamma-irradiation after intraperitoneal (i.p.) injection of pregnant mare's serum gonadotrophin (PMSG) followed by injection of human chorionic gonadotrophin (HCG) and mating with non-irradiated NMRI male mice. Pregnant animals were sacrificed and embryos flushed from the oviducts and fixed on slides. Cells were treated for MN observation using standard method. To investigate the protective effect of vitamin C (ascorbic acid) on the frequency of MN, 100 mg/kg vitamin C was i.p. injected 1 h before irradiation. Results show that the frequency of MN generated in the embryos of irradiated mother compared to those of control in the non-irradiated group increased dramatically (P < 0.001). Frequency of MN in embryos generated in irradiated female mice treated with vitamin C dramatically and statistically decreased relative to the frequency observed in the irradiation only group (P < 0.001). This decrease returned the combined treatment group to a level that was not statistically different from the controls (P > 0.05). Thus, irradiation of preovulatory stage oocytes leads to stable chromosome abnormalities expressed as micronuclei in successive preimplantation embryos. Vitamin C reduces these clastogenic effects of radiation in preovulatory oocytes and thus the reduced frequency of MN in embryos is probably due to its antioxidation and radical scavenging properties.

Ascorbic acid monoglucoside as antioxidant and radioprotector

Ascorbic acid monoglucoside (AsAG), a glucoside derivative of ascorbic acid, has been examined for its antioxidant and radioprotective abilities. AsAG neutralized 1, 1 diphenyl -2-picryl-hydrazyl (DPPH), a stable free radical in a concentration dependent manner thus indicating its antioxidant ability. AsAG protected mice liver tissues in vitro from peroxidative damage in lipids (measured as TBARS) resulting from 25Gy gamma irradiation. It also protected plasmid pBR322 DNA from gamma-radiation induced strand breaks as evidenced from studies on agarose gel electrophoresis of the plasmid DNA after radiation exposure. Oral administration of AsAG to mice prior to whole body gamma radiation exposure (4Gy) resulted in a reduction of radiation induced lipid peroxides in the liver tissue indicating in vivo radiation protection of membranes. Pulse radiolysis studies indicated that AsAG offered radioprotection by scavenging free radicals. The rate constants for the reactions OH and N(3) radicals with AsAG were determined to be 6.4 x 10(9) dm(3) mol(-1) s(-1) and 2.3 x 10(9) dm(3) mol(-1) s(-1), respectively at pH 7. It was observed that AsAG radicals undergo conjugation as the pH of the solution is raised to 11 in the case of a one-electron oxidation reaction. As the OH(*) radical adds to the ring, the conjugation effect starts appearing at pH 10.

Ascorbic acid increases healing of excision wounds of mice whole body exposed to different doses of gamma-radiation

Because of the practical importance of acute radiation exposure associated with combined injuries, it is imperative to investigate the efficacy of cost-effective nutritional factors in the reconstruction of irradiated wounds. Therefore, effect of pretreatment of ascorbic acid was studied on the healing of excised wounds in mice exposed to 2, 4, 6 and 8 Gy whole body gamma-radiation. A full-thickness wound was created on the dorsum of the irradiated mice and the progression of wound contraction was monitored by capturing video images of the wound at various varying days after irradiation. Irradiation caused a dose dependent delay in wound contraction and wound healing time, while ascorbic acid pretreatment resulted in a significant acceleration in the rate of wound contraction and a decrease in the mean wound healing time. To understand the mechanism of healing, collagen, hexosamine, DNA, nitrite and nitrate contents were measured in the granulation tissue of wounded mice treated with ascorbic acid before exposure to 6 Gy gamma-radiation. Ascorbic acid treatment prior to irradiation enhanced the synthesis of collagen, hexosamine, DNA, nitrite and nitrate contents. The histological assessment of wound biopsy revealed an improved collagen deposition, and increase in fibroblast and vascular densities. The present study demonstrates that ascorbic acid pretreatment has a beneficial effect on the irradiated wound and could be a substantial therapeutic strategy to accelerate wound repair in irradiated wounds and in the cases of combined injury situations.

Radioprotective effect of transferrin targeted citicoline liposomes

The high level of expression of transferrin receptors (Tf-R) on the surface of endothelial cells of the blood-brain-barrier (BBB) had been widely utilized to deliver drugs to the brain. The primary aim of this study was to use transferrin receptor mediated endocytosis as a pathway for the rational development of holo-transferrin coupled liposomes for drug targeting to the brain. Citicoline is a neuroprotective agent used clinically to treat for instance Parkinson disease, stroke, Alzheimer's disease and brain ischemia. Citicoline does not readily cross the BBB because of its strong polar nature. Hence, citicoline was used as a model drug. (Citicoline liposomes have been prepared using dipalmitoylphosphatidylcholine (DPPC) or distearoylphosphatidylcholine (DSPC) by dry lipid film hydration-extrusion method). The effect of the use of liposomes composed of DPPC or DSPC on their citicoline encapsulation efficiency and their stability in vitro were studied. Transferrin was coupled to liposomes by a technique which involves the prevention of scavenging diferric iron atoms of transferrin. The coupling efficiency of transferrin to the liposomes was studied. In vitro evaluation of transferrin-coupled liposomes was performed for their radioprotective effect in radiation treated cell cultures. In this study, OVCAR-3 cells were used as a model cell type over-expressing the Tf-R and human umbilical vein endothelial cells (HUVEC) as BBB endothelial cell model. The average diameter of DPPC and DSPC liposomes were 138 +/- 6.3 and 79.0 +/- 3.2 nm, respectively. The citicoline encapsulation capacity of DPPC and DSPC liposomes was 81.8 +/- 12.8 and 54.9 +/- 0.04 microg/micromol of phospholipid, respectively. Liposomes prepared from DSPC showed relatively better stability than DPPC liposomes at 37 degrees C and in the presence of serum. Hence, DSPC liposomes were used for transferrin coupling and an average of 46-55 molecules of transferrin were present per liposome. Free citicoline has shown radioprotective effect at higher doses tested. Interestingly, encapsulation of citicoline in pegylated liposomes significantly improved the radioprotective effect by 4-fold compared to free citicoline in OVCAR-3 but not in HUVEC. Further, citicoline encapsulation in transferrin-coupled liposomes has significantly improved the radioprotective effect by approximately 8-fold in OVCAR-3 and 2-fold in HUVEC cells with respect to the free drug. This is likely due to the entry of citicoline into cells via transferrin receptor mediated endocytosis. In conclusion, our results suggest that low concentrations of citicoline encapsulated in transferrin-coupled liposomes could offer therapeutic benefit in treating stroke compared to free citicoline.

Effects of melatonin and vitamin E on oxidative-antioxidative status in rats exposed to irradiation

Bone marrow is known to be particularly susceptible to radiation. In this study, the effects of treatment with Vitamin E and melatonin and irradiation-induced lipid peroxidation and its association with antioxidant enzymes in the total bone (bone and bone marrow) and skeletal muscle of rats subjected to total body irradiation was investigated. Wistar-Albino rats were intraperitoneally treated with 100mg/kg Vitamin E or melatonin before exposure to 720cGy irradiation. Control, irradiation, Vitamin E plus irradiation, melatonin plus irradiation groups were sacrificed by decapitation under ether anaesthesia on the 10th day after irradiation exposure. Application of total body irradiation elevated malondialdehyde (MDA) levels in rat skeletal muscle (p<0.001), but glutathione peroxidase (GSH-Px) and catalase activities remained unchanged. Application of Vitamin E with irradiation or melatonin decreased the MDA levels in skeletal muscle (p<0.01), but did not affect the GSH-Px and catalase activity. MDA levels were found elevated in total bone (p<0.001), GSH-Px activity decreased (p<0.001) and catalase activity remained unchanged in the group treated with irradiation. Application of Vitamin E with irradiation increased the GSH-Px activity in total bone (p<0.01), but the activity of MDA and catalase remained unchanged. Treatment of the animals with melatonin concurrent with total body irradiation reduced the degree of lipid peroxidation and elevation in antioxidant enzymes in total bone (p<0.01). We conclude that melatonin may protect the total bone from the damaging effects of irradiation exposure, and its actions protect total bone from oxidative stress. However, protective effects of Vitamin E were not observed in this study.

Radioprotective effect of sesamol on γ-radiation induced DNA damage, lipid peroxidation and antioxidants levels in cultured human lymphocytes

Sesamol pretreated (1, 5 and 10 microg/ml) lymphocytes were exposed to different doses of gamma-radiation, i.e., 1, 2 and 4 Gray (Gy) and the cellular changes were estimated by using cytokinesis blocked micronucleus assay (MN), dicentric aberration (DC), thiobarbituric acid reactive substances (TBARS), reduced glutathione (GSH) and the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx). Radiation significantly increased MN, DC frequencies, TBARS levels and decreased GSH and antioxidant enzyme levels in a dose dependent manner. The highest damage to lymphocytes was observed at 4 Gy irradiation. On the other hand, sesamol pretreatment significantly decreased MN, DC frequencies, TBARS levels and increased GSH levels and SOD, CAT and GPx activities in a concentration dependent manner. At 1 Gy irradiation all concentrations of sesamol (1, 5 and 10 microg/ml) significantly protects the lymphocytes from radiation damage. At 2 Gy irradiation 5 and 10 microg/ml of sesamol shows significant radioprotection. Since the highest damage was observed at 4 Gy irradiation both 1 and 5 microg/ml of sesamol pretreatment were not sufficient to protect the lymphocytes from radiation damage but 10 microg/ml of sesamol significantly (p<0.05) protects the lymphocytes from radiation effect. Thus, sesamol pretreatment gives significant protection to cultured human lymphocytes against gamma-radiation induced cellular damage. The possible mechanism involved in the radioprotective influence of sesamol is discussed.

Effects of the olive, extra virgin olive and canola oils on cisplatin-induced clastogenesis in Wistar rats

Cisplatin is one of the mostly used antineoplastic drugs in the treatment of cancer, but its clastogenic potential has become of great interest. In patients treated with long-term cisplatin, genetic damage can be observed during chemotherapy or many years later. The aim of this study was to investigate the possible anticlastogenic effect of pretreatment with olive, extra virgin olive, canola or corn oils on cisplatin-induced chromosomal aberrations in Wistar rat bone marrow cells. The animals received pretreatment with a single dose of vegetable oils (5 ml/kg b.w.) by gavage before cisplatin i.p. (5 mg/kg b.w.), and were sacrificed 24 h after cisplatin injection. The pretreatment with a single dose of olive, extra virgin olive and canola oils caused a statistically significant decrease in the total of chromosomal aberrations and abnormal metaphases induced by cisplatin when compared with the groups treated with cisplatin alone. The possible explanation for the anticlastogenic effects observed in the pretreatment with olive, extra virgin olive and canola oils is ascribed to the oil contents. In conclusion, from the findings we suggest that these oils have some antioxidant effect, and the anticlastogenesis mechanisms of these oils need to be explored further before their use during cisplatin chemotherapy.

Prophylactic effects of magnesium and vitamin E in rat spinal cord radiation damage: evaluation based on lipid peroxidation levels

This study investigated the neuroprotective effects of magnesium sulfate prophylaxis and vitamin E prophylaxis in a rat model of spinal cord radiation injury. Groups were subjected to different treatment conditions for 5 days prior to irradiation, and outcomes were evaluated on the basis of lipid peroxidation levels in cord tissue. Four groups of rats were investigated: no radiation/treatment (n = 4), intraperitoneal (i.p.) saline 1 ml/day (n = 6), i.p. vitamin E 100 mg/kg/day (n = 6), and i.p. magnesium sulfate 600 mg/kg/day (n = 6). The thoracic cord of each non-control rat was exposed to 20 Gy radiation in a LINAC system using 6 MV x-rays, and malondialdehyde (MDA) levels (reflecting lipid peroxidation level) were determined 24 hours post-irradiation. The MDA levels in thoracic cord segments from the control rats were used to determine baseline lipid peroxidation. The mean levels in the control, saline-only, vitamin E, and magnesium sulfate groups were 12.12 +/- 0.63, 27.0 +/- 2.81, 17.71 +/- 0.44, and 14.40 +/- 0.47 nmol/mg tissue, respectively. The MDA levels in the saline-only group were significantly higher than baseline, and the levels in the vitamin E group were significantly lower than those in the saline group (P < 0.05 for both). The levels in the magnesium sulfate group were dramatically lower than those in the saline group (P < 0.001). The results indicate that i.p. magnesium sulfate has a marked neuroprotective effect against radiation-induced oxidative stress in the rat spinal cord.

Protective effect of alpha-tocopherol in head and neck cancer radiation-induced mucositis: a double-blind randomized trial

BACKGROUND

the study was designed to test whether vitamin E (VE) provides oral mucosal protection in patients with irradiated cancers of the head and neck.

METHODS

Fifty-four patients with cancer of the oral cavity and oropharynx were randomly assigned to rinse the oral cavity in an oil solution containing either VE or placebo before every conventional fraction of 2 Gy and again 8 to 12 hours later during the 5 to 7 weeks of radiotherapy (RT).

RESULTS

Thirty-six events/167 patient-weeks (21.6%) and 54 events/161 patient-weeks (33.5%) of symptomatic mucositis were observed in VE and placebo groups, respectively (p =.038). VE reduced the risk by 36%. Subjective data at the end of the treatment revealed that VE decreased pain grades 2 to 3 during RT (3 of 28 patients vs 14 of 26 patients, p =.0001). No significant influence was detected in survival.

CONCLUSION

VE decreased the incidence of symptomatic oral radio-induced mucositis in patients with cancer of the oropharynx and oral cavity.

Effect of Antioxidant Vitamins on Radiation-Induced Apoptosis in Cells of a Human Lymphoblastic Cell Line

Modulating the amount of radiation-induced apoptosis by administering antioxidant vitamins offers a possible way to influence radiation-induced side effects in normal tissues. Therefore, we investigated the effect of beta-carotene, vitamin C and alpha-tocopherol on radiation-induced apoptosis in cells in culture. Human T-lymphoblastic MOLT-3 cells were irradiated with a dose of 3 Gy 1 h after or immediately prior to the addition of vitamins in three concentrations (0.01 microM, 1 microM and 100 microM). Eight hours later, apoptosis was scored morphologically by staining the nuclear DNA with Hoechst 33342. When given prior to irradiation, beta-carotene and vitamin E reduced the amount of radiation-induced apoptosis significantly at concentrations of 0.01 microM and 1 microM. In contrast, vitamin C did not show any protective effect when given at these two concentrations and caused a slight but significant radiosensitization at 100 microM. At 0.01 microM, all combinations of two vitamins showed a protective effect. This was also observed for the combination of all three vitamins at concentrations of 0.01 and 1 microM. When given immediately after irradiation, each of the three vitamins showed a protective effect at 0.01 microM. In addition, the combination of alpha-tocopherol and vitamin C reduced radiation-induced apoptosis slightly when given at 1 microM. In all other cases, no statistically significant modulation of radiation-induced apoptosis was observed. In our experimental system, the protective effect of beta-carotene and vitamin E was dependent on concentration and occurred only in the micromolar and sub-micromolar concentration range, while vitamin C alone, but not in combinations, had a sensitizing effect, thus arguing for a careful consideration of vitamin concentrations in clinical settings.

Estudo morfológico do efeito radioprotetor da vitamina E (dl-alfa-tocoferil) na reparação tecidual em ratos

Esta pesquisa teve por finalidade avaliar a ação da vitamina E como radioprotetora no processo de reparação tecidual em ratos, após sofrerem um procedimento cirúrgico, que consistiu da produção de uma ferida na região dorsal anterior. Os animais foram divididos em cinco grupos: grupo CO (controle) - constituído de animais em que foi produzida somente a ferida; grupo VE - pré-tratamento com vitamina E (90 UI); grupo IR - irradiação três dias após a cirurgia; grupo VEIR - pré-tratamento com 90 UI de vitamina E e irradiação de suas bordas três dias após a cirurgia; grupo OIR - pré-tratamento com óleo de oliva e irradiação de suas bordas três dias após a cirurgia. A ação radioprotetora da vitamina E foi avaliada pela coloração por hematoxilina-eosina para análise morfológica do tecido de granulação, aos 4, 7, 14 e 21 dias após a cirurgia. A análise dos resultados mostrou que o retardo no processo de reparação tecidual causado por 6 Gy de radiação de elétrons com feixe de 6 MeV não ocorreu no grupo de animais que recebeu vitamina E, mostrando-se esta substância efetiva como radioprotetora.

Final report on the safety assessment of Tocopherol, Tocopheryl Acetate, Tocopheryl Linoleate, Tocopheryl Linoleate/Oleate, Tocopheryl Nicotinate, Tocopheryl Succinate, Dioleyl Tocopheryl Methylsilanol, Potassium Ascorbyl Tocopheryl Phosphate, and Tocophersolan

Tocopherol and its several ester and ether derivatives all function as antioxidants in cosmetic formulations; they also have other functions, such as skin conditioning. Tocopheryl Acetate, Tocopherol, and Tocopheryl Linoleate are used in 2673 formulations, generally at concentrations of up to 36%, 5%, and 2%, respectively, although Tocopheryl Acetate is 100% of vitamin E oil. Tocophersolan, Tocopheryl Linoleate/Oleate, Tocopheryl Nicotinate, Tocopheryl Succinate, Dioleyl Tocopheryl Methylsilanol, and Potassium Ascorbyl Tocopheryl Phosphate, combined, are used in 36 formulations at concentrations lower than those reported for the frequently used ingredients. Tocopherol may be isolated from vegetable oils or synthesized using isophytol and methylhydroquinone. Tocopherol, Tocopheryl Acetate, Tocopheryl Linoleate, and Tocopheryl Succinate all were absorbed in human skin. In rat skin, Tocopheryl Acetate is hydrolyzed to Tocopherol. Tocopherol is a natural component of cell membranes thought to protect against oxidative damage. Tocopherol, Tocopheryl Acetate, and Tocopheryl Succinate each were reported to protect against ultraviolet radiation-induced skin damage. These ingredients are generally not toxic in animal feeding studies, although very high doses (>2 g/kg/day) have hemorrhagic activity. These ingredients are generally not irritating or sensitizing to skin or irritating to eyes, although a Tocopheryl Acetate did produce sensitization in one animal test, and Tocophersolan was a slight eye irritant in an animal test. Reproductive and developmental toxicity tests in animals using Tocopherol, Tocopheryl Acetate, Tocopheryl Succinate, and Tocophersolan were all negative or showed some effect of reducing toxicity. Tocopherol, Tocopheryl Acetate, Tocopheryl Succinate, and Dioleyl Tocopheryl Methylsilanol were almost uniformly negative. These ingredients exhibit antimutagenic activity consistent with their antioxidant properties. Tocopherol was not carcinogenic. The ability of Tocopherol, Tocopheryl Acetate, and Tocopheryl Succinate to modulate the carcinogenic effect of other agents (e.g., tumor promotion) has been extensively studied. One study showing tumor promotion in mice may be discounted as not reproducible and not consistent with the large volume of data suggesting that the antioxidant properties of these agents protect against tumor induction. Specifically, the frequent use of Tocopherol as a negative control in other tumor promotion studies suggests that Tocopherol is not a tumor promoter. Tocopherol has been shown to reduce the photocarcinogenic effect of ultraviolet radiation in mice. Similar studies with Tocopheryl Acetate and Tocopheryl Succinate, however, demonstrated some enhancement of photocarcinogenesis, although the effect was not dose related. In clinical studies, Tocopherol, Tocopheryl Acetate, and Tocopheryl Nicotinate were not irritants or sensitizers. A report of a large number of positive patch-tests to Tocopheryl Linoleate in one cosmetic product were considered to result from a contaminant or metabolite. The Cosmetic Ingredient Review Expert Panel considered that these data provide an adequate basis on which to conclude that Tocopherol, Tocophersolan, Tocopheryl Acetate, Tocopheryl Linoleate, Tocopheryl Linoleate/Oleate, Tocopheryl Nicotinate, Tocopheryl Succinate, Dioleyl Tocopheryl Methylsilanol, and Potassium Ascorbyl Tocopheryl Phosphate are safe as used in cosmetic formulations. Although there were no inhalation toxicity data, these ingredients are used at such low concentrations in hair sprays that no inhalation toxicity risk was considered likely. Because methylhydroquinone is used in the chemical synthesis of Tocopherol, there was concern that hydroquinone may be present as an impurity. In such cases, residual levels of hydroquinone would be expected to be limited to those achieved by good manufacturing practices.

Alteration in the glutathione, glutathione peroxidase, superoxide dismutase and lipid peroxidation by ascorbic acid in the skin of mice exposed to fractionated gamma radiation

BACKGROUND

In spite of the immense therapeutic gains produced by the fractionated irradiation (IR) regimen, radiation burden on the skin increases significantly. Protection of skin might enable use of higher radiation doses for better therapeutic gains. Ascorbic acid (AA), an essential ingredient of the human diet, is known to be a free radical scavenger and radioprotective agent. This study was undertaken to evaluate the effect of ascorbic acid on the radiation-induced changes in the status of glutathione (GSH), glutathione peroxidase (GPx), superoxide dismutase (SOD) and lipid peroxidation (LPx) in the skin of mice exposed to 10, 16 and 20 Gy of fractionated gamma radiation.

METHODS

One group of the animals was administered daily with double distilled water (DDW), while the other group received 250 mg/kg b. wt. of ascorbic acid once daily, consecutively for 5, 8 or 10 days, before hemibody (below rib cage) exposure to 2 Gy/day of gamma-rays. Skin biopsies from both the groups were collected for the biochemical estimations.

RESULTS

The irradiation of animals resulted in a dose-dependent decline in the activities of superoxide dismutase, glutathione peroxidase and glutathione contents. Ascorbic acid pretreatment resulted in a significant increase in the activities of both the enzymes and glutathione in the irradiated mouse skin. Normal concentrations of glutathione could not be restored even by day 6 post-irradiation. Conversely, lipid peroxidation increased in a dose-dependent manner in both the groups reaching a peak concentration by 3 h post-irradiation, while the ascorbic acid pretreatment inhibited the radiation-induced increase in lipid peroxidation.

CONCLUSIONS

The ascorbic acid treatment arrested the decline in the activities of superoxide dismutase and glutathione peroxidase, glutathione contents and inhibited the radiation-induced lipid peroxidation in the skin of mice exposed to different doses of fractionated gamma radiation.

Evaluation of the effect of ascorbic acid treatment on wound healing in mice exposed to different doses of fractionated gamma radiation

Alteration of the radiation-induced changes in wound contraction, collagen synthesis and wound histology by ascorbic acid was studied in mice exposed to 10, 16 and 20 Gy of fractionated (2 Gy/fraction) gamma radiation. The animals were given double-distilled water or ascorbic acid daily before exposure to 2 Gy/day of fractionated irradiation. A full-thickness skin wound was created on the dorsum of the irradiated mice, and the progression of wound contraction and collagen synthesis were examined and histological evaluations were carried out at various times after wounding. Irradiation caused a dose-dependent delay in wound contraction, and pretreatment with ascorbic acid resulted in a significant increase in wound contraction. The greatest increase in wound contraction was observed 6 and 9 days after wounding in both groups. Pretreatment with ascorbic acid augmented the synthesis of collagen significantly as revealed by an increase in hydroxyproline content. The collagen deposition and fibroblast and vasculature densities declined in a dose-dependent manner in groups receiving radiation alone as indicated by histological evaluation. Pretreatment with ascorbic acid ameliorated the observed effect significantly. These studies demonstrate that pretreatment with ascorbic acid resulted in a significant reduction of radiation-induced delay in wound healing as shown by earlier wound closure and increased collagen content and fibroblast and vascular densities.

Vitamin E protection from/potentiation of the cytogenetic toxicity of cisplatin in Swiss mice

Possible protection from or potentiation of the cytogenetic toxic effects of cisplatin (CP) 5 mg/kg b.w. in mouse bone marrow, spermatogonia by three different doses of alpha-tocopheryl acetate (vitamin E) 100, 200 and 300 mg/kg, and the transmission of such effects in the male germline, were assessed. CP-induced chromosomal aberrations (CAs) in bone marrow were decreased in vitamin E pretreated mice, but significantly (P < or = 0.05) only with vitamin E 300 mg/kg. The percentages of dividing cells in bone marrow were increased in vitamin E-pretreated groups of mice, but not significantly. However, the frequency of CP-induced micronuclei (MN) in polychromatic erythrocytes (PCEs) declined significantly (P < or = 0.01) in all the vitamin E-pretreated groups of mice. In spermatogonia the CP-induced CAs were also decreased significantly by vitamin E 200 mg/kg (P < or = 0.01), and 100 and 300 mg/kg (P < or = 0.05). However, transmission of CP-induced cytogenetic toxic effects from spermatogonia to spermatocyte, resulting in the formation of aberrant primary spermatocytes, was enhanced significantly in the mice pretreated with vitamin E 100 mg/kg (P < or = 0.05) and 200 mg/kg (P < or = 0.01). But the enhancement in the transmission of such effects was not significant in the mice pretreated with vitamin E 300 mg/kg. Besides, there was no significant change in vitamin E-pretreated groups of mice in the transmission of cytogenetic toxicity of CP from spermatogonia to sperm with the manifestation of abnormal sperm morphology. Thus, vitamin E protected bone marrow and spermatogonia from the cytogenetic toxic effects of CP, particularly efficiently at the highest tested dose (300 mg/kg), but it failed to protect from the transmission of such effects in the male germline of mouse and rather potentiated them to some extent. Treatment with vitamin E, an antioxidant, might be capable of protecting noncancerous cells from the oxidative damage caused by cisplatin but it might also reduce the effects of cisplatin on cancerous cells. Thus, the benefits of antioxidant treatment during cancer chemotherapy is yet to be demonstrated clearly.

In vivo antimutagenic effect of vitamins C and E against rifampicin-induced chromosome aberrations in mouse bone-marrow cells

-The genotoxic effect of rifampicin (RMP), one of the most active antituberculosis agents is studied. Also, the possible protection provided by the natural antioxidant vitamins C (VC) and E (VE) against the genotoxic effect of RMP is assessed. Mice were orally treated by gavage with 10, 50, 150 and 300 mg RMP kg(-1) body weight (bw). Also, oral treatment was conducted with RMP plus the vitamins. Mice received 300 mg RMP kg(-1) bw plus 100, 200 and 400mg VC or VE kg(-1) bw. Samples were taken 24h after the treatment. Repeated treatments with: (1) the therapeutic dose of RMP (10 mg kg(-1) bw); (2) RMP plus a dose of 25, 50 and 75 mg VC kg(-1); (3) RMP plus 10, 20 and 40 mg VE kg(-1) bw for 30 consecutive days were conducted. The tested doses of RMP induced a significant increase in the percentage of chromosome aberrations. However, a lower percentage of chromosome aberrations was observed when animals were treated with the therapeutic dose for 30 consecutive days. The obtained results revealed that chromosome aberrations induced by RMP decreased to a significant extent when mice were treated with RMP plus VC. The repeated doses of VC reduced the percentage of chromosome aberrations induced by RMP in a significant and dose-dependent manner. On the other hand, repeated doses of VE were not very effective in reducing the percentage of chromosome aberrations induced by RMP. Only the highest dose (3 x 40 mg kg(-1) bw) showed a significant effect (P<0.01). The results on the induction of chromosome damage clearly show that only VC appears able to efficiently protect the bone-marrow cells when given together with RMP, while no significant reduction in the yield of chromosome aberrations was observed for VE in combination with the antituberculosis drug.

Roles of vitamin C in radiation-induced DNA damage in presence and absence of copper

Exposure to either ionizing radiation or certain transition metals results in generation of reactive oxygen species that induce DNA damage, mutation, and cancer. Vitamin C (a reactive oxygen scavenger) is considered to be a dietary radioprotective agent. However, it has been reported to be genotoxic in the presence of certain transition metals, including copper. In order to explore the capacity of vitamin C to protect DNA from radiation-induced damage, and the influence of the presence of copper on this protection, we investigated vitamin C-mediated protection against radiation-induced damage to calf thymus DNA in vitro in the presence or absence of copper(II). Vitamin C (0.08-8.00 mM, pH 7.0) significantly reduced DNA damage induced by gamma-irradiation (30-150 Gy) by 30-50%, similar to the protective effect of glutathione. However, vitamin C plus copper (50 microM) significantly enhanced gamma-radiation-induced DNA damage. Low levels of added copper (5 microM), or chelation of copper with 1-N-benzyltriethylenetetraine tetrahydrochloride (BzTrien) and bathocuprinedisulfonic acid (BCSA), abolished the enhanced damage without diminishing the protective effect of vitamin C. These results indicate that vitamin C can act as: (1) an antioxidant to protect DNA damage from ionizing radiation; and (2) a reducing agent in the presence of copper to induce DNA damage. These effects are important in assessing the role of vitamin C, in the presence of mineral supplements or radioprotective therapeutic agents, particularly in patients with abnormally high tissue copper levels.

Vitamin E and genome stability

Free radicals and reactive oxygen species (ROS) which are generated continuously cause mutagenic alterations resulting in cancer, aging and abnormalities in the nervous system. Accumulating evidence indicates that Vitamin E, the most potent lipid peroxyl radical scavenger, may reduce free radical induced chromosomal damages through inhibition of free radical formation, and activation of endonuclease that can be triggered by intracellular oxidative stress, and by increasing the rate of removal of damaged DNA. Although some studies suggest a potential usefulness of Vitamin E in the prevention of mutagenic effects caused by genotoxic free radicals, other studies report no effects. Thus the data are not conclusive enough to be used as a basis to change the current recommended dietary allowances (RDA). Future research should address molecular mechanisms underlying the protective effects of Vitamin E and develop appropriate biologically relevant biomarkers of DNA damage to further help in determining the dietary levels of Vitamin E needed to protect the genetic pool from internally and externally induced DNA damages.

Antioxidant vitamins C, E and beta-carotene reduce DNA damage before as well as after gamma-ray irradiation of human lymphocytes in vitro

The protective effect of Vitamins C, E and beta-carotene against gamma-ray-induced DNA damage in human lymphocytes in vitro was investigated. Cultured lymphocytes were exposed to increasing concentration of these vitamins either before or after irradiation with 2Gy of gamma-rays and DNA damage was estimated using micronucleus assay. A radioprotective effect was observed when antioxidant vitamins were added to cultured cells before as well after irradiation; the strongest effect was observed when they were added no later than 1h after irradiation. The radioprotective effect of vitamins also depended on their concentration; Vitamins C added at low concentration (1 microg/ml) before exposure of the cells to radiation prevented induction of micronuclei. Vitamin E at the concentration above 2 microg/ml decreased the level of radiation-induced micronuclei when compared to the cells irradiated without vitamin treatment. beta-Carotene was effective at all tested concentrations from 1 to 5 microg/ml and reduced the number of micronuclei in irradiated cells. The vitamins had no effect on radiation-induced cytotoxicity as measured by nuclear division index. The radioprotective action of antioxidant Vitamins C, E and beta-carotene was dependent upon their concentration as well as time and sequence of application.