Antioxidative effects of melatonin in protection against cellular damage caused by ionizing radiation

Ameliorating mitochondrial dysfunction restores carbon ion-induced cognitive deficits via co-activation of NRF2 and PINK1 signaling pathway

Carbon ion therapy is a promising modality in radiotherapy to treat tumors, however, a potential risk of induction of late normal tissue damage should still be investigated and protected. The aim of the present study was to explore the long-term cognitive deficits provoked by a high-linear energy transfer (high-LET) carbon ions in mice by targeting to hippocampus which plays a crucial role in memory and learning. Our data showed that, one month after 4 Gy carbon ion exposure, carbon ion irradiation conspicuously resulted in the impaired cognitive performance, neurodegeneration and neuronal cell death, as well as the reduced mitochondrial integrity, the disrupted activities of tricarboxylic acid cycle flux and electron transport chain, and the depressed antioxidant defense system, consequently leading to a decline of ATP production and persistent oxidative damage in the hippocampus region. Mechanistically, we demonstrated the disruptions of mitochondrial homeostasis and redox balance typically characterized by the disordered mitochondrial dynamics, mitophagy and glutathione redox couple, which is closely associated with the inhibitions of PINK1 and NRF2 signaling pathway as the key regulators of molecular responses in the context of neurotoxicity and neurodegenerative disorders. Most importantly, we found that administration with melatonin as a mitochondria-targeted antioxidant promoted the PINK1 accumulation on the mitochondrial membrane, and augmented the NRF2 accumulation and translocation. Moreover, melatonin pronouncedly enhanced the molecular interplay between NRF2 and PINK1. Furthermore, in the mouse hippocampal neuronal cells, overexpression of NRF2/PINK1 strikingly protected the hippocampal neurons from carbon ion-elicited toxic insults. Thus, these data suggest that alleviation of the sustained mitochondrial dysfunction and oxidative stress through co-modulation of NRF2 and PINK1 may be in charge of restoration of the cognitive impairments in a mouse model of high-LET carbon ion irradiation.

Synthesis and suggestion of a new nanometric gold(III) melatonin drug complex: an interesting model for testicular protection

AIM

Melatonin (MLT) is a major hormone secreted by the pineal gland. In this study, a gold(III) MLT (Au⁺³/MLT) complex has been synthesized and investigating its protective effects against testicular damage.

METHODOLOGY

The structural features of the complex were investigated. For biological assessment, 30 male rats were divided into three groups for 30 days. The first control group, the second received MLT and the third received Au⁺³/MLT complex.

RESULTS

The Au⁺³/MLT complex was found to be nonelectrolytic with formula (Au[MLT]₂[Cl][H₂O]). The ligand is monodentate and adopt square-planar geometry. Its particles range in diameter from 35 to 100 nm. MLT affords slight oxidative stress protection. The Au⁺³/MLT complex significantly decreases TNF-α and IL-1β levels but elevates antioxidant enzyme capacities, reducing lipid peroxidation markers and improving testicular histological structure.

CONCLUSION

The Au⁺³/MLT complex improves the anti-inflammatory actions of MLT, exhibits potent antioxidant activity and enhances reproductive capacity.

Acute Effect of Low-Dose Space Radiation on Mouse Retina and Retinal Endothelial Cells

There is concern that degradation of vision as a result of space flight may compromise both mission goals and long-term quality of life after space travel. The visual disturbances may be due to a combination of intracerebral pressure changes and exposure to ionizing radiation. The retina and the retinal vasculature play important roles in vision, yet have not been studied extensively in relationship to space travel and space radiation. The goal of the current study was to characterize oxidative damage and apoptosis in retinal endothelial cells after whole-body gamma-ray, proton and oxygen (¹⁶O) ion radiation exposure at 0.1 to 1 Gy. Six-month-old male C57Bl/6J mice were whole-body irradiated with 600 MeV/n ¹⁶O ions (0, 0.1, 0.25, 1 Gy), solar particle event (SPE)-like protons (0, 0.1, 0.25, 0.5 Gy) or ⁶⁰Co gamma rays (0, 0.1, 0.25, 0.5 Gy). Eyes were isolated for examining endothelial nitric oxide synthase (eNOS) expression and characterization of apoptosis in retina and retinal endothelial cells at two weeks postirradiation. The expression of eNOS was significantly increased in the retina after proton and ¹⁶O ion exposure. ¹⁶O ions induced over twofold increase in eNOS expression compared to proton exposure at two weeks postirradiation ( P < 0.05). TUNEL assays showed dose-dependent increases in apoptosis in the retina after irradiation. Low doses of ¹⁶O ions elicited apoptosis in the mouse retinal endothelial cells with the most robust changes observed after 0.1 Gy irradiation ( P < 0.05) compared to controls. Data also showed that ¹⁶O ions induced a higher frequency of apoptosis in retinal endothelial cells compared to protons ( P < 0.05). In summary, our study revealed that exposure to low-dose ionizing radiation induced oxidative damage and apoptosis in the retina. Significant changes in retinal endothelial cells occur at doses as low as 0.1 Gy. There were significant differences in the responses of endothelial cells among the radiation types examined here.

Anti-apoptotic effect of melatonin in sperm of mithun

The present study was designed to measure the effect of melatonin (MT) on apoptosis of sperm in mithun. Ejaculates (20) were collected from mithun bulls and were split into five equal aliquots, diluted with the TEYC extender. (Gr 1: semen without additives (control), Gr 2 to Gr 6: semen was diluted with 1, 2, 3, 4 and 5 mM of MT respectively). Apoptotic sperm percentage was estimated using commercially available apoptotic assessment kit at immediately after dilution, equilibration and post-thaw. Inclusion of MT into diluent resulted in a significant decrease in apoptotic sperm percentage at different stage of semen preservation as compared to untreated control group. Moreover, MT at 3 mM had significantly lower apoptotic sperm percentage than MT at 1 mM, 2 mM or 4 mM or 5 mM stored sperm at different stage. It was concluded that MT at 3 mM is suitable to minimize apoptosis in mithun sperm to pursuit future sperm preservation protocols.

Therapeutic potential of melatonin for breast cancer radiation therapy patients

Melatonin is an endogenous hormone primarily known for its action on the circadian rhythms. But pre-clinical studies are reporting both its radioprotective and radiosensitizing properties, possibly mediated through an interaction between melatonin and the regulation of estrogens. Melatonin pre-treatment prior to ionizing radiation was associated with a decrease in cell proliferation and an increase in p53 mRNA expression, leading to an increase in the radiosensitivity of breast cancer cells. At the same time, a decrease in radiation-induced side effects was described in breast cancer patients and in rodent models. This review examines the potential for melatonin to improve the therapeutic outcomes of breast radiation therapy, specifically estrogen receptor positive patients. Evidence suggests that melatonin may offer a novel, non-toxic and cheap adjuvant therapy to improve the existing treatment modalities. But further research is required in the clinical setting before a clear understanding of its therapeutic benefits is determined.

Melatonin as a potential anticarcinogen for non-small-cell lung cancer

Non-small-cell lung cancer (NSCLC) is a leading cause of death from cancer worldwide. Melatonin, an indoleamine discovered in the pineal gland, exerts pleiotropic anticancer effects against a variety of cancer types. In particular, melatonin may be an important anticancer drug in the treatment of NSCLC. Herein, we review the correlation between the disruption of the melatonin rhythm and NSCLC incidence; we also evaluate the evidence related to the effects of melatonin in inhibiting lung carcinogenesis. Special focus is placed on the oncostatic effects of melatonin, including anti-proliferation, induction of apoptosis, inhibition of invasion and metastasis, and enhancement of immunomodulation. We suggest the drug synergy of melatonin with radio- or chemotherapy for NSCLC could prove to be useful. Taken together, the information complied herein may serve as a comprehensive reference for the anticancer mechanisms of melatonin against NSCLC, and may be helpful for the design of future experimental research and for advancing melatonin as a therapeutic agent for NSCLC.

Radioprotective effect of atorvastatin against ionizing radiation-induced nephrotoxicity in mice

PURPOSE

Kidneys are exposed to ionizing radiation during radiotherapy in patients with abdominal malignancy. The aim of this study is to investigate the protective effect of atorvastatin (ATV) against ionizing radiation-induced nephrotoxicity in mice.

MATERIALS AND METHODS

Sixty male BALB/c mice were randomly divided into six groups (10 mice per group); control, irradiation (IR), IR plus ATV (10, 20 and 50 mg/kg) and only ATV (50 mg/kg). ATV groups received ATV for seven days via oral gavage before exposure to IR. Animals were exposed to 2 Gy whole body of X-ray on day 8. After exposure to IR, biochemical, histological and immunohistological assays were performed.

RESULTS

ATV significantly decreased the level of oxidative stress biomarkers in irradiated mice in comparison with IR alone. A significant reduction in the urea and creatinine levels was observed in ATV plus IR group compared to IR alone. Tubular degeneration, glomerular atrophy, interstitial expansion and fibrosis were observed in irradiated mice. Tubular degeneration and atrophy in the kidneys of IR plus ATV group were less than IR group. In addition, pre-treated animal with ATV significantly showed reduction in caspase-3 immunoreactivity.

CONCLUSION

ATV has significant protective effect against radiation-induced nephrotoxicity in mice and is a promising medication for protection of patients during radiotherapy.

Role of drugs in the prevention and amelioration of radiation induced toxic effects

As the use of radiation technology for nuclear warfare or for the benefits of mankind (e.g. in radiotherapy or radio-diagnosis) is increasing tremendously, the risk of associated side effects is becoming a cause of concern. These effects, ranging from nausea/vomiting to death, may result from accidental or deliberate exposure and begin in seconds. Through this review paper, efforts have been done to critically review different compounds which have been investigated as radioprotectors and radiation mitigators. Radioprotectors are compounds which are administered just before or at the time of irradiation so as to minimize the radiation induced damage to normal tissues. And radiation mitigators are the compounds which can even minimize or ameliorate post irradiaion-toxicity provided they are administered before the onset of toxic symptoms. A variety of agents have been investigated for their preventive and ameliorative potential against radiation induced toxic effects. This review article has focused on various aspects of the promising representative agents belonging to different classes of radioprotectors and mitigators. Many compounds have shown promising results, but till date only amifostine and palifermin are clinically approved by FDA. To fill this void in pharmacological armamentarium, focus should be shifted towards novel approaches.

Modifiers of radiation effects in the eye

World events, including the threat of radiological terrorism and the fear of nuclear accidents, have highlighted an urgent need to develop medical countermeasures to prevent or reduce radiation injury. Similarly, plans for manned spaceflight to a near-Earth asteroid or journey to Mars raise serious concerns about long-term effects of space radiation on human health and the availability of suitable therapeutic interventions. At the same time, the need to protect normal tissue from the deleterious effects of radiotherapy has driven considerable research into the design of effective radioprotectors. For more than 70 years, animal models of radiation cataract have been utilized to test the short and long-term efficacy of various radiation countermeasures. While some compounds, most notably the Walter Reed (WR) class of radioprotectors, have reported limited effectiveness when given before exposure to low-LET radiation, the human toxicity of these molecules at effective doses limits their usefulness. Furthermore, while there has been considerable testing of eye responses to X- and gamma irradiation, there is limited information about using such models to limit the injurious effects of heavy ions and neutrons on eye tissue. A new class of radioprotector molecules, including the sulfhydryl compound PrC-210, are reported to be effective at much lower doses and with far less side effects. Their ability to modify ocular radiation damage has not yet been examined. The ability to non-invasively measure sensitive, radiation-induced ocular changes over long periods of time makes eye models an attractive option to test the radioprotective and radiation mitigating abilities of new novel compounds.

Melatonin protects bone marrow mesenchymal stem cells against iron overload-induced aberrant differentiation and senescence

Bone marrow mesenchymal stem cells (BMSCs) are an expandable population of stem cells which can differentiate into osteoblasts, chondrocytes and adipocytes. Dysfunction of BMSCs in response to pathological stimuli contributes to bone diseases. Melatonin, a hormone secreted from pineal gland, has been proved to be an important mediator in bone formation and mineralization. The aim of this study was to investigate whether melatonin protected against iron overload-induced dysfunction of BMSCs and its underlying mechanisms. Here, we found that iron overload induced by ferric ammonium citrate (FAC) caused irregularly morphological changes and markedly reduced the viability in BMSCs. Consistently, osteogenic differentiation of BMSCs was significantly inhibited by iron overload, but melatonin treatment rescued osteogenic differentiation of BMSCs. Furthermore, exposure to FAC led to the senescence in BMSCs, which was attenuated by melatonin as well. Meanwhile, melatonin was able to counter the reduction in cell proliferation by iron overload in BMSCs. In addition, protective effects of melatonin on iron overload-induced dysfunction of BMSCs were abolished by its inhibitor luzindole. Also, melatonin protected BMSCs against iron overload-induced ROS accumulation and membrane potential depolarization. Further study uncovered that melatonin inhibited the upregulation of p53, ERK and p38 protein expressions in BMSCs with iron overload. Collectively, melatonin plays a protective role in iron overload-induced osteogenic differentiation dysfunction and senescence through blocking ROS accumulation and p53/ERK/p38 activation.

Assessing liver proteins and enzymes of medical workers exposed to ionizing radiation (IR)

The cross-sectional study was conducted to examine hepatic function via liver enzymes/proteins assessments, along with the estimation of an inflammatory response from C-reactive protein (CRP)-which is a liver-synthesized protein. The liver function tests with aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP) and bilirubin (BBN), and CRP test were conducted for radiation-exposed workers-REW (n = 32) and radiation-unexposed workers-RUW (n = 21). The annual average effective doses (AAED) were measured from thermoluminescent dosimeter. A t test and bivariate correlation analyses were applied. Only one worker had a high AST value (50 U/L), one worker had a negligible high ALT value (43 U/L) and only one worker had a negligible high bilirubin value (1.3 g/dL). There were normal levels of CRP (up to 6 mg/L) in all individuals. There existed a nonsignificant difference (p < 0.050) between the mean values of liver enzymes and proteins in all exposed and unexposed workers. Nonsignificant weak correlations are reported in liver enzymes/proteins parameters: AST, ALT, ALP, BBN, CRP with the AAED range (whole-body: 0.91-3.39 mSv) during 2011-2015. The normal values of liver enzymes/proteins' (AST, ALT, ALP, BBN, CRP) values may ensure a good hepatic health of radiation-exposed medical workers with AAED range mentioned. We found that low ionizing radiation doses did not alter the liver function test parameters and did not affect the concentration of an inflammatory response protein, i.e., CRP.

Melatonin, a Full Service Anti-Cancer Agent: Inhibition of Initiation, Progression and Metastasis

There is highly credible evidence that melatonin mitigates cancer at the initiation, progression and metastasis phases. In many cases, the molecular mechanisms underpinning these inhibitory actions have been proposed. What is rather perplexing, however, is the large number of processes by which melatonin reportedly restrains cancer development and growth. These diverse actions suggest that what is being observed are merely epiphenomena of an underlying more fundamental action of melatonin that remains to be disclosed. Some of the arresting actions of melatonin on cancer are clearly membrane receptor-mediated while others are membrane receptor-independent and involve direct intracellular actions of this ubiquitously-distributed molecule. While the emphasis of melatonin/cancer research has been on the role of the indoleamine in restraining breast cancer, this is changing quickly with many cancer types having been shown to be susceptible to inhibition by melatonin. There are several facets of this research which could have immediate applications at the clinical level. Many studies have shown that melatonin's co-administration improves the sensitivity of cancers to inhibition by conventional drugs. Even more important are the findings that melatonin renders cancers previously totally resistant to treatment sensitive to these same therapies. Melatonin also inhibits molecular processes associated with metastasis by limiting the entrance of cancer cells into the vascular system and preventing them from establishing secondary growths at distant sites. This is of particular importance since cancer metastasis often significantly contributes to death of the patient. Another area that deserves additional consideration is related to the capacity of melatonin in reducing the toxic consequences of anti-cancer drugs while increasing their efficacy. Although this information has been available for more than a decade, it has not been adequately exploited at the clinical level. Even if the only beneficial actions of melatonin in cancer patients are its ability to attenuate acute and long-term drug toxicity, melatonin should be used to improve the physical wellbeing of the patients. The experimental findings, however, suggest that the advantages of using melatonin as a co-treatment with conventional cancer therapies would far exceed improvements in the wellbeing of the patients.

Melatonin Ameliorates The Production of COX-2, iNOS, and The Formation of 8-OHdG in Non-Targeted Lung Tissue after Pelvic Irradiation

In this study, we evaluated the bystander effect of radiation on the regulation of cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), and 8-hydroxydeoxyguanosine (8-OHdG) in lung tissues of Sprague-Dawley rats with and without pre-administration of melatonin. A 2×2 cm² area of the pelvis of male Sprague-Dawley rats with and without pre-administration of melatonin (100 mg/kg) by oral and intraperitoneal injection was irradiated with a 3 Gy dose of 1.25 MeV γ-rays. Alterations in the levels of COX-2, iNOS, and 8-OHdG in the out-of-field lung areas of the animals were detected by enzyme immunoassay. The bystander effect significantly increased COX-2, iNOS, and 8-OHdG levels in non-targeted lung tissues (P<0.05). Melatonin ameliorated the bystander effect of radiation and significantly reduced the level of all examined biomarkers (P<0.05). The results indicated that the ameliorating effect of a pre-intraperitoneal (IP) injection of melatonin was noticeably greater compared to oral pre-administration. Our findings revealed that the bystander effect of radiation could induce oxidative DNA damage and increase the levels of imperative COX-2 and iNOS in non-targeted lung tissues. Interestingly, melatonin could modulate the indirect destructive effect of radiation and reduce DNA damage in non-targeted cells.

Melatonin attenuates 60 Co γ-ray-induced hematopoietic, immunological and gastrointestinal injuries in C57BL/6 male mice

Protection of hematopoietic, immunological, and gastrointestinal injuries from deleterious effects of ionizing radiation is prime rational for developing radioprotector. The objective of this study, therefore, was to evaluate the radioprotective potential of melatonin against damaging effects of radiation-induced hematopoietic, immunological, and gastrointestinal injuries in mice. C57BL/6 male mice were intraperitoneally administered with melatonin (50-150 mg/kg) 30 min prior to whole-body radiation exposure of 5 and 7.5 Gy using ⁶⁰ Co-teletherapy unit. Thirty-day survival against 7.5 Gy was monitored. Melatonin (100 mg/kg) pretreatment showed 100% survival against 7.5 Gy radiation dose. Melatonin pretreatment expanded femoral HPSCs, and inhibited spleenocyte DNA strands breaks and apoptosis in irradiated mice. At this time, it also protected radiation-induced loss of T cell sub-populations in spleen. In addition, melatonin pretreatment enhanced crypts regeneration and increased villi number and length in irradiated mice. Translocation of gut bacteria to spleen, liver and kidney were controlled in irradiated mice pretreated with melatonin. Radiation-induced gastrointestinal DNA strand breaks, lipid peroxidation, and expression of proapoptotic-p53, Bax, and antiapoptotic-Bcl-xL proteins were reversed in melatonin pretreated mice. This increase of Bcl-xL was associated with the decrease of Bax/Bcl-xL ratio. ABTS and DPPH radical assays revealed that melatonin treatment alleviated total antioxidant capacity in hematopoietic and gastrointestinal tissues. Present study demonstrated that melatonin pretreatment was able to prevent hematopoietic, immunological, and gastrointestinal radiation-induced injury, therefore, overcoming lethality in mice. These results suggest potential of melatonin in developing radioprotector for protection of bone marrow, spleen, and gastrointestine in planned radiation exposure scenarios including radiotherapy. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 501-518, 2017.

Radioprotective effect of hesperidin on reducing oxidative stress in the lens tissue of rats

Introduction:

Oxidative stress is a common factor in cataract. Considering the antioxidant properties of hesperidin as a flavanone glycoside from the flavonoid family with radioprotective effect, this study aimed to determine the protective effect of this flavanone glycoside on reducing oxidative stress in the eye lens tissue of mature rats caused by gamma irradiation.

Materials and Methods:

A total of 48 adult rats were randomly divided into six groups, namely, control, Dimethyl sulfoxide (DMSO), hesperidin, radiation, radiation + DMSO, and radiation + hesperidin. 15 Gy irradiation was carried out using Cobalt-60 teletherapy instrument with a source-to-surface distance of 80 cm at a dose rate of 98.5 cGy/min. 2 days following irradiation, we removed the rats' lenses and analyzed them to determine the effects of hesperidin.

Results:

The comparison of control and intervention groups after irradiation showed that malondialdehyde (MDA) level in the lens tissue was significantly higher in the irradiation groups than the control group. Furthermore, a significant difference between radiation and radiation + hesperidin groups were observed. The level of glutathione (GSH) in the lens tissue was significantly lower in the irradiation groups compared to the control group. Nonetheless, significant elevation of GSH in the radiation + hesperidin group compared to radiation group was seen.

Conclusions:

Radiation exposure reduced GSH and enhanced MDA levels in the lens tissue. However, GSH and MDA levels were modulated after hesperidin consumption. These results show the antioxidative properties of hesperidin in the lens and demonstrated that radiation complications such as cataract can be reduced by hesperidin through reducing oxidative stress.

Effects of Hesperidin as a Radio-protector on Apoptosis in Rat Peripheral Blood Lymphocytes after Gamma Radiation

INTRODUCTION

Hesperidin (HES), as the most abundant flavonoid existing in the citrus, is widely used by human daily. The radio-protective effects of Hesperidin have been confirmed in various measurement systems. This study aimed to evaluate the effects of Hesperidin on the changes in the apoptosis level and expression of apoptotic genes target (bax, bcl-2 and ration of bax/bcl-2) in the peripheral blood lymphocytes of male rats after gamma radiation.

MATERIALS AND METHODS

64 male rats were divided into eight groups: Control, HES (100 mg/kg b.w, orally, 7 days), whole body irradiation with 2 and 8Gy, pre-administrated with 50 and 100 mg/kg body weight of Hesperidin for 7 days before irradiation with 2 and 8 Gy. 24 hours after radiation, apoptotic lymphocytes were evaluated using PE Annexin V Apoptosis detection I kit and the levels of mRNA for bax and bcl-2 were evaluated by real time reverse transcription polymerase chain reaction.

RESULTS

A significant reduction in apoptosis of the lymphocytes was demonstrated in group animals receiving 8 Gy compared to the group which received 2 Gy irradiation (p<0.0001). However, apoptosis significantly increased in group of rats who received Hesp before irradiation (p<0.05). The increase of apoptosis by Hesperidin administration can be attributed to the decreased expression of bax and significantly reduced expression of bcl-2 and finally increasing the ration of bax/bcl-2.

CONCLUSION

The results suggest that administration of 50 and 100 mg/kg of Hesperidin induces apoptotic effects by changing expression level of bax, bcl-2 and also the ratio of bax/bcl2.

The flavonolignan-silymarin protects enzymatic, hematological, and immune system against γ-radiation-induced toxicity

The main focus of this study is evaluation of radioprotective efficacy of silymarin, a flavonolignan, against γ-radiation-induced damage to hematological, vital organs (liver and intestine), and immune system. Survival studies revealed that silymarin (administered orally for 3 days) provided maximum protection (67%) at 70 mg/kg body weight (b.wt.) against lethal 9 Gy γ-irradiation (dose reduction factor = 1.27). The study revealed significant (p < 0.05) changes in levels of catalase (12.57 ± 2.58 to 30.24 ± 4.89 units), glutathione peroxidase (6.23 ± 2.95 to 13.26 ± 1.36 µg of reduced glutathione consumed/min/mg protein), glutathione reductase (0.25 ± 5.6 to 11.65 ± 2.83 pM NADPH consumed/min/mg protein), and superoxide dismutase (11.74 ± 0.2 to 16.09 ± 3.47 SOD U/mg of protein) activity at 30th day. Silymarin pretreated irradiated group exhibited increased proliferation in erythrocyte count (1.76 ± 0.41 × 10(6) to 9.25 ± 0.24 × 10(6) ), hemoglobin (2.15 ± 0.48g/dL to 14.77 ± 0.25g/dL), hematocrit (4.55 ± 0.24% to 37.22 ± 0.21%), and total leucocyte count (1.4 ± 0.15 × 10(6) to 8.31 ± 0.47 × 10(6) ) as compared with radiation control group on 15th day. An increase in CD4:CD8 ratio was witnessed (0.2-1%) at 30th day time interval using flow cytometry. Silymarin also countered radiation-induced decrease (p < 0.05) in regulatory T-cells (Tregs ) (11.23% in radiation group at 7th day versus 0.1% in pretreated silymarin irradiated group at 15th day). The results of this study indicate that flavonolignan-silymarin protects enzymatic, hematological, and immune system against γ-radiation-induced toxicity and might prove useful in management of nuclear and radiological emergencies. © 2014 Wiley Periodicals, Inc. Environ Toxicol 31: 641-654, 2016.

Highly Catalytic Nanodots with Renal Clearance for Radiation Protection

Ionizing radiation (gamma and X-ray) is widely used in industry and medicine, but it can also pose a significant hazardous effect on health and induce cancer, physical deformity, and even death, due to DNA damage and invasion of free radicals. There is therefore an urgent unmet demand in designing highly efficient radioprotectants with synergetic integration of effective renal clearance and low toxicity. In this study, we designed ultrasmall (sub-5 nm) highly catalytically active and cysteine-protected MoS2 dots as radioprotectants and investigated their application in protection against ionizing radiation. In vivo preclinical studies showed that the surviving fraction of MoS2-treated mice can appreciably increase to up to 79% when they were exposed to high-energy ionizing radiation. Furthermore, MoS2 dots can contribute in cleaning up the accumulated free radicals within the body, repairing DNA damage, and recovering all vital chemical and biochemical indicators, suggesting their unique role as free radical scavengers. MoS2 dots showed rapid and efficient urinary excretion with more than 80% injected dose eliminated from the body after 24 h due to their ultrasmall hydrodynamic size and did not cause any noticeable toxic responses up to 30 days.

Hepatoprotective effect of grape seed oil against carbon tetrachloride induced oxidative stress in liver of γ-irradiated rat

Carbon tetrachloride (CCl4) and ionizing radiation are well known environmental pollutants that generate free radicals and induce oxidative stress. The liver is the primary and major target organ responsible for the metabolism of drugs, toxic chemicals and affected by irradiation. This study investigated the effect of grape seed oil (GSO) on acute liver injury induced by carbon tetrachloride (CCl4) in γ-irradiated rats (7Gy). CCl4-intoxicated rats exhibited an elevation of ALT, AST activities, IL-6 and TNF-α level in the serum. Further, the levels of MDA, NO, NF-κB and the gene expression of CYP2E1, iNOS and Caspase-3 were increased, and SOD, CAT, GSH-Px, GST activities and GSH content were decreased. Furthermore, silent information regulator protein 1 (SIRT1) gene expression was markedly down-regulated. Additionally, alterations of the trace elements; copper, manganese, zinc and DNA fragmentation was observed in the hepatic tissues of the intoxicated group. These effects were augmented in CCl4-intoxicated-γ-irradiated rats. However, the administration of GSO ameliorated these parameters. GSO exhibit protective effects on CCl4 induced acute liver injury in γ-irradiated rats that could be attributed to its potent antioxidant, anti-inflammatory and anti-apoptotic activities. The induction of the antioxidant enzymes activities, down-regulation of the CYP2E1, iNOS, Caspase-3 and NF-κB expression, up-regulation of the trace elements concentration levels and activation of SIRT1 gene expression are responsible for the improvement of the antioxidant and anti-inflammatory status in the hepatic tissues and could be claimed to be the hepatoprotective mechanism of GSO.

Micronuclei Assessment of The Radioprotective Effects of Melatonin and Vitamin C in Human Lymphocytes

Objective

Critical macromolecules such as DNA maybe damaged by free radicals that are generated from the interaction of ionizing radiation with biological systems. Melatonin and vitamin C have been shown to be direct free radical scavengers. The aim of this study was to investigate the in vivo/in vitro radioprotective effects of melatonin and vitamin C separately and combined against genotoxicity induced by 6 MV x-ray irradiation in human cultured blood lymphocytes.

Materials and Methods

In this experimental study, fifteen volunteers were divided into three groups of melatonin, vitamin C and melatonin plus vitamin C treatment. Peripheral blood samples were collected from each group before, and 1, 2 and 3 hours after melatonin and vitamin C administration (separately and combined). The blood samples were then irradiated with 200 cGy of 6 MV x-ray. In order to characterize chromosomal aberrations, the lymphocyte samples were cultured with mitogenic stimulus on cytokinesisblocked binucleated cells.

Results

The samples collected 1hour after melatonin and vitamin C (separately and combined) ingestion exhibited a significant decrease in the incidence of micronuclei compared with their control group (P<0.05). The maximum synergic protection and reduction in frequency of micronuclei (57%) was observed 1 hour after vitamin C and melatonin administration combined.

Conclusion

We conclude that simultaneous administration of melatonin and vitamin C as radioprotector substances before irradiation may reduce genotoxicity caused by x-ray irradiation.

Radioprotective Effects of Amifostine and Lycopene on Human Peripheral Blood Lymphocytes In Vitro

BACKGROUND

Radiation protection is a pivotal challenge for radiation workers employed in medical fields, industry, and also space professionals with an increasing role in medical diagnostic and therapeutic applications. Radioprotective effects of amifostine and lycopene and their ability to moderate the level of radiation-induced chromosomal aberrations were investigated using the dicentric chromosome assay.

METHODS

Parallel human whole blood samples, pretreated with amifostine (250 μg/mL), lycopene (5 μg/mL), and/or their combinations were irradiated for 30 minutes with ⁶⁰Co γ rays (1, 2, 3, and 4 Gy) with a dose rate of 98.46 cGy/min at SAD = 100 cm, in vitro and cocultured with control groups. The frequencies of chromosomal aberrations in the lymphocyte of the cells were analyzed.

RESULTS

There were no apparent chromosome aberrations in controls and also in the drug-treated groups in the absence of radiation. Radiodrug treatment significantly decreased frequency of the radiation-induced chromosome aberrations compared with radiation alone (P < .05). Amifostine reduced the frequency of radiation-induced dicentrics by 15.8%, 21.9%, 4.5%, and 11.6%, with dose protection factors (DPFs) of 1.2 ± 0.02, 1.3 ± 0.1, 1.05 ± 0.03, and 1.13 ± 0.02. Lycopene reduced the frequency by 17.2%, 3.07%, 1.63%, and 16.6%, with DPFs of 1.21 ± 0.12, 1.03±0.05, 1.02±0.03 and 1.12±0.03. The combination treatment reduced the frequency by 28%, 24.9%, 9%, and 31.2%, with DPFs of 1.38 ± 0.06, 1.33 ± 0.06, 1.09 ± 0.02, and 1.45 ± 0.03 with radiation doses of 1, 2, 3, and 4 Gy, respectively.

CONCLUSIONS

It can be suggested that pretreatment with combined amifostine and lycopene may reduce the extent of ionizing radiation damage in cells.

Melatonin attenuates sepsis-induced cardiac dysfunction via a PI3K/Akt-dependent mechanism

Myocardial dysfunction is an important manifestation of sepsis. Previous studies suggest that melatonin is protective against sepsis. In addition, activation of the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) signaling pathway has been reported to be beneficial in sepsis. However, the role of PI3K/Akt signaling in the protective effect of melatonin against sepsis-induced myocardial dysfunction remains unclear. Here, LY294002, a PI3K inhibitor, was used to investigate the role of PI3K/Akt signaling in mediating the effects of melatonin on sepsis-induced myocardial injury. Cecal ligation and puncture (CLP) surgery was used to establish a rat model of sepsis. Melatonin was administrated to rats intraperitoneally (30 mg/kg). The survival rate, measures of myocardial injury and cardiac performance, serum lactate dehydrogenase level, inflammatory cytokine levels, oxidative stress level, and the extent of myocardial apoptosis were assessed. The results suggest that melatonin administration after CLP surgery improved survival rates and cardiac function, attenuated myocardial injury and apoptosis, and decreased the serum lactate dehydrogenase level. Melatonin decreased the production of the inflammatory cytokines TNF-α, IL-1β, and HMGB1, increased anti-oxidant enzyme activity, and decreased the expression of markers of oxidative damage. Levels of phosphorylated Akt (p-Akt), unphosphorylated Akt (Akt), Bcl-2, and Bax were measured by Western blot. Melatonin increased p-Akt levels, which suggests Akt pathway activation. Melatonin induced higher Bcl-2 expression and lower Bax expression, suggesting inhibition of apoptosis. All protective effects of melatonin were abolished by LY294002, the PI3K inhibitor. In conclusion, our results demonstrate that melatonin mitigates myocardial injury in sepsis via PI3K/Akt signaling activation.

Comparison of the effects of melatonin and genistein on radiation-induced nephrotoxicity: Results of an experimental study

The aim of the present study was to compare the effects of melatonin and genistein on radiation-induced nephrotoxicity (RIN). A total of 70 Swiss Albino mice were divided into 7 groups. Five control groups were defined, which were sham irradiation (C, G1), radiation therapy only (RT, G2), melatonin (M, G3), genistein (G, G4) and polyethylene glycol-400 (G5), respectively. The co-treatment groups were the RT plus melatonin (RT+M, G6) and RT plus genistein (RT+G, G7) groups. Irradiation was applied using a cobalt-60 teletherapy machine (80-cm fixed source-to-surface distance, 2.5-cm depth). Melatonin was administered (100 mg/kg, intraperitoneal injection) 30 min before the single dose of irradiation, whereas genistein was administered (200 mg/kg, subcutaneous injection) 1 day before the single dose of irradiation. All the mice were sacrificed 6 months after irradiation. As an end point, the extent of renal tubular atrophy for each mouse was quantified with image analysis of histological sections of the kidney. Tissue malondialdehyde (MDA) levels were also measured in each animal. In the histopathological examination of the mouse kidneys, there was a statistically significant reduction (P<0.05) in the presence of tubular atrophy between the RT+M and RT+G groups and the RT group. There was a statistically significant increase in MDA levels in the irradiated versus sham groups (RT vs. C; P<0.05); however, MDA levels were significantly decreased by co-treatment with melatonin or genistein vs. RT alone (RT+M and RT+G vs. RT; P<0.05). In conclusion, the present experimental study showed that melatonin and genistein supplementation prior to irradiation-protected mice against RIN, which may have therapeutic implications for radiation-induced injuries.

Melatonin: A Potential Anti-Oxidant Therapeutic Agent for Mitochondrial Dysfunctions and Related Disorders

Mitochondria play a central role in cellular physiology. Besides their classic function of energy metabolism, mitochondria are involved in multiple cell functions, including energy distribution through the cell, energy/heat modulation, regulation of reactive oxygen species (ROS), calcium homeostasis, and control of apoptosis. Simultaneously, mitochondria are the main producer and target of ROS with the result that multiple mitochondrial diseases are related to ROS-induced mitochondrial injuries. Increased free radical generation, enhanced mitochondrial inducible nitric oxide synthase (iNOS) activity, enhanced nitric oxide (NO) production, decreased respiratory complex activity, impaired electron transport system, and opening of mitochondrial permeability transition pores have all been suggested as factors responsible for impaired mitochondrial function. Because of these, neurodegenerative diseases, such as Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), Huntington's disease (HD), and aging, are caused by ROS-induced mitochondrial dysfunctions. Melatonin, the major hormone of the pineal gland, also acts as an anti-oxidant and as a regulator of mitochondrial bioenergetic function. Melatonin is selectively taken up by mitochondrial membranes, a function not shared by other anti-oxidants, and thus has emerged as a major potential therapeutic tool for treating neurodegenerative disorders. Multiple in vitro and in vivo experiments have shown the protective role of melatonin for preventing oxidative stress-induced mitochondrial dysfunction seen in experimental models of PD, AD, and HD. With these functions in mind, this article reviews the protective role of melatonin with mechanistic insights against mitochondrial diseases and suggests new avenues for safe and effective treatment modalities against these devastating neurodegenerative diseases. Future insights are also discussed.

Melatonin ameliorates oxidative damage induced by maternal lead exposure in rat pups

During the particular period of cerebellum development, exposure to lead (Pb) decreases cerebellum growth and can result in selective loss of neurons. The detection and prevention of Pb toxicity is a major international public health priorities. This research study was conducted to evaluate the effects of melatonin, an effective antioxidant and free radical scavenger, on Pb induced neurotoxicity and oxidative stress in the cerebellum. Pb exposure was initiated on gestation day 5 with the addition of daily doses of 0.2% lead acetate to distilled drinking water and continues until weaning. Melatonin (10mg/kg) was given once daily at the same time. 21 days after birth, several antioxidant enzyme activities including superoxide dismutase (SOD) and glutathione peroxidase (GPx) were assayed. Thiobarbituric acid reactive substance (TBARS) levels were measured as a marker of lipid peroxidation. Rotarod and locomotor activity tests were performed on postnatal days (PDs) 31-33 and a histological study was performed after completion of behavioral measurements on PD 33. The results of the present work demonstrated that Pb could induce lipid peroxidation, increase TBARS levels and decrease GPx and SOD activities in the rat cerebellum. We also observed that Pb impaired performance on the rotarod and locomotor activities of rats. However, treatment with melatonin significantly attenuated the motoric impairment and lipid peroxidation process and restored the levels of antioxidants. Histological analysis indicated that Pb could decrease Purkinje cell count and melatonin prevented this toxic effect. These results suggest that treatment with melatonin can improve motor deficits and oxidative stress by protecting the cerebellum against Pb toxicity.

The protective effects of apocynin on ionizing radiation-induced intestinal damage in rats

BACKGROUND AND AIMS

Radiation colitis typically emerges during radiotherapy of intra-abdominal malignancies. While the underlying mechanism remains unclear, it is considered that free oxygen radicals act like cellular mediators to cause colonic damage. Apocynin (APO) prevents oxidative stress and apoptotic cell death by inhibiting NADPH oxidase, and preventing the formation of free oxygen radicals. The aim of the present study was to investigate the protective effect of APO, a strong antioxidant and antiinflammatory agent, on radiation induced colonic oxidative damage in rats.

MATERIALS AND METHODS

Rats were randomly divided into four groups (n = 8/group). Group I (control group); Group II (Group RAD) received a single dose of 800 cGy ionizing radiation to the whole abdomen with a linear accelerator (LINAC); Group III (Group APO) received a single dose of 20 mg/kg of APO intraperitoneally for five days; Group IV (Group APO+RAD) received APO for five days before radiation exposure (similar to Group III), (similar to Group II).

RESULTS

APO treatment prior to radiation led to protection in the biochemical and histopathological parameters.

CONCLUSIONS

Our study shows that APO treatment before radiation improves radiation induced colonic injury in rats, by decreasing oxidative stress and apoptosis.

Effects of melatonin and prolactin in reproduction: review of literature

Summary The pineal gland is responsible for producing a hormone called melatonin (MEL), and is accepted as the gland that regulates reproduction in mammals. Prolactin (PRL) also exhibits reproductive activity in animals in response to photoperiod. It is known that the concentrations of PRL are high in the summer and reduced during winter, the opposite of what is seen with melatonin in these seasons. In placental mammals, both prolactin and melatonin affect implantation, which is considered a critical point of pregnancy, since a successful pregnancy requires the development of a synchronous interaction between the endometrium and blastocyst for placental development. It is also known that PRL levels during pregnancy are essential for the maintenance of pregnancy, because this hormone induces the corpus luteum to produce progesterone, in addition to stimulating blastocyst implantation to maintain pregnancy and form the placenta. However, melatonin levels in plasma have also been shown to increase during pregnancy, peaking at the end of this period, which suggests that this hormone plays an important role in the maintenance of pregnancy. Thus, it is clear that treatment with prolactin or melatonin interferes with the processes responsible for the development and maintenance of pregnancy.

Radioprotective effect of melatonin on radiation-induced lung injury and lipid peroxidation in rats

Objective

Free radicals generated by ionizing radiation attack various cellular components such as lipids. The lung is a very radiosensitive organ and its damage is a doselimiting factor in radiotherapy treatments. Melatonin (MLT), the major product of the pineal gland acts as a radioprotective agent. This study aims to investigate the radioprotective effects of MLT on malondialdehyde (MDA) levels and histopathological changes in irradiated lungs.

Materials and Methods

In this experimental study, a total of 62 rats were divided into five groups. Group 1 received no MLT and radiation (unT), group 2 received oral MLT (oM), group 3 received oral MLT and their thoracic areas were irradiated with 18 Gy (oMR), group 4 received MLT by intraperitoneal (i.p.) injection and their thoracic areas were irradiated with 18 Gy (ipM-R), group 5 received only 18 Gy radiation in the thoracic area (R). Following radiotherapy, half of the animals in each group were sacrificed at 48 hours for evaluation of lipid peroxidation and early phase lung injuries. Other animals were sacrificed in the eighth week of the experiment for evaluation of the presence of late phase radiation induced lung injuries.

Results

Pre-treatment of rats with either i.p injection (p<0.05) and oral administration of MLT (p<0.001) significantly reduced MDA levels in red blood cell (RBC) samples compared to the R group. Furthermore, i.p. injection of MLT decreased MDA levels in plasma and tissue (p<0.05). In the early phase of lung injury, both administration of MLT significantly increased lymphocyte (p<0.05) and macrophage frequency (p<0.001). MLT reduced the lung injury index in the lungs compared to the R group (p<0.05).

Conclusion

The result of this study confirms the radioprotective effect of MLT on lipid peroxidation, and in both early and late phases of radiation induced lung injuries in an animal model.

Melatonin reduces oxidative stress and restores mitochondrial function in the liver of rats exposed to chemotherapeutics

This study was undertaken to investigate whether administration of melatonin protects PVB-Induced oxidative and metabolic toxicity in the liver of Wistar rats. Adult male Wistar rats were intraperitoneally injected with either melatonin or PVB (cisplatin, vinblastine, and bleomycin) alone or combination for a period of 9 weeks. A significant increase in lipid peroxidation levels and decrease in catalase and superoxide dismutase activity levels were observed in the liver mitochondria of rats treated with PVB indicating increased oxidative stress. PVB treatment significantly decreased the succinate dehydrogenase activity with a significant increase in lactate dehydrogenase, glucose-6-phosphate dehydrogenase, aspartate aminotransaminase, alanine aminotransaminase, and glutamate dehydrogenase activities indicating deranged hepatic metabolism. Melatonin administration, on the other hand was found to significantly improve PVB-Induced biochemical changes, bringing them closer to the controls. The results from the study provide evidence that treatment with PVB affects hepatic metabolism in rats by inducing oxidative stress followed by decreasing mitochondrial oxidation and also point towards the clinical potential of melatonin as an adjuvant therapy to conventional chemotherapeutic regimens.

Edaravone protects human peripheral blood lymphocytes from γ-irradiation-induced apoptosis and DNA damage

Radiation-induced cellular injury is attributed primarily to the harmful effects of free radicals, which play a key role in irradiation-induced apoptosis. In this study, we investigated the radioprotective efficacy of edaravone, a licensed clinical drug and a powerful free radical scavenger that has been tested against γ-irradiation-induced cellular damage in cultured human peripheral blood lymphocytes in studies of various diseases. Edaravone was pre-incubated with lymphocytes for 2 h prior to γ-irradiation. It was found that pretreatment with edaravone increased cell viability and inhibited generation of γ-radiation-induced reactive oxygen species (ROS) in lymphocytes exposed to 3 Gy γ-radiation. In addition, γ-radiation decreased antioxidant enzymatic activity, such as superoxide dismutase and glutathione peroxidase, as well as the level of reduced glutathione. Conversely, treatment with 100 μM edaravone prior to irradiation improved antioxidant enzyme activity and increased reduced glutathione levels in irradiated lymphocytes. Importantly, we also report that edaravone reduced γ-irradiation-induced apoptosis through downregulation of Bax, upregulation of Bcl-2, and consequent reduction of the Bax:Bcl-2 ratio. The current study shows edaravone to be an effective radioprotector against γ-irradiation-induced cellular damage in lymphocytes in vitro. Finally, edaravone pretreatment significantly reduced DNA damage in γ-irradiated lymphocytes, as measured by comet assay (% tail DNA, tail length, tail moment, and olive tail moment) (p < 0.05). Thus, the current study indicates that edaravone offers protection from radiation-induced cytogenetic alterations.

Melatonin sensitizes human breast cancer cells to ionizing radiation by downregulating proteins involved in double-strand DNA break repair

Radiation and adjuvant endocrine therapy are nowadays considered a standard treatment option after surgery in breast cancer. Melatonin exerts oncostatic actions on human breast cancer cells. In the current study, we investigated the effects of a combination of radiotherapy and melatonin on human breast cancer cells. Melatonin (1 mm, 10 μm and 1 nm) significantly inhibited the proliferation of MCF-7 cells. Radiation alone inhibited the MCF-7 cell proliferation in a dose-dependent manner. Pretreatment of breast cancer cells with melatonin 1 wk before radiation led to a significantly greater decrease of MCF-7 cell proliferation compared with radiation alone. Melatonin pretreatment before radiation also decreased G2 -M phase arrest compared with irradiation alone, with a higher percentage of cells in the G0 -G1 phase and a lower percentage of cells in S phase. Radiation alone diminished RAD51 and DNA-protein kinase (PKcs) mRNA expression, two main proteins involved in double-strand DNA break repair. Treatment with melatonin for 7 days before radiation led to a significantly greater decrease in RAD51 and DNA-PKcs mRNA expression compared with radiation alone. Our findings suggest that melatonin pretreatment before radiation sensitizes breast cancer cells to the ionizing effects of radiation by decreasing cell proliferation, inducing cell cycle arrest and downregulating proteins involved in double-strand DNA break repair. These findings may have implications for designing clinical trials using melatonin and radiotherapy.

Semiquinone fraction isolated from Bacillus sp. INM-1 protects hepatic tissues against γ-radiation induced toxicity

Present study was focused on evaluation of a semiquinone glucoside derivative (SQGD) isolated from radioresistant bacterium Bacillus sp. INM-1 for its ability against γ radiation induced oxidative stress in irradiated mice. Animals were divided into four group, i.e., (i) untreated control mice; (ii) SQGD treated (50 mg/kg b. wt. i.p.) mice; (iii) irradiated (10 Gy) mice; and (iv) irradiated mice which were pre-treated (-2 h) with SQGD (50 mg/kg b. wt. i.p.). Following treatment, liver homogenates of the treated mice were subjected to endogenous antioxidant enzymes estimation. Result indicated that SQGD pre-treatment, significantly (P < 0.05) induced superoxide dismutase (SOD) (19.84 ± 2.18% at 72 h), catalase (CAT) (26.47 ± 3.11% at 12 h), glutathione (33.81 ± 1.99% at 24 h), and glutathione-S-transferase (24.40 ± 2.65% at 6 h) activities in the liver of mice as compared with untreated control. Significant (P < 0.05) induction in SOD (50.04 ± 5.59% at 12 h), CAT (62.22 ± 7.50 at 72 h), glutathione (42.92 ± 2.28% at 24 h), and glutathione-S-transferase (46.65 ± 3.25 at 12 h) was observed in irradiated mice which were pre-treated with SQGD compared with only irradiated mice. Further, significant induction in ABTS(+) radicals (directly proportional to decrease mM Trolox equivalent) was observed in liver homogenate of H2 O2 treated mice which were found to be significantly inhibited in H2 O2 treated mice pre-treated with SQGD. Thus, it can be concluded that SQGD treatment neutralizes oxidative stress caused by irradiation not only by enhancing endogenous antioxidant enzymes but also by improving total antioxidant status of cellular system and thus cumulative effect of the phenomenon may contributes to radioprotection.

Consequences of lethal-whole-body gamma radiation and possible ameliorative role of melatonin

Gamma radiation induces the generation of free radicals, leading to serious cellular damages in biological systems. Radioprotectors act as prophylactic agents that are administered to shield normal cells and tissues from the deleterious effects of radiation. Melatonin synergistically acts as an immune-stimulator and antioxidant. We investigated the possible radioprotective role of melatonin (100 mg/kg i.p.) against lethal-whole-body radiation- (10 Gy) induced sickness, body weight loss, and mortality in rats. Results of the present study suggest that exposure to lethal-whole-body radiation incurred mortality, body weight loss, and apoptosis and it also depleted the immunity and the antioxidant status of the rats. Our results show that melatonin pretreatment provides protection against radiation induced mortality, oxidative stress, and immune-suppression. The melatonin pretreated irradiated rats showed less change in body weight as compared to radiation only group. On the other hand, melatonin appeared to have another radioprotective role, suggesting that melatonin may reduce apoptosis through a caspase-3-mediated pathway by blocking caspase-3 activity.

The role of genetic polymorphisms in antioxidant enzymes and potential antioxidant therapies in neonatal lung disease

SIGNIFICANCE

Oxidative stress is involved in the development of newborn lung diseases, such as bronchopulmonary dysplasia and persistent pulmonary hypertension of the newborn. The activity of antioxidant enzymes (AOEs), which is impaired as a result of prematurity and oxidative injury, may be further affected by specific genetic polymorphisms or an unfavorable combination of more of them.

RECENT ADVANCES

Genetic polymorphisms of superoxide dismutase and catalase were recently demonstrated to be protective or risk factors for the main complications of prematurity. A lot of research focused on the potential of different antioxidant strategies in the prevention and treatment of lung diseases of the newborn, providing promising results in experimental models.

CRITICAL ISSUES

The effect of different genetic polymorphisms on protein synthesis and activity has been poorly detailed in the newborn, hindering to derive conclusive results from the observed associations with adverse outcomes. Therapeutic strategies that aimed at enhancing the activity of AOEs were poorly studied in clinical settings and partially failed to produce clinical benefits.

FUTURE DIRECTIONS

The clarification of the effects of genetic polymorphisms on the proteomics of the newborn is mandatory, as well as the assessment of a larger number of polymorphisms with a possible correlation with adverse outcome. Moreover, antioxidant treatments should be carefully translated to clinical settings, after further details on optimal doses, administration techniques, and adverse effects are provided. Finally, the study of genetic polymorphisms could help select a specific high-risk population, who may particularly benefit from targeted antioxidant strategies.

Modulation of radiation-induced alterations in oxidative stress and cytokine expression in lung tissue by Panax ginseng extract

We investigated the modulating effect of Panax ginseng extract (PGE) on radiation-induced lung injury (RILI) by measuring early changes in oxidative stress levels, cytokine expression, and the histopathology of mouse lung tissue treated with high dose of X-ray radiation. The mice were pretreated with 25, 50, and 100-mg/kg doses of PGE orally for four consecutive days, and their thoraces were then exposed to 15-Gy X-ray radiation 1 h after the last administration of PGE on day 4. The pretreatments with 50 and 100 mg/kg PGE led to significant reductions in the elevation of lipid peroxidation levels at 2 and 10 days, respectively, after irradiation. The mice pretreated with PGE exhibited dose-dependent reductions in the irradiation-induced production of tumor necrosis factor α and transforming growth factor β1 cytokines 10 days after irradiation, with these reductions nearly reaching the control levels after the 100-mg/kg dose. Furthermore, together with providing significant protection against reductions in catalase activity and glutathione content, pretreatment with 100 mg/kg PGE resulted in a marked attenuation of the severity of inflammatory changes in lung tissue 10 days after irradiation. A high pretreatment dose of PGE may be a useful pharmacological approach for protection against RILI.

Possible modulating impact of glutathione disulfide mimetic on physiological changes in irradiated rats

Glutathione disulfide mimetic (NOV-002) is a complex of oxidized glutathione (GSSG) formulated with cisplatin at approximately 1000:1 molar ratio. Cisplatin serves to stabilize GSSG but does not assert any therapeutic effect. The objective of this study is to evaluate the impact of NOV-002 on hematological suppression, excessive free radical damage and DNA fragmentation in splenocytes, and metabolite disorders in whole-body γ-irradiated rats. The obtained data revealed that rats treated with 25 mg kg(-1) NOV-002 injected intraperitoneally (i.p.) for 5 days after whole-body γ-irradiation (IR) at 6.5 Gy attenuated the decrease of red blood cells, platelets, total white blood cells, absolute lymphocytes and neutrophils counts, hematocrit value, and hemoglobin content. NOV-002 treatment inhibits serum advanced oxidation protein products, malondialdehyde concentrations as well as cholesterol, triglycerides, urea, and creatinine levels, while enhances glutathione content and superoxide dismutase activity and improves DNA fragmentation in splenocytes. These findings provide a better understanding of the NOV-002 modulating impact in whole-body γ-rays-induced hematological toxicities, oxidative stress, and biological disturbances in γ-irradiated rats and could enhance the tolerance to high doses of ionizing IR utilized in radiotherapy.

Synthesis and structural characterization of dioxomolybdenum and dioxotungsten hydroxamato complexes and their function in the protection of radiation induced DNA damage

The synthesis and structural characterization of two novel dioxomolybdenum(VI) (1) and dioxotungsten(VI) (2) complexes with 2-phenylacetylhydroxamic acid (PAHH) [M(O)2(PAH)2] [M = Mo, W] have been accomplished. The dioxomolybdenum(VI) and dioxotungsten(VI) moiety is coordinated by the hydroxamate group (-CONHO(-)) of the 2-phenylacetylhydroxamate (PAH) ligand in a bi-dentate fashion. In both the complexes the PAHH ligand is coordinated through oxygen atoms forming a five membered chelate. The hydrogen atom of N-H of the hydroxamate group is engaged in intermolecular H-bonding with the carbonyl oxygen of another coordinated hydroxamate ligand, thereby forming an extended 1D chain. The ligand as well as both the complexes exhibit the ability to protect from radiation induced damage both in CTDNA as well as in pUC19 plasmid DNA. As the damage to DNA is caused by the radicals generated during radiolysis, its scavenging imparts protection from the damage to DNA. To understand the mechanism of protection, binding affinities of the ligand and the complex with DNA were determined using absorption and emission spectral studies and viscosity measurements, whereby the results indicate that both the complexes and the hydroxamate ligand interact with calf thymus DNA in the minor groove. The intrinsic binding constants, obtained from UV-vis studies, are 7.2 × 10(3) M(-1), 5.2 × 10(4) M(-1) and 1.2 × 10(4) M(-1) for the ligand and complexes 1 and 2 respectively. The Stern-Volmer quenching constants obtained from a luminescence study for both the complexes are 5.6 × 10(4) M(-1) and 1.6 × 10(4) M(-1) respectively. The dioxomolybdenum(VI) complex is found to be a more potent radioprotector compared to the dioxotungsten(VI) complex and the ligand. Radical scavenging chemical studies suggest that the complexes have a greater ability to scavenge both the hydroxyl as well as the superoxide radicals compared to the ligand. The free radical scavenging ability of the ligand and the complexes was further established by EPR spectroscopy using a stable free radical, the DPPH, as a probe. The experimental results of DNA binding are further supported by molecular docking studies.