Radiation Countermeasure Agents Research Articles

Development of radiation countermeasure agents for acute radiation syndromes.

The risk of internal and external exposure to ionizing radiation (IR) has increased alongside the development and implementation of nuclear technology. Therefore, serious security issues have emerged globally, and there has been an increase in the number of studies focusing on radiological prevention and medical countermeasures. Radioprotective drugs are particularly important components of emergency medical preparedness strategies for the clinical management of IR-induced injuries. However, a few drugs have been approved to date to treat such injuries, and the related mechanisms are not entirely understood. Thus, the aim of the present review was to provide a brief overview of the World Health Organization's updated list of essential medicines for 2023 for the proper management of national stockpiles and the treatment of radiological emergencies. This review also discusses the types of radiation-induced health injuries and the related mechanisms, as well as the development of various radioprotective agents, including Chinese herbal medicines, for which significant survival benefits have been demonstrated in animal models of acute radiation syndrome.

History of the research laboratory (medicinal and environmental toxicology) of the Military medical academy named after S.M. Kirov

This paper presents the history of the formation of the Research Department of the Experimental Medicine of the Research Center of the Military Medical Academy named after S.M. Kirov. The department is the only division of the academy that conducts experiments on animal models and field tests using laboratory animals in the interests of the Armed Forces of the Russian Federation. The paper also presents the main scientific achievements and development prospects of one of the three laboratories of the department Research Laboratory of Medicinal and Environmental Toxicology. In the direction of drug toxicology, the laboratory staff worked for 15 years in cooperation with the Scientific Center of the Russian Academy of Sciences (Pushchino) on the problems of perfluorocarbon-based blood substitutes. The results of the study helped deepen the understanding of the mechanisms of the physiological activity of perfluorocarbon emulsions and the expansion of the areas of clinical application of perftoran. The ecotoxicological direction of scientific research is represented by two large-scale cycles of scientific studies. The first was devoted to the medical support of oil refining to increase the protection of personnel who have been professionally exposed to toxic chemicals from the damage caused by chemical accidents. The second area of environmental research, which has been significantly updated in recent years, is devoted to the study of remote environmental and biomedical consequences of the use of chemical weapons by the US Army in the period from 1966 to 1972 in Vietnam. In recent years, the laboratory has focused on problems related to the search and development of new radiation countermeasure agents including biotechnological products and their compositions. Studies are also being conducted to improve the complex therapy of patients with sepsis, in which methods of extracorporeal blood purification are used in the treatment. These works are relevant for military and civilian health care and are performed in cooperation with the departments of the academy and several leading research organizations in St. Petersburg.

Challenges in the Design of Russian Radiation Protection Means in the Crisis Period: The Search for Key Directions of Development

This review discusses the development of radiation countermeasure agents (RCA) in its historical progression with the description of the key radiobiological concepts and drug classifications at various stages. The rationale for classifying antiradiation drugs into two main groups, the radioprotectors/oxidomodulators and radiomodifiers/cytomodulators, which act at the two stages of radiation damage development, namely, the radiochemical and cell death stages, respectively, is provided. One way to overcome the currently observed crisis in RCA development may prove to be bringing the known efficient RCA to approvement as medical preparations by using pharmacological approaches such as combining the preparations belonging to the two groups indicated and using preparations that are able to mitigate side effects. Out of the two possible scenarios of radiation disease in humans (exposure to cosmic radiation with a dense ionizing component and delayed radiation effects) most relevant in terms of RCA search, the latter has been considered with description of the results of experiments using a model of prolonged exposure of mice to gamma-irradiation with a small dose rate. Suggestions for possible prospective directions in the field of radiobiology are provided. The conclusion has been made that there are still a lot of unresolved issues concerning the sufficiency of medicines to ensure radiation safety under various scenarios of radiation incidents.

Repurposing sodium diclofenac as a radiation countermeasure agent: A cytogenetic study in human peripheral blood lymphocytes

We assessed the radioprotective and mitigative actions of sodium diclofenac, a non-steroidal anti-inflammatory drug using cultured human peripheral blood as a model. Both pre- and post-irradiation treatments with the drug reduced gamma radiation-induced formation of dicentric chromosome, cytochalasin-blocked micronuclei and γ-H2AX foci in human peripheral blood lymphocytes. This work supports the concept that sodium diclofenac may be a useful radiation countermeasure agent.

Protection to immune system of mice by N-acetyl tryptophan glucoside (NATG) against gamma radiation induced immune suppression

Immune system is a critical modulator of radiation-induced biological effects. In this study, we have assessed protective potential of N-acetyl tryptophan glucoside (NATG) pre-treatment in bone marrow of gamma radiation challenged mice. Isolated bone marrow cells were analysed for cell cycle progression by flow cytometry, while various pro-/anti-inflammatory cytokine profiles were performed by ELISA method. Overall radioprotective ability of NATG in ensuring protection against gamma radiation-induced damage was assessed by evaluating whole body survival analysis and haematological studies on 9 Gy irradiated mice with/without NATG pre-treatment. Results exhibited pre-treatment with 150 mg/kg b.wt oral administration of NATG as most effective against 9 Gy radiation exposure. Moreover, NATG showed non-interfering effect on cell cycle progression in pre-treated irradiated mice group when compared to radiation alone group. In addition, cytokine expression analysis indicated significant (p > 0.05) elevation in levels of IFN-γ, IL-2, IL-12, IL-13 and IL-17 in NATG pre-treated irradiated mice in comparison to radiation alone group. On the contrary, NATG pre-treatment was observed to alleviate levels of TNF-α and IL-10 significantly (p < 0.05) in radiated group as compared to only irradiated mice group. Furthermore, NATG pre-treatment to 9 Gy radiation exposed mice aided in restoring their haematological parameters in terms of haemoglobin counts, RBC counts, WBC counts, hematocrit levels, platelets and granulocyte levels in comparison to irradiated alone mice, thus enhancing their immune system and contributing towards a better survival against gamma radiation-induced deleterious effects. Conclusively, this study highlights the potential of NATG as a prospective radiation countermeasure agent against ionizing radiation-induced assaults to the immune system.

Epicatechin as a promising agent to countermeasure radiation exposure by mitigating mitochondrial damage in human fibroblasts and mouse hematopoietic cells.

Accidental radiation exposure that is due to a nuclear accident or terrorism using radioactive materials has severe detrimental effects on human health, and it can manifest as acute radiation syndrome depending on the dose and distribution of the radiation. Therefore, the development of radiation countermeasure agents is urgently needed to protect humans against radiation injury. Besides nuclear DNA, the mitochondria are important targets of ionizing radiation (IR) because these organelles generate reactive oxygen species (ROS). Recently, we revealed that mitochondrial ROS-activated cell signaling is associated with IR-induced tumor formation. Here, we investigated the effectiveness of ascorbic acid and epicatechin (EC) in scavenging ROS as radiation countermeasure agents by using human cells and mouse. Preradiation and postradiation treatments with EC mitigate ROS-mediated mitochondrial damage, IR-induced oxidative stress responses including reduction of superoxide dismutase activity, and elevated nuclear factor erythroid 2-related factor 2 expression, and they improve human fibroblast survival. As well as in vitro, EC mitigated ROS-mediated mitochondrial damage after exposure to IR in vivo in mouse platelets. Furthermore, oral administration of EC significantly enhanced the recovery of mouse hematopoietic cells from radiation injury in vivo. In summary, EC is a potentially viable countermeasure agent that is immediately effective against accidental IR exposure by targeting mitochondria-mediated oxidative stress.-Shimura, T., Koyama, M., Aono, D., Kunugita, N. Epicatechin as a promising agent to countermeasure radiation exposure by mitigating mitochondrial damage in human fibroblasts and mouse hematopoietic cells.

Targeting DNA Repair through Podophyllotoxin and Rutin Formulation in Hematopoietic Radioprotection: An in Silico, in Vitro, and in Vivo Study.

Drug discovery field has tremendously progressed during last few decades, however, an effective radiation countermeasure agent for the safe administration to the victims of radiation exposure is still unavailable. This multi-model study is aimed at elucidating the mechanistic aspects of a novel podophyllotoxin and rutin combination (henceforth referred as G-003M) in the hematopoietic radioprotection and its involvement in the DNA damage and repair signaling pathways. Using in silico study, we identified the binding sites and structural components of G-003M and validated in vitro. We further studied various in vivo endpoints related to the DNA repair and cell death pathways in mice pre-administered with G-003M, irradiated and subsequently euthanized to collect blood and bone marrow cells. In silico study showed the binding of podophyllotoxin to β-tubulin and presence of a functional hydroxyl group in the rutin, suggested their involvement in G2/M arrest and the free radical scavenging respectively. This experimentation was further validated through in vitro studies. In vivo mice studies confirmed that G-003M pre-administration attenuated DNA damage and enhanced repair after whole body exposure. We further noticed a decrease in the levels of γH2AX, p53BP1, and ATM kinase and an increase in the levels of DNA pk, Ku 80, Ligase IV, Mre 11, Rad 50 and NBS 1 in the blood and bone marrow cells of the G-003M pre-administered and irradiated mice. We noticed an overall increase in the pro-survival factors in the G-003M pre-treated and irradiated groups establishing the radioprotective efficacy of this formulation. The lead obtained from this study will certainly help in developing this formulation as a safe and effective radioprotector which could be used for humans against any planned or emergency exposure of radiation.

Radiation Countermeasures: Current Status

Deleterious effects of ionising radiation leading to significant morbidity and mortality have been studied elaborately. A range of synthetic, semisynthetic and herbal compounds have been screened as radiation countermeasure agents and a number of promising radiation countermeasure agents are under development. Amifostin is the only drug which has been approved by the United State Food and Drug Administration (US-FDA), but that too for use in a defined population under strict medical supervision. Granulocyte Colony Stimulating Factor/filgrastim, γ-tocotrienol, genistein are at an advanced stage of development and are tested on higher animal models as per required norms of FDA. Herbal compounds are also considered very safe and of high value as radiation countermeasure agents owing to various properties like antioxidant, immunomodulation activity etc. Histone deacetylase inhibitors such as Trichostatin A, Diallyl sulphide, Sulforaphane are being viewed as very promising radiomitigating agents by our laboratory and active research in the same direction is going on. Infusion of hematopoietic stem cells and growth factors are in practice as potent therapeutics. This review gives an overview on various radioprotectors, radiomitigators and therapeutic agents either available or under development currently.

Biological Radioprotection: Six Decades of Scientific Struggle

Welcome to this special issue on ‘biological radioprotection’ of Defence Life Science Journal (DLSJ). The journal is published by Defence Scientific Information &amp;amp; Documentation Centre (DESIDOC) on behalf of Defence Research and Development Organization (DRDO), Govt. of India. Biological radioprotection is an uncherris goal for radiation biologist at global scale. Despite six decade’s continuous efforts, global scientific community is still searching for a radiation countermeasure agent which can be used during radiation emergency scenario. Though, few radioprotective agents received IND status by US-FDA however, so far not a single drug is approved for human uses globally. The major obstacles to achieve biological radioprotection are i.e. variable severity of biological damage with different types of radiation and dose rate, differential RBE for low LET and high LET radiation, variable radiosensitivity of biological systems, unpractical time and drug therapeutic dose window and unacceptable toxicity at efficacious dose of a radioprotective agent, etc.

Emerging targets for radioprotection and radiosensitization in radiotherapy.

Radiotherapy is the biggest force acting behind cancer treatment, yet the vast majority of patients get only modest benefit. The successive failure of targeted therapies in radiotherapy lies in the non-discriminative killing of both normal and cancer cells. However, there is still a reason for optimism due to recent advancement made in cancer biology which unrevealed many new deregulated pathways in cancer and their response towards drug and radiation. In this review, we comprehensively discussed novel and promising druggable target which can be exploited for tumor radiosensitization in addition to normal tissue radioprotection in radiotherapy, for better tumor controllability and patient quality of life. In the last part, we also discussed the radiation countermeasure agents in brief.

In-vitro evaluation of rutin and rutin hydrate as potential radiation countermeasure agents

Background : DNA damage is one of the major consequences of radiaon exposure onto the biological systems. A series of compounds including flavanoids were found to render DNA protecon against radiaon damage. In this study we elucidated the potenal of run and r un hydrate to protect plasmid DNA against damage induced by irradiaon. Materials and Methods: DPPH and hydroxyl radical scavenging assays were performed to assess the anradical potenal of run and run hydrate. Absor pon measurements were performed to assess binding parameters of run and run hydrate with calf thymus (CT)-DNA. Plasmid relaxaon assay was performed to compare the radio protecve potenal of run and run hydra te against gamma irradiaon mediated oxidave damage of pET28 plasmi d DNA. Results: DPPH ·

NF-kB as a key player in regulation of cellular radiation responses and identification of radiation countermeasures.

Nuclear factor (NF)-κB is a transcription factor that plays significant role in immunity, cellular survival and inhibition of apoptosis, through the induction of genetic networks. Depending on the stimulus and the cell type, the members of NF-κB related family (RelA, c-Rel, RelB, p50, and p52), forms different combinations of homo and hetero-dimers. The activated complexes (Es) translocate into the nucleus and bind to the 10bp κB site of promoter region of target genes in stimulus specific manner. In response to radiation, NF-κB is known to reduce cell death by promoting the expression of anti-apoptotic proteins and activation of cellular antioxidant defense system. Constitutive activation of NF-κB associated genes in tumour cells are known to enhance radiation resistance, whereas deletion in mice results in hypersensitivity to IR-induced GI damage. NF-κB is also known to regulate the production of a wide variety of cytokines and chemokines, which contribute in enhancing cell proliferation and tissue regeneration in various organs, such as the GI crypts stem cells, bone marrow etc., following exposure to IR. Several other cytokines are also known to exert potent pro-inflammatory effects that may contribute to the increase of tissue damage following exposure to ionizing radiation. Till date there are a series of molecules or group of compounds that have been evaluated for their radio-protective potential, and very few have reached clinical trials. The failure or less success of identified agents in humans could be due to their reduced radiation protection efficacy. In this review we have considered activation of NF-κB as a potential marker in screening of radiation countermeasure agents (RCAs) and cellular radiation responses. Moreover, we have also focused on associated mechanisms of activation of NF-κB signaling and their specified family member activation with respect to stimuli. Furthermore, we have categorized their regulated gene expressions and their function in radiation response or modulation. In addition, we have discussed some recently developed radiation countermeasures in relation to NF-κB activation

Recent Patents in the Field of Radioprotector Development: Opportunities and Challenges

Ionizing radiation-induced Acute Radiation Syndrome (ARS) can be prevented/treated using radioprotective agents including; radioprotectors, radiomitigators and radio-therapeutics. Most of the radioprotective molecules currently being developed have emerged from classical drug discovery approaches and have certain shortcomings related to efficacy and toxicity. In order to overcome these issues, adoption of new target-based drug development approaches is required. Like other pharmaceutical drug development programs, patents are being used to protect the new radioprotective compounds that provide right of exclusivity to the inventors. In addition to patents, the FDA approval for safety and efficacy is required for the development of radioprotective drugs that is often being done under FDA's animal rule and requires huge amount of funding. However, radiation countermeasure agents considered emergency medicines and not carrying attractive revenue generation opportunities and are often granted 'orphan drug status'. Thus, pharma giants do not take much interest in such molecules that limit the funding options only to the government agencies, which in turn reduces the interest of researchers in this particular area. In addition to their emergency use, these agents could also be employed for clinical radiotherapy purposes and may provide reasonable incentive to the inventor. Thus, encouraging the development of new radioprotective agent with cutting-edge drug discovery approaches needs more public-private partnership ensuring affordable access; that may stimulate researchers to engage in the area of radioprotector development. This article attempts to cover information available so far on the products/patents/major compounds, known in this critical area of development, along with most relevant regulatory issues and future perspectives.

Cycloxygenase-2 (COX-2) - A Potential Target for Screening of Small Molecules as Radiation Countermeasure Agents: An In Silico Study

Cycloxygenase-2 (COX-2) - A Potential Target for Screening of Small Molecules as Radiation Countermeasure Agents: An In Silico Study

Cycloxygenase-2 (COX-2) - A Potential Target for Screening of Small Molecules as Radiation Countermeasure Agents: An In Silico Study

Cyclooxygenase-2 (COX-2) is well established for its role in inflammation, cancer and has also been reported to play a significant role in radiation induced inflammation and bystander effect. It has already been reported to have a role in protection against radiation induced damage, suggesting it to be an important target for identifying novel radiation countermeasure agents. Present study aims at identifying novel small molecules from pharmacopeia using COX-2 as target in silico. Systematic search of the molecules that are reported to exhibit radiation protection revealed that around 30% (40 in 130) of them have a role in inflammation and a small percentage of these molecules (20%; 8 in 40) are reported to act as non-steroidal anti-inflammatory drugs (NSAIDS). Docking studies further clarified that antiinflammatory compounds exhibited higher binding energy (BE). Out of 15 top hits, 14 molecules are reported to have anti-inflammatory property, suggesting the significant role of COX-2 in radiation protection. Further, Johns Hopkins Clinical Compound Library (JHCCL), a collection of small molecule clinical compounds, was screened virtually for COX-2 inhibition by docking approach. Docking of around 1400 small molecules against COX-2, leads to identification of a number of previously unreported molecules, which are likely to act as radioprotectors.

In vitro studies on radioprotective efficacy of silymarin against γ-irradiation

Purpose: Silymarin has been widely exploited for its hepatoprotective activities. This study aimed to evaluate the protective efficacy of silymarin against γ-radiation.Materials and methods: The radioprotective properties of silymarin were studied using different assays. Cytotoxicity of silymarin on Human embryonic kidney (HEK) cells was evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay. Protective efficacy against γ-radiation was assessed by studying reduction in micronuclei frequency and free radical generation using 2′,7′-dichlorodihydroflurescin diacetate (H2DCFDA). Radiation-induced apoptosis was estimated by Annexin V-PI (propidium iodide) analysis and cell cycle analysis. γ-radiation induced changes in mitochondrial membrane potential (MMP) and DNA damage was estimated employing flow-cytometry and comet assay respectively.Results: MTT assay and Annexin V-PI studies showed that pre-incubation of HEK cells with silymarin protected them from γ-irradiation. Significant reduction in apoptosis (76.36%) was observed. Silymarin also decreased the percentage of radiation-induced micronuclei (> 69%) (p < 0.05 ). Measurement of intracellular reactive oxygen species (ROS) by H2DCFDA revealed a reduction in ROS (21%) at 0.5 h. Cell cycle analysis revealed G1 block in the unirradiated control, which declined in the silymarin pretreated irradiated group (0.5 h). Silymarin treatment resulted in a significant increase in MMP (2 h) against the radiation control. Moreover, the presence of silymarin during irradiation significantly decreased the DNA damage (as measured by comet assay).Conclusions: Protection against radiation-induced cell-death and DNA damage by silymarin could be attributed to a reduction in ROS induced by γ-radiation. In vitro experiments on HEK cells explicitly prove that silymarin is a promising, effective and safe radiation countermeasure agent.

In vitro evaluation of antioxidant and radioprotective properties of a novel extremophile from mud volcano: implications for management of radiation emergencies

A thermophilic bacterium, designated as RH 127, was isolated from mud volcano (Baratang Islands) of Andaman region, India (12°07'N 92°47'E/12.117°N 92.783°E) for the first time. Biochemical tests and 16S rRNA gene sequencing indicate that it belongs to the genus Geobacillus. The strain showed 98% confirmed 16S rRNA gene sequence homology with Geobacillus toebii. The bacteria was extracted in various solvent systems and three different fractions prepared. In the present study, antioxidant and radioprotective activity of extracts (INM-7860, INM-7861, and INM-7862) of bacterium G. toebii (strain RH 127) were evaluated. The fractions were evaluated for their introspective comparison of the relative antioxidant efficiency. The antioxidative activities, DPPH radical scavenging effects, hydroxyl radical scavenging effects, membrane protection, antihemolytic activity, and linoleic acid degradation efficacies were assayed. INM-7861 and INM-7862 activated NF-κB expression, as evidenced by reporter assay studies, and thereby contributed to overall radioprotective effect. INM-7862 exhibited best results. This study explicitly shows that the extracts of G. toebii have immense potential as a radiation countermeasure agent.

Contemporary Radiation Countermeasure

Radiation countermeasures have been investigated for decades, but the search for ideal protective agents for use prior to or after irradiation still continues. This review focuses on agents that have demonstrated as potential as in vivo countermeasure agents and may subsequently be effectively used in human beings. Such agents are categorised as radioprotectors, radiation mitigators, or therapeutic agents dependening upon their time of administration. These protective or mitigating agents are designed to reduce inadvertent damage to normal tissue caused by radiation. These interventions function via various mechanisms of action ranging from modulating signalling pathways to inhibiting cell death, cytokines, and growth factor. Many agents demonstrated promising results in murine models and are being tested in human beings. Amifostine, and curcumin have shown radioprotection, while genistein, palifermin, and halofuginone have been shown to alleviate the side effects in patients undergoing radiotherapy. Though these compounds show some promise as radiation countermeasure agents, there are several associated limitations and the search for perfect agents still continues.

Radiation countermeasure agents: an update

Importance of the field: Ionizing radiation (IR) can produce deleterious effects in living tissues, leading to significant morbidity and a potentially fatal illness affecting various organs dose-dependently. As people may be exposed to IR during cancer radiotherapy or as a result of a radiological/nuclear incident or act of terrorism, the danger of irradiation represents a serious public health problem. At present, however, this problem remains largely impervious to medical management. There is, therefore, a pressing need to develop safe and effective radiation countermeasure (RC) agents to prevent, mitigate or treat the harmful consequences of IR exposure.Areas covered in this review: Recent advances in the search for RC agents as reflected by the relevant patent literature of the past five years along with peer-reviewed publications are surveyed.What the reader will gain: A total of 43 patents, describing ∼ 38 chemically diverse compounds with RC potential are analyzed. These include antioxidants capable of scavenging IR-induced free radicals, modulators of cell death signaling or cell cycle progression, cytokines or growth factors promoting tissue repair and inhibitors of inflammatory cytokines.Take home message: Several of these RC candidates appear promising, including at least two that are undergoing evaluation for fast-track clinical development.