Herbal Radioprotectors: A mini-review of the Current Status

Because of our increased dependency on the use of radiation in areas such as the food industry, agriculture, space exploration, diagnostics and treatment of various diseases including cancer, the possibilities of unnecessary exposure to ionizing radiation have considerably increased. Hence, there is a need to develop an effective radioprotective agent that can protect against the deleterious effects of ionizing radiation. So far, many synthetic and natural substances studied for use as radioprotectors have failed to reach clinics. Natural compounds are becoming more popular in radiation research due to their low toxicity, higher efficacy and cost-effectiveness. Plants and herbs contain a plethora of bioactive compounds having antioxidants, anti-inflammatory and immunostimulant properties which can act either in isolation or in combination to protect against the harmful effects of ionizing radiation This review mainly focuses on the radioprotective potential of various herbs and plants. The results obtained from various herbal extracts have shown protection against radiation-induced injuries in preclinical studies. This evaluation may help develop a potent radioprotector of desired efficacy.

Molecular Hydrogen as a Potential Clinically Applicable Radioprotective Agent

Although ionizing radiation (radiation) is commonly used for medical diagnosis and cancer treatment, radiation-induced damages cannot be avoided. Such damages can be classified into direct and indirect damages, caused by the direct absorption of radiation energy into DNA and by free radicals, such as hydroxyl radicals (•OH), generated in the process of water radiolysis. More specifically, radiation damage concerns not only direct damages to DNA, but also secondary damages to non-DNA targets, because low-dose radiation damage is mainly caused by these indirect effects. Molecular hydrogen (H2) has the potential to be a radioprotective agent because it can selectively scavenge •OH, a reactive oxygen species with strong oxidizing power. Animal experiments and clinical trials have reported that H2 exhibits a highly safe radioprotective effect. This paper reviews previously reported radioprotective effects of H2 and discusses the mechanisms of H2, not only as an antioxidant, but also in intracellular responses including anti-inflammation, anti-apoptosis, and the regulation of gene expression. In doing so, we demonstrate the prospects of H2 as a novel and clinically applicable radioprotective agent.

Ferulago Angulata as a Good Radioprotector against Genotoxicity

Introduction: Natural products can be used as radioprotector agents because of containing phenolic compounds and several flavonoids with antioxidant properties. When the normal cells are exposed to ionizing radiation, they generate free radicals and reactive oxygen species that can cause damage in DNA, which leads to cellular dysfunction or even cell death. However, it is necessary to identify new radioprotective agents to protect normal cells. Ferulago angulata (F.angulata), a medicinal plant, can be used as a new radioprotective agent. Purpose: The antioxidant activity of F.angulata was assayed using FRAP and DPPH methods. Then, the human blood samples were incubated with F.angulata at different concentrations (25, 50, 100 and 200 μM) and subsequently exposed to IR at a dose of 2Gy. The radioprotective effectof F.angulata on the exposed cells was assessed by micronucleus (MN) method. Also, biomarkers of oxidative stress in the exposed cells were evaluated by malondialdehyde (MDA) and superoxide dismutase (SOD) methods. Methods: The antioxidant activity of F.angulata was assayed using FRAP and DPPH methods. Then, the human blood samples were incubated with F.angulata at different concentrations (25, 50, 100 and 200 μM) and subsequently exposed to IR at a dose of 2Gy. The radioprotective effectof F.angulata on the exposed cells was assessed by micronucleus (MN) method. Also, biomarkers of oxidative stress in the exposed cells were evaluated by malondialdehyde (MDA) and superoxide dismutase (SOD) methods. Results: Our findings showed that F. angulata reduced the frequency of MN induced by IR in exposed cells. At 200μM concentration of F. angulata, maximum reduction in the frequency of MN (63.11%) was observed that demonstrated a high degree of radioprotection. Afterward, pretreatment at 200μM concentration of F.angulata inhibited oxidative stress in irradiated lymphocytes, leading to a reduction in MN frequency and MDA levels while SOD activity was enhanced in the exposed cells. Conclusion: F. angulata as a natural radioprotective agent can protect normal cells against reactive oxygen species and genetic damage induced by IR.

Hydrogen-rich water attenuates the radiotoxicity induced by tritium exposure in vitro and in vivo

Radionuclide tritium is widely used in the nuclear energy production industry and creates a threat to human health through radiation exposure. Herein, the radioactive elimination and radioprotective effect of hydrogen-rich water (HRW), a potential antioxidant with various medical applications, on tritiated water (HTO) exposure, was studied in vitro and in vivo. Results showed that intragastric administration of HRW effectively promoted the elimination of urinary tritium, decreased the level of serum tritium and tissue-bound tritium (OBT), and attenuated the genetic damage of blood cells in mice exposed to HTO (18.5 MBq/kg). Pretreatment with HRW effectively reduces tritium accumulation in HTO-treated human blood B lymphocyte AHH-1 cells. In addition, the anti-oxidative properties of HRW could attenuate the increased intracellular ROS (such as O2•-, •OH and ONOO−), resulting in reversing the exhaustion of cellular endogenous antioxidants (reduced GSH and SOD), decreasing lipid peroxidation (MDA), relieving DNA oxidative damage, and depressing cell apoptosis and cytotoxicity induced by HTO exposure. In conclusion, HRW is expected to be an effective radioactive elimination agent through the competition effect of isotope exchange or a radioprotective agent by scavenging free radicals induced by HTO exposure.