The seaweed Ecklonia cava, a brown algae abundant in JeJu Island, South Korea, has large amounts of the polyphenol compound phloroglucinol (PG, 1,3,5-trihydroxybenzene), which has been proposed to exert interesting biological properties including antioxidant and radioprotective effects against ionizing radiation-induced damages in various cells and tissues. To identify antioxidant and radioprotective effects of PG in skin tissues, we exposed mice to 8.5 Gy whole body irradiation (WBI) at day 6 after depilation with and without PG treatment. In PG treated cases, PG was applied twice, once at 17.8 hours before and then at the time of WBI. At 8 hours after WBI, a reduction in the formation of thiobarbituric acid-reactive substrates (TBARS) was observed in the PG treated group. Upon western blot analysis, PG treatment overexpressed the MnSOD, catalase, and GPx-1, although the difference was not significant. In parallel with the results of western blot analysis, the percentage of MnSOD-and catalase-positive cells was significantly increased at 8 and 24 hours after WBI, while no significant difference was observed over 48 hours in PG treated skins. Moreover, PG treatment increased the percentage of Ki-67 positive cells compared with that of irradiated only mice at 8 hours after WBI. Our results suggest that PG is effective at attenuating oxidative stress, and that the promotion of antioxidant enzymes such as MnSOD and catalase may be an important aspect for its radioprotection in skin.

Sasa quelpaertensis Nakai is a type of edible bamboo grass distributed on Jeju Island, Korea. S. quelpaertensis has been used as afolk medicine for treatment of a variety of ailments. It has been reported to present biological effects, including anti-inflammatory and antioxidant effects. In this study, we demonstrate that S. quelpaertensis Nakai extract (SNE) rescues immunocytes from gamma radiation-induced apoptosis and oxidative DNA damage. We examined the cytotoxicity, cell proliferation, DNA damage, apoptosis, and generation of reactive oxygen species (ROS) in mice given SNE for 45 days in immune cells. To determine the splenocytes protection capability of SNE, gamma-ray was irradiated to the whole body of C57BL/6 mice. Our results suggest that SNE stimulated the proliferation of splenocytes without cytotoxic effects. In addition, SNE not only decreased DNA damage but also reduced apoptosis of splenocytes, and attenuated the production of ROS generation in hydrogen peroxide-induced splenocytes. Therefore, SNE can protect against gamma radiation-induced damage in mice.

Our previous research on sulfated polysaccharide purified from Ecklonia cava, a brown alga found in Jeju island, Korea, showed that sulfated polysaccharides modulate the apoptotic threshold of intestinal cells, thereby preventing intestinal damage caused by ionizing radiation. In this study, we investigated the ability of sulfated polysaccharide to augment restoration of small intestinal stem cells from γ-ray-induced damage. In our results, sulfated polysaccharide treatment increased the numbers of Ki-67-positive cells as well as inducible nitric oxide synthase (iNOS)-expressing cells in the small intestine compared with those of irradiated only mice. Meanwhile, exposure to irradiation increased the number of paneth cells, which are frequently associated with intestinal inflammation, whereas sulfated polysaccharide treatment reduced the number of paneth cells in the small intestinal crypt. Conclusively, our data suggest that reduction of iNOS-expressing cells and paneth cells in sulfated polysaccharide-treated mice contributes to the inhibition of radiation-induced intestinal inflammation.

Vanadium, a dietary micronutrient, has been reported to present interesting biological and pharmacological properties, including superoxide and nitric oxide scavenging effects. Low-dose ionizing radiation (LDR) is known to damage DNA and cause apoptosis of peripheral immunocytes by producing reactive oxygen species (ROS). The aim of this study was to elucidate the capacity of immune activation of Jeju water containing vanadium on immunosuppression caused by LDR. We examined the ROS production, DNA damage, cell apoptosis and proliferation of peripheral immunocytes in irradiated mice drinking different concentrations for 90 days; V0 (vanadium 0㎍/L, control), V1 (vanadium 15～20㎍/ L) and V2 (vanadium 20∼25㎍/L). Compared to V0 control where level of ROS showed tendency to increase, the ROS production was attenuated in peripheral immunocytes of irradiated mice drinking V1 and V2. DNA damage of peripheral immunocytes triggered by LDR significantly increased in mice drinking V0 compared to non-irradiated control, whereas V1 and V2 dramatically induced remission of DNA damage. On the observation of apoptosis of peripheral immunocytes, V1 and V2 showed the potency to reduce the number of apoptotic cells. On the other hand irradiated mice drinking V0 exhibited raised number of apoptotic cells. From the results obtained, we speculated that Jeju water containing vanadium (V1 and V2) has a potential role in decreasing DNA damage and apoptosis of immune cell by inhibiting ROS production. Consistent with this, Jeju water containing vanadium (V1 and V2) exhibits a capacity to enhance cell proliferation of peripheral immunocytes, which is suppressed by LDR as shown in V0 control. Collectively, Jeju water containing vanadium reduced DNA damage and apoptosis and induced the stimulatory potential on immunocytes. These results suggest that Jeju water containing vanadium sustained immune activities under immunosuppression caused by LDR.