Study On⁶⁰Co-γ Radioprotection By Fucoidan

Objective After the launch of China’s manned spacecraft, spacewalk and spacestation, the issues of contacting the radiation have attracted more attention than everbefore. Boosting the astronaut’s tolerance and protecting their health from the naturaland artificial radiation is the key to the success of aviation task, which have fueled highdemands for the radiation protection drug and health food products.[1].Fucoidan, alsoknown as fucose glycans, is a polysaccharide present in all brown algae. In addition tothe main component L-fucose and sulfate, it also contains galactose, xylose, mannose,glucose, uronic acid and protein. As a water-soluble polysaccharide, it is a polymerformatted with esterified polysaccharide and sulfuric acid-based compounds. Fucoidanhas a broad spectrum of biological activities, such as anti-clotting, anti-tumor, anti-virus,and chronic renal failure therapy[2-6]. The systemic research of Fucoidan on radiationprotection has not been documented. In this study, for the first time, we extracted theFucoidan from Laminaria japonica Aresch and measured the content of polysaccharideand sulfate, then observed the micronuleus rate of human peripheral bloodlymphocytes（PBLs） and effects on hematopoiesis in mice caused by⁶⁰Co-γ radiation.The results were presented in this thesis.Methods We extracted fucoidan from Laminaria japonica Aresch by extraction withAcid and precipitation with alcohol method, and determine the content of sulfate andtotal polysaccharides by phenol-vitriolic colorimetry and barium sulfate turbidity. Thenwe studied the radioprotective activity of fucoidan through observation of themicronuleus rate of human peripheral blood lymphocytes （PBLs） in vitro. The venousblood used in this study was drawn from4healthy male volunteers who have neverbeen exposed to harmful chemicals. PBLs were cultured in vitro by the routine small volumes blood culture method. The cultures were divided into three groups: controlgroup, irradiated group and treatment group. The changes of the lymphocyticmicronucleus rate were observed in three groups. BABL/C mice was irradiated afterintraperitoneal injection of fucoidan for3consecutive days. Spleen index （7.5Gy）, thenumber of colony forming units-spleen （7.5Gy）, peripheral hemogram （5.5Gy） andnucleated cell count in bone marrow （5.5Gy） were observedResults （20.52±0.57）％Polysaccharide content and sulfate content of FPS was（42.63±0.78）%and （20.52±0.57）%, respectively.1h before or after2Gy⁶⁰Co-γirradiation treated with fucoidan at the doses of80,160,320μg/ml all markedly reducedthe lymphocytic micronucleus rate. Mouse hematopoietic system in vivo experimentsshowed that for the treatment group, spleen index and the number of colony formingunits-spleen of all treatment groups significantly increased compared to control groupafter7.5Gy⁶⁰Co-γradiation. Treated with100mg fucoidan, the spleen size and structureof radiation group were significant differences from that of control group. After6.0Gy⁶⁰Co-γradiation, nucleated cell count in bone marrow of each treatment group wassignificantly higher than that of control group.30days after5.5Gyradiation,fucoidan significantly increased WBC of irradiated mice compared with the controlgroup.Conclusion Fucoidan can significantly inhibit the generation of lymphocytemicronuclei and micronucleated cells induced by⁶⁰Co-γray. Intraperitoneal injectionwith fucoidan before irradiation can effectively inhibit the injury to mice induced by⁶⁰Co-γ ray, such as injury of spleen, decline of spleen index as well as reduction of thenucleated cell count in bone marrow, hematopoietic stem cells and peripheral WBC.Studies showed that Fucoidan had a significant and dose-related protective effect on⁶⁰Co-γ ray-induced human peripheral blood lymphocyte micronucleus and micehemopoietic system.