Structural Characterization And Radioprotection Of Polysaccharides From The Root Of Angelica Sinensis (Oliv.) Diels

Aim When ionizing radiation penetrates living tissues or cells,the constituent high-energy particles and electromagnetic radiation usually transfer energy to the biomolecules,break chemical bonds of biologically macromolecules.Most of the radiation induced damage of biomolecules in living systems is induced by secondary reactions caused by the free radicals.Danggui,the root of Angelica sinensis(Oliv.)Diels(Umbelliferae),has been traditionally applied to the treatment of anemia,cardiovascular and gynecological diseases in China and some other Asian countries.At present,researches on Angelica sinensis were focused on biological activities of crude polysaccharides,however,up to now,no detailed investigation has been conducted on radioprotection in vivo and in vitro of different polysaccharides with clear structural features isolated from the root of Angelica sinensis.In the present study,we prepared polysaccharides from the root of Angelica sinensis,determined their chemical features,and investigated the protective potential of two homogeneous polysaccharides on radiation damage induced by gamma-irradiation in vivo and in vitro.Methods(I)The root of A.sinensis extracted with ethanol and then the residues were decocted 3 times with distilled water at 100?,dialyzed against distilled water for 3 days,thawed and centrifuged to remove insoluble materials and then the supernatant was concentrated and lyophilized to give crude polysaccharides.The crude polysaccharides were dissolved in distilled water and applied to a DEAE sephadex A-25 column to get four polysaccharide fractions(APS-0,APS-1,APS-3 and APS-5),and detected their radioprotection in mice after irradiation.(2)APS-1 and APS-3 were further fractionated by Superdex-200 and get homogeneous polysaccharide APS-1 a and APS-3 a.(3)The contents of carbohydrates,molecular weight,optical rotation and uronic acid content were determined with the phenol-sulfuric acid assay,carbazole method,HPSEC and polarimeter,respectively.(4)Analysis of monosaccharide composition by GC-MS,NMR and methylation analysis.(5)We determined the effects of APS-1a and APS-3a on the cell vitality and the apoptosis rate of irradiated AHH-1 cell.(6)We determined the effects of APS-1a and APS-3a on peripheral blood counts,micronucleus assay and cellularity of bone marrow cells in mice.(7)We determined the average survival day of irradiated mice at lethal dose.Results and Conclusion(1)APS-1 ? APS-3 are two parts of the anti-radiation activity.APS-la and APS-3a were eluted as a single peak in HPSEC,which suggested they were homogeneous polysaccharides.(2)APS-1a(molecular weight 49.0kDa)was composed of arabinose,glucose and galactose in a relatively molar percentage of 27.67%,14.98%and 57.34%,respectively.APS-1a mainly consisted of 1-ARA,135-ARA,15-ARA,136-GAL,1-GAL,16-GAL,14-GAL,1-GLC and 14-GLC.(3)APS-3a(molecular weight 65.4kDa)was composed of arabinose,glucose and galactose in a relatively molar percentage of 6.5%,84.54%and 8.96%,respectively.APS-la mainly consisted of 16-GAL,136-GAL,1-ARA,14-GLC and 16-GLC?(4)Bioactivity analysis showed that APS-1a and APS-3a increased peripheral thymus and spleen indexes,WBC,RBC and the cellularity of bone marrow cells,and protected mice against radiation-induced micronucleus formation in bone marrow,suggesting that polysaccharides could be used as radioprotective agents,especially for promoting bone marrow hematopoiesis.APS-1a and APS-3a can increased cell viability and reduce the apoptosis AHH-lcell after irradiation,and promote the proliferation of mesenchymal stem cells.APS-1a and APS-3a with different structure character have a significant contribution to reduce the hematopoiesis damage induced by whole body irradiation.The mechanisms related to the effects of APS on hematopoiesis in irradiated mice,and the relationship between structure and radioprotective activity will require further studies.