| Red seaweed Bangia fusco-purpurea,belongs to Bangia species,is widely distributed in Fujian and Guangdong coastal areas of China.Recently,as an important commercial seaweed,B.fusco-purpurea has been abundantly cultivated in Putian City of Fujian province and proposed to be superior to Porphyra sp.in nutritional value and taste.B.fusco-purpurea contains extremely abundant natural active compounds.Among these compounds,polysaccharide is considered to be one of the main components which are responsible for its physiological bioactivity.In this study,we firstly extracted and purified the polysaccharide fractions from B.fusco-purpure,and subsequently analyzed their basic chemical composition characteristics and in vitro immune-modulatory activities and antibacterial activities,and finally aimed to clarify the potential action mechanisms of consumption and medicinal properties of B.fusco-purpure.1.Crude polysaccharides were extracted from B.fusco-purpurea by hot water extraction and alcohol precipitation.After removal proteins,crude polysaccharides were applied to Dowex cation exchanges resins and Sephadex G75 gel filtration chromatography for the preliminary purification,and only one polysaccharide fraction was obtained and named BFP.Furthermore,BFP was loaded on DEAE cellulose 52 anion exchange chromatography,and finally three polysaccharide fractions(F1,F2 and F3)were purified.The yields of F1,F2 and F3 purified from 50 mg of BFP were 40.8 %,26.0%,and 6.8% respectively.2.The monosaccharide compositions and chemical composition of B.fusco-purpure polysaccharides were analyzed by high performance liquid chromatography(HPLC)and chemical methods,respectively.The composition analysis revealed that BFP and its factions F1,F2 and F3 were heteropolysaccharides.BFP was consisted of mannose,glucose,galactose,and Glucuronic acid as the major monosaccharide compositions together with a small amount of fucose,xylose,and arabinose.The molar of D-glucose was considered as 1,the molar ratio of monosaccharide compositions of BFP was 1.02: 1.00: 11.23: 1.14: 0.34: 0.35: 0.16.The contents of sulfated groups and proteins of BFP were determined to be 10.34% and 0.31%,respectively.F1 was mainly composed by mannose,glucose,galactose,arabinose,and fucose,and its molar ratio of monosaccharide compositions was determined to be 0.62: 1.00: 1.43: 0.51: 0.50.The sulfated groups and proteins contained in F1 were 2.73% and 0.15%,respectively.The basic monosaccharide compositions of F2 were mannose,glucose,galactose,and arabinose,and its molar ratio was 1.38: 1.00: 1.15: 1.12.The sulfated groups and proteins of F2 were evaluated to be 3.03% and 0.15%,respectively.F3 mainly contained mannose,glucose,galactose,arabinose,and Glucuronic acid,and its molar ratio was estimated to be 1.99: 1.00: 0.53: 2.29: 0.29.The sulfated groups and proteins of F3 were estimated to be 2.20% and 2.19%,respectively3.The immune-modulatory activities of polysaccharide fractions BFP,F1,F2 and F3 were investigated by using the in vitro immune activity analysis cell model(RAW264.7 macrophages).Our results revealed that BFP,F1,F2 and F3 significantly induced the production of Nitric Oxide(NO)and tumor necrosis factor-?(7)TNF-?(8)from RAW264.7 cells in the test concentration ranges(0~100 ?g/mL),and the activities of F1 and F2 to induce NO and TNF-? production in RAW264.7 cells were stronger than those of BFP and F3.Our results suggested that B.fusco-purpure polysaccharides BFP,F1,F2 and F3 possess potent immune-stimulatory activities to active RAW264.7 cells.4.Analysis using mitogen-activated protein(MAP)kinase and nuclear factor-kappa B(NF-?B)inhibitors suggested that the NF-?B,JNK MAPK,Erk MAPK and the NF-?B,Erk MAPK,p38 MAPK signal transduction pathways are mainly involved in BFP-induced NO and TNF-? production from RAW264.7 cells,respectively.The NF-?B,JNK MAPK and the JNK,Erk,p38 MAPK signal transduction pathways may be mainly involved in NO and TNF-? production induced by F1 severally in RAW264.7 cells.The activations of RAW264.7 macrophages by F2 and F3 are similar.Both of them are able to mediate RAW264.7 cells to release NO and TNF-? production via the NF-?B,JNK MAPK and NF-?B,JNK MAPK,Erk MAPK signal pathways,respectively.5.In present study,the in vitro direct antibacterial activities of polysaccharide fractions BFP,F1,F2 and F3 against 5 strains of common food borne pathogens including Escherichia coli,Staphylococcus aureus,Salmonella typhimurium,Vibrio parahaemolyticus,and Listeria monocytogenes were also evaluated.Our results demonstrated that at the concentration reached 125 ?g/m L,BFP showed significant inhibitory effect on S.aureus in a concentration dependent manner,and at the concentration reached 500 ?g/m L,obvious inhibition of BFP against E.coli was also observed.As the concentrations of F1 arrived at 125 ?g/m L,significant inhibitory activities against S.aureus were observed in concentration dependent manners.Only F2 at the concentrations reached 125 ?g/mL exhibited significant inhibitory effects on S.typhimurium in a concentration dependent manner.The results obtained in present study can provide basic information for the development and application of B.fusco-purpurea and its polysaccharides as functional food and natural antibacterial agent in food industry. |
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