| Gracilaria lemaneiformisbelongs to Rhodophyta(Rhodophyta)and Gracilaria genus(Gracilaria).In the eastern region of C hina,Gracilaria lemaneiformis has been used as an edible plant as well as a drug for a long time.Traditional C hinese medicine literature described it as a drug which was used to cure asparagus gall knot steam.And modern research indicated that it showed antioxidant,immunomodulatory and hypoglycemic effects in vitro or in vivo.The content of polysaccharides in Gracilaria lemaneiformis is so high that it has been used as a food grade agar source.Due to the excellent biological activities,polysaccharides from Gracilaria lemaneiformis have the potentiality to be applied in functional food.In this study,we extracted Gracilaria lemaneiformis polysaccharides using a variety of methods and studied their structure,anti-photoaging and immunomodulatory activities.The main results are as follows:(1)The traditional water extraction,acid extraction and enzymatic extraction were used in this study.The yield of polysaccharides extracted using citric acid was 27.66 + 0.49%,indicating it was the highest among those polysaccharides.Total sugarcontent,protein content,sulfates content and uronic acids content of the polysaccharides were 62.24 + 1.09%,1.54±0.15%,16.74±0.11% and 6.25±0.72%,repectively.Phenolics were not detected.Average molecular weight of the polysaccharides was 48214 Da.the polysaccharides were consist of arabinose,fucose,xylose,mannose,glucose and galactose at a mole percent of 0.32%,0.45%,5.91%,0.75%,34.23% and 57.96%.Content of(1?2)and(1?4)glycosidic bondthe polysaccharides was 6.67%,while contents of(1?6)glycosidic bond and(1?3)glycosidic bond were 27.73% and 65.60%,respectively.(2)DEAE-Sepharose fast flow chromatography was used to separate and purify the polysaccharides.Five fractions were obtained and named as GLP-1,GLP-2,GLP-3,GLP-4 and GLP-5,respectively.The Congo-red analysis indicated that those five fractions had no helix conformation.The monosaccharide composition analysis showed that GLP-1 was mainly composed of glucose,while GLP-5 was mainly composed of galatose.Contents of glucose and galatose were 35.68% and 46.62%,respectively.GLP-3 and GLP-4 were consist of a large amount of galactose;while the contents of xylose and glucose were low.Periodate Oxidation analysis showed that GLP-1,GLP-3,GLP-4 and GLP-5 contained many(1?3)glycosidic bonds except GLP-2,which implied that GLP-2 might show some different characteristics.The galactose might mainly linked by(1?3)glycosidic bond because GLP-5 was consist of masssive(1?3)glycosidic bonds.(3)UVB induced cell photoaging mode l showed that crude Gracilaria lemaneiformis polysaccharides and purified polysaccharides components could not relieve the apoptosis of HaCaT cells induced by UVB at the concentrations of 0.5,1 and 2 mg/mL,indicating that Gracilaria lemaneiformis polysaccharides might have no direct effect on photoaging skin.(4)The mice photoaging model induced by UVB showed that Gracilaria lemaneiformis polysaccharides could alleviate the skin structure damage caused by the UVB and prevent the excessive increase of epidermis and dermis thickness of skin.The oxidative stress was alleviated in treated photoaging mice.Besides,Gracilaria lemaneiformis polysaccharides had weak water holding effect on the photoaging mice.O n the other hand,Gracilaria lemaneiformis polysaccharides alleviated the immune suppression in mice photoaging phenomenon by improving the thymus index,spleen index and controling immune serum cytokine levels.(5)Among Gracilaria lemaneiformis polysaccharides fractions,GLP-2 contributed to the immunomodulatory activity mostly.GLP-2 could not only promote the proliferation of RAW 264.7 cells,but also promote the secretion of cytokines.Q-RTPCR tesets showed that GLP-2 promoted the secretion of cytokines by promoting the cytokine gene expression.(6)The repeat unit of GLP-2 was as follows:?6)-Glcp-(1?4)-Glcp-(1?4)-Galp-(1?4)-Galp-(1?3,6)-Galp-(1?6)-Galp-(1?Xylp-(1? linked with ?3,6)-Galp-(1? by O-3 linkage. |
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