| Russula cyanoxantha f.peltereaui,belonging to Russulaceae and Russula,is the petlu variation of Russula cyanoxantha(Schaeff.)Fr..It is commonly found in summer broad-leaved forests in Fujian and Jiangxi,and grows singly to in groups.Be rich in minerals,carbohydrates and protein,R.cyanoxantha f.peltereaui is one of the common edible fungi in China.In order to better develop and utilize R.cyanoxantha f.peltereaui resources,the extraction process of R.cyanoxantha f.peltereaui polysaccharides was optimized.Furthermore,the crude polysaccharides were separated to obtain purified polysaccharides,and the structure analysis and biological activity evaluation of the purified polysaccharides were carried out in this paper.The main research results were as follows:Response surface methodology(RSM) was used to optimize the ultrasound-assisted hot water extraction of R.cyanoxantha f.peltereaui polysaccharides.The optimal parameters was obtained as follows: temperature 85℃,liquid-solid ratio 1: 30,extraction time 180 min,ultrasonic time 25 min.With these treatments,the yield of crude polysaccharides reached9.03±0.97%.The crude polysaccharides were decolorized by D354 FD macroporous resin,deproteinized by Sevag method and precipitated by alcohol to obtain crude polysaccharides RCPs.Two homogeneous purified polysaccharides RCP-Ⅰ and RCP-Ⅱ and two macromolecular polysaccharides RCP-Ⅲ and RCP-Ⅳ were isolated from crude polysaccharides by using DEAE-52 cellulose ion exchange resin.The average molecular weights of RCP-Ⅰ and RCP-Ⅱ were 15138 Da and 16455 Da,respectively.The total sugar contents of RCPS,RCP-Ⅰ,RCP-Ⅱ,RCP-Ⅲ and RCP-Ⅳ were 89.22%,84.10%,85.96%,89.65% and 87.25%,respectively,and the protein contents were 6.09%,0.97%,0.24%,4.74% and 3.35%,respectively,without starch.RCPS,RCP-Ⅰ and RCP-Ⅳ contained a small amount of uronic acid(4.08%,1.36% and 2.29%),while RCP-Ⅱ and RCP-Ⅲ did not contain uronic acid.The structures of two homogeneous polysaccharides(RCP-Ⅰ and RCP-Ⅱ) with smaller molecular weights were characterized.According to the results,the main chain of the primary structure of RCP-Ⅰ is mainly composed of T-α-D-Glcp,T-α-D-Manp,T-β-L-Fucp,1,6-α-D-Galp and 1,2,3,6-β-D-Glcp composition.The primary structure of RCP-Ⅱ is mainly composed of T-α-D-Glcp,1,6-α-D-Galp,1,3-β-D-Glcp,T-α-L-Fucp,1,2-α-D-Manp,1,4-β-D-Galp,1,5-α-DAraf and 1,3,6-α-D-Manp.RCP-Ⅰ and RCP-Ⅱ have no triple helix structure.The surface morphology of RCP-Ⅰ was flat and smooth,while the surface morphology of RCP-Ⅱ was slightly rough.In vitro antioxidant and hypoglycemic tests showed that RCP-Ⅲ has the strongest reduction ability for ferric ions,followed by RCP-Ⅰ,RCPS and RCP-Ⅱ,while RCP-Ⅳ has no obvious reduction ability for ferric ions.However,RCP-Ⅳ had the strongest capture ability for ·OH,followed by RCP-Ⅱ,RCPS and RCP-Ⅰ.And RCP-Ⅲ had the weakest capture ability for ·OH,which might be caused by the differences in its structure.In addition,RCPs and RCPIII inhibited the activity of α-glucosidase and α-amylase,while the other purified polysaccharides had little inhibition on α-glucosidase activity,but had inhibition on α-amylase activity,and the inhibition rate was more than 50%.The inhibitory effects of the polysaccharides in vitro on tumor cells(Hep G-2,A549 and C666-1) showed that RCP-Ⅰ has the strongest anti-proliferation effect on tumor cells,followed by RCPs.The differences inhibition on tumor cells may be caused by structural differences.The immunoregulatory activity of the polysaccharides in vitro showed that R.cyanoxantha f.peltereaui polysaccharides at medium and high concentration(125-500 μg/mL) could not only enhance the phagocytosis ability of RAW264.7,but also increase the accumulation of NO,TNF-α and IL-6 by up-regulating the mRNA expression of iNOS,TNF-α and IL-6 to achieve the immunoregulatory effect.The results showed that R.cyanoxantha f.peltereaui polysaccharides have the potential to develop as functional factors,laying a certain foundation for the development of R.cyanoxantha f.peltereaui. |
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