Extraction, Antioxidant Activity And Preparation Of Polysaccharide/Mesoporous Silica Nanoparticles From Dendrobium Candidum

Dendrobium candidum(Dendrobium candidum Wall.ex Lind1)is a valuable traditional Chinese medicine.The polysaccharide is the main medicinal active ingredient of Dendrobium candidum.Reserch on the extraction,quality evaluation,and biological activity of polysaccharide is significant for the quality control and application of Dendrobium candidum.In this paper,the polysaccharides of Dendrobium candidum were extracted by enzymatic hydrolysis of Dendrobium candidum.The polysaccharides of Dendrobium candidum with different molecular weight were obtained by fractional alcohol precipitation.The polysaccharides of Dendrobium candidum were analyzed and identified.The differences of Dendrobium candidum were compared.The antioxidant activity of Dendrobium candidum polysaccharides was studied,and the nanocrystallization process of polysaccharides from Dendrobium candidum was discussed,which provided scientific basis for improving the medicinal value of Dendrobium candidum.The extraction process conditions of Dendrobium candidum were extracted by water extraction with enzymatic hydrolysis.The extraction conditions and the microstructure of Dendrobium candidum were evaluated.The advantages and disadvantages of the two methods were compared.The results showed that the optimal extraction conditions were as follows: the ratio of material to liquid was 1:20,extraction temperature was 88?,extraction time was 2.5 h,extraction time was 2 times and extraction rate was 15.35%.The optimum extraction conditions were as follows: The amount of cellulose enzyme 28.00g/L,extraction temperature 41.30?,extraction time 3.38 h,pH5.14,polysaccharide extraction rate of 25.83%.By comparison,enzymatic extraction of Dendrobium candidum polysaccharide was more moderate,as well as the extraction rate was higher.From the microscopic morphology of polysaccharides,it can be seen that the polysaccharide morphology of Dendrobium candidum extracted by water extraction presented a cluster structure,and the polysaccharide morphology of Dendrobium candidum extracted by enzymatic hydrolysis presented fibrous structure,that was more favorable for absorption,indicating that enzymatic hydrolysis can be better protected Bioactivity of polysaccharides from Dendrobium candidum.The polysaccharide in Dendrobium candidum from different habitats were separated and indentified.Polysaccharide with 40% ethanol precipitation(DSP1),Polysaccharide with 70% ethanol precipitation(DSP2),Polysaccharide with 90% ethanol precipitation(DSP3)were obtained with ethanol precipitation at different concentration.DSP1,DSP2 and DSP3 were characterized by Fourier transform infrared spectroscopy(FTIR),X-ray diffraction(XRD)and three-dimensional fluorescence spectroscopy.The content of polysaccharide in Dendrobium candidum was determined by fluorescence spectroscopy.The results showed that the characteristic characteristic peaks of polysaccharides of Dendrobium candidum could be used as the basis for qualitative identification of polysaccharides.From the quantitative analysis,the polysaccharide content of Dendrobium candidum was different in habitats.The content of polysaccharide was the highest in 25.83% in Yunnan,the content of Polysaccharides in Dendrobium candidum was 22.15% in Zhejiang,and the polysaccharide content of Dendrobium candidum was 20.26% in Guangxi,indicating the habitat differenceThe antioxidant activity and DNA repair activity of polysaccharides DSP,DSP1,DSP2 and DSP3 were evaluated.The effects of reducing force,total antioxidant capacity,hydroxyl radical scavenging rate,DPPH radical scavenging rate,iron ion chelating force,H2O2 removal rate,superoxide anion radical scavenging ability and DNA damage protection were determined respectively.The results showed that the polysaccharide of Dendrobium candidum presented strong antioxidant ability,and had some protective and repair effect on DNA damage.The order of antioxidant capacity was DSP3> DSP2> DSP1> DSP.MSN-DOP was prepared by solution diffusion method using the mesoporous silica nanoparticles(MSN)as carrier and Dendrobium polysaccharide(DOP)as model drug.Field emission scanning electron microscopy(FESEM)and transmission electron microscopy(TEM)were used to observe the microstructure of MSN-DOP,Fourier transform infrared spectroscopy(FT-IR)and differential scanning calorimetry(DSC)were used to characterize MSN-DOP,so that the structure-activity relationship of drug-loaded nanoparticles was established.The in vitro release behavior of drug-loaded nanoparticles and the antioxidant activity of drug-loaded nanoparticles were investigated.The results showed that the morphology of MSN-DOP was regular and uniform size,and the dispersion was uniform.FT-IR and DSC showed that DOP was loaded in MSN mesoporous with amorphous state loading,leading to a good sustained-release effect.The bioactivity test showed that the antioxidant activity,protective and repairing effect of DNA damage of DOP loaded nanoparticles,was significantly higher than that of DOP.The results show that the polysaccharide loaded nanoparticles could enhance the bioavailability of Polysaccharides from Dendrobium candidum,providing the scientific basis for the potential application of Dendrobium candidum.