Extraction And Characterization Of Ginger Glycoprotein And Its Application As Curcumin-loading Nanoparticles

Ginger(Zingiber officinale Roscoe)is a kind of perennial herb with homology of medicine and food,which has antioxidant,anti-tumor,antibacterial,antiinflammatory and other pharmacological activities.Studies have shown that glycoproteins can bind to the receptors in cells,selectively located on the lesion site,and improve curative effect,so they have the potential to be used as targeted nanoparticle carriers.However,little information is available regarding the ginger glycoproteins.Free curcumin has the disadvantages of poor stability and low bioavailability,which greatly limits its application in food and drug fields.Based on this,ginger crude glycoprotein was extracted by alcohol precipitation method,and further purified by DEAE-52 and Sephadex G-100,to obtain GGP-1 and GGP-2 glycoprotein.The physicochemical and functional properties of GGP-1 and GGP-2 were preliminatively investigated by SDS-PAGE,automatic amino acid analyzer,infrared spectrum,circular dichroism(CD)and differential scanning calorimeter(DSC).On this basis,curcumin-loaded ginger glycoprotein nanoparticles were prepared by p H migration method.These results provide insight into understanding the structural characteristics of ginger glycoprotein and expanding its application.The main research contents and experimental results are summarized as follows:(1)Extraction and purification of ginger glycoprotein.The extraction conditions were as follows: solid-liquid ratio 1:15,extraction temperature 50℃,extraction time 4 h,free protein was removed by Sevage method,95% ethyl alcohol was deposited overnight,and small molecular impurities were removed by dialysis to obtain crude glycoprotein.The common absorption peaks of protein and polysaccharide were collected by DEAE-52 anion exchange column and Sephadex G-100 dextran gel column.Finally,the two components,i.e.,GGP-1and GGP-2 were obtained by dialysis and freeze drying.(2)Analysis of physicochemical and functional properties of ginger glycoprotein.SDSPAGE electrophoresis showed that both GGP-1 and GGP-2 were single bands with molecular weights of 25-35 KDa,composed of 17 common amino acids,among which glutamic acid and aspartic acid were the highest.The infrared spectrum scanning results showed that both GGP-1 and GGP-2 contained characteristic absorption peaks of glycoprotein.The UV spectra showed that the glycopeptide bond of the two components was O-glycopeptide bond.The results of circular dichroic chromatography showed that the both GGP-1 and GGP-2 were mainly β-folded.DSC results showed that the denaturation temperatures were 89.9℃ and93.9℃,respectively,and the denaturation enthalpy values were 101.3 J/g and 94.22 J/g,respectively.After acid-base treatment,the solubility,emulsification,water and oil retention and foaming ability of ginger glycoprotein were improved.The results of fluorescence spectra showed that after p H adjustment,the maximum emission wavelength of glycoprotein was increased to 336 nm,with λmax value presenting a red shift phenomenon.The p H change led to the development of tertiary structure of protein,with more hydrophobic regions being exposed.In addition,compared with soybean β-accompanying globulin and soybean globulin,glycoprotein had higher surface hydrophobicity(increased by 62.54%)after acid-base regulation,providing more binding sites for curcumin.(3)Preparation and characterization of curcumin-loaded ginger glycoprotein(GGP-2/Cur)nanoparticles.GGP-2,which has better functional properties such as emulsification and surface hydrophobicity than GCP-1,was used to prepare nanoparticles.Curcumin-loaded ginger glycoprotein nanoparticles were prepared successfully by p H migration method.The nanoparticles had a particle size of 170.87 nm,PDI 0.242,and zeta potential-19 m V.The DSC atlas showed that curcumin existed in amorphous form in the nano system and underwent thermal denaturation at 127.8℃.Transmission electron microscopy(TEM)showed that the nanoparticle did not break the membrane wall.The particle size was about200 nm with rounded spherical shape.The encapsulation rate of curcumin by nanoparticles was 79.62% and the drug loading was 5.92%.The bioaccessibility of curcumin after glycoprotein loading reached 43.24%.