Study On The Compound Of Astragalus Polysaccharide-nano Selenium Complex And Its Toxicity To HepG2 Cells

In this study,two novel types of selenium nanoparticles had been synthesized in an aqueous solution with sodium selenite and vitamin C by using polysaccharides from Astragalus membranaceus,and their surface characteristics and anti-tumor activity in vitro were studied,which provided theoretical basis for seeking new antitumor drugs.In the redox system of sodium selenite and vitamin C,two kinds of astragalus polysaccharides with different molecular weights were used as stabilizer and dispersant to compound selenium nanoparticles with good dispersity and stability.Firstly,two kinds of astragalus polysaccharides nano-selenium were characterized.The results showed that when the molar ratio of vitamin C to sodium selenite was 4:1,the concentrations of low-molecular-weight astragalus polysaccharides(LAPS:2.1 × 103 Da)and high-molecular-weight astragalus polysaccharides(HAPS:1.61×106 Da)were 2 mg/mL,and the mass ratios of polysaccharides to sodium selenite were 20:1 and 15:1,respectively,the solution was orange-red,showing a uniform spherical structure,and could be stored in the dark place of refrigerator at 4℃ for 35 days without precipitation.In addition,the particle sizes of low-molecular-weight astragalus polysaccharide nano-selenium(LAPS-SeNPs)and high-molecular-weight astragalus polysaccharide nano-selenium(HAPS-SeNPs)were 35.30 nm and 62.10 nm,respectively,and the potentials were-37.08 mV and-25.36 mV,respectively,by nano particle size analyzer and Zeta potential analyzer.The anti-tumor activities of LAPS-SeNPs and HAPS-SeNPs were tested on HepG2 cells in vitro.The results showed that the apoptosis of HepG2 cells induced by two kinds of astragalus polysaccharides nano-selenium was in a dose-dependent manner.And it was found that LAPS-SeNPs and HAPS-SeNPs made HepG2 cells undergo typical morphological changes of apoptosis such as volume reduction,nuclear pyknosis and cell fragmentation through inverted microscope and Hoechst 33258 staining.The Annexin V-FITC/PI double staining experiment showed that the cell viability of LAPS-SeNPs and HAPS-SeNPs decreased from 98.96%to 14.21%and from 98.46%to 34.70%respectively with the increase of the concentration of drug.Furthermore,the cellular reactive oxygen species experiment showed that the fluorescence intensity of HepG2 cells treated with LAPS-SeNPs and HAPS-SeNPs was obviously enhanced in a dose-dependent manner,and the reactive oxygen species level increased from 1.05%to 86.91%,and from 2.74%to 69.92%,respectively,indicating that reactive oxygen species,as a key medium,participated in the apoptosis induced by astragalus polysaccharide nano-selenium.The cell cycle distribution showed that the cell cycle of HepG2 cells was arrested in S phase and decreased in G0/G1 phase to varying degrees.In addition,JC-1 experiment showed that LAPS-SeNPs and HAPS-SeNPs could reduce the mitochondrial membrane potential of HepG2 cells.Western blot experiments confirmed that LAPS-SeNPs and HAPS-SeNPs induced down-regulation of anti-apoptotic protein Bcl-2 expression,up-regulation of pro-apoptotic protein Bax expression and promotion of Cytochrome C release in HepG2 cells,indicating that both LAPS-SeNPs and HAPS-SeNPs can accelerate cell apoptosis through mitochondrial pathway.These results show that LAPS-SeNPs and HAPS-SeNPs prepared with astragalus polysaccharides as stabilizer and dispersant have significant antitumor effect,which provide a theoretical basis for the development of novel drugs for the treatment of liver cancer.