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It has been reported in our previous work that selenized Artemisia sphaerocephala polysaccharides (SeASPs) with the Se content range of 168–1703 μg/g were synthesized by using Na 2 SeO 3 /HNO 3 /BaCl 2 system. In the present work, the solution property of SeASP was studied by using size exclusion chromatography combined with multi angle laser light scattering (SEC-MALLS). A decrease in d f values indicated that SeASPs with different conformational features that were highly dependent on M W . SeASPs exhibited a more rigid conformation ( d f value of 1.29–1.52) in low molecular weight range ( M W of 1.026–1.426 × 10 4 g/mol) and compact spherical conformation in high molecular weight range ( M W of 2.268–4.363 × 10 4 g/mol). It could be due to the degradation of polysaccharide chains in HNO 3 , which was supported in monosaccharide composition analysis. Congo red (CR) spectrophotometric method and atomic force microscopy (AFM) results also confirmed the conformational transition and the evidence on the shape of the rigid chains. In vitro anti-tumor assays, SeASP 2 displayed greater anti-proliferative effects against three tumor cell lines (hepatocellular carcinoma HepG-2 cells, lung adenocarcinom A549 cells and cervical squamous carcinoma Hela cells) in a dose-dependent manner. This suggested that selenylation could significantly enhance the anti-tumor activities of polysaccharide derivatives in vitro. [ABSTRACT FROM AUTHOR]

Regioselective modification is an effective approach to synthesize polysaccharides with different structure features and improved properties. In this study, regioselective sulfation of Artemisia sphaerocephala polysaccharide (S RS ASP) was prepared by using triphenylchloromethane (TrCl) as protecting precursor. The decrease in fractal dimension ( d f ) values (1.56–2.04) of S RS ASP was observed in size-exclusion chromatography combined with multi angle laser light scattering (SEC-MALLS) analysis. Compared to sample substituted at C-6, S RS ASP showed a more expanded conformation of random coil, which was attributed to the breakup of hydrogen bonds and elastic contributions. Circular dichroism (CD), methylene blue (MB) and congo red (CR) spectrophotometric method and atomic force microscopy (AFM) results confirmed the conformational transition and stiffness of the chains after sulfation. S RS ASP exhibited enhanced antioxidant activities in the DPPH, superoxide and hydroxyl radical scavenging assay. Sulfation at C-2 or C-3 was favorable for the chelation which might prevent the generation of hydroxyl radicals. It concluded that the degree of substitution and substitution position were the factors influencing biological activities of sulfated polysaccharides. [ABSTRACT FROM AUTHOR]

The biological activities of sulfated polysaccharides are related to the substitution positions of functional groups. In this study, regioselective sulfation of Artemisia sphaerocephala polysaccharides (S RS ASP) was prepared by using triphenylchloromethane (TrCl) as protecting precursor. FT-IR spectra and X-ray photoelectron spectroscopy (XPS) showed that SO 3− group (S 6+ , high binding energy of 168.7 eV) was widely present in sulfated polysaccharides. 13 C NMR spectroscopy showed that C-2 and C-3 substitution was occurred but not fully sulfation. Meanwhile, C-6 substituted signals near 65 ppm were not observed. The degree of substitution varied from 0.44 to 0.63 in S RS ASP which could be attributed to the low reactivity at secondary hydroxyl. Monosaccharide composition result showed a decrease in the ratio of mannose/glucose, indicating the change of chemical composition in sulfated polysaccharides. In size-exclusion chromatograph analysis, a decrease in molecular weight and broadening of molecular weight distribution of sulfated polysaccharides was also observed. It could be attributed to the hydrolysis of polysaccharide in the sulfated reaction. [ABSTRACT FROM AUTHOR]

Abstract: Selenium (Se) is an essential trace element for human beings and many other forms of life. Organic Se from natural foods has higher bioavailability and is safer than inorganic Se species. In the present study, selenium-containing derivatives of Artemisia sphaerocephala polysaccharide with the highest Se content of 1703μg/g were synthesized using H2SeO3/HNO3 and BaCl2 as a catalyst. The effects of the ratio of HNO3 concentration and reaction temperature were investigated. Results of Raman and 13C NMR spectroscopy indicated that C-6 substitution was predominant in selenized polysaccharide. A sharp decrease in M w was observed in the selenized reaction due to the acid environment. The in vitro antioxidant results suggest that selenium-containing polysaccharide should be applied as a novel selenium source in dietary supplements, with potent antioxidant properties. [Copyright &y& Elsevier]

Abstract: Sulfated polysaccharides exerted potent biological property which was relative to degree of sulfation (DS), M w, substitution position and chain conformation. In the present study, sulfated derivatives of Artemisia sphaerocephala polysaccharide (ASP) with different DS were synthesized by chlorosulfuric acid/pyridine method. FT-IR and 13C NMR analysis indicated that C-6 substitution was predominant in sulfated ASP (SASP) compared with other positions at C-2. In the sulfation reaction, a sharp decrease in M w was observed in SASP. The d f values from 1.96 to 2.77 indicated that the –SO3H groups leading to the relatively expanded conformation of SASP. Antioxidant assays showed that SASP had better antioxidant activities. The data obtained in vitro models indicated that high DS and moderate M w showed the best antioxidant capacities. [Copyright &y& Elsevier]