Changhai Jin

Characterization, antioxidant activity and hepatoprotective effect of purple sweetpotato polysaccharides.

In this study, three kinds of polysaccharides (named PSWP, PSAP-1 and PSAP-2) were successively isolated from purple sweetpotato tubers by hot water, 0.5M and 2M sodium hydroxide solutions. The characterization, in vitro antioxidant activity and in vivo hepatoprotective effect of these polysaccharides were investigated. Results indicated that PSWP, PSAP-1 and PSAP-2 were all β-type polysaccharides containing different contents of uronic acid, protein and polyphenol. Both PSWP and PSAP-1 were composed by arabinose, glucose and galactose, whereas PSAP-2 was consisted of arabinose, rhamnose and glucose. All the polysaccharides exhibited moderate 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and reducing power. As compared with tetrachloromethane (CCl4) treatment group, mice administrated with PSWP, PSAP-1 and PSAP-2 exhibited decreased levels of serum enzymes (alkaline phosphatase, alanine transaminase and aspartate transaminase) and hepatic lipid peroxidation, whereas increased levels of hepatic antioxidant enzymes (superoxide dismutase, catalase and glutathione peroxidase) and non-enzymatic antioxidant (glutathione). Notably, PSWP displayed stronger antioxidant activity and hepatoprotective effect than PSAP-1 and PSAP-2. The hepatoprotective effect of PSWP was comparable to positive standard of silymarin. Our results suggested polysaccharides from purple sweetpotato possessed potential antioxidant activity and protective effect against CCl4-induced acute liver damage.

Recent advances in flavonoid-grafted polysaccharides: Synthesis, structural characterization, bioactivities and potential applications

Plant derived flavonoids have been demonstrated to possess many valuable biological functions. In recent years, flavonoids have been successfully conjugated with polysaccharides through different graft copolymerization methods including chemical coupling, enzyme catalysis, free radical mediated grafting, and acid catalyzed condensation reactions. The successful grafting of flavonoids onto polysaccharides can be confirmed by several instrumental methods. The conjugation of flavonoids can significantly improve the antioxidant, antimicrobial, antitumor, hepatoprotective and enzyme inhibition properties of polysaccharides. Moreover, the applications of polysaccharides in food and pharmaceutical industries can be greatly broadened by grafting with flavonoids. Flavonoid-grafted polysaccharides can be developed as films for active packaging, hydrogels for controlled drug release, micelles for oral drug delivery, and emulsions for nutraceutical delivery. In general, the bioactivities and applications of conjugates are closely related to the type of flavonoid grafted, the grafting method used as well as the grafting efficiency. Recent advances in the synthesis, structural characterization, bioactivities and potential applications of flavonoid-grafted polysaccharides are summarized in this review.

Protective effect of an arabinogalactan from black soybean against carbon tetrachloride-induced acute liver injury in mice

In vivo hepatoprotective effect of a novel arabinogalactan (AG) from black soybean on carbon tetrachloride (CCl4)-induced acute liver injury was evaluated for the first time. Our results showed that administration of AG could significantly attenuate the increase in the levels of alkaline phosphatase, alanine transaminase and aspartate transaminase in the serum caused by CCl4 treatment. AG treatment not only significantly elevated the levels of antioxidant enzymes including superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase; but also increased the levels of non-enzyme antioxidants (glutathione and total antioxidant capacity in liver tissues) when compared with CCl4-induced acute liver injury model. In addition, AG significantly reduced lipid peroxidation levels in liver tissues. The hepatoprotective effect of high-dose of AG was comparable to that of silymarin, which served as a positive standard. This study indicated that AG had a protective effect on CCl4-induced acute liver injury.

Comparison of the structural characterization and physicochemical properties of starches from seven purple sweet potato varieties cultivated in China

In this study, the structural characterization and physicochemical properties of starches from seven purple sweet potato varieties (Fuzi No. 1, Guang No. 161, Jihei No. 1, Ningzi No. 1, Ningzi No. 2, Xuzi No. 6 and Xuzi No. 8) cultivated in China were compared. Starch granules of purple sweet potatoes all exhibited round, polygonal and hemispherical shapes with granule sizes ranging from 4.3 to 23.6 μm. X-ray powder diffraction patterns and 13C nuclear magnetic resonance spectra revealed purple sweet potato starches were CA-type with relative crystallinity varying from 34.0% to 37.3%. Small-angle X-ray scattering spectra indicated the lamellar repeat distances of starch granules were in the range of 9.962-10.137 nm. Ratios of 1045/1022 cm-1 and 1022/995 cm-1 of Fourier transform infrared spectra varied in the range of 0.689-0.887 and 0.850-0.974, respectively. Amylose contents of purple sweet potato starches differed from 18.2 to 27.2%. Purple sweet potato starches exhibited different gelatinization properties but similar thermal stability. Moreover, resistant starch contents varied from 29.25% to 43.50%. Our study indicated the granule size, relative crystallinity, the degree of short-range order, amylose content, gelatinization property and in vitro digestibility of purple sweet potato starches were greatly influenced by the variety of purple sweet potato.

Effects of ascorbate and hydroxyl radical degradations on the structural, physicochemical, antioxidant and film forming properties of chitosan

In this study, chitosan (CS) was degraded by ascorbate radical (Asc•-) and hydroxyl radical (•OH), respectively. The structural, physicochemical, antioxidant and film forming properties of Asc•- and •OH degraded CS were compared for the first time. Results showed the structure and physicochemical property of Asc•- degraded CS were significantly different from those of CS. Asc•- had a deamination effect on CS with the formation of several unsaturated bonds. Accordingly, Asc•- degraded CS showed decreased crystallinity and thermal stability as well as a planar morphology. By contrast, OH degraded CS showed similar structure, crystallinity and thermal stability to CS. However, OH had an erosion effect on CS with the formation of many cavities inside. Antioxidant assay further demonstrated that the in vitro antioxidant activity of CS was improved by Asc•- and OH degradations. Moreover, film forming property of CS was also altered by Asc•- and OH degradations. Asc•- and OH degraded CS films showed higher thicknesses, UV-vis light barrier property and water vapor permeability than CS film. Besides, Asc•- degraded CS film had better mechanical properties than CS and OH degraded CS films. Therefore, Asc•- degradation could be a useful approach to improve the antioxidant and film forming properties of CS.