Anti-inflammatory properties and gut microbiota modulation of an alkali-soluble polysaccharide from purple sweet potato in DSS-induced colitis mice.

In this study, the potential effects of a novel alkali-soluble polysaccharide (ASPP) from purple sweet potato on colonic histopathology, inflammation and microbiota composition in dextran sulfate sodium (DSS)-induced colitis mice were evaluated. The results indicated that ASPP restored the immune organ indices, increased colon length, improved colonic histopathology in colitis mice as well as inhibited the levels of pro-inflammatory cytokines (IL-1ß, IL-6 and TNF-α) in colonic tissue and serum. Moreover, 16S rRNA phylogenetic sequencing revealed that ASPP ameliorated the compositions and functions of gut microbiota in DSS-induced colitis mice. It was found that Parasutterella, Desulfovibrio, Lachnospiraceae, Lactobacillus, Erysipelotrichaceae, Bacteroidetes were the key bacteria associated with ulcerative colitis (UC). Taken together, ASPP alleviated colonic inflammation via blocking pro-inflammatory cytokines; meanwhile ASPP could modulate the structure of gut microbiota in DSS-induced colitis mice.

Anti-inflammatory activity of a water-soluble polysaccharide from the roots of purple sweet potato.

In this study, a water-soluble polysaccharide was isolated from purple sweet potato roots. The in vitro and in vivo anti-inflammatory effects of the polysaccharide were evaluated by lipopolysaccharide (LPS)-induced inflammatory RAW264.7 macrophages and mice, respectively. The in vitro anti-inflammatory assay showed that the polysaccharide could effectively inhibit the overproduction of nitric oxide and pro-inflammatory cytokines (TNF-α, IL-1ß, IL-6) while increasing the secretion of anti-inflammatory cytokine (IL-10). The in vivo anti-inflammatory assay revealed that mice administered with the polysaccharide showed higher IL-10, SOD, and T-AOC levels but lower TNF-α, IL-1ß, IL-6 and MDA levels as compared to the LPS-treated model. Meanwhile, mice administered with the polysaccharide showed increased abundance of Lachnospiraceae, Lactobacillales and Parabacteroides but decreased amounts of Psychrobacter and Staphylococcus as compared to the LPS model group. Moreover, mice administered with polysaccharide showed enhanced production of short chain fatty acids by gut microbiota in the lipopolysaccharide-induced inflammatory mice. Our results suggested that the water-soluble polysaccharide from purple sweet potato roots could be utilized as a novel anti-inflammatory agent.

Structural characterization and anti-inflammatory activity of alkali-soluble polysaccharides from purple sweet potato.

In this study, the structural characterization and anti-inflammation effect of dilute alkali-soluble polysaccharides from purple sweet potato were investigated. Three fractions (F-1, F-2 and F-3) were obtained by purifying crude polysaccharides on DEAE-52 cellulose column. The main fraction (F-1) was further purified on Sephadex G-200 column to afford purified alkali-soluble sweet potato polysaccharide (ASPP). The chemical structure of ASPP was analyzed by gas chromatography, Fourier transform infrared spectroscopy, methylation analysis and nuclear magnetic resonance spectroscopy. Monosaccharide compositional analysis showed ASPP was composed of rhamnose, arabinose, xylose, mannose and glucose in the molar ratio of 2.8:1.9:1.0:7.6:53.3. Moreover, the backbone of ASPP was composed of 1,4-linked Glcp with side chains attached to the O-6 position. The anti-inflammation effect of ASPP was further investigated by in vitro and in vivo experiments. Results showed ASPP could inhibit the levels of nitric oxide, interleukin (IL)-6, IL-1ß and TNF-α but increase the production of IL-10 in lipopolysaccharide (LPS)-treated RAW 264.7 macrophage cells. In addition ASPP could reduce the secretion of IL-6, IL-1ß and TNF-α in LPS-treated mice. Our results suggest ASPP can be developed as a novel anti-inflammation agent.

Immune-enhancing effects of polysaccharides from purple sweet potato.

Immune-enhancing effects of three kinds of purple sweet potato polysaccharides (PSPPs) including water-soluble polysaccharide (WSP), dilute alkali-soluble polysaccharide (DASP) and concentrated alkali-soluble polysaccharide (CASP) were evaluated. Scanning electron microscope analysis showed that all PSPPs could stimulate the formation of microvilli-like structures in cellular surfaces, which was possibly related to activation of macrophages. Neutral red uptake assay showed that PSPPs could increase the phagocytic activity of cells. High dose (400 µg/mL) of PSPPs could notably augment the level of nitric oxide (NO). ELISA analysis revealed that 200 and 400 µg/mL of PSPPs distinctly elevated the production of IL-1ß. Cells received 200 and 400 µg/mL of WSP as well as 400 µg/mL of DASP exhibited higher level of IL-6. Results of animal experiments showed that WSP treatment (400 mg/kg) could promote the secretions of IgA, IgG, IgM and sIgA in both normal and immunosuppressed mice. Moreover, CASP treatment (400 mg/kg) elevated the production of IgM in the serum of normal and immunosuppressive mice, while DASP (400 mg/kg) only improved the secretion of IgM in normal mice. In summary, all three polysaccharides can stimulate immune responses of macrophages and positively regulate adaptive immunity by enhancing the production of immunoglobulins in mice.

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 ß-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.