A novel heteropolysaccharide isolated from custard apple pulp and its immunomodulatory activity in mouse macrophages and dendritic cells.

In this study, a novel heteropolysaccharide (ASPA80-1) with an average molecular weight of 5.48 × 104 Da was isolated and structurally elucidated from custard apple pulp (Annona squamosa) through DEAE-cellulose, Sephadex G-100 and Sephacryl S-300 HR chromatography and spectral analysis. ASPA80-1 is a water-soluble polysaccharide and it is a polymer consisting of predominant amounts of (1 â†’ 3)-linked-L-arabinose (Ara) residues, small amounts of (1 â†’ 6)-linked-D-galactose (Gal), (1 â†’ 3,5)-linked-L-arabinose (Ara) residues and terminal linked-L-arabinose (Ara) residues, trace amount of (1 â†’ 4)-linked-D-glucose (Glc) residues and (1 â†’ 2)-linked-L-rhamnose (Rham) residues. ASPA80-1 showed significant effect on antigen-presenting cells (APCs) activation. On the one hand, ASPA80-1 activated RAW264.7 macrophage cells by inducing morphology change, enhancing phagocytic ability, increasing nitric oxide (NO) secretion and promoting expression of major histocompatibility complex class II (MHC II) and cluster of differentiation 86 (CD 86). On the other hand, ASPA80-1 promoted the maturation of dendritic cells (DCs) by inducing longer dendrites, decreasing phagocytic ability and increasing MHC II and CD86 expression. Furthermore, mitogen-activated protein kinases (MAPKs) and nuclear factor kappa B (NF-κB) signaling pathways were activated after the intervention of ASPA80-1 on RAW264.7 cells or DCs. Thus, the novel heteropolysaccharide ASPA80-1 has the potential to be used as an immunoenhancing component in functional foods.

Isolation, characterization and bioactivities of a new polysaccharide from Annona squamosa and its sulfated derivative.

A new water-soluble polysaccharide, designated as ASPW80-1, was first isolated from the fruit pulp of Annona squamosa. The structure of ASPW80-1 was elucidated based on the physicochemical and instrumental analyses. The results indicated that ASPW80-1 was a homogeneous heteropolysaccharide with an average molecular weight of 2.29×10(5)Da. Another novel modified polysaccharide, the sulfated derivative of ASPW80-1 namely as ASPW80-M1, was also synthesized. The ultra-structures of both ASPW80-1 and ASPW80-M1 were further characterized by scanning electron microscopy and atomic force microscopy. The antioxidant assays showed that ASPW80-1 and ASPW80-M1 exhibited DPPH and hydroxyl radicals scavenging activities. The results of immunomodulatory assays in vitro showed that ASPW80-1 and ASPW80-M1 could markedly promote the proliferation of mouse splenocytes. These results proposed that ASPW80-M1 might be proposed to be developed as a potential value-added product with the activities of immunomodulator and free-radical inhibitors.

A novel polysaccharide isolated from Litchi chinensis by using a simulated gastric medium and its immunomodulatory activity.

A novel polysaccharide (LCPA50-S1) with immunomodulatory activity was extracted with simulated gastric medium from Litchi chinensis, and purified by DEAE-52 cellulose column, Sephadex G-50 column and Sephacryl S-300 HR chromatography. The structural characteristics of LCPA50-S1 were expounded through complete acid hydrolysis, partial acid hydrolysis, methylation and instrumental analysis. The results demonstrated that LCPA50-S1 is a heteropolysaccharide with a molecular weight of 1.58 × 10(5) Da. The backbone was composed of (1→4)-linked ß-D-glucopyranosyl residues, (1→6)-linked ß-D-galactopyranosyl, (1→3,6)-linked ß-D-galactopyranosyl residues, (1→4,6)-linked α-D-glucopyranosyl residues and branched at O-6. The branches were consisted of (1→2)-linked α-L-rhamnopyranosyl residues, (1→4)-linked ß-D-glucopyranosyl residues, and (1→6)-linked ß-D-galactopyranosyl, terminated with (1→)-linked α-L-arabinopyranosyl residues and (1→)-linked ß-D-galactopyranosyl residues, respectively. The immunoregulatory activity of LCPA50-S1 was evaluated through determination the effect of LCPA50-S1 on nitric oxide (NO) production of RAW264.7 macrophages and spleen lymphocyte proliferation as well as its cytokines secretion level. The results demonstrated that LCPA50-S1 increased NO and TNF-α production in RAW264.7 macrophages significantly, enhanced the proliferation as well as the interleukin-2 (IL-2) production of splenocytes. The data indicated that LCPA50-S1 had the potential to be explored as a novel natural immunomodulator for application in functional foods and medicine.