Abstract
The discovery of safe and effective plant polysaccharides with immunomodulatory effects has become a research hotspot. Raspberry is an essential commercial fruit and is widely distributed, cultivated, and consumed worldwide. In the present study, a homogeneous acidic polysaccharide (RPP-2a), with a weight-average molecular weight (Mw) of 55582 Da, was isolated from the pulp of raspberries through DEAE-Sepharose Fast Flow and Sephadex G-200 chromatography. RPP-2a consisted of rhamnose, arabinose, galactose, glucose, xylose, galacturonic acid and glucuronic acid, with a molar ratio of 15.4:9.6:7.6:3.2:9.1:54.3:0.8. The results of Fourier transform infrared spectroscopy (FT-IR), gas chromatography-mass spectrometer (GC-MS), 1D-, and 2D-nuclear magnetic resonance (NMR) analyses suggested that the backbone of RPP-2a was primarily composed of →2)-α-L-Rhap-(1→, →2,4)-α-L-Rhap-(1→, →4)-α-D-GalAp-(1→, and →3,4)-α-D-Glcp-(1→ sugar moieties, with side chains of α-L-Araf-(1→, α-L-Arap-(1→, and β-D-Galp-(1→3)-β-D-Galp-(1→ residues linked to the O-4 band of rhamnose and O-3 band of glucose residues. Furthermore, RPP-2a exhibited significant macrophage activation activity by increasing the production of nitric oxide (NO), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-1β (IL-1β), and the expression of inducible nitric oxide synthase (iNOS) and cytokines at the transcriptional level in RAW264.7 cells. Overall, the results indicate that RPP-2a can be utilized as a potential natural immune-enhancing agent.
Highlights
Macrophages are the first line of defense, with various activities performed by the multitudinous immune cells, such as phagocytosis, surveillance, chemotaxis, and destruction of targeted organisms [7–9]
The terminal residue α-L-Araf-(1→ was located on the backbone of raspberry pulp polysaccharides (RPPs)-2a with the O-4 band of rhamnose to form one branch, and the α-L-Arap-(1→ and β-D-Galp-(1→3)-β-D-Galp-(1→ sugar moieties were connected to the O-3 band of glucose to form the other two side chains
Taking the monosaccharide composition for example, Ke, et al have reported that the polysaccharide from Rubus chingii Hu was composed of mannose, rhamnose, glucuronic acid, galacturonic acid, glucose, galactose, arabinose and fucose with a molar ratio of 1.31:4.41:1.13:43.20:8.65:9.51:31.17:0.61 [16]
Summary
Polysaccharides, naturally occurring flexible macromolecular polymers with complex structures, are the primary components of plants, fungi, bacteria, algae, and even animals [1]. Polysaccharides possess numerous pharmacological activities, including antitumor, anti-inflammatory, antioxidant, antimicrobial, antidiabetic, immunomodulatory, etc. Their immunoregulatory effects are considered to be the primary activity of polysaccharides. Several polysaccharides are widely utilized as potent immunomodulators in the food and medicine industries [5]. Previous studies have reported that most polysaccharides-induced actions are dependent on macrophage functional ability [6]. Macrophages are the first line of defense, with various activities performed by the multitudinous immune cells, such as phagocytosis, surveillance, chemotaxis, and destruction of targeted organisms [7–9]. Research has been proven that macrophage activation is a promising approach to improve host immune capability and strengthen disease resistance [10]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
