Isolation, Structural Characterization and Macrophage Activation Activity of an Acidic Polysaccharide from Raspberry...

Area of Science:

• Food Science and Technology
• Immunology
• Natural Product Chemistry

Background:

• Plant polysaccharides are increasingly recognized for their immunomodulatory potential.
• Raspberries are a globally consumed fruit with potential health benefits.
• Identifying novel, safe, and effective immune-enhancing agents from natural sources is a key research area.

Purpose of the Study:

• To isolate and characterize an acidic polysaccharide from raspberry pulp.
• To investigate the immunomodulatory effects of the isolated polysaccharide on macrophage activity.

Main Methods:

• Isolation of polysaccharide RPP-2a using DEAE-Sepharose Fast Flow and Sephadex G-200 chromatography.
• Structural elucidation using Fourier transform infrared spectroscopy (FT-IR), gas chromatography-mass spectrometer (GC-MS), and nuclear magnetic resonance (NMR) spectroscopy.
• Assessment of macrophage activation in RAW264.7 cells, measuring nitric oxide (NO), cytokines (TNF-α, IL-6, IL-1β), and inducible nitric oxide synthase (iNOS) expression.

Main Results:

• A homogeneous acidic polysaccharide, RPP-2a (Mw: 55582 Da), was successfully isolated.
• Structural analysis revealed a backbone composed of rhamnose, galacturonic acid, and glucose, with arabinose and galactose side chains.
• RPP-2a significantly enhanced macrophage activation, increasing NO, TNF-α, IL-6, IL-1β production, and iNOS expression.

Conclusions:

• Raspberry polysaccharide RPP-2a possesses a unique structure with significant immunomodulatory activity.
• RPP-2a demonstrates potential as a natural immune-enhancing agent.
• Further research into RPP-2a could lead to novel applications in functional foods and immunotherapies.