Ginseng-derived type I rhamnogalacturonan polysaccharide binds to galectin-8 and antagonizes its function

Area of Science:

• Glycoscience
• Biochemistry
• Pharmacology

Background:

• Panax ginseng polysaccharides modulate galectin-3 functions.
• Galectin-8 (Gal-8) is vital in biological processes and pathology.
• The impact of ginseng polysaccharides on Gal-8 remains largely unknown.

Purpose of the Study:

• To investigate the interaction between ginseng-derived polysaccharides and Galectin-8.
• To determine which components of ginseng pectin are responsible for Gal-8 binding.
• To assess the functional consequences of this interaction.

Main Methods:

• Isolation and enzymatic digestion of P. ginseng pectin to yield polysaccharides.
• Biolayer Interferometry (BLI) to quantify binding affinity to Gal-8.
• Assays for hemagglutination, cell migration, and T-cell apoptosis to assess inhibitory effects.

Main Results:

• Ginseng pectin polysaccharides are rich in rhamnogalacturonan-I (RG-I) and homogalacturonan (HG).
• RG-I, especially its β-1,4-galactan side chains, demonstrated high affinity binding to Gal-8 (sub-micromolar K_D).
• Binding involved both N- and C-terminal Gal-8 domains and correlated with functional inhibition.

Conclusions:

• The β-1,4-galactan side chains of P. ginseng RG-I pectin are critical for binding and antagonizing Gal-8.
• This study advances the understanding of galectin-carbohydrate interactions.
• Findings may inform the development of novel pharmaceutical agents targeting Gal-8.