Modulating Effects of Arabinogalactans from Plant Gum Exudates on Human Complement System

Area of Science:

• Immunology
• Food Science
• Pharmacology

Background:

• Plant polysaccharides like gum arabic and cashew nut tree gum exudate polysaccharide (CNTG) are known as arabinogalactans (AGs).
• AGs are utilized in food and pharmaceutical industries, but allergic reactions have been reported.
• Previous studies suggest AGs modulate the classical (CP) and alternative pathways (AP) of the complement system (CS).

Purpose of the Study:

• To investigate the effects of gum arabic and CNTG on both the classical and alternative pathways of the complement system.
• To determine if these AGs act as modulators or activators of the CS.
• To assess the potential pro-inflammatory action of these plant-derived polysaccharides.

Main Methods:

• Complement fixation tests were conducted with and without pre-incubation (CP-30/AP-30 and CP-0/AP-0).
• The impact of gum arabic and CNTG on CP-induced and AP-induced hemolysis was measured.
• Half maximal inhibitory concentration (IC50) values were determined for AP-30 assays.

Main Results:

• CNTG and gum arabic significantly reduced CP-induced hemolysis when pre-incubated (CP-30), but not without pre-incubation (CP-0).
• Both polysaccharides markedly reduced AP-induced hemolysis (AP-30), with gum arabic showing a lower IC50 (7 μg/ml) than CNTG (100 μg/ml).
• Gum arabic showed a slight reduction in AP-0 induced hemolysis, while CNTG had no effect.

Conclusions:

• Gum arabic and CNTG appear to activate the complement system, particularly the alternative pathway.
• This activation suggests a potential pro-inflammatory action, indicating possible harm.
• Further studies are essential to confirm the immunomodulatory effects and ensure the safe application of these AGs.