Effects of extracted polysaccharides from a Chlorella vulgaris biomass on expression of interferon-γ and interleukin-2 in chicken peripheral blood mononuclear cells

Abstract

Polysaccharides isolated from algae species have been shown to have various biological properties including immunomodulatory activities. In the present study, the effects of water-extractable polysaccharides from a Chlorella vulgaris biomass on the expression of immunostimulatory cytokines by chicken peripheral blood mononuclear cells (PBMCs) were evaluated. Extracted polysaccharides were fractionated using a DEAE Sepharose FF column yielding two fractions (F1 and F2). Crude polysaccharide (CP) and fractions mostly consisted of carbohydrates (71.9 to 82.9%), protein (6 to 13.8%), and uronic acids (4.8 to 7.9%). Monosaccharide constituents were predominantly galactose (13.1 to 53.2%), glucose (15.3 to 38.6%), mannose (5.5 to 11.2%), arabinose (5.6 to 20.7%), and rhamnose (5.8 to 14.7%). Crude, F1, and F2 polysaccharides contained 1 or 2 sub-fractions with average molecular weight ranging from 19.2 to 161.1 × 103 g mol−1. Evaluation of immunostimulatory activities of CP and fractions (200 to 1000 μg mL−1) revealed significant effects on PBMC interferon-γ (IFN-γ) and interleukin-2 (IL-2) expression. The most potent immunostimulating fraction F1 was consisted of a homogeneous polysaccharide with relatively low molecular weight (23.9 × 103 g mol−1), low structural compactness, and mixed linkages of (→1)-, (1→3)-, (1→3,6)-galactopyranose and -glucopyranose residues.