Polysaccharides isolated from Alchornea cordifolia modulate monocyte/macrophage function (P3006)

Abstract

Abstract Extracts of leaves from different species of the genus Alchornea have been used for centuries to treat medical problems in tropical Africa; however, little is known about the active components conferring therapeutic properties to these extracts. We investigated the phagocyte immunomodulatory properties of water-soluble polysaccharides extracted from the leaves of Achornea cordifolia. Extracted polysaccharides were fractionated by DEAE-cellulose, Diaion HP-20 resin, and preparative Sepharose 6B size-exclusion chromatography and characterized. Fractions containing type II arabinogalactan had potent immunomodulatory activity. Specifically, the parent fraction AP-AU and its high-molecular weight sub-fraction AP-AU1 induced nitric oxide and cytokine (IL-1β, IL-6, IL-10, TNF-α, and GM-CSF) production by human peripheral blood mononuclear cells and human and murine monocyte/macrophages cell lines in vitro. We also evaluated the ability of selected fractions to activate mitogen activated phagocyte protein kinase (MAPK) pathways using a phospho-MAPK array and found that treatment of phagocytes with AP-AU1 induced phosphorylation of Akt2, p38δ/p38γ, p70S6K1, RSK2, and mTOR, as well as stimulation of NF-κB transcriptional activity. Thus, these results provide a molecular basis to explain a portion of the beneficial therapeutic properties of water extracts from A. cordifolia leaves in traditional folk medicine of Africa.