Structural characterization of blackberry wine polysaccharides and immunomodulatory effects on LPS-activated RAW 264.7 macrophages

Abstract

Three polysaccharide fractions were isolated from blackberry wine. The crude extract BWPs was obtained with ethanol precipitation and freeze-thawing process, it was then submitted to Fehling treatment, giving soluble BWPFs and insoluble BWPFp fractions. These fractions were characterized by Gas Chromatography-Mass Spectrometry (GC–MS) and Nuclear Magnetic Resonance (NMR). Major polysaccharides were identified for each fraction: mannan, type II arabinogalactan and type I rhamnogalacturonan for BWPs, a mannan formed by a major chain of α-Manp(1 → 6)-linked units, O-2 substituted with α-d-Manp(1 → 2)-linked side chains for BWPFp and a AG II formed by a major chain of β-d-Galp(1 → 3)-linked, substituted at O-6 by side chains of the β-d-Galp(1 → 6)-linked, which then are substituted at O-3 by non-reducing units of α-l-Araf and a RG I, formed by [→4)-α-d-GalpA-(1 → 2)-α-l-Rhap-(1→]n for BWPFs. Anti-inflammatory effects of polysaccharide fractions were evaluated in RAW 264.7 cells. Fractions markedly reduced nitric oxide (NO) and pro-inflammatory cytokine production (TNF-α and IL-1β) in LPS-treated cells.