Structural characterisation and evaluation of antioxidant activity of coffee pericarp polysaccharides

Abstracts: Polysaccharides are a key active component in the coffee pericarp. Here we carried out an in-depth study of coffee pericarp polysaccharides (CPP) to improve the high-value utilization of coffee by-products. CPP was extracted from coffee pericarp by thermal extraction, and was isolated and purified to obtain a purified PCPP-D2, which had a relative molecular mass of 8.798 kDa. The structure of PCPP-D2 was characterized. The analysis of its monosaccharide composition showed that PCPP-D2 primarily comprised rhamnose (12.71 %), arabinose (31.66 %), and galactose (26.38 %). Nuclear magnetic resonance (NMR) spectroscopy indicated the presence of α- and β-glycosidic bonds in PCPP, and the main chain structures in it were →4)-α-d-GalpA-(1→ and →3,6)-β-d-Galp-(1→. In vitro antioxidant activity analysis showed that PCPP-D2 exhibited scavenging effects against 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis(3-ethylbenzothiazoline-6- sulfonic acid) (ABTS+), hydroxyl (-.OH), and superoxide anion (O2.-) radicals, which suggested that CPP might be used as a potential antioxidant.