Isolation, purification, structure and antioxidant activity of polysaccharide from pinecones of Pinus koraiensis

The polysaccharides (PKP-E) extracted from the pinecones of Pinus koraiensis were studied, which was fractionated using DEAE-52 cellulose and Sephadex G-100. Four novel polysaccharide fractions were obtained, which were PKP-E-1-1, -1-2, -2-1, and -2-2, respectively. The structural features were characterized using HPGPC, monosaccharide composition analysis, Congo red test, periodate oxidation, Smith degradation, FTIR and NMR spectroscopy. The results showed the 4 purified fractions were non-triple helical structured heteropolysaccharides and composed of l-rhamnose, l-arabinose, d-mannose, d-glucose, and d-galactose. The fractions were mainly linked by 1→6 or 1→ glycosidic bonds and the backbone of 4 fractions was probably composed of→2, 6)-β-d-Man-(1→ and α-d-GalpA-(1→), which resembles pectin. Moreover, the antioxidant activities of the polysaccharides were measured by scavenging radical capacity tests. The PKP-E-2-1 was the most stable and active fraction, and the respective IC₅₀ for the hydroxyl and ABTS^·+ radicals were 3.0 and 23.6 mg/mL.