Fractionation, physicochemical properties and structural features of non-arabinoxylan polysaccharide from the seeds of Plantago asiatica L.

• Seeds of Plantago asiatica L. contained non-arabinoxylan polysaccharide.
• Five non-arabinoxylan polysaccharides were isolated and purified from the seeds.
• The fine structure of one fraction was characterized by methylation, 1D/2D NMR spectra.

Polysaccharide from seeds of Plantago asiatica L. is rich in Ara and Xyl. However, it contains small amounts of other monosaccharides, such as Rha, Gal and GalA. It is the first time to systematically elucidate structural features as well as fractionation, physicochemical properties of non-arabinoxylan polysaccharide from the seeds of Plantago asiatica L.. Non-arabinoxylan polysaccharide named as PLWE-NAX was successfully isolated and separated from the water extract of the seeds at a temperature of 50 °C. PLWE-NAX was purified into five fractions by anion exchange chromatography and gel permeation chromatography. The non-arabinoxylan fractions included arabinogalactan (PLWE-1), xylan (PLWE-2) and pectin (PLWE-3, PLWE-4, PLWE-5). PLWE-2, PLWE-3, PLWE-4 and PLWE-5 were acidic polysaccharide. PLWE-4 was subjected for structural characterization by methylation analysis and 1D/2D NMR. It was mainly consisted of α-1,2-linked Rhap (25.01%), T-linked Araf (12.11%) and β-1,3,4-linked Xylp (20.01%) residues. Uronic acid in PLWE-4 was α-1,4-linked GalAp (31.55%). PLWE-4 had the back bone as following, →1)-α-GalAp-(4 → 1)-α-Rhap-(2 → 1)-α-GalAp-(4 → .

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