Structural characterization and antioxidant activities of one neutral polysaccharide and three acid polysaccharides from the roots of Arctium lappa L.: A comparison

In this work, we comparatively analyzed the structure and antioxidant activities of different polysaccharide fractions from Arctium lappa L. A total of four water-soluble polysaccharide fractions (ALP-1, ALP-2, ALP-3 and ALP-4) were obtained from the roots of Arctium lappa L. They differed in monosaccharide composition, molecular weight and linkage mode. ALP-1 and ALP-2 mainly consisted of fructose, with average molecular weights of 2.676 × 10 3 and 2.503 × 10 4 g/mol, respectively. ALP-3 and ALP-4 were mainly composed of fructose, arabinose and galactose, with average molecular weights of 9.709 × 10 4 and 6.790 × 10 4 g/mol, respectively. Furthermore, Fourier transform infrared spectrometry, methylation analysis and nuclear magnetic resonance spectroscopy suggested that the main polysaccharide ALP-1 had a linear chain of (1 → 2)-linked β -D- Fructofuranosyl backbone (n ≈ 15) linked to a terminal (1 → 2)-linked α - d - Glucopyranosyl at the non-reducing end. All five polysaccharides displayed high antioxidant ability, especially ALP-4 in H 2 O 2 -induced HepG2 cell model and ALP-1 in metronidazole [MET]-induced zebrafish model. These findings provided comparative information on the structure and biological activity of different burdock polysaccharides and highlighted their potential as antioxidants in functional foods. • Four purified polysaccharide components were obtained from Arctium lappa L. • They differed in monosaccharide composition, molecular weight and linkage mode. • The main component had a (1 → 2)-linked β -D- Fructofuranosyl chain structure. • ALP-4 showed the most excellent antioxidant ability in H 2 O 2 -induced HepG2 cells. • ALP-1 had the best protective effect on metronidazole-damaged zebrafish embryos.