A polysaccharide PFH-3a from Fritillariae hupehensis bulbus: Preparation, structural characterization and antioxidant activity in vitro

This study reports the structural characterization and in vitro antioxidant activity of a novel polysaccharide, PFH-3a from Fritillariae hupehensis bulbus (FHB) with a weight-average molecular weight (Mw) of about 92.34 KDa, which exhibits a unique glycosidic linkage pattern that has not been previously reported in FHB. Structure of PFH-3a was elucidated through NMR spin system assignment based on comprehensive analyses of 1D and 2D NMR spectroscopy, identification of sugar residue types by iterative matching against a self-constructed NMR database containing 1875 diverse sugar residues, monosaccharide composition analysis, 1D ¹H qNMR analysis, and glycosidic linkage determination. It revealed that PFH-3a comprises a backbone of β-D-Xylp-(1→[3,6)-β-D-Galp-(1→3,6)-β-D-Galp-(1→]_n, with two branches α-L-Araf-(1→ and α-L-Araf-(1→5)-α-L-Araf-(1→ attached to position 3 of the main chain →3,6)-β-D-Galp-(1→. In vitro bioactivity assays demonstrated that PFH-3a exhibits dose-dependent antioxidant activity, indicating its potential as a natural antioxidant. However, further investigation is needed to explore the in vivo efficacy and the underlying mechanisms.