A glucan isolated from flowers of Lonicera japonica Thunb. inhibits aggregation and neurotoxicity of Aβ42

Highlight
• A neutral glucan LJW0F2 was isolated and purified from flowers of Lonicera japonica Thunb.
• The structure of LJW0F2 was elucidated as to an α-d-(1→4)-glucan with an α-(1→4) linked branch attached to C-6 position.
• The polysaccharide LJW0F2 could block Aβ42 aggregation directly and attenuated its cytotoxicity in SH-SY5Y cells.

Inhibition of Aβ aggregation and attenuation of its cytotoxicity are considered to valuable therapeutics for Alzheimer's disease (AD). Here, a glucan named as LJW0F2 was purified from flowers of Lonicera japonica Thunb. Using monosaccharides composition analysis, methylation analysis, IR and NMR spectroscopy, this polysaccharide was elucidated to be an α-d-(1→4)-glucan with an α-(1→4) linked branch attached to the C-6 position. Its inhibitory effect on Aβ42 aggregation was measured by fluorescence spectroscopic analysis with thioflavine T (ThT) and atomic force microscopy (AFM). We showed that polysaccharide LJW0F2 could inhibit Aβ42 aggregation in a dose-dependent-manner. Besides, LJW0F2 could attenuate the cytotoxicity induced by Aβ42 aggregation in SH-SY5Y neuroblastoma cells. To the best of our knowledge, this was the first report that the exogenous plant-derived polysaccharide might block Aβ42 aggregation directly and reduce its toxicity in SH-SY5Y cells.