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

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.