A Novel Pectin-Like Glycopeptide Isolated from the Fruit of <i>Fructus Mori</i> Impedes Aggregation and Production of Aβ<sub>42</sub>
Saijuan Li, Can Jin, Pengcheng Gao, Wanqi Zhou, Rongrong Xiao, Zhenqiang Zhang, Wenfeng Liao, Kan Ding
Abstract
The fruit of Fructus Mori is food and medicine, which has been demonstrated to have a significant neuroprotective effect. However, the effective constituent remains unknown. We speculate that the glycopeptide in the extract of the fruit has similar activity. To address this hypothesis, we isolated a novel pectin-like glycopeptide (FMP-6-S4) with a molecular weight of 11.23 kDa from the fruit. It contains about 20% of peptide comprising 17 amino acids and 80% glycan consisting of L-rhamnose (L-Rha), D-galactose (D-Gal), D-galacturonic acid (D-GalA), L-arabinose (L-Ara) and d-glucose (D-Glc) in molar ratios of 7.25:4.62:77.66:5.62:4.85. The backbone of the glycan part consisted of 1,4-linked α-D-GalpA and 1, 2-linked α-L-Rhap, while the branches were composed of hexenuronic acid (HexA) substituted at the C-3 position of partial galacturonic acid, and traces of galactose, glucose, and arabinose were substituted at the C-4 position of rhamnose. The in vitro experiments revealed that FMP-6-S4 might inhibit Aβ42 (β-amyloid peptides 42) aggregation and decrease Aβ42 production by modulating APP (amyloid precursor protein) processing.