Characterization of a New Anti-dementia β-secretase Inhibitory Peptide from Arctoscopus japonicus

Amyloid plaque is a product of aggregation of β-amyloid peptide (Aβ) and is an important factor in the pathogenesis of Alzheimer’s Disease (AD). Aβ is a major component of amyloid plaque and vascular deposits in the AD brain. The enzyme β- secretase is required for the production of Aβ; thus, prevention of the formation of Aβ through the inhibition of β-secretase is a major focus in the study of the treatment of AD. In this study, we investigated β-secretase inhibitory activity of an Arctoscopus japonicus peptide. An Alcalase hydrolysate had the highest β-secretase inhibitory activity. A β-secretase inhibitory activity peptide was separated using ion exchange column chromatography (carboxy-methyl: CM, quaternary methyl ammonium: QMA) and reverse phase high performance liquid chromatography (RP-HPLC) on a C18 column. The IC50 value of the purified peptide was 248.2±1.73 μg/mL. The β-secretase inhibitory peptide was identified as a six amino acid residue of Gly-Pro-Val-Gly-Ala- Pro (MW: 497.27 Da). In cell viability experiments, the final purified fraction, the carboxy-methyl ion exchange column fraction (CM-F1) showed no significant cytotoxic effect in SH-SY5Y cells at concentrations below 100 μg/mL in 24 h. The results of this study suggest that peptides separated from Arctoscopus japonicus may be beneficial as β-secretase inhibitor compounds in functional foods.