Alzheimer's disease is a neurodegenerative disease that induces symptoms such as a decrease in motor function and cognitive impairment. Increases in the aggregation and deposition of amyloid beta protein (Aβ) in the brain may be closely correlated with the development of Alzheimer's disease. In this study, the effects of an adzuki bean extract on the aggregation of Aβ were examined; moreover, the anti-Alzheimer's activity of the adzuki extract was examined.

First, we undertook thioflavin T (ThT) fluorescence analysis and transmission electron microscopy (TEM) to evaluate the effect of an adzuki bean extract on Aβ₄₂ aggregation. To evaluate the effects of the adzuki extract on the symptoms of Alzheimer's disease in vivo , Aβ₄₂-overexpressing Drosophila were used. In these flies, overexpression of Aβ₄₂ induced the formation of Aβ₄₂ aggregates in the brain, decreased motor function, and resulted in cognitive impairment.

Based on the results obtained by ThT fluorescence assays and TEM, the adzuki bean extract inhibited the formation of Aβ₄₂ aggregates in a concentration-dependent manner. When Aβ₄₂-overexpressing flies were fed regular medium containing adzuki extract, the Aβ₄₂ level in the brain was significantly lower than that in the group fed regular medium only. Furthermore, suppression of the decrease in motor function, suppression of cognitive impairment, and improvement in lifespan were observed in Aβ₄₂-overexpressing flies fed regular medium with adzuki extract.

The results reveal the delaying effects of an adzuki bean extract on the progression of Alzheimer's disease and provide useful information for identifying novel prevention treatments for Alzheimer's disease.