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Sci Rep. 2017 Aug 8;7(1):7523. doi: 10.1038/s41598-017-07581-2.

Shedding Light on Alzheimer's β-Amyloidosis: Photosensitized Methylene Blue Inhibits Self-Assembly of β-Amyloid Peptides and Disintegrates Their Aggregates.

Author information

1
KAIST Institute for the BioCentury, Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Korea.
2
Neurophysiology & Metabolism Research Group, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Korea.
3
Convergence Research Center for Dementia, Korea Institute of Science and Technology (KIST), Seoul, Korea.
4
Department of Functional Genomics, University of Science and Technology, Daejeon, Korea.
5
KAIST Institute for the BioCentury, Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Korea. parkcb@kaist.ac.kr.

Abstract

Abnormal aggregation of β-amyloid (Aβ) peptides is a major hallmark of Alzheimer's disease (AD). In spite of numerous attempts to prevent the β-amyloidosis, no effective drugs for treating AD have been developed to date. Among many candidate chemicals, methylene blue (MB) has proved its therapeutic potential for AD in a number of in vitro and in vivo studies; but the result of recent clinical trials performed with MB and its derivative was negative. Here, with the aid of multiple photochemical analyses, we first report that photoexcited MB molecules can block Aβ42 aggregation in vitro. Furthermore, our in vivo study using Drosophila AD model demonstrates that photoexcited MB is highly effective in suppressing synaptic toxicity, resulting in a reduced damage to the neuromuscular junction (NMJ), an enhanced locomotion, and decreased vacuole in the brain. The hindrance effect is attributed to Aβ42 oxidation by singlet oxygen (1O2) generated from photoexcited MB. Finally, we show that photoexcited MB possess a capability to disaggregate the pre-existing Aβ42 aggregates and reduce Aβ-induced cytotoxicity. Our work suggests that light illumination can provide an opportunity to boost the efficacies of MB toward photodynamic therapy of AD in future.

PMID:
28790398
PMCID:
PMC5548810
DOI:
10.1038/s41598-017-07581-2
[Indexed for MEDLINE]
Free PMC Article

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