Near-Infrared Photoactivatable Oxygenation Catalysts of Amyloid Peptide

Toxic aggregation of amyloid peptide and protein is intimately related to a number of human diseases, including Alzheimer's disease (AD). Here, we developed biocompatible photooxygenation catalyst 9, which can selectively oxygenate and degrade the pathogenic aggregation of AD-related amyloid-beta peptide (A beta) under near-infrared (NIR) light irradiation. On the basis of the structure of a fluorescent A beta probe, CRANAD-2, a bromine atom was introduced to increase the production of singlet oxygen for photooxygenation. The use of julolidine and perfluoroalkylborate moieties as electron-donor and -acceptor components, respectively, markedly enhanced the photocatalytic activity and reduced phototoxicity. Photooxygenation of aggregated A beta by 9 under NIR irradiation in the presence of cells attenuated the cytotoxicity of A beta. The tissue permeability of NIR enabled catalytic photooxygenation of aggregated A beta under the mouse skin. Moreover, injection of the catalyst to the AD-model mouse brain along with NIR light irradiation led to a significant decrease in the intact A beta level in the brain.