Biocompatible photooxygenation catalyst could be conceivably used to treat amyloid infections

Overview

• Post By : Kumar Jeetendra


• Source: Japan Science and Technology Agency


• Date: 26 Nov,2020

The catalyst was able to oxygenate Aβ embedded beneath the skin of a living mouse, and diminished intact Aβ degree in AD-model mouse brain. The new catalyst is potentially useful for the treatment of peripheral amyloid diseases and AD.

Toxic aggregation of amyloid peptide and protein is closely associated with a number of human diseases.

The development of an artificial chemical system that selectively converts toxic amyloid aggregates to non-toxic species under physiologic conditions, thereby potentially suppressing the pathogenic process, could be a novel therapeutic strategy to treat currently-incurable amyloid diseases, such as AD.

We envisioned that photocatalyzed aerobic oxygenation are a suitable chemical reaction to attenuate the pathogenic aggregative properties of Aβ under physiological conditions.

Because peptide and protein aggregation generally depends on intermolecular hydrophobic interactions, covalent setup of hydrophilic oxygen atoms to a peptide or protein (i.e., oxygenation) would decrease the aggregative property.

We previously reported that aerobic oxygenation of Aβ proceeds in the presence of Flavin (vitamin B2)-based photocatalysts, and the resulting oxygenated Aβ exhibits very low aggregative ability and toxicity.

Thereafter, more selective photooxygenation catalysts, activated only when sensing a poisonous higher-order amyloid structure, were developed based on a fluorescence probe for aggregated amyloid peptide and protein.

For in vivo application, photocatalysts need to have the ability to operate under excitation with longer wavelength light, known as the”optical window” in which living tissue absorbs relatively little light.

We developed biocompatible photooxygenation catalyst that can selectively oxygenate and degrade the pathogenic aggregation of Aβ beneath near-infrared (NIR) light irradiation.

The catalyst exhibited four main advantages compared with the previous catalysts for degrading aggregated and toxic Aβ: High selectivity for aggregated Aβ that stems from the higher-order amyloid structure-sensing on/off switch for the catalyst action.

The exact target selectivity allowed for photooxygenation of aggregated Aβ from the presence of the cells and in mouse brain lysate. Low toxicity to the cells.

High oxygenation potency under NIR photoirradiation. Because of tissue-permeability of NIR light, photooxygenation of aggregated Aβ under the mouse skin was possible in high yield.

Injection of the catalyst into the AD-model mouse brain combined with NIR light irradiation led to significant decrease of the intact Aβ level in the brain. The results obtained in this study are an essential step to utilizing artificial catalysis as a possible therapeutic strategy against amyloid diseases.