Inhibition of beta-amyloid peptide aggregation and neurotoxicity by alpha-D-mannosylglycerate, a natural extremolyte

Abstract

The aggregation of soluble β-amyloid (Aβ) peptide into oligomers/fibrils is one of the key pathological features in Alzheimer's disease (AD). The use of naturally occurring small molecules for inhibiting protein aggregation has recently attracted many interests due to their effectiveness for treating protein folding diseases such as AD, Parkinson's, Huntington's disease, and other amyloidosis diseases. α-d-Mannosylglycerate (MG), a natural extremolyte identified in microorganisms growing under extremely high temperatures up to 100 °C, had been shown to protect proteins against various stress conditions such as heat, freezing, thawing, and drying. Here, we report the effectiveness of MG on the suppression of Alzheimer's Aβ aggregation and neurotoxicity to human neuroblastoma cells. According to our study - carried out by using thioflavin-T induced fluorescence, atomic force microscopy, and cell viability assay - MG had significant inhibitory effect against Aβ amyloid formation and could reduce the toxicity of amyloid aggregates to human neuroblastoma cells while MG itself was innocuous to cells. On the other hand, the structural analogs of MG such as α-d-mannosylglyceramide, mannose, methylmannoside, glycerol, showed negligible effect on Aβ aggregate formation. The results suggest that MG could be a potential drug candidate for treating Alzheimer's disease.