Hexa (ethylene glycol) derivative of benzothiazole aniline promotes dendritic spine formation through the RasGRF1-Ras dependent pathway.

Our recent study demonstrated that an amyloid-ß binding molecule, BTA-EG4, increases dendritic spine number via Ras-mediated signaling. To potentially optimize the potency of the BTA compounds, we synthesized and evaluated an amyloid-ß binding analog of BTA-EG4 with increased solubility in aqueous solution, BTA-EG6. We initially examined the effects of BTA-EG6 on dendritic spine formation and found that BTA-EG6-treated primary hippocampal neurons had significantly increased dendritic spine number compared to control treatment. In addition, BTA-EG6 significantly increased the surface level of AMPA receptors. Upon investigation into the molecular mechanism by which BTA-EG6 promotes dendritic spine formation, we found that BTA-EG6 may exert its effects on spinogenesis via RasGRF1-ERK signaling, with potential involvement of other spinogenesis-related proteins such as Cdc42 and CDK5. Taken together, our data suggest that BTA-EG6 boosts spine and synapse number, which may have a beneficial effect of enhancing neuronal and synaptic function in the normal healthy brain.

A tetra(ethylene glycol) derivative of benzothiazole aniline enhances Ras-mediated spinogenesis.

The tetra(ethylene glycol) derivative of benzothiazole aniline, BTA-EG4, is a novel amyloid-binding small molecule that can penetrate the blood-brain barrier and protect cells from Aß-induced toxicity. However, the effects of Aß-targeting molecules on other cellular processes, including those that modulate synaptic plasticity, remain unknown. We report here that BTA-EG4 decreases Aß levels, alters cell surface expression of amyloid precursor protein (APP), and improves memory in wild-type mice. Interestingly, the BTA-EG4-mediated behavioral improvement is not correlated with LTP, but with increased spinogenesis. The higher dendritic spine density reflects an increase in the number of functional synapses as determined by increased miniature EPSC (mEPSC) frequency without changes in presynaptic parameters or postsynaptic mEPSC amplitude. Additionally, BTA-EG4 requires APP to regulate dendritic spine density through a Ras signaling-dependent mechanism. Thus, BTA-EG4 may provide broad therapeutic benefits for improving neuronal and cognitive function, and may have implications in neurodegenerative disease therapy.

Design, synthesis and structure-activity relationship (SAR) studies of 2,4-disubstituted pyrimidine derivatives: dual activity as cholinesterase and Aß-aggregation inhibitors.

A novel class of 2,4-disubstituted pyrimidines (7a-u, 8a-f, 9a-e) that possess substituents with varying steric and electronic properties at the C-2 and C-4 positions, were designed, synthesized and evaluated as dual cholinesterase and amyloid-ß (Aß)-aggregation inhibitors. In vitro screening identified N-(naphth-1-ylmethyl)-2-(pyrrolidin-1-yl)pyrimidin-4-amine (9a) as the most potent AChE inhibitor (IC(50)=5.5 µM). Among this class of compounds, 2-(4-methylpiperidin-1-yl)-N-(naphth-1-ylmethyl)pyrimidin-4-amine (9e) was identified as the most potent and selective BuChE inhibitor (IC(50)=2.2 µM, selectivity index=11.7) and was about 5.7-fold more potent compared to the commercial, approved reference drug galanthamine (BuChE IC(50)=12.6 µM). In addition, the selective AChE inhibitor N-benzyl-2-(4-methylpiperazin-1-yl)pyrimidin-4-amine (7d), exhibited good inhibition of hAChE-induced aggregation of Aß(1-40) fibrils (59% inhibition). Furthermore, molecular modeling studies indicate that a central pyrimidine ring serves as a suitable template to develop dual inhibitors of cholinesterase and AChE-induced Aß aggregation thereby targeting multiple pathological routes in AD.

Inhibitors of catalase-amyloid interactions protect cells from beta-amyloid-induced oxidative stress and toxicity.

Compelling evidence shows a strong correlation between accumulation of neurotoxic ß-amyloid (Aß) peptides and oxidative stress in the brains of patients afflicted with Alzheimer disease (AD). One hypothesis for this correlation involves the direct and harmful interaction of aggregated Aß peptides with enzymes responsible for maintaining normal, cellular levels of reactive oxygen species (ROS). Identification of specific, destructive interactions of Aß peptides with cellular anti-oxidant enzymes would represent an important step toward understanding the pathogenicity of Aß peptides in AD. This report demonstrates that exposure of human neuroblastoma cells to cytotoxic preparations of aggregated Aß peptides results in significant intracellular co-localization of Aß with catalase, an anti-oxidant enzyme responsible for catalyzing the degradation of the ROS intermediate hydrogen peroxide (H(2)O(2)). These catalase-Aß interactions deactivate catalase, resulting in increased cellular levels of H(2)O(2). Furthermore, small molecule inhibitors of catalase-amyloid interactions protect the hydrogen peroxide-degrading activity of catalase in Aß-rich environments, leading to reduction of the co-localization of catalase and Aß in cells, inhibition of Aß-induced increases in cellular levels of H(2)O(2), and reduction of the toxicity of Aß peptides. These studies, thus, provide evidence for the important role of intracellular catalase-amyloid interactions in Aß-induced oxidative stress and propose a novel molecular strategy to inhibit such harmful interactions in AD.