(157k) Compounds to Modify Plaque Formation and Toxicity of A-beta in Alzheimer’s Disease

Alzheimer’s disease (AD) is the seventh leading cause of death in the United Sates, affecting 5.5 million Americans with the number expected to double by 2050 due to the expected continued increase in average life expectancy and US population. As such, AD is expected to be a major public health problem in the upcoming decades. The current treatment (behavioral and symptom management) does not address the need to treat the underlying condition, the formation and deposition of A-beta oligomers. Since A-beta formation is a fact of existence, it becomes necessary to identify dietary and nutraceutical solutions that can be lifelong preventive measures. As such, we will look to utilize cutting-edge technologies and well-established techniques to evaluate readily available food-based options (polyphenols) to identify viable targets for such long-term preventative measures. We will utilize quartz crystal microbalance technology (QCM) and in vitro toxicity studies to determine the efficacy of such compounds. Additionally, the cross-disease utility of the techniques and devices implemented in these studies show promise for long term commercialization and effectiveness.

Therapeutic screening protocol development

We were able to implement a new evaluation procedure for determining the efficacy of a compound to disrupt A beta aggregation. We utilize quartz crystal microbalance (QCM) technology to follow the aggregation pathway of A beta in the presence and absence of target therapeutics. Changes in the aggregation pattern are stronger indicators of the potential influence of these compounds on the A beta behavior, in vitro. Compounds that are effective in this regime are more viable candidates as preventative measures and for treatment during the early stages of Alzheimer’s disease. This combined approach of evaluating treatments for the entire Alzheimer’s lifecycle is critical to what we believe is the best approach to minimizing the impact of this disease.

Data Collection

A. QCM evaluation

Initial studies with QCM proved to be more interesting and potential useful in diagnosis and compound evaluation than we had hoped. The shape of the A beta aggregation curve can be seen in Figure 1 below:

[view figure 1 below text]

Figure 1: QCM of A beta Aggregation – The curve in represents the frequency of oscillation as the protein aggregates in solution and at the surface. The yellow highlighted region represents the delay in surface aggregation. The green highlighted section represents the aggregation to the surface from solution. The difference labelled as change in frequency (Δν) represents the total change in mass due to surface aggregation

As can be seen from figure 1, there are two characteristic regimes (yellow and green highlighted sections). The surface aggregation portion (green highlight) was expected. However, the identification of the delay due to solution rearrangement is pleasant surprise. By monitoring changes in both regions with the frequency, changes in aggregation kinetics can be identified as follows:

Table 1: Expected QCM Changes from Changes in Aggregation

[see table image below text]

B. Resveratrol & EGCGBy evaluating the combination of the events for each confounder, we can determine the likelihood of a compound to have beneficial effects both in vitro and in vivo.

Resveratrol is a compound found in red wine that is known to have strong antioxidant properties and believed to be beneficial in general neuroprotection. Similarly, Epigallocatechin gallate (EGCG) is neuroprotective antioxidant found in green tea. The neuroprotective properties of these compound made them ideal candidates for evaluation. Initial results demonstrated the following:

Table 2: Qualitative Results from Initial Compound Screening

[see table image below text]

As can be seen from Table 2, the initial compounds that we have evaluated show very little natural toxicity. This is an important characteristic for any compound that we want to use as a therapeutic, for obvious reasons. As for anti-aggregation, the compounds, both of which are antioxidant polyphenols, showed no appreciable anti-aggregation characteristics in the initial studies. This finding was not surprising give then expected protective mechanism (interaction with the neuron directly). While this may seem like a lack of result, the outcome of the aggregation study was beneficial in validating the efficacy of the protocol developed. Finally, both showed some degree of neuroprotection, with resveratrol showing higher neuroprotection the ECGC. The results thus far are going to require additional testing to quantify the results with the necessary statistical accuracy, initial studies have been promising and are driving the direction of research and compound selection.