Abstract
Alzheimer’s Disease (AD) is a progressive disease associated with severe memory loss and is the sixth leading cause of death in the United States. Symptoms worsen as the disease progresses and ultimately leads to death of the patient. Though no known definitive cause of the disease, previous research suggests the accumulation of beta-amyloid plaques, tau-tangles, neuronal inflammation, and oxidative stress are leading hypotheses for AD. Oxidative stress can induce chronic inflammation which results in both neuronal death and aggregation of amyloid fibrils. Previous studies have shown that berries have high antioxidant capabilities and can reduce cognitive decline up to two and half years in an observational clinical study. This research focuses on the use of blueberries to both delay the amyloid fibril aggregation and rescue oxidatively damaged neurons. Six different blueberry extracts were created and tested for antioxidant capability by conducting a DPPH assay. Results of the DPPH assay suggested a polar fresh fruit blueberry extract, created in a solvent mixture of acetone, methanol, water, and formic acid in a 40:40:19:1 ratio, as the extract with the most antioxidant power as it had the lowest IC50value. Because of this, the fresh fruit solvent mix extract was utilized for ex vivo studies of oxidative stress on M17 human neuroblastoma cell line following oxidative stress induced by hydrogen peroxide. Our results showed that blueberry extract was able to increase cell viability from hydrogen peroxide treatment and reduce the intracellular level of reactive oxygen species induced by hydrogen peroxide. This suggested that blueberries can protect neuronal cells from oxidation stress, and therefore protect neuronal cells. Following oxidative rescue success, mitigating the formation of abnormal amyloid fibrils was targeted. After developing an amyloid fibril model using HEWL at a low pH (pH 2, glycine buffer) and high temperature (70oC) with agitation, both Congo Red (CR) and Nile Red (NR) were used to determine if blueberry treatment could delay the aggregation formation. Congo Red binds to amyloid fibrils and is detected by a UV-Vis as a peak growing at around 540 nm, while Nile Red binds to hydrophobic surfaces, which increase with aggregation, and causes a blue shift in fluorescence reading. The amyloid fibril formation of HEWL was observed for eight consecutive days and results suggest blueberry extract’s ability to delay fibril formation for about 24 hours.