The purpose of this project was to examine the anti-oxidative effects of flavonoids present in the three different cultivars of apples in an in vitro model of Parkinson's disease.  Using a human neuroblastoma cell line (SH-SY5Y), we investigated the neuroprotective effects of flavonoid extracts from three cultivars of apples (Malus × domestica: Red Delicious, Granny Smith and Ida Red). The anti-oxidative activity of the apple extract was tested against the hydrogen peroxide induced oxidative stress model of SH-SY5Y cells. Cell viability was assessed via an MTT assay over four days. 

The experiments indicated that the Red Delicious cultivar protected SH-SY5Y cells against the oxidative stress induced by the H₂O₂, whereas both Granny Smith and Ida Red extracts were not neuroprotective. The flavonoid composition of each extract was then examined.  We found that the flavonoid, Cyanidine 3-glucoside was exclusively present in the Red Delicious, and not in the other two cultivars.  Subsequently, cell viability assays were conducted using different concentration of Cyanidine 3-glucoside.  We found that Cyanidine 3-glucoside was not neuroprotective on its own. This indicates that the flavonoids present in the Red Delicious cultivar may act synergistically to contribute to its neuroprotective activity.

Understanding the neuroprotective potential of various apple extracts could have tremendous application in the medical field especially in treating neurodegenerative diseases such as Parkinson's disease and Alzheimer's disease. This project indicated that the apple cultivars vary in their neuroprotective activity with maximum neuroprotection attributed by the Red Delicious cultivar.  Still the question remains "Could an apple a day keep the neurologist away?"