Alzheimer’s disease is a neurodegenerative one characterized by gradual changes in behavior because of aggregation of amyloid β protein and tau (τ) protein which blocks signal transduction pathway. There is one hypothesis that accounts for the heterogeneous nature of Alzheimer in the involvement of free radicals. The probability of this involvement includes oxidative stress that accumulates free radicals and leads to excessive lipid peroxidation and neuronal degeneration in certain brain regions. Our brain utilizes more oxygen than other tissues and undergoes mitochondrial respiration, which increases the potential for reactive oxygen species (ROS) exposure. In this way, oxidative imbalance and stress play a crucial role in the pathogenesis of neuron degeneration and it remains as a challenge to design some sort of treatment intervention because it lacks typical treatment target. In this chapter, we will describe natural antioxidants that are capable of scavenging free radicals, donating hydrogen and electrons, and providing reducing activity.