Abstract
Free radicals are the byproducts of physiological aerobic cellular metabolism. Intrinsic antioxidant system plays its pivotal function in prevention of any loss due to free radicals. Though, incorporation or excess production of free radicals from environment to living system or imbalanced defense mechanism of antioxidant system leads to severe consequences like neuro-degeneration. Sensory or functional loss occurs in neural cells in neurodegenerative diseases. Besides numerous other genetic or environmental factors, oxidative stress is the major cause which leads to damage of neurons and production of neurodegenative diseases. However, oxygen is vital for existence, excessive reactive oxygen species production and imbalanced metabolism leads to a variety of diseases such as aging, Parkinson's disease, Alzheimer's disease, and many other neurodegenative diseases. Free radicals toxicity contributes to DNA and proteins damage, tissue damage, inflammation and consequent cellular apoptosis. Neuroprotection is a broad term commonly used to refer therapeutic strategies that can prevent, delay or even reverse neuronal damage. Since thousands of years, lots of medicinal plants have been used in a group of herbal preparations of Ayurveda (Indian traditional health care system) named Rasayana because of the antioxidant principles present in it, responsible for their medicinal use in neurodegenerative diseases. This work constitutes a literature review on natural products contain antioxidant principles used in the treatment of neurodegenerative disease.