The antioxidant and anti-inflammatory properties of Citrus flavonoids can play a key role in their activity against several degenerative diseases and particularly brain diseases. In Brazil promising studies deposited in the patents "pharmaceutical formulation" form was obtained from the inclusion of Citrus sinensis L. (orange) essential oil with β-cyclodextrin and Citrus limon (lemon) compounds and their applications in therapy of Alzheimer's disease. In this chapter, we report activities of active compounds present in the genus Citrus, which include antioxidant, anti-inflammatory, anxiolytic, insecticidal, and anticholinesterase activities. These activities are associated with some neurodegenerative diseases such as Alzheimer's disease (AD). Pharmaceutical formulations containing such compounds (for example, inhibitors such as acetylcholinesterase (AChE) of C. limon (5,8-dimethoxy-psoralen and 5,7-dimethoxycumarin) and essential oil from C. sinensis oils are reported in this chapter. These results indicate that the effects of the essential oil and substances of Citrus species are very interesting for further isolation of AChE inhibitors that can be used in the formulation of natural products for neurodegenerative diseases.