Comparative Study on the Antioxidant Capacity and Cholinesterase Inhibitory Activity of Citrus aurantifolia Swingle, C. aurantium L., and C. bergamia Risso and Poit. Peel Essential Oils

The interest in medicinal plant research and in the aroma-therapeutic effects of essential oils in humans has increased in recent years, especially for the treatment of pathologies of relevant social impact such as Alzheimer's disease. The present study was taken up to evaluate the antioxidant capacity and the acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activity of the peel essential oils from three Citrus species, C. aurantifolia Swingle, C. aurantium L., and C. bergamia Risso & Poit. Essential oils were analyzed by GC and GC-MS and they contain mainly limonene, a-pinene, beta-pinene, -terpinene, and linalyl acetate. C. aurantifolia oil showed the highest radical scavenging activity on ABTS assay (IC50 value of 19.6 mu g/mL), while C. bergamia exhibited a good antioxidant activity evaluated by the beta-carotene bleaching test (IC50= 42.6 mu g/mL after 60 min of incubation). C. aurantifolia inhibited more selectively AChE. Obtained data suggest a potential use of Citrus oils as a valuable new flavor with functional properties for food or nutraceutical products with particular relevance to supplements for the elderly.