Olive biophenols: A natural weapon against Alzheimer's disease

The most common form of dementia is Alzheimerâ''s disease (AD) which affects a high percentage of people over the age 65 years. Globally, there are more than 36 million people with dementia and it is predicted that numbers will reach 115 million by 2050. Currently, there is no cure or treatment for AD. The FDA approved medicines have only shown a palliative effect. Due to the severity of adverse effects and the narrow therapeutic index, researchers suggested that some dietary and herbal constituents may offer certain cognitive benefits alone or as adjunct to approved medication. Amongst various phytochemicals, biophenols have attracted a great deal of attention. In addition to their well known antioxidant and radical scavenging activities, biophenols are multi-potent chemical entities with a wide array of pharmacological activities. Thus, they may be able to counteract or halt the progression of neuronal damage in AD. Olive (Olea europaea) fruit, leaf and extra-virgin oil are rich sources of biophenols. We investigated the effect of these biophenols on the activity of key enzymes implicated in AD disease: acetylcholine esterase, butyrylcholinesterase, β-secretase, tyrosinase and histone deacetylase enzymes. Olive biophenols showed potent cholinesterase (quercetin: IC50= 9.42 μM), tyrosinase (quercetin: IC50= 10.73 μM) and histone deacetylase (Quercetin: IC50 = 105.1μM) inhibitory activities. In transgenic mice (APPswe), our results showed significant improvement in memory and obvious reduction in amyloid plaques deposition in the brains of olive extract treated mice. In conclusion, olive biophenols can present a powerful and safe nutraceutical weapon to fight AD.