Omani date palm fruit varieties (Naghal and A'Seedi) inhibit amyloid beta protein fibrilization: A possible lead for therapeutic target to Alzheimer's disease

Alzheimer's disease (AD) is the most common type of dementia characterized by loss of memory, learning, daily routine activities and neuronal cell damage. This neuronal damage may occur due to the accumulation of a peptide named amyloid beta protein (Aβ) outside the neuronal cells leading to neuronal cell death. The mechanism of aggregation and fibrillization of Aβ is still unclear. Identification of compounds that can inhibit Aβ fibrillization is of great significance for possible therapeutic and preventive measures for AD. Date palm (Phoenix dactylifera) fruits, DPF) are used since centuries in Middle Eastern countries for nutritional/medicinal purposes. Present study was designed to investigate the effect of two different Omani date palm fruit varieties (Naghal and A'Seedi) at four different growth stages (Khalal, Biser, Rutab and Tamar) on the inhibition of Aβ fibrillization under in vitro conditions analysed by Thioflavin T fluorescence method. Results showed that 20μg of gallic acid equivalent (GAE) methanolic extract of both DPF varieties offered a variable rate of inhibition on Aβ fibrillization due to their varying levels of total poly phenols, total flavonoids and total antioxidant capacity. The highest inhibition rate of Aβ fibrillization was shown in the khalal stage for Naghal and in Biser stage for A'Seedi. Our data indicate that Omani date palm fruits could offer anti-amyloidogenic activity, which may be due to their variable bioactive components and antioxidant properties, which confirm the previous reports. However, the exact mechanism of action is still unknown and further preclinical and clinical studies are warranted.