Effect of olive-fruit Roghani cultivar extract on the aggregation and cytotoxicity of alphasynuclein in Parkinson s disease

The neurodegenerative diseases are dependent on the formation of amyloidal fibrils of proteins/peptides without any factual treatment. The α-synuclein (α-Syn) is an abundant protein in the brain which its toxic fibrillar aggregates have a key role in diseases called synucleinopathies like Parkinson’s disease. Olives could be candidates to inhibit the fibrillization. The populations with Mediterranean diet regime that contains a high level of olive products are more health and longevity. In this study, the extracts of olive fruits of some Iranian olive cultivars including Zard, Mary, Arghavan, and Roghani were investigated on the fibrillization of α-Syn. Among the assessed extracts, Roghani extract showed significant effects on the rate of formation and the levels of end product fibrils. Structural characterization using circular dichroism indicated that in the presence of the extract, the protein strongly resisted the formation of beta sheets. TEM results confirmed that unlike control with extended fibrils after 24 h incubation, the treated protein did not proceed to fibrillization. Treating OLN-93 with the aggregated α-Syn indicated that the viability of cells considerably increased in the presence of the extract. Given that other extracts did not show these obvious effects whether on α-Syn fibrillization and cytotoxicity and moreover since Roghani is an Iranian olive cultivar with high consumption, more investigation is needed to elucidate its high therapeutic potential including using different fruits which are harvested in a different period or using other parts of the tree. These studies may provide valuable information for therapeutic and nutrition field.