Melatonin, protocatechuic acid and hydroxytyrosol effects on vitagenes system against alpha-synuclein toxicity

Preventing the abnormal assembly of α-synuclein (α-Syn) and the correct modulation of vitagenes system exercise strong neuroprotective effects. It has been reported that melatonin (MEL), protocatechuic acid (PCA) and hydroxytyrosol (HT) reduce α-Syn toxicity. Their effect on the vitagenes system of PC12 cells have not been explored yet. These bioactive can cross the blood brain barrier (BBB). Therefore, this work aims to evaluate the inhibitory and destabilising capacities of MEL, PCA, HT, and their combinations on α-Syn kinetics and effects on vitagenes system (sirtuin-1 (SIRT-1), sirtuin-2 (SIRT-2), heme oxygenase (HO-1) and heat shock protein 70 (Hsp-70)). In vitro techniques (Thioflavin T (ThT), Transmission Electronic Microscopy (TEM), electrophoresis, MTT assay and qPCR) were used. Compounds, both individually and simultaneously were able to decrease the toxicity induced by α-Syn. Concurrently, occurrence of PCA (100 μM) +HT (100 μM) showed the highest inhibitory effect against α-Syn fibril formation and destabilisation of α-Syn fibrils (88 and 62%, respectively). Moreover, these compounds increased the expression of SIRT-2, HO-1 and Hsp70, contributing to a neuroprotective effect. In addition, the most important result is the increase on the expression of SIRT-2 caused by the combination of MEL + HT + PCA in the absence of α-Syn fibrils.