Blueberry leaf extract as a new potent neuroprotection agent – phytochemical, biochemical and molecular study in simplified, cellular in vitro model of human neurons

In this study, we investigated whether highbush blueberry leaves (BL) can serve as a source of bioactive compounds with neuroprotective properties. The ultrasonic extraction of the bioactive compounds from BL was optimized, followed by the phytochemical analysis of extract and the evaluation of its neuroprotective properties using a SH-SY5Y-differentiated cells. The findings demonstrate that extraction for 600 s with 50 % ethanol yields an extract with a polyphenols content of 313 mg GAE/g. The predominant group of polyphenols in the extract consisted of putative chlorogenic acid derivatives, as well as putative proanthocyanidins. Moreover, it was demonstrated that the extract abolishes oxidative stress in SH-SY5Y exposed to H₂O₂, leading to the restoration of normal synaptic signaling and prevention of inflammation. This was evidenced by an increase in the expression of SYN1, SYN2, SYNAP-25, AChE proteins (markers of communication between synapses) and a decrease in the expression of NF-κB and COX-1 (markers of inflammation).