ConA-glutamate interactions: New insights into its neuroprotective effect

Abstract

L-Glutamate is the primary excitatory neurotransmitter in the brain; excessive levels induce L-glutamate-mediated excitotoxicity, linked to Alzheimer's and Parkinson's. Plant-derived molecules with antioxidant and anti-inflammatory properties that modulate this are of interest. Canavalia ensiformis lectin (ConA) serves as a model lectin for CNS studies. This study aimed to analyze in vitro and in silico the neuroprotective potential of ConA against glutamatergic excitotoxicity and identify the involved protein domain and mechanisms. Native and demetallized ConA were used for cytotoxicity and neuroprotection assays in PC12 cells. Molecular docking and fluorescence spectroscopy were also employed. ConA (1-50 mM) did not show cytotoxicity in PC12 cells and protected them from glutamatergic excitotoxicity at 15.6 μg/mL, significantly increasing cell viability from 80 % to over 90 %. Furthermore, affinity and binding assays indicated that the carbohydrate recognition domain was not involved in neuroprotection; instead, the amino acid-binding site played a crucial role. Our findings conclude that ConA possesses neuroprotective potential against glutamatergic excitotoxicity in PC12 cells via an L-glutamate sequestration mechanism mediated by the amino acid-binding site.