Viola cornuta and Viola x wittrockiana: Phenolic compounds, antioxidant and neuroprotective activities on Caenorhabditis elegans

Abstract

DifferentViolaspecies are known for their traditional use as analgesic, antitussive, febri-fuge, hipnotic, analgesic and anti-inflammatory medicinal agents. Additionally, they areconsidered edible flowers in certain cultures. Thus, the aim of this work was to charac-terize the phenolic composition and to assess the neuroprotective properties ofViola cor-nutaandViolaxwittrockianausingin vitroandin vivomethodologies withCaenorhabditiselegansas model. The identification of the phenolic compounds was carried out with a LC-DAD-ESI/MSn. The antioxidant activity of the extracts was determinedin vitrousing Folin-Ciocalteu, DPPH and FRAP assays andin vivowith a juglone-induced oxidative stress inC.elegans. The neuroprotective properties were evaluated measuring the ability to inhibit CNSenzymes (MAO A, AChE), and the capability to avoid paralyzing theC. elegansCL4176, anAlzheimer disease model. The phenolic content was higher inV.xwittrockiana, beingquercetin-3-O-(6-O-rhamnosylglucoside)-7-O-rhamnoside the predominant compound inthe extract, which also exhibited a stronger antioxidant capacityin vitroand a higherresponse to lethal oxidative stress onC. elegansthanV. cornuta.OnlyV.xwittrockianashowed inhibitory effect on CNS enzymes, such as acetylcholinesterase and monoamineoxidase A, but both had protective effect against the paralysis ofC. elegans.These findingssuggest that the studiedV. cornutaandV.xwittrockianacould be interesting candidates forage related neurodegenerative disorder associated with oxidative stress.