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

Abstract

Different Viola species are known for their traditional use as analgesic, antitussive, febrifuge, hipnotic, analgesic and anti-inflammatory medicinal agents. Additionally, they are considered edible flowers in certain cultures. Thus, the aim of this work was to characterize the phenolic composition and to assess the neuroprotective properties of Viola cornuta and Viola x wittrockiana using in vitro and in vivo methodologies with Caenorhabditis elegans as model. The identification of the phenolic compounds was carried out with a LC-DAD-ESI/MSn. The antioxidant activity of the extracts was determined in vitro using Folin-Ciocalteu, DPPH and FRAP assays and in vivo with a juglone-induced oxidative stress in C. elegans . The neuroprotective properties were evaluated measuring the ability to inhibit CNS enzymes (MAO A, AChE), and the capability to avoid paralyzing the C. elegans CL4176, an Alzheimer disease model. The phenolic content was higher in V. x wittrockiana , being quercetin-3- O -(6- O -rhamnosylglucoside)-7- O -rhamnoside the predominant compound in the extract, which also exhibited a stronger antioxidant capacity in vitro and a higher response to lethal oxidative stress on C. elegans than V. cornuta. Only V. x wittrockiana showed inhibitory effect on CNS enzymes, such as acetylcholinesterase and monoamine oxidase A, but both had protective effect against the paralysis of C. elegans. These findings suggest that the studied V. cornuta and V . x wittrockiana could be interesting candidates for age related neurodegenerative disorder associated with oxidative stress.

Jasonia glutinosa (L.) DC., a Traditional Herbal Tea, Exerts Antioxidant and Neuroprotective Properties in Different In Vitro and In Vivo Systems

“…To further investigate the in vivo neuroprotective effect of rock tea, an examination was carried out as to whether diet supplementation may affect the progression of paralysis induced by Aβ toxicity in the C. elegans transgenic strain CL4176. This strain has proven to be a good model for screening potential neuroprotective natural products [ 15 , 22 , 23 ]. Nematodes were exposed to different concentrations of RT extract (5, 10 and 25 µg/mL) from the egg stage.…”

“…The accumulation of Aβ peptide caused by free radicals would result in neuron dysfunction and death. Different works have shown that phenolic compounds present neuroprotective activity, decreasing the deleterious effects of oxidative stress, increasing ACh availability, reducing the anti-inflammatory effect and interacting directly with Aβ peptides inhibit their aggregation and oligomerization [ 15 , 23 , 38 , 39 ]. The reduction of the IIS pathway and expression of genes as DAF-16, HSF-1, HSP-16 and Nrf2/SKN-1 have also been related to a neuroprotective effect by decreasing the expression of Aβ peptides and improved the paralysis and lifespan in a C. elegans model of AD [ 40 ].…”

“…RT extract has demonstrated the ability to inhibit the AChE, MAO and TYR enzymes, which could explain its traditional uses as a stimulant, memory enhancer or antidepressant, reinforcing its neuroprotective role. Others isolated extracts of plants and flavonoids have demonstrated the capacity to inhibit CNS enzymes [ 15 , 18 , 23 , 42 , 43 ] and decrease the toxicity by Aβ accumulation [ 15 , 23 , 38 , 44 ]. Due to these mechanisms, many natural products have neurotherapeutic potential for the prevention and treatment of different CNS disorders.…”

Edible Flowers: Antioxidant Compounds and Their Functional Properties

“…Inhibited AChE and monoamine oxidase A [49] In addition, when compared with other matrices such as fruit, flowers such as marigold (Tagetes erecta) [61] and E. elatior [18] showed higher chlorogenic acid content when compared to Mulberries fruit extract (0.136-0.517 mg / g) [33]. This information indicates the high potential of edible flowers to be a neuroprotective agent.…”

“…Phenolic acid, such as syringic acid, salicylic acid, chlorogenic acid from Butea monosperma and Sesbania grandiflora inhibit the enzymes AChE and BuChE which leads to prevent the breakdown of acetylcholine, so that the acetylcholine content in the nerves does not decrease [17]. Viola wittrockiana flower is also known to inhibit AChE and monoamine oxidase A [49]. This inhibitory activity may be due to the high content of quercetin and other flavonoids such as anthocyanin.…”