Comparing the Effects of Ferulic Acid and Sugarcane Aqueous Extract in In Vitro and In Vivo Neurotoxic Models

Abstract

Molecules exhibiting antioxidant, neuroprotective, and regulatory properties inherent to natural products consumed by humans are gaining attention in biomedical research. Ferulic acid (FA) is a phenolic compound possessing antioxidant and cytoprotective properties. It is found in several vegetables, including sugarcane, where it serves as the main antioxidant component. Here, we compared the antioxidant and cytoprotective effects of FA with those of the total sugarcane aqueous extract (SCAE). Specifically, we assessed biochemical markers of cell dysfunction in rat cortical brain slices and markers of physiological stress in Caenorhabditis elegans upon exposure to toxins evoking different mechanisms of neurotoxicity, including direct oxidative stress and/or excitotoxicity. In rat cortical slices, FA (250 and 500 μM), but not SCAE (~ 270 μM of total polyphenols), prevented the loss of reductive capacity induced by the excitotoxin quinolinic acid (QUIN, 100 μM), the pro-oxidant agent ferrous sulfate (FeSO, 25 μM), and the dopaminergic pro-oxidant 6-hydroxydopamine (6-OHDA, 100 μM). In wild-type (N2) C. elegans, FA (38 mM) exerted protective effects on decreased survival induced by FeSO (15 mM) and 6-OHDA (25 mM), and the motor alterations induced by QUIN (100 mM), FeSO, and 6-OHDA. In contrast, SCAE (~ 13.5 mM of total polyphenols) evoked protective effects on the decreased survival induced by the three toxic agents, the motor alterations induced by FeSO, and the reproductive deficit induced by FeSO. In addition, FA was unable to reverse the decreased survival induced by all these toxins in the skn-1 strain (VC1772), which lacks the homolog of mammalian Nrf2, a master antioxidant gene. Altogether, our results suggest that (1) both FA and SCAE afford protection against toxic conditions, (2) not all the effects inherent to SCAE are due to FA, and (3) FA requires the skn-1 pathway to exert its protective effects in C. elegans.

Comparing the Neuroprotective Effects of Caffeic Acid in Rat Cortical Slices and Caenorhabditis elegans: Involvement of Nrf2 and SKN-1 Signaling Pathways

“…Ten male Wistar adult rats (260-280 g) were obtained from the vivarium of the Instituto Nacional de Neurología y Neurocirugía (Mexico), and later euthanized by decapitation in order to obtain the brain and isolate the cortical slices. Before euthanized, rats were kept under room conditions previously described (Colonnello et al 2018). All experiments were carried out in compliance with the "Guidelines for the Use of Animals in Neuroscience Research" from the Society of Neuroscience.…”

“…Then, ten μl of CA at increasing concentrations (50, 100, 250, 500 and 750 μM; final concentrations), were incubated with 200 μl FRAP solution (3.1 mg sodium acetate plus 16 ml acetic acid, 40 mM HCl, 10 mM 2,4,6-Tri(2-pyridyl)-s-triazine (TPTZ) and 20 mM FeCl3). Optical density was recorded and processed, and the reduction capacity values were calculated according to a method previously described (Colonnello et al, 2018).…”

“…The frontal cortex from each rat was rapidly isolated from the brain. Cortical slices (250-300 μm thickness)were obtained with a chopper, according to a previous report (Colonnello et al, 2018) and then incubated in Krebs buffer (124 mM NaCl, 5 mM KCl, 1.2 mM CaCl 2 , 1.2 mM MgSO 4 , 1.2 mM KH 2 PO 4 , 23 mM NaHCO 3 , 3 mM HEPES and 10 mM D-glucose) for thirty minutes at 37°C and CO 2 5%. Four slices per probe were incubated in the presence of CA (100 μM) for 60 minutes under the same conditions mentioned above.…”

“…The optical density from each sample was measured in a Cytation Multifunctional Imaging Reader at 570 nm. Results were calculated as the percentage of MTT reduction vs. the control by interpolation of the absorbance of reduced products per mg of protein (Colonnello et al, 2018).…”

“…elegans cultures-Nematodes were grown and maintained using standard procedures. N2 and skn-1(ok2315) strains were kept at 21° C in a Nematode Growth Medium (NGM) agar plate till they reach gravid stage (Colonnello et al 2018;Kotlar et al 2018). Afterwards, 40,000 gravid worms were lysed in a 10 M NaOH/hypochlorite solution to obtain eggs, which were kept on empty NGM plates overnight to hatch at larva 1 (L1) stage.…”