Neuroprotective Effect of Sulforaphane against Methylglyoxal Cytotoxicity

Abstract

Glycation, an endogenous process that leads to the production of advanced glycation end products (AGEs), plays a role in the etiopathogenesis of different neurodegenerative diseases, such as Alzheimer's disease (AD). Methylglyoxal is the most potent precursor of AGEs, and high levels of methylglyoxal have been found in the cerebrospinal fluid of AD patients. Methylglyoxal may contribute to AD both inducing extensive protein cross-linking and mediating oxidative stress. The aim of this study was to investigate the role of sulforaphane, an isothiocyanate found in cruciferous vegetables, in counteracting methylglyoxal-induced damage in SH-SY5Y neuroblastoma cells. The data demonstrated that sulforaphane protects cells against glycative damage by inhibiting activation of the caspase-3 enzyme, reducing the phosphorylation of MAPK signaling pathways (ERK1/2, JNK, and p38), reducing oxidative stress, and increasing intracellular glutathione levels. For the first time, we demonstrate that sulforaphane enhances the methylglyoxal detoxifying system, increasing the expression and activity of glyoxalase 1. Sulforaphane modulated brain-derived neurotrophic factor and its pathway, whose dysregulation is related to AD development. Moreover, sulforaphane was able to revert the reduction of glucose uptake caused by methylglyoxal. In conclusion, sulforaphane demonstrates pleiotropic behavior thanks to its ability to act on different cellular targets, suggesting a potential role in preventing/counteracting multifactorial neurodegenerative diseases such as Alzheimer's.

A Proteomic Approach to Uncover Neuroprotective Mechanisms of Oleocanthal against Oxidative Stress

“…Cells were grown in DMEM supplemented with 10% ( v / v ) of FBS, 2 mM glutamine, 50 U/mL of penicillin, and 50 μg/mL of streptomycin and maintained at 37 °C in a humidified incubator with 5% CO 2 as previously reported [64]. Cell differentiation was induced, reducing serum levels of the medium to 1% with 10 µM of RA for seven days prior to treatments.…”

“…Cell viability was evaluated by measuring formazan formation as previously reported [64,65]. Briefly, after treatments, cells were incubated with 0.5 mg/mL of MTT solution for 1 h at 37 °C.…”

“…The levels of reduced glutathione (GSH) were evaluated by a fluorometric assay, using the fluorescent probe MCB [64,67]. Briefly, differentiated SH-SY5Y pretreated with oleocanthal were exposed to H 2 O 2 for 1 h and incubated with 50 µM MCB in serum-free medium for 30 min at 37 °C.…”

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“…Methylglyoxal (MG) is the major precursor in the formation of AGEs and has been reported to found in high concentrations in the cerebrospinal fluid of AD patients. [2] MG and its glycation products, both stimulating extensive protein cross-linking and triggering oxidative stress, causes several violent pathological incidents, especially in nervous tissue. [3,4] Glyoxalase-1 (GLO-1) system consists of two enzymes: GLO-1 and GLO-2 and represents the most effective defense system for the detoxification of cytotoxic MG and MG-derived AGEs.…”

The role of phytochemicals in modulating intrinsic human cellular defence processes

“…In a 2015 study, high levels of methylglyoxal have been found in the cerebrospinal fluid of Alzheimer patients. 719 In the same study, SFN was shown to enhance the methylglyoxal detoxifying system, increasing the expression and activity of GLO1 (glyoxalase -1) in a glutathione-dependent manner. As SFN demonstrated a protective anti-glycative effect in that study, one might postulate that the direction of expression of the Methylglyoxal pathway in the EASYGENEX Study was downregulation.…”