Thiamine and benfotiamine protect neuroblastoma cells against paraquat and β-amyloid toxicity by a coenzyme-independent mechanism

Abstract

Background Benfotiamine (BFT) is a synthetic thiamine precursor with high bioavailability. It is efficient in treating complications of type 2 diabetes and has beneficial effects in mouse models of neurodegenerative diseases. The mechanism of action of BFT remains unknown, though it is sometimes suggested that it may be linked to increased thiamine diphosphate (ThDP) coenzyme function. Methods We used a mouse neuroblastoma cell line (Neuro2a) grown in thiamine-restricted medium. The cells were stressed by exposure to paraquat (PQ) or amyloid β 1-42 peptide in the presence or absence of BFT and the cell survival was measured using the MTT method. In each case, BFT was compared with sulbutiamine (SuBT), an unrelated thiamine precursor, and thiamine. Metabolites of BFT were determined by HPLC and mass spectrometry. Results At 50 μM, BFT protects the cells against PQ and amyloid β 1-42 peptide-induced toxicity with the same efficacy. Protective effects were also observed with SuBT and with higher concentrations of thiamine. The main metabolites of BFT were thiamine and S-benzoylthiamine (S-BT). Treatment with both precursors induces a strong increase in intracellular content of thiamine. Protective effects of BFT and SuBT are directly related to thiamine (but not ThDP) levels in Neuro2a cells. Conclusions BFT, SuBT and thiamine all protect the cells against oxidative stress, suggesting an antioxidant effect of thiamine. Our results are not in favor of a direct ROS scavenging effect of thiamine but rather an indirect effect possibly mediated by some antioxidant signaling pathway. It is however not clear whether this effect is due to thiamine itself, its thiol form or an unknown metabolite. General significance Our results suggest a role of thiamine in protection against oxidative stress, independent of the coenzyme function of thiamine diphosphate.

Benfotiamine and Cognitive Decline in Alzheimer’s Disease: Results of a Randomized Placebo-Controlled Phase IIa Clinical Trial

“…Thiamine also regulates activities of enzyme like malate dehydrogenase and glutamate dehydrogenase [71]. Thiamine can act as an antioxidant [13] [19,26,72,73] and may act directly in cholinergic transmission [74]. Thiamine serves as an allosteric regulator of many proteins [73].…”

“…In animal models of amyloid plaque formation, benfotiamine reduces amyloid plaque numbers and phosphorylated tau levels, elevates the phosphorylation of glycogen synthase kinase-3α and -3β, and improves memory [31]. In other animal models, benfotiamine modulates activation of GSK3-β [32], restores neurogenesis [26,33], modulates AMPA receptor expression [25] and decreases oxidative stress [26]. Together, these results suggest that benfotiamine may be therapeutically beneficial for AD.…”

“…For example, mice [22] and humans [23] that have genetic defects in the thiamine transporter can be treated with high dose benfotiamine. Benfotiamine is an antioxidant [24][25][26], modulates arachidonic acid inflammation pathways, nuclear transcription Factor κB (NF-κβ), protein kinase B, mitogen-activated protein kinases (MAPK) and vascular endothelial growth factor receptor 2 (VEGFR2) signaling pathways [14]. Recent studies suggest that restoring cerebral perfusion by preventing neutrophil adhesion may provide another strategy for improving cognition in AD participants [27].…”

Prevention of Lung Complications following Paraquat Poisoning by Silymarin, N-acetyl Cysteine and Hydrocortisone: An Experimental Study

“…Charao et al have shown significant antioxidant property of melatonin in paraquat poisoning [13]. The oxidative injuries of paraquat have also been demonstrated due to its chronic exposure [14][15][16][17][18].…”

Understanding the molecular mechanisms of aggression in BALB/c and TPH2-deficient mice

“…For this reason, we chose thiamine as a new pharmacological way for the management of excessive aggression, induced by ultrasound stress, which was shown to be associated with oxidative stress and inflammation Costa-Nunes et al, in press) (Chapter 2, Chapter 3). We also tested benfotiamine, a synthetic thiamine precursor, which dephosphorylation product S-benzoylthiamine has high lipid solubility, that facilitates permeation in cell membranes (Sambon et al, 2019). As a result, it allows for higher levels of thiamine in the brain, and thus we expected it to be more effective than thiamine in preventing stress-induced aggression and other behavioral and molecular changes.…”