Selective activation of cellular stress response pathways by fumaric acid esters.

The cellular response to oxidants or xenobiotics comprises two key pathways, resulting in modulation of NRF2 and FOXO transcription factors, respectively. Both mount a cytoprotective response, and their activation relies on crucial protein thiol moieties. Using fumaric acid esters (FAEs), known thiol-reactive compounds, we tested for activation of NRF2 and FOXO pathways in cultured human hepatoma cells by dimethyl/diethyl as well as monomethyl/monoethyl fumarate.

Activation of Nrf2 by Electrophiles Is Largely Independent of the Selenium Status of HepG2 Cells.

Selenoenzymes, whose activity depends on adequate selenium (Se) supply, and phase II enzymes, encoded by target genes of nuclear factor erythroid 2-related factor 2 (Nrf2), take part in governing cellular redox homeostasis. Their interplay is still not entirely understood. Here, we exposed HepG2 hepatoma cells cultured under Se-deficient, Se-adequate, or Se-supranutritional conditions to the Nrf2 activators sulforaphane, cardamonin, or diethyl maleate.

Nuclear trapping of inactive FOXO1 by the Nrf2 activator diethyl maleate.

Diethyl maleate (DEM), a thiol-reactive α,β-unsaturated carbonyl compound, depletes glutathione (GSH) in exposed cells and was previously shown by us to elicit a stress response in Caenorhabditis elegans that, at lower concentrations, results in enhanced stress resistance and longer lifespan. This hormetic response was mediated through both the Nrf2 ortholog, SKN-1, and the forkhead box O (FOXO) family transcription factor DAF-16. As FOXO signaling is evolutionarily conserved, we analyzed here the effects of DEM exposure on FOXO in cultured human cells (HepG2, HEK293).

Non-linear impact of glutathione depletion on C. elegans life span and stress resistance.

The redox environment in cells and organisms is set by low-molecular mass and protein-bound thiols, with glutathione (GSH) representing a major intracellular redox buffer. Subtle thiol oxidation elicits signal transduction processes and adaptive responses to cope with stressors, whereas highly oxidizing conditions may provoke cell death. We here tested how thiol depletion affects life span, stress resistance and stress signaling in the model organism Caenorhabditis elegans.

Analysis of Marine Biotoxins Using LC-MS/MS.

Different clinical types of algae-related poisoning have attracted scientific and commercial attention: paralytic shellfish poisoning (PSP), diarrhetic shellfish poisoning (DSP), and amnesic shellfish poisoning (ASP). Bioassays are common methods for the determination of marine biotoxins. However, biological tests are not completely satisfactory, mainly due to the low sensitivity and the absence of specialized variations.

Effect of E-beam treatment on the chemistry and on the antioxidant activity of lycopene from dry tomato peel and tomato powder.

Tomato powder (TP) and dry tomato peel (DTP) have been previously used in our laboratory as a source of lycopene to manufacture meat products ready-to-eat (RTE) submitted to E-beam irradiation with good technological and sensory results. Present work describes the studies performed in order to investigate the effect of radiation on chemical changes and antioxidant properties of lycopene. DTP and TP were irradiated (4 kGy).

Characteristic profiles of Ciguatera toxins in different strains of Gambierdiscus spp.

Ciguatera fish poisoning characterizes the intoxication caused by consumption of fish from tropical and subtropical areas, which have accumulated ciguatoxins (CTXs). The observed pattern of ciguatoxins in fish highly depends on the marine region and the causative organisms. It is evident that differences exist between ciguatoxins produced by certain strains of the dinoflagellate Gambierdiscus toxicus and other Gambierdiscus spp.

Saxitoxins accumulation by freshwater tilapia (Oreochromis niloticus) for human consumption.

The accumulation of saxitoxins (STXs) in fish from freshwater aquaculture was investigated for the first time in the present study. Cyanotoxins have been monitored in liver and muscle samples of Oreochromis niloticus by chromatographic methods, both before and after the depuration process. The results show that tilapia can accumulate STXs.

Paralytic shellfish poisoning toxin profile of mussels Perna perna from southern Atlantic coasts of Morocco.

During the monitoring programme of harmful algal blooms established along the south Atlantic coast of Morocco, a bimonthly determination of harmful algae and phycotoxins analysis in Perna perna was carried out from May 2003 to December 2004. Results of mouse bioassay (in organs and whole flesh) showed a seasonal evolution of paralytic shellfish poisoning (PSP) toxin. The mussel's contamination was associated with the occurrence in water of Alexandrium minutum.

Application of a new zwitterionic hydrophilic interaction chromatography column for determination of paralytic shellfish poisoning toxins.

A novel method for paralytic shellfish poisoning (PSP) toxins which is based on the chromatographic separation of the toxins using a zwitterionic (ZIC) hydrophilic interaction chromatography (HILIC) column is presented. Efficient retention of the polar PSP toxins on the ZIC-HILIC column allowed their selective and sensitive determination by the application of mass spectrometric (MS/MS) detection or as derivatives after oxidation prior to fluorescence detection (FD). Low buffer concentrations and the omission of ion-pair reagents decreased the limits of detection (LODs) by MS/MS analysis and showed a good linearity for both methods of detection.

Detection of harmful cyanobacteria and their toxins by both PCR amplification and LC-MS during a bloom event.

We briefly report here the occurrence of toxic blooms in the eutrophic reservoir Billings, São Paulo city, Brazil. Water samples were collected in May 2004, during a cyanobacterial bloom. The presence of toxic species was confirmed by using PCR amplifications of a fragment region of genes encoding microcystin synthetase-mcyB.