Acute and subchronic 90-days toxicity assessment of propyl-propane-thiosulfinate (PTS) in rats.

The organosulfur compounds (OSC) extracted from Allium spp. exhibit antibacterial, antifungal, and antioxidant properties. The agri-food industry is taking advantage of these properties by using them as natural feed and food additives. In the present work, an acute and a subchronic 90-days toxicity studies have been conducted for the first time to assess the safety of the OSC propyl-propane-thiosulfinate (PTS). Both studies were carried out following the Organization for Economic Co-operation and Development test guidelines (425 and 408, respectively). The acute study provided a maximum tolerated dose (MTD) of 175 mg/kg and the subchronic study established the Non Observed Adverse Effect Level (NOAEL) ≥ 55 mg/kg body weight (b.w.)/day in both sexes. In addition, the subchronic study performed on rats exposed to 14, 28 and 55 mg/kg b.w./day PTS, revealed no changes in any of the hematological parameters measured as well as no differences in body weight and water/food consumption. However, biochemical parameters were altered in some groups, although they were not biologically significant (Ca2+ in female rats, and the thyroids hormones T3 and T4 in rat males). Furthermore, the histopathological assessment evidenced no abnormality on the gastrointestinal, respiratory, lymphoid, urinary, circulatory, nervous, musculoskeletal, and reproductive systems.

Molecular characterisation of a bio-based active packaging containing Origanum vulgare L. essential oil using pyrolysis gas chromatography-mass spectrometry.

BACKGROUND: Environmental, economic and safety challenges motivate shift towards safer materials for food packaging. New bioactive packaging techniques, i.e. addition of essential plant oils (EOs), are gaining attention by creating barriers to protect products from spoilage. Analytical pyrolysis gas chromatography-mass spectrometry (Py-GC-MS) was used to fingerprint a bioactive polylactic acid (PLA) with polybutylene succinate (PBS) (950 g kg(-1) :50 g kg(-1) ) film extruded with variable quantities (0, 20, 50 and 100 g kg(-1) ) of Origanum vulgare EO. RESULTS: Main PLA:PBS pyrolysis products were lactide enantiomers and monomer units from the major PLA fraction and succinic acid anhydride from the PBS fraction. Oregano EO pyrolysis released cymene, terpinene and thymol/carvacrol peaks as diagnostic peaks for EO. In fact, linear correlation coefficients better than 0.950R(2) value (P < 0.001) were found between the chromatographic area of the diagnostic peaks and the amount of oregano EO in the bioplastic. CONCLUSION: The pyrolytic behaviour of a bio-based active package polymer including EO is studied in detail. Identified diagnostic compounds provide a tool to monitor the quantity of EO incorporated into the PLA:PBS polymeric matrix. Analytical pyrolysis is proposed as a rapid technique for the identification and quantification of additives within bio-based plastic matrices. © 2015 Society of Chemical Industry.

Beneficial effects of vitamin E supplementation against the oxidative stress on Cylindrospermopsin-exposed tilapia (Oreochromis niloticus).

Cylindrospermopsin (CYN) is known to produce changes in some oxidative stress biomarkers in fish acutely and subchronically exposed to the toxin. The present study investigated the effects of vitamin E supplementation against the oxidative stress induced by pure CYN in tilapia (Oreochromis niloticus). Fish were pretreated with 700 mg vitamin E/kg fish body weight (bw)/day for 7 days by oral route, and on day seven, they received a single oral dose of 400 µg pure CYN/kg fish bw, and were killed after 24 h. The biomarkers evaluated included lipid peroxidation (LPO), protein and DNA oxidation, glutathione-S-transferase (GST), glutathione peroxidase (GPx), superoxide dismutase (SOD), catalase (CAT) and γ-glutamyl-cysteine synthetase (γ-GCS) activities, and ratio of reduced glutathione-oxidized glutathione (GSH/GSSG). This is the first study showing that vitamin E supplementation is effective at reducing the toxicity induced by CYN, recovering the biomarkers assayed to basal levels. Therefore, vitamin E can be considered a useful chemoprotectant that reduces hepatic and renal oxidative stress and can be used in the prophylaxis and treatment of CYN-related intoxication in fish.

In vitro toxicological evaluation of essential oils and their main compounds used in active food packaging: A review.

Essential oils (EOs) and their main constituent compounds have been extensively investigated due to their application in the food industry for improving the shelf life of perishable products. Although they are still not available for use in food packaging in the market in Europe, considerable research in this field has been carried out recently. The safety of these EOs should be guaranteed before being commercialized. The aim of this work was to review the scientific publications, with a primary focus on the last 10 years, with respect to different in vitro toxicological aspects, mainly focussed on mutagenicity/genotoxicity. In general, fewer genotoxic studies have been reported on EOs in comparison to their main components, and most of them did not show mutagenic activity. However, more studies are needed in this field since the guidelines of the European Food Safety Authority have not always been followed accurately. The mutagenic/genotoxic activities of these substances have been related to metabolic activation. Therefore, in vivo tests are required to confirm the absence of genotoxic effects. Considering the great variability of the EOs and their main compounds, a case-by-case evaluation is needed to assure their safe use in food packaging.

Protective role of dietary N-acetylcysteine on the oxidative stress induced by cylindrospermopsin in tilapia (Oreochromis niloticus).

Cylindrospermopsin (CYN) is a toxin produced by various cyanobacteria species. Fish can be exposed to this cyanotoxin in their natural environments and in aquaculture ponds, and toxic effects can be derived. The present study investigated the effects of dietary N-acetylcysteine (NAC) on the oxidative stress induced by pure CYN and CYN from lyophilized cells of Aphanizomenon ovalisporum in tilapia (Oreochromis niloticus). Fish were pretreated with 0, 22, and 45 mg NAC/fish/d for a week, and on day seven, they received a single dose of 200 µg/kg CYN and were killed after 24 h. Oxidative biomarkers evaluated included lipid peroxidation, protein oxidation, glutathione (GSH)/oxidized glutathione (GSSG) ratio, activity of the enzyme γ-glutamylcysteine synthetase, and activity and gene expression of glutathione-S-transferase and glutathione peroxidase. Results showed that CYN induced oxidative stress as evidenced by the increase of lipid peroxidation and protein oxidation, the decrease in GSH/GSSG, and the alteration of the enzymatic activities assayed. Moreover, exposure to cyanobacterial cells containing CYN induced higher toxic effects in comparison to pure CYN. N-acetylcysteine supplementation was effective at reducing the toxicity induced by CYN, particularly at the highest dose employed, with a recovery of some of the biomarkers assayed to basal levels. Therefore, NAC can be considered a useful chemoprotectant that reduces hepatic and renal oxidative stress in the prophylaxis and treatment of CYN-related intoxication in fish.

Effects of dietary N-acetylcysteine on the oxidative stress induced in tilapia (Oreochromis niloticus) exposed to a microcystin-producing cyanobacterial water bloom.

Fish can be exposed to toxic cyanobacterial cells in natural waters and fish farms and suffer from oxidative damage. The present study investigates the effects of N-acetylcysteine (NAC), a glutathione (GSH) precursor, on the oxidative stress induced by Microcystis cyanobacterial cells containing microcystins (MCs) in tilapia fish (Oreochromis niloticus). Variation in lipid peroxidation (LPO) levels, carbonyl group content, reduced glutathione to oxidized glutathione ratio (GSH:GSSG), and catalase (Enzyme Commission [EC] 1.11.1.6), superoxide dismutase (SOD; EC 1.15.1.1), glutathione reductase (GR; EC 1.8.1.7), glutathione peroxidase (GPx; EC 1.11.1.9), and glutathione S-transferase (EC 2.5.1.18) activities in liver and kidney of tilapia exposed to a single oral dose of 120 microg MC-LR (with leucine [L] and arginine [R])/fish and killed in 24 h were investigated in the absence and presence of 20.0, 44.0, and 96.8 mg NAC/fish/d. Results showed a protective role of NAC, depending on the dose and the biomarker considered. The increase in LPO (1.9- and 1.4-fold in liver and kidney, respectively) and the decreased protein content and GSH: GSSG in the liver induced by MCs were recovered mainly by the lower doses of NAC employed. Antioxidant enzyme activities increased (range, 1.4- to 1.7-fold) by MCs also were ameliorated by NAC, although the highest level used induced significant alteration of some enzymatic activities, such as SOD, GPx, and GR. Thus, NAC can be considered to be a useful chemoprotectant that reduces hepatic and renal oxidative stress in the prophylaxis and treatment of MC-related intoxications in fish when careful attention is given to its application dose because of its own pro-oxidant activity, as shown in the present study at 96.8 mg NAC/fish/d.

Effects of dietary selenium on the oxidative stress and pathological changes in tilapia (Oreochromis niloticus) exposed to a microcystin-producing cyanobacterial water bloom.

The present study investigates the role of selenium (Se) supplementation (as sodium selenite) on the oxidative stress and histopathological changes induced by cyanobacterial cells containing microcystins (MCs) in tilapia fish (Oreochromis niloticus). Variation in lipid peroxidation (LPO) levels and carbonyl groups content, reduced glutathione/oxidized glutathione (GSH/GSSG) ratio, and catalase (CAT), superoxide dismutase (SOD), glutathione reductase (GR), glutathione peroxidase (GPx) and glutathione S-transferase (GST) activities in liver and kidney of tilapia fish exposed to a single oral dose of 120 microg MC-LR/fish and sacrificed in 24 h, were investigated in the absence and presence of 1.5, 3.0 and 6.0 microg Se/g diet. Results showed a protective role of Se depending on the dose and the biomarker considered. Thus, the lower Se dose made CAT, liver GR and kidney SOD converged to basal values, whereas LPO and liver SOD and GST needed the higher dose. Kidney GR, however, was not protected at any Se dose. Moreover, Se has also shown to have a pro-oxidant effect with increased kidney LPO values and liver and kidney GPx activities in MC-free fish. The microscopic study revealed tissue alterations induced by cyanobacterial cells in the liver, kidney, heart and gastrointestinal tract that were ameliorated by the highest Se dose assayed. The level of Se supplementation must be therefore carefully selected to provide beneficial effects and to avoid potential negative consequences.

Protective role of vitamin E on the microcystin-induced oxidative stress in tilapia fish (Oreochromis niloticus).

Microcystins (MCs) are potent hepatotoxins produced by cyanobacteria in water systems that induce oxidative stress in fish. The present study investigated the effect of vitamin E pretreatment on MC-induced oxidative damage in the liver, kidneys, and gills of tilapia fish (Oreochromis niloticus). Groups of fish were fed vitamin E supplements (200 or 700 mg per kilogram of diet) for 7 d or received only commercial fish food and then were exposed to a single oral dose of cyanobacterial cells (120 microg of MC-LR [2:Leu, 4:Arg] per fish), and were sacrificed in 24 h. The potential benefits of vitamin E were evaluated based on lipid peroxidation (LPO), protein oxidation, catalase (CAT, Enzyme Commission [EC] 1.11.1.6), superoxide dismutase (EC 1.15.1.1), glutathione peroxidase (EC 1.11.1.9), glutathione reductase (EC 1.8.1.7), and the ratio of reduced glutathione to oxidized glutathione (GSH/GSSG). Microcystins induced a 1.6-fold increase in LPO values in liver, whereas vitamin E-pretreated fish showed no alteration on this biomarker. Enzyme activities levels were also ameliorated by the chemoprotectant, whereas protein oxidation and GSH/GSSG did not show any significant change. The higher vitamin E dose used proved to have the greater protective effects, particularly on the biomarkers LPO and CAT. The results show that vitamin E could have a potential use as a preventive or therapeutic measure in MC-exposed fish.