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137 result(s) for "Marko, Doris"
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Fatty Acid Composition and Cytotoxic Activity of Lipid Extracts from Nannochloropsis gaditana Produced by Green Technologies
Microalgae are alternatives and sustainable sources of omega-3 long chain-polyunsaturated fatty acids (LC-PUFA). However, the eco-friendly extraction of these bioactives remains unexplored. In this work, the use of enzyme-based methods in combination with ultrasounds was evaluated as green approaches to extract the omega-3 lipids from Nannochloropsis gaditana. Three commercial enzymatic solutions (Viscozyme® L, Celluclast® 1.5 L, and Saczyme®) were investigated, and results were compared with the traditional Folch method. A promising extraction approach was developed by using Saczyme®, achieving a lipid yield of 25.7% ± 0.5, comparable to the traditional method (27.3% ± 0.7) (p > 0.05). Similar omega-3 content was found by GC–MS analysis for both lipid extracts (30.2% ± 2.4 and 29.3% ± 0.8 for the green and the traditional method, respectively), showing that the green approaches did not affect the fatty acid profile. Moreover, the cytotoxic activity of produced lipids was assessed by comparing human colon cancer cells (HCT-116) and epithelial nontumorigenic immortalized cells (HCEC-1CT). Results suggest that the lipid extracts have a selective effect, reducing the viability of the colon carcinoma cells but not the nontumorigenic cells. Thus, this study provides new eco-innovative approaches for extracting the omega-3 LC-PUFA from microalgae with promising biological properties.
Transfer and Metabolism of the Xenoestrogen Zearalenone in Human Perfused Placenta
Pregnancy is a sensitive condition during which adverse environmental exposures should be monitored thoroughly and minimized whenever possible. In particular, the hormone balance during gestation is delicate, and disturbance may cause acute or chronic long-term health effects. A potential endocrine disruption may be provoked by exposure to xenoestrogens mimicking endogenous estrogens. The mycoestrogen zearalenone (ZEN), a toxic fungal secondary metabolite and mycotoxin found frequently in food and feed, constitutes a prominent example. We performed a comprehensive assessment of the transfer as well as phase I and phase II metabolism of ZEN at the human placental barrier. Human placentas were perfused with ( ) ZEN for 6 h. Samples from the maternal and fetal compartment, placental tissue, and fetal plasma were analyzed by a highly sensitive UHPLC-MS/MS assay to detect ZEN as well as nine key metabolites ( , , zearalanone, , , ZEN-14-glucuronide, , , ZEN-14-sulfate). The model revealed a fast maternofetal transfer of ZEN across the human placental barrier. We also unraveled phase I and phase II metabolism of the parent toxin ZEN into the approximately 70-times more estrogenic and the less active ZEN-14-sulfate conjugate, which are effectively released into the maternal and fetal circulation in considerable amounts. Our findings suggest that exposure to ZEN (such as through consumption of ZEN-contaminated cereal-based products) during pregnancy may result in exposure of the fetus, not only to ZEN but also some of its highly estrogenically active metabolites. In the light of the known affinity of ZEN and potentially co-occurring xenoestrogens to the estrogen receptor, and our results demonstrating placental transfer of ZEN and its metabolites in an model, we recommend further research and more comprehensive assessment of gestational exposures in women. https://doi.org/10.1289/EHP4860.
Fungal Melanin Biosynthesis Pathway as Source for Fungal Toxins
Mycotoxins are a major threat for human health. Food safety control relies on the identification of the toxins or the detection of the expression of the respective genes. Contamination of food and feed with toxin-producing fungi is a major threat in agriculture and for human health. The filamentous fungus Alternaria alternata is one of the most widespread postharvest contaminants and a weak plant pathogen. It produces a large variety of secondary metabolites with alternariol and its derivatives as characteristic mycotoxin. Other important phyto- and mycotoxins are perylene quinones (PQs), some of which have anticancer properties. Here, we discovered that the PQ altertoxin (ATX) biosynthesis shares most enzymes with the 1,8-dihydroxynaphthalene (1,8-DHN) melanin pathway. However, melanin was formed in aerial hyphae and spores, and ATXs were synthesized in substrate hyphae. This spatial separation is achieved through the promiscuity of a polyketide synthase, presumably producing a pentaketide (T4HN), a hexaketide (AT4HN), and a heptaketide (YWA1) as products. T4HN directly enters the altertoxin and DHN melanin pathway, whereas AT4HN and YWA1 can be converted only in aerial hyphae, which probably leads to a higher T4HN concentration, favoring 1,8-DHN melanin formation. Whereas the production of ATXs was strictly dependent on the CmrA transcription factor, melanin could still be produced in the absence of CmrA to some extent. This suggests that different cues regulate melanin and toxin formation. Since DHN melanin is produced by many fungi, PQs or related compounds may be produced in many more fungi than so far assumed. IMPORTANCE Mycotoxins are a major threat for human health. Food safety control relies on the identification of the toxins or the detection of the expression of the respective genes. The latter method, however, relies on the knowledge of the biosynthetic pathway and the key genes. Alternaria alternata is a major food contaminant and produces many different mycotoxins with altertoxins and other perylene quinones as prominent examples. Here, we discovered that the biosynthetic pathway for altertoxins shares most of the enzymes with the dihydroxynaphthalene (DHN) melanin pathway. Because the DHN melanin pathway is widespread among fungi, the production of mycotoxins of the perylene quinone class could be more widespread than so far anticipated.
In Vitro Inhibitory Potential of Different Anthocyanin-Rich Berry Extracts in Murine CT26 Colon Cancer Cells
Anti-oxidant, -inflammatory, and -carcinogenic activities of bioactive plant constituents, such as anthocyanins, have been widely discussed in literature. However, the potential interaction of anthocyanin-rich extracts with routinely used chemotherapeutics is still not fully elucidated. In the present study, anthocyanin-rich polyphenol extracts of blackberry (BB), bilberry (Bil), black currant (BC), elderberry (EB), and their respective main anthocyanins (cyanidin-3-O-glucoside, delphinidin-3-O-glucoside, cyanidin-3-O-rutinoside, and cyanidin-3-O-sambubioside) were investigated concerning their cytotoxic and DNA-damaging properties in murine CT26 cells either alone or in combination with the chemotherapeutic agent SN-38. BB exerted potent cytotoxic effects, while Bil, BC, and EB only had marginal effects on cell viability. Single anthocyanins comprised of the extracts could not induce comparable effects. Even though the BB extract further pronounced SN-38-induced cytotoxicity and inhibited cell adhesion at 100–200 µg/mL, no effect on DNA damage was observed. In conclusion, anti-carcinogenic properties of the extracts on CT26 cells could be ranked BB >> BC ≥ Bil ≈ EB. Mechanisms underlying the potent cytotoxic effects are still to be elucidated since the induction of DNA damage does not play a role.
Co-Occurrence and Combinatory Effects of Alternaria Mycotoxins and Other Xenobiotics of Food Origin: Current Scenario and Future Perspectives
Mycotoxins are low-molecular weight compounds produced by diverse genera of molds that may contaminate food and feed threatening the health of humans and animals. Recent findings underline the importance of studying the combined occurrence of multiple mycotoxins and the relevance of assessing the toxicity their simultaneous exposure may cause in living organisms. In this context, for the first time, this work has critically reviewed the most relevant data concerning the occurrence and toxicity of mycotoxins produced by Alternaria spp., which are among the most important emerging risks to be assessed in food safety, alone or in combination with other mycotoxins and bioactive food constituents. According to the literature covered, multiple Alternaria mycotoxins may often occur simultaneously in contaminated food, along with several other mycotoxins and food bioactives inherently present in the studied matrices. Although the toxicity of combinations naturally found in food has been rarely assessed experimentally, the data collected so far, clearly point out that chemical mixtures may differ in their toxicity compared to the effect of toxins tested individually. The data presented here may provide a solid foothold to better support the risk assessment of Alternaria mycotoxins highlighting the actual role of chemical mixtures on influencing their toxicity.
Risk assessment of aflatoxins in food
EFSA was asked to deliver a scientific opinion on the risks to public health related to the presence of aflatoxins in food. The risk assessment was confined to aflatoxin B1 (AFB1), AFB2, AFG1, AFG2 and AFM1. More than 200,000 analytical results on the occurrence of aflatoxins were used in the evaluation. Grains and grain‐based products made the largest contribution to the mean chronic dietary exposure to AFB1 in all age classes, while ‘liquid milk’ and ‘fermented milk products’ were the main contributors to the AFM1 mean exposure. Aflatoxins are genotoxic and AFB1 can cause hepatocellular carcinomas (HCCs) in humans. The CONTAM Panel selected a benchmark dose lower confidence limit (BMDL) for a benchmark response of 10% of 0.4 μg/kg body weight (bw) per day for the incidence of HCC in male rats following AFB1 exposure to be used in a margin of exposure (MOE) approach. The calculation of a BMDL from the human data was not appropriate; instead, the cancer potencies estimated by the Joint FAO/WHO Expert Committee on Food Additives in 2016 were used. For AFM1, a potency factor of 0.1 relative to AFB1 was used. For AFG1, AFB2 and AFG2, the in vivo data are not sufficient to derive potency factors and equal potency to AFB1 was assumed as in previous assessments. MOE values for AFB1 exposure ranged from 5,000 to 29 and for AFM1 from 100,000 to 508. The calculated MOEs are below 10,000 for AFB1 and also for AFM1 where some surveys, particularly for the younger age groups, have an MOE below 10,000. This raises a health concern. The estimated cancer risks in humans following exposure to AFB1 and AFM1 are in‐line with the conclusion drawn from the MOEs. The conclusions also apply to the combined exposure to all five aflatoxins. This publication is linked to the following EFSA Supporting Publications article: http://onlinelibrary.wiley.com/doi/10.2903/sp.efsa.2020.EN-1798/full
Isoflavones in Animals: Metabolism and Effects in Livestock and Occurrence in Feed
Soybeans are a common ingredient of animal feed. They contain isoflavones, which are known to act as phytoestrogens in animals. Isoflavones were described to have beneficial effects on farm animals. However, there are also reports of negative outcomes after the consumption of isoflavones. This review summarizes the current knowledge of metabolization of isoflavones (including the influence of the microbiome, phase I and phase II metabolism), as well as the distribution of isoflavones and their metabolites in tissues. Furthermore, published studies on effects of isoflavones in livestock species (pigs, poultry, ruminants, fish) are reviewed. Moreover, published studies on occurrence of isoflavones in feed materials and co-occurrence with zearalenone are presented and are supplemented with our own survey data.
Proposal of a comprehensive definition of modified and other forms of mycotoxins including “masked” mycotoxins
As the term “masked mycotoxins” encompasses only conjugated mycotoxins generated by plants and no other possible forms of mycotoxins and their modifications, we hereby propose for all these forms a systematic definition consisting of four hierarchic levels. The highest level differentiates the free and unmodified forms of mycotoxins from those being matrix-associated and from those being modified in their chemical structure. The following lower levels further differentiate, in particular, “modified mycotoxins” into “biologically modified” and “chemically modified” with all variations of metabolites of the former and dividing the latter into “thermally formed” and “non-thermally formed” ones. To harmonize future scientific wording and subsequent legislation, we suggest that the term “modified mycotoxins” should be used in the future and the term “masked mycotoxins” to be kept for the fraction of biologically modified mycotoxins that were conjugated by plants.
Combinatory Effects of Acrylamide and Deoxynivalenol on In Vitro Cell Viability and Cytochrome P450 Enzymes of Human HepaRG Cells
Acrylamide (AA) can be formed during the thermal processing of carbohydrate-rich foods. Deoxynivalenol (DON), a mycotoxin produced by Fusarium spp., contaminates many cereal-based products. In addition to potential co-exposure through a mixed diet, co-occurrence of AA and DON in thermally processed cereal-based products is also likely, posing the question of combinatory toxicological effects. In the present study, the effects of AA (0.001–3 mM) and DON (0.1–30 µM) on the cytotoxicity, gene transcription, and expression of major cytochrome P450 (CYP) enzymes were investigated in differentiated human hepatic HepaRG cells. In the chosen ratios of AA–DON (10:1; 100:1), cytotoxicity was clearly driven by DON and no overadditive effects were observed. Using quantitative real-time PCR, about twofold enhanced transcript levels of CYP1A1 were observed at low DON concentrations (0.3 and 1 µM), reflected by an increase in CYP1A activity in the EROD assay. In contrast, CYP2E1 and CYP3A4 gene transcription decreased in a concentration-dependent manner after incubation with DON (0.01–0.3 µM). Nevertheless, confocal microscopy showed comparably constant protein levels. The present study provided no indication of an induction of CYP2E1 as a critical step in AA bioactivation by co-occurrence with DON. Taken together, the combination of AA and DON showed no clear physiologically relevant interaction in HepaRG cells.
Endoplasmic Reticulum Adaptation and Autophagic Competence Shape Response to Fluid Shear Stress in T24 Bladder Cancer Cells
Accumulation of xenobiotics and waste metabolites in the urinary bladder is constantly accompanied by shear stress originating from the movement of the luminal fluids. Hence, both chemical and physical cues constantly modulate the cellular response in health and disease. In line, bladder cells have to maintain elevated mechanosensory competence together with chemical stress response adaptation potential. However, much of the molecular mechanisms sustaining this plasticity is currently unknown. Taking this as a starting point, we investigated the response of T24 urinary bladder cancer cells to shear stress comparing morphology to functional performance. T24 cells responded to the shear stress protocol (flow speed of 0.03 ml/min, 3 h) by significantly increasing their surface area. When exposed to deoxynivalenol-3-sulfate (DON-3-Sulf), bladder cells increased this response in a concentration-dependent manner (0.1–1 µM). DON-3-Sulf is a urinary metabolite of a very common food contaminant mycotoxin (deoxynivalenol, DON) and was already described to enhance proliferation of cancer cells. Incubation with DON-3-Sulf also caused the enlargement of the endoplasmic reticulum (ER), decreased the lysosomal movement, and increased the formation of actin stress fibers. Similar remodeling of the endoplasmic reticulum and area spread after shear stress were observed upon incubation with the autophagy activator rapamycin (1–100 nM). Performance of experiments in the presence of chloroquine (chloroquine, 30 μM) further contributed to shed light on the mechanistic link between adaptation to the biomechanical stimulation and ER stress response. At the molecular level, we observed that ER reshaping was linked to actin organization, with the two components mutually regulating each other. Indeed, we identified in the ER stress–cytoskeletal rearrangement an important axis defining the physical/chemical response potential of bladder cells and created a workflow for further investigation of urinary metabolites, food constituents, and contaminants, as well as for pharmacological profiling.