Wim Wätjen

Martin Luther University Halle-Wittenberg | MLU · Institute of Agricultural and Nutritional Sciences

Since 2006, the responsible regulatory bodies have proposed five health-based guidance values (HBGV) for bisphenol A (BPA) that differ by a factor of 250,000. This range of HBGVs covers a considerable part of the range from highly toxic to relatively non-toxic substances. As such heterogeneity of regulatory opinions is a challenge not only for scie...

Dietary exposure to N-nitrosamines has recently been assessed by the European Food Safety Authority (EFSA) to result in margins of exposure that are conceived to indicate concern with respect to human health risk. However, evidence from more than half a century of international research shows that N-nitroso compounds (NOC) can also be formed endoge...

Smoking has multiple detrimental effects on health, and is a major preventable cause of premature death and chronic disease. Despite the well-described effect of inhaled substances from tobacco smoke on cell toxicity, the association between smoking and suicidal erythrocyte death, termed eryptosis, is virtually unknown. Therefore, the blood samples...

The Senate Commission on Food Safety (SKLM) of the German Research Foundation (DFG) has reviewed the currently available data in order to assess the health risks associated with the use of acetaldehyde as a flavoring substance in foods. Acetaldehyde is genotoxic in vitro. Following oral intake of ethanol or inhalation exposure to acetaldehyde, syst...

Vitamin D, besides its classical effect on mineral homeostasis and bone remodeling, can also modulate apoptosis. A special form of apoptosis termed eryptosis appears in erythrocytes. Eryptosis is characterized by cell shrinkage, membrane blebbing, and cell membrane phospholipid disorganization and associated with diseases such as sepsis, malaria or...

This opinion of the Senate Commission on Food Safety (SKLM) of the German Research Foundation (Deutsche Forschungsgemeinschaft, DFG) presents arguments for an updated risk assessment of diet-related exposure to acrylamide (AA), based on a critical review of scientific evidence relevant to low dose exposure. The SKLM arrives at the conclusion that a...

Opinion on acetaldehyde as a flavouring substance: considerations for risk assessment Acetaldehyde occurs naturally in many foods and is also used as a flavouring due to its fruity aroma. The International Agency for Research on Cancer (IARC) classified acetaldehyde as possibly carcinogenic to humans and, in combination with oral intake via alcohol...

Subsequent to the dietary uptake of nitrate/nitrite in combination with acetaldehyde/ethanol, combination effects resulting from the sustained endogenous exposure to nitrite and acetaldehyde may be expected. This may imply locoregional effects in the upper gastrointestinal tract as well as systemic effects, such as a potential influence on endogeno...

Acetaldehyd kommt natürlicherweise in zahlreichen Lebensmitteln vor, wird aufgrund seines fruchtigen Aromas aber auch als Aromastoff eingesetzt. Die Internationale Agentur für Krebsforschung (IARC) stufte Acetaldehyd als möglicherweise krebserregend sowie in Verbindung mit der oralen Aufnahme über alkoholhaltige Getränke als humanes Kanzerogen ein....

Vitamin D deficiency due to, e.g., nutritional and life style reasons is a health concern that is gaining increasing attention over the last two decades. Vitamin D3, the most common isoform of vitamin D, is only available in food derived from animal sources. However, mushrooms and yeast are rich in ergosterol. This compound can be converted into vi...

In Lebensmitteln können toxische Substanzen vorkommen, die aus natürlichen Quellen gebildet werden, z. B. Pilzgifte oder pflanzliche Abwehrstoffe. Diese Toxine können beim Menschen sowohl chronische Effekte verursachen (z. B. Krebs induzieren) als auch akut toxisch wirken (Grüner Knollenblätterpilz, ungekochte Bohnen, Maniokwurzel). Bestimmte Bakte...

Lebensmitteln können im Rahmen des Produktionsprozesses bestimmte Substanzen aktiv zugefügt werden, um bestimmte chemische, physikalische oder physiologische Effekte zu generieren (z. B. Farbstoffe, Konservierungsmittel). Ebenso wie die Pflanzenschutzmittel (Fungizide, Herbizide, Insektizide), welche nach Anwendung auf dem Feld als Rückstand auf/im...

Dioxin in Schweinefleisch, Fipronil in Hühnereiern, Acrylamid in Kartoffelchips, Glyphosat im Bier – Diskussionen über die Sicherheit unserer Lebensmittel gehören zum Alltag, insbesondere wenn medienwirksam festgestellt wurde, dass es zu Überschreitungen der gesetzlichen Höchstmengen in den Lebensmitteln gekommen ist („Lebensmittelskandale“). Mit d...

Background Rosmarinus officinalis L. (rosemary) is traditionally used for food flavoring, as antioxidant preservative in food industry but also for medical properties. We investigated antioxidative and anti-aging effects of an aqueous rosemary extract over a broad concentration range in the model organism Caenorhabditis elegans. Methods Thermal st...

Beauvericin is an ubiquitous mycotoxin with relevant occurrence in food and feed. It causes a high toxicity in several cell lines, but its general mechanism of action is not fully understood and only limited in vivo studies have been performed. We used Caenorhabditis elegans as a model organism to investigate effects of beauvericin. The mycotoxin d...

Purpose Hibiscus sabdariffa L. is commonly used as an ingredient for herbal teas and food supplements. Several studies demonstrated the beneficial effects of Hibiscus sabdariffa L. extracts (HSE); however, the bioactive components and their mode of action still remain unclear. Caenorhabditis elegans (C. elegans) was used to study health-related eff...

Edible insects as an alternative source of protein are discussed as an important contribution to future feed and food security. However, it has to be ensured that the consumption is non-hazardous. This systematic review summarizes findings concerning contaminations of insects with mycotoxins and heavy metal ions (SciFinder, Pubmed, until 26 June 20...

The contamination of phytopharmaceuticals and herbal teas with toxic plants is an increasing problem. Senecio vulgaris L. is a particularly noxious weed in agricultural and horticultural crops due to its content of toxic pyrrolizidine alkaloids (PAs). Since some of these compounds are carcinogenic, the distribution of this plant should be monitored...

Objectives Recent studies showed that distinct extracts of Erythrina species used in the traditional medicine of sub‐Saharan Africa are protective against stress conditions. However, the underlying molecular mechanisms as well as relevant compounds remain unclear. Methods We used the model organism Caenorhabditis elegans to investigate compounds i...

Agrimonia procera is a pharmacologically interesting plant which is proposed to protect against various diseases due to its high amount of phytochemicals, e.g., polyphenols. However, in spite of the amount of postulated health benefits, studies concerning the mechanistic effects of Agrimonia procera are limited. Using the nematode Caenorhabditis el...

Extracts of the Chinese plant Polygonum multiflorum (PME) are used for medicinal purposes as well as food supplement due to anti-aging effects. Despite of the common use of these food supplements, experimental data on physiological effects of PME and its underlying molecular mechanisms in vivo are limited. We used the model organism Caenorhabditis...

Fifteen pyrrole alkaloids were isolated from the Red Sea marine sponge Stylissa carteri and investigated for their biological activities. Four of them were dibrominated [(+) dibromophakelline, Z-3-bromohymenialdisine, (±) ageliferin and 3,4-dibromo-1H-pyrrole-2-carbamide], nine compounds were monobrominated [(−) clathramide C, agelongine, (+) manza...

We investigated cytotoxic effects of the anthraquinone derivatives 1′-deoxyrhodoptilometrin (SE11) and (S)-(−)-rhodoptilometrin (SE16) isolated from the marine echinoderm Comanthus sp. in two tumor cell lines (C6 glioma, Hct116 colon carcinoma). Both compounds showed cytotoxic effects, with SE11 [IC50-value (MTT assay): 13.1 µM in Hct116 cells] sho...

Epidemiological studies suggest that a high intake of Brassica vegetables protects against colon carcinogenesis. Brassica vegetables are rich in glucosinolates which are hydrolysed during digestion to various products including indole-3-carbinol. In animal studies, a protective effect of indole-3-carbinol has been demonstrated in colon carcinogenes...

Food supplements based on herbal products are widely used during pregnancy as part of a self-care approach. The idea that such supplements are safe and healthy is deeply seated in the general population, although they do not underlie the same strict safety regulations than medical drugs. We aimed to characterize the neurodevelopmental effects of th...

Objectives: Resveratrol (trans-3,4',5-trihydroxystilbene (1)) was previously shown to extend the lifespan of different model organisms. However, its pharmacological efficiency is controversially discussed. Therefore, the bioactivity of four newly synthesized stilbenes (trans-3,5-dimethoxy-4-fluoro-4'-hydroxystilbene (3), trans-4'-hydroxy-3,4,5-tri...

The flavonoid baicalein has been demonstrated to be an activator of the transcription factor Nrf2 in mammalian cell lines. We show that it further modulates the Nrf2 homolog SKN-1 in Caenorhabditis elegans and by this pathway mediates beneficial effects in the nematode: Baicalein enhances the resistance of C. elegans against lethal thermal and sodi...

Context: Baicalein is a major compound in extracts derived from Scutellaria baicalensis Georgi (Lamiaceae) which are used in the Traditional Chinese Medicine for the treatment of inflammatory and gastrointestinal diseases. This flavonoid is an activator of the Nrf2 signalling pathway but the molecular mechanism is not clearly established. Objecti...

Only distinct flavonoids have been shown to enhance life span. This was pointed out for e.g. myricetin in the nematode Caenorhabditis elegans. However, the structural requirements responsible for this effect are not known. We used methylated derivatives of myricetin (laricitrin, syringetin, myricetintrimethylether) to investigate if free OH moietie...

2,3,5,4′-Tetrahydroxystilbene-2-O-β-D-glucoside (TSG) was isolated from Polygonum multiflorum, a plant which is traditionally used as an anti-ageing drug. We have analysed ageing-related effects of TSG in the model organism C. elegans in comparison to resveratrol. TSG exerted a high antioxidative capacity both in a cell-free assay and in the nemato...

The lignan pinoresinol is a constituent of flaxseed, sesame seeds and olive oil. Because of different molecular effects reported for this compound, e.g. antioxidative activity, pinoresinol is suggested to cause positive effects on humans. Because experimental data are limited, we have analysed the effects of the lignan on the nematode Caenorhabditi...

Purpose: The flavanone isoxanthohumol (IX) has gained attention as antioxidative and chemopreventive agent, but the molecular mechanism of action remains unclear. We investigated effects of this secondary plant compound in vivo using the model organism Caenorhabditis elegans. Methods: Adult C. elegans nematodes were incubated with IX, and then,...

Oxidative stress contributes to the process of carcinogenesis in several ways: an oxidation of DNA bases by reactive oxygen species (ROS), e.g. oxidation of guanosine to 8-hydroxyguanosine, has been linked to the formation of mutations thereby triggering the process of carcinogenesis. Furthermore, ROS contribute to the process of carcinogenesis by...

Unlabelled: CAPE is an active constituent of propolis which is widely used in traditional medicine. This hydroxycinnamic acid derivate is a known activator of the redox-active Nrf2 signalling pathway in mammalian cells. We used C. elegans to investigate the effects of this compound on accumulation of reactive oxygen species and the modulation of t...

Nephrotoxicity is the major dose-limiting adverse effect of cisplatin (CisPt) and results from CisPt-induced damage of tubular cells. Nephroprotective strategies are preferential to improve supportive care in cancer. We investigated a subset of purified substances originating from various plants or from marine sponges as to their potency to protect...

Flavonoids are secondary plant compounds that mediate diverse biological activities, for example, by scavenging free radicals and modulating intracellular signalling pathways. It has been shown in various studies that distinct flavonoid compounds enhance stress resistance and even prolong the life span of organisms. In the last years the model orga...

Psoralea corylifolia is a plant widely used in traditional Chinese medicine, e.g. for its chemopreventive effect. To identify active substances responsible for this effect, we investigated pharmacological effects of 11 compounds isolated from the seeds of this plant (newly described substances: 7, 2', 4'-trihydroxy-3-arylcoumarin and psoracoumestan...

Myricetin is a naturally occurring flavonol found in many plant based food sources. It increases the lifespan of Caenorhabditis elegans, but the molecular mechanisms are not yet fully understood. We have investigated the impact of this flavonoid on the transcription factors DAF-16 (C. elegans FoxO homologue) and SKN-1 (Nrf2 homologue), which have c...

Investigation of the marine sponge Dysidea avara, family Dysideidae, afforded a new sesquiterpene (-)-N-methylmelemeleone-A (5), in addition to four known sesquiterpenes (+)-avarol (1), (+)-avarone (2), (-)-3'-methylaminoavarone (3) and (-)-4'-methylaminoavarone (4). The structure elucidation of compound 5 was based on 1D and 2D NMR spectroscopic,...

Baicalein is a major compound of extracts derived from Scutellaria baicalensis Lamiaceae which are used as food supplements. Baicalein possesses a high radical scavenging activity and decreases intracellular reactive oxygen species in Hct116 human colon carcinoma cells and in Caenorhabditis elegans. It activates Nrf2, a key transcription factor tha...

Objectives Psoralea corylifolia is a plant widely used in traditional Chinese medicine, e.g. for its chemopreventive effect. To identify active substances responsible for this effect, we investigated pharmacological effects of 11 compounds isolated from the seeds of this plant (newly described substances: 7, 2′, 4′‐trihydroxy‐3‐arylcoumarin and pso...

A series of p-cymene ruthenium(II) complexes with imidazol-2-yl phosphines as PN ligands was prepared. Depending on the number of imidazolyl substituents in the ligands Ph3−nP(im)n {1–3: n = 1–3, im = imidazol-2-yl (a), 1-methylimidazol-2-yl (b)} different coordination modes were observed: κP, κ2N,N or κ3N,N,N. The complexes were tested for their c...

Caenorhabditis elegans open reading frame T21C9.1 encodes an uncharacterized protein, which is here named MICS-1 (mitochondrial scaffolding protein-1). It is predicted to be the homolog of human outer mitochondrial membrane protein 25 (OMP25 or synaptojanin-2-binding protein), which is a PDZ domain containing protein with a putative role in cellula...

CO-releasing molecules (CORMs) were coordinated to polymeric carrier systems for passive transport to tumour tissue or sites of inflammation, as described by the enhanced permeability and retention (EPR) effect. The developed conjugates consist of an organometallic fac-Mn(CO)(3) fragment, which is bound to a methacrylate or methacrylamide polymer b...

Gold(I) complexes of imidazole and thiazole-based diphos type ligands were prepared and their potential as chemotherapeutics investigated. Depending on the ligands employed and the reaction conditions complexes [L(AuCl)(2)] and [L(2)Au]X (X = Cl, PF(6)) are obtained. The ligands used are diphosphanes with azoyl substituents R(2)P(CH(2))(2)PR(2) {R...

Ruthenium complexes have gained increasing significance as possible anti-cancer agents during the past few years. Promising characteristics such as decreased side effects and lack of cross-resistance with platinum-based chemotherapeutics such as cisplatin, and recent events such as the successful phase I clinical trial of the ruthenium complex NAMI...

The tetranuclear ruthenium arene compound [(cym)4Ru4(2)Cl6]Cl2 (3) (cym = η6-p-cymene, 2 = 1,2-bis(di-N-methylimidazol-2-ylphosphino)ethane) was prepared and characterised by one- and two-dimensional NMR techniques. Its cytotoxicity against four different cell lines was determined and, with an approximate IC50 of >100 μM 3 can be regarded as non-to...

VorbemerkungenKohlenmonoxidCyanwasserstoffSchwefelwasserstoffNitrose GaseIsocyanateFormaldehydZusammenfassungFragen zur SelbstkontrolleWeiterführende Literatur

EinleitungChemische Reaktionen der Phase IChemische Reaktionen der Phase IIZusammenfassungFragen zur Selbstkontrolle (Exercises)Literatur

The redox-sensitive nuclear factor kappa-B (NF-κB) signaling pathway is an important cellular pathway often misregulated in various cancer cells. Therefore, blockade of NF-κB signaling in cancer cells presents a promising strategy and enormous effort has been invested to identify potent and specific inhibitors. The aim of this study was the identif...

The redox-sensitive nuclear factor kappa-B (NF-κB) signaling pathway is an important cellular pathway often misregulated in various cancer cells. Therefore, blockade of NF-κB signaling in cancer cells presents a promising strategy and enormous effort has been invested to identify potent and specific inhibitors. The aim of this study was the identif...

The cytostatic drug doxorubicin is a well-known chemotherapeutic agent which is used in treatment of a wide variety of cancers. A key factor in the response of cancer cells to chemotherapeutic drugs is the activation of the apoptotic pathway, a pathway that is often impaired in chemoresistant colon cancer cells. The aim of the present study was to...

Phenolic compounds, named integracin D (1), (7'R, 8'S, 8S)-8-hydroxyisoguaiacin (3), (2R, 3R) pinobanksin-3-caffeoylate (5) and threo-8S-7-methoxysyringylglycerol (6), respectively, were isolated from the Chinese mangrove plant Laguncularia racemosa (L) Gaertn. f. (Combretaceae), together with 23 known phenolic metabolites. Their structures were el...