A novel carbon skeletal trichothecane, tenuipesine A, isolated from an entomopathogenic fungus, Paecilomyces tenuipes

Tenuipesine A (1), a novel trichothecane with an unprecedented carbon-migrated skeleton that embodies of a cyclopropane ring, was isolated from cultivated fruiting bodies of Paecilomyces tenuipes (Isaria japonica), a popular entomopathogenic fungi employed in folk medicine and health foods in China, Korea, and Japan. The structure was determined on the basis of two-dimensional NMR data. Its stereochemistry was elucidated by spectroscopic data and the chemical transformation of the coexisting trichothecene, 4beta-acetoxy-12,13-epoxytrichothec-9-ene-3alpha,15-diol (2). [structure: see text]     

Novel trichothecanes, paecilomycine A, B, and C, isolated from entomopathogenic fungus, Paecilomyces tenuipes

Paecilomycine A (1), B (2), and C (3) were isolated from cultivated fruiting bodies of Paecilomyces tenuipes (Isaria japonica), which is a popular entomopathogenic fungus used in folk medicine and health foods in China, Korea, and Japan. The structures of 1-3 were deduced from their spectroscopic data and their absolute configurations were elucidated by preparing their MPA esters. Compound 1 showed activity in the neurotrophic factor biosynthesis in glial cells.     

从细脚拟青霉分离的新环二肽与新十元环内酯

利用反相色谱、 凝胶色谱和硅胶色谱从细脚拟青霉发酵液中分离得到4个活性化合物. 通过核磁共振波谱、 质谱、 X射线晶体衍射分析和理化数据鉴定化合物1为新环二肽[(3S)-6-苯乙基-3-异丙基-1-甲基-2,5-二酮哌嗪], 化合物2为新十元环内酯[(4S,10R)-4-羟基-8-氧代-10-甲基癸内酯], 化合物3为Cepharosporolide C, 化合物4为Cepharosporolide E. 细胞毒性实验结果表明, 5 μmol/L的化合物1对前列腺癌细胞22RV1和DU-145的抑制率分别为37.8%和38.6%, 5 μmol/L的化合物2对前列腺癌细胞22RV1和DU-145的抑制率分别为32.5%和40.6%, 具有一定抗肿瘤活性.     

Formation,determination and significance of masked and other conjugated mycotoxins

Mycotoxins are secondary metabolites of fungi poisonous for humans or animals which can be found on a great variety of food and feed commodities. Food is not necessarily safe just because the presence of well-known mycotoxins has been ruled out, as they might still be there in disguise. Mycotoxins may also occur in conjugated form, either soluble (masked mycotoxins) or incorporated into/associated with/attached to macromolecules (bound mycotoxins). These conjugated mycotoxins can emerge after metabolization by living plants, fungi and mammals or after food processing. Awareness of such altered forms of mycotoxins is increasing, but reliable analytical methods, measurement standards and occurrence and toxicity data are still lacking. In this paper currently known conjugated mycotoxins, their formation and determination are reviewed. For the latter, liquid chromatography-(tandem) mass spectrometry or ELISA methods are employed with or without conversion to the parent mycotoxins. Sample preparation to transform the bound forms into soluble forms can involve enzymatic or acidic/alkaline treatment. Especially mycotoxins which are in contact with living plants in the field are prone to be metabolized. This transformation process is not only important regarding food safety but also for the resistance of plants towards fungal-induced diseases, such as Fusarium head blight of wheat.     

Mycotoxins from Mold Fungi — Weapons of Uninivited Fellow-Boarders of Man and Animal: Structures,Biological Activity,Biosynthesis, and Precautions

In addition to the antibiotics, mycotoxins represent a second large group of biologically active substances of microbial origin. Over 300 mycotoxins are so far known and can be subdivided into 25 structural types. They are formed by approximately 350 molds of which there are 10 000 different strains. As mycotoxin-producing molds tend to spread aggressively on foodstuffs, they can cause epidemic mycotoxicoses.—The mycotoxins have been isolated, their structures determined, and their biological activities investigated; their biosynthesis has now also largely been elucidated. Accordingly, mycotoxins are derived from only three groups of key biogenetic building blocks: polyketides, isopentenyl pyrophosphate, and amino acids. Mycotoxins are mainly non-polar, chemically stable, are formed in high concentrations, and do not contain—unlike antibiotics—any sugars. Mycotoxins display an enormous variety of toxic-pharmacological activities, e.g. liver degradation, hemorrhages, carcinomas. The identification of mycotoxicoses is impeded by their long incubation periods and the fact that the mycotoxins tend to accumulate in the mammalian organism, which means that even very low concentrations in food are a potential danger. The particularly dangerous aflatoxin B₁ 1 may not exceed a limit in food of 5 ppb (5 μg/kg), which is difficult to control.     

Natural toxins: risks,regulations and the analytical situation in Europe

Natural toxins in food and feed are considered important food safety issues of growing concern, in particular mycotoxins, phycotoxins and plant toxins. Most scientific developments have occurred in the past few decades in the area of mycotoxins. Formal health risk assessments have been carried out by the Joint Expert Committee on Food Additives of the World Health Organization and the Food and Agriculture Organization. Limits and regulations for mycotoxins in food and feed have been established in many countries, including practically all European countries. An array of (formally validated) analytical methods and (certified) reference materials have become available. Several European research projects, funded by the European Commission and supported by the European Standardization Committee, have significantly contributed to this development. Quantitative methods of analysis for mycotoxins often make use of immunoaffinity cleanup with liquid chromatographic or gas chromatographic separation techniques in combination with various types of detectors, including mass spectroscopy. For screening purposes (bio)sensor-based techniques are among the promising newcomers. For the phycotoxins the situation is less advanced. Formal risk assessments by authoritative international bodies have not been carried out. Methods of analysis, formally validated according to internationally harmonized protocols, are scarce and animal testing still plays a key role in official methodology. The development of the analytical methodology is partly hampered by the limited availability of certain reliable calibrants and reference materials, although this situation is gradually improving. New regulations in the European Union have increased the pressure to develop and validate chemical methods of analysis. Joint efforts in the European context are now directed towards significantly improving this situation, and techniques such as liquid chromatography–mass spectroscopy offer promise in this respect. Both the working group on biotoxins of the European Standardization Committee and the network of National Reference Laboratories for Marine Biotoxins have taken up responsibilities here. The plant toxins are a category of natural toxins, where the situation is the least developed with respect to regulations, validated methods of analysis and reference materials. Yet, their occurrence in a wide range of consumable plant species demands the attention of the analytical community.     

Evaluation of mycotoxins and their metabolites in human breast milk using liquid chromatography coupled to high resolution mass spectrometry

Humans can be exposed to mycotoxins through the food chain. Mycotoxins are mainly found as contaminants in food and could be subsequently excreted via biological fluids such as urine or human breast milk in native or metabolised form. Since breast milk is usually supposed as the only food for new-borns, the occurrence of mycotoxins in thirty-five human milk samples was evaluated by a newly developed method based on QuEChERS extraction and UHPLC–HRMS detection. The method described here allows the detection of target mycotoxins in order to determine the quality of this initial feeding. The method has been fully validated, with recoveries ranging from 64% to 93% and relative standard deviations (RSD, %) being lower than 20%. Using the method described, non-metabolised mycotoxins such as ZEA, NEO, NIV, ENA, ENA₁, ENB, ENB₁ and metabolites, such as ZEA metabolites, HT-2, DOM and T-2 triol were detected in human milk samples. Results obtained help to estimate the exposure of mothers and infants to mycotoxins. Moreover, to the best of our knowledge, this is the first work describing the simultaneous detection, quantification and screening of mycotoxins and their metabolites in human mature milk.     

Stereocontrolled approach to trichothecane derivatives via tricarbonylcyclo-hexadieneiron complexes: synthesis of a key intermediate.

The potential of tricarbonyl(4-methoxy-1-methylcyclohexadienylium) iron hexafluorophosphate (2) as a trichothecane precursor is demonstrated by the stereocontrolled elaboration of the advanced intermediate (14).     

固相萃取材料在食品真菌毒素检测中的研究进展

被真菌毒素污染的食品可引发严重的健康问题,如癌症和畸形等,已成为全球公共卫生关注的焦点.因此,精准检测食品中痕量真菌毒素对保障人类健康具有重要意义.真菌毒素在食品中的浓度水平较低且易与复杂的食品基质成分结合,基质干扰严重影响检测的灵敏度,需采用有效的样品前处理技术进行富集和净化.固相萃取作为一种高效的样品前处理技术,其...     

高效液相色谱与液相色谱-质谱分析冬虫夏草相关产品之麦角固醇与其衍生物

采用HPLC与LC-MS分析西藏冬虫夏草(Cord yceps sinensis,Cs)子实体、Cs分离的无性世代中国被毛孢(Hirsutella sinensis)菌丝体(Hsm)RS6-3、市售蛹虫草(Cordyceps militaris,Cm)和蝙蝠蛾拟青霉(Paecilomyces hepiali,Cs-4)...     

Reliable identification and quantification of trichothecenes and other mycotoxins by electron impact and chemical ionization-gas chromatography-mass spectrometry, using an ion-trap system in the multiple mass spectrometry mode. Candidate reference method for complex matrices

Highly toxic mycotoxins like the trichothecenes can be found as contaminants from the metabolism of fungi in food and food preparations. They can be identified and quantified with great accuracy by GC/MS-measurements. Reliable analytical methods are urgently needed because such mycotoxins are not only toxic substances occurring in nature but also are in the list of biological weapons (e.g. T2-toxin, HT-2-toxin) and have some potential for terroristic attacks. By using GC/MS in the EI- and NCI- or PCI-mode and MS(n)-measurements with a 30 m Rtx 5MS fused-silica capillary column it is possible to identify and quantify all relevant mycotoxins either as underivatized substances or as their TMS-derivatives in extracts from food, food preparations or beverages with very complex matrix-derived background. This method can also be used to determine free ricinine as a biological marker for ricine in terroristic attacks. So laborious and time-consuming steps of sample-preparation can often be diminished. The LOD is in the range of 10-50 pg and the LOQ with linear calibration curves is in the range of 50-5000 pg. The high specificity of these methods helps not only to detect the existence of intentional terroristic or natural food contamination but also to avoid faulty alarm with unnecessary panic in the public. Furthermore, these methods have a high potential in ameliorating the safety of basic food and food products.     

Current Applications of Magnetic Nanomaterials for Extraction of Mycotoxins,Pesticides, and Pharmaceuticals in Food Commodities

Environmental pollutants, such as mycotoxins, pesticides, and pharmaceuticals, are a group of contaminates that occur naturally, while others are produced from anthropogenic sources. With increased research on the adverse ecological and human health effects of these pollutants, there is an increasing need to regularly monitor their levels in food and the environment in order to ensure food safety and public health. The application of magnetic nanomaterials in the analyses of these pollutants could be promising and offers numerous advantages relative to conventional techniques. Due to their ability for the selective adsorption, and ease of separation as a result of magnetic susceptibility, surface modification, stability, cost-effectiveness, availability, and biodegradability, these unique magnetic nanomaterials exhibit great achievement in the improvement of the extraction of different analytes in food. On the other hand, conventional methods involve longer extraction procedures and utilize large quantities of environmentally unfriendly organic solvents. This review centers its attention on current applications of magnetic nanomaterials and their modifications in the extraction of pollutants in food commodities.     

Albaconol,A Novel Prenylated Resorcinol (=Benzene‐1,3‐diol) from Basidiomycetes Albatrellus confluens

The new substance albaconol ( 1 ) was isolated along with grifolin ( 2 ), emeheterone ( 3 ), and the pyrazinol derivative 4 from the fresh fruiting bodies of the basidiomycetes Albatrellus confluens. Structures were established by spectral analysis, including 2D NMR spectroscopy. Albaconol ( 1 ) possesses the skeleton of a drimane‐type sesquiterpenoid, which is directly connected to a resorcinol (=benzene‐1,3‐diol) moiety; this prenylated resorcinol represents a new C skeleton.     

Tenuipyrone, a novel skeletal polyketide from the entomopathogenic fungus, Isaria tenuipes, cultivated in the presence of epigenetic modifiers

The concomitant addition of the histone deacetylase inhibitor and the DNA methyltransferase inhibitor to the culture medium of an entomopathogenic fungus, Isaria tenuipes, greatly enhanced its secondary metabolite production and led to the isolation of tenuipyrone (1), a novel polyketide with an unprecedented tetracyclic ring system bearing a spiroketal structural component, along with two known C(10)-polyketides, cephalosporolide B (2), which is a plausible biosynthetic precursor of 1, and cephalosporolide F (3).     

High Pressure Processing Impact on Alternariol and Aflatoxins of Grape Juice and Fruit Juice-Milk Based Beverages

High-pressure processing (HPP) has emerged over the last 2 decades as a good alternative to traditional thermal treatment for food safety and shelf-life extension, supplying foods with similar characteristics to those of fresh products. Currently, HPP has also been proposed as a useful tool to reduce food contaminants, such as pesticides and mycotoxins. The aim of the present study is to explore the effect of HPP technology at 600 MPa during 5 min at room temperature on alternariol (AOH) and aflatoxin B1 (AFB1) mycotoxins reduction in different juice models. The effect of HPP has also been compared with a thermal treatment performed at 90 °C during 21 s. For this, different juice models, orange juice/milk beverage, strawberry juice/milk beverage and grape juice, were prepared and spiked individually with AOH and AFB1 at a concentration of 100 µg/L. After HPP and thermal treatments, mycotoxins were extracted from treated samples and controls by dispersive liquid–liquid microextraction (DLLME) and determined by HPLC-MS/MS-IT. The results obtained revealed reduction percentages up to 24% for AFB1 and 37% for AOH. Comparing between different juice models, significant differences were observed for AFB1 residues in orange juice/milk versus strawberry juice/milk beverages after HPP treatment. Moreover, HPP resulted as more effective than thermal treatment, being an effective tool to incorporate to food industry in order to reach mycotoxins reductions.     

Recent Advances in Electrochemical Sensors for Mycotoxin Detection in Food

Mycotoxins pose a grave global threat to human life and health by contaminating food and feed and cause enormous losses in healthcare and trading. Trace mycotoxin concentrations and diverse matrices in food make identification and measurement challenges, necessitating highly specific and sensitive detection methods. Electrochemical (EC) sensors are characterized by simple operation, outstanding sensitivity, low cost, and facile miniaturization and have become a promising strategy for addressing specificity and sensitivity in detection. Recent studies on EC sensors for mycotoxin detection for food safety are reviewed here. First, we summarize the fabrication of EC sensors and techniques with enhanced specificity and sensitivity. Then, we review state-of-the-art EC sensors for detecting major mycotoxins. Challenges and opportunities for this technology are further discussed. Finally, in-depth information is provided on using EC sensors to detect mycotoxins for food safety, as well as the development of EC sensors for academic study and practical application.     

Trichothecenes in Food and Feed,Relevance to Human and Animal Health and Methods of Detection: A Systematic Review

Trichothecene mycotoxins are sesquiterpenoid compounds primarily produced by fungi in taxonomical genera such as Fusarium, Myrothecium, Stachybotrys, Trichothecium, and others, under specific climatic conditions on a worldwide basis. Fusarium mold is a major plant pathogen and produces a number of trichothecene mycotoxins including deoxynivalenol (or vomitoxin), nivalenol, diacetoxyscirpenol, and T-2 toxin, HT-2 toxin. Monogastrics are sensitive to vomitoxin, while poultry and ruminants appear to be less sensitive to some trichothecenes through microbial metabolism of trichothecenes in the gastrointestinal tract. Trichothecene mycotoxins occur worldwide however both total concentrations and the particular mix of toxins present vary with environmental conditions. Proper agricultural practices such as avoiding late harvests, removing overwintered stubble from fields, and avoiding a corn/wheat rotation that favors Fusarium growth in residue can reduce trichothecene contamination of grains. Due to the vague nature of toxic effects attributed to low concentrations of trichothecenes, a solid link between low level exposure and a specific trichothecene is difficult to establish. Multiple factors, such as nutrition, management, and environmental conditions impact animal health and need to be evaluated with the knowledge of the mycotoxin and concentrations known to cause adverse health effects. Future research evaluating the impact of low-level exposure on livestock may clarify the potential impact on immunity. Trichothecenes are rapidly excreted from animals, and residues in edible tissues, milk, or eggs are likely negligible. In chronic exposures to trichothecenes, once the contaminated feed is removed and exposure stopped, animals generally have an excellent prognosis for recovery. This review shows the occurrence of trichothecenes in food and feed in 2011–2020 and their toxic effects and provides a summary of the discussions on the potential public health concerns specifically related to trichothecenes residues in foods associated with the exposure of farm animals to mycotoxin-contaminated feeds and impact to human health. Moreover, the article discusses the methods of their detection.     

Total synthesis of spirotenuipesines A and B

Spirotenuipesines A and B, isolated from the entomopathogenic fungus Paecilomyces tenuipes by Oshima and co-workers, have been synthesized. The synthesis features the highly stereoselective construction of two vicinal all-carbon quaternary centers (C(5) and C(6)) via an intramolecular cyclopropanation/radical initiated fragmentation sequence and a diastereoselective intermolecular Diels-Alder reaction between alpha-methylenelactone dienophile 20 and synergistic diene 6a. Installation of the C(9) tertiary alcohol occurred via nucleophilic methylation. An RCM reaction to produce a tetrasubstituted double bond in the presence of free allylic alcohol and homoallylic oxygenated functional group is also described. This route shortened the synthesis of 11 from 9 steps to 3 steps. We have further developed a strategy to gain access to optically active spirotenuipesines A and B through the synthesis of enantioenriched 10 from commercially available R-(-)-epichlorohydrin.     

Immunochemical tools for mycotoxin detection in food

Abstract  

As a result of the deleterious effects of mycotoxins on human and animal health, and the consequently increasing stringency in the determination of food contamination levels, many researchers have focused their efforts on developing new devices for the detection of these compounds. Biosensors merit special mention due to their sensitivity, accuracy, cost-effectiveness and simplicity, not only of the construction, but also of the sample pre-treatment, if necessary, and the measurement step. Furthermore, biosensor arrays offer additional advantages, such as the possibility to measure multiple samples and provide multi-mycotoxin profiles in one assay. In this case, apart from shortening the analysis time, accuracy is improved by the assessment of matrix interferences and synergistic effects among mycotoxins. Biosensors and arrays for mycotoxins are thus promising biotechnological tools for mycotoxin detection in food.     

The Existing Methods and Novel Approaches in Mycotoxins’ Detection

Mycotoxins represent a wide range of secondary, naturally occurring and practically unavoidable fungal metabolites. They contaminate various agricultural commodities like cereals, maize, peanuts, fruits, and feed at any stage in pre- or post-harvest conditions. Consumption of mycotoxin-contaminated food and feed can cause acute or chronic toxicity in human and animals. The risk that is posed to public health have prompted the need to develop methods of analysis and detection of mycotoxins in food products. Mycotoxins wide range of structural diversity, high chemical stability, and low concentrations in tested samples require robust, effective, and comprehensible detection methods. This review summarizes current methods, such as chromatographic and immunochemical techniques, as well as novel, alternative approaches like biosensors, electronic noses, or molecularly imprinted polymers that have been successfully applied in detection and identification of various mycotoxins in food commodities. In order to highlight the significance of sampling and sample treatment in the analytical process, these steps have been comprehensively described.