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In recent pharmacokinetically based risk assessments for methylene chloride, Andersen et al.(1) argued that total reactive metabolite (TRM) divided by liver weight was the proper measure of dose to target tissue, while the EPA argued that TRM divided by body weight to the two‐thirds power was more appropriate.(2) We demonstrate that the proper tissue metric for a reactive metabolite is dependent upon the mode of deactivation: metabolic or spontaneous. It is argued that the most appropriate measure of tissue dosimetry is: (1) TRM divided by the three‐fourths power of body weight if the reactive metabolite is metabolically deactivated; or (2) TRM divided by body weight if the reactive metabolite is spontaneously deactivated.

1 Introduction -- 1.1 Primary and secondary metabolism -- 1.2 Stereochemistry and biosynthesis -- 1.3 Some reactions of general importance in secondary metabolism -- 2 Techniques for biosynthesis -- 2.1 Introduction -- 2.2 Isotopic labelling -- 2.3 Enzymes and mutants -- 3 Polyketides -- 3.1 Introduction -- 3.2 Formation of poly-?-keto-acyl-CoA's -- 3.3 Tetraketides -- 3.4 Pentaketides -- 3.5 Hexaketides -- 3.6 Heptaketides -- 3.7 Octaketides -- 3.8 Nona- and deca-ketides -- 3.9 Polyketides with mixed origins -- 4 Terpenes and steroids -- 4.1 Introduction -- 4.2 Steroids -- 4.3 Pentacyclic triterpenes -- 4.4 Squalene -- 4.5 Monoterpenes -- 4.6 Sesquiterpenes -- 4.7 Diterpenes -- 4.8 Sesterpenes -- 4.9 Carotenoids and vitamin A -- 5 The shikimic acid pathway -- 5.1 Introduction -- 5.2 Quinones -- 5.3 Coumarins -- 5.4 Flavonoids -- 6 Alkaloids -- 6.1 Introduction -- 6.2 Piperidine and pyrrolidine alkaloids -- 6.3 Isoquinoline and related alkaloids -- 6.4 Amaryllidaceae and mesembrine alkaloids -- 6.5 Quinoline and related alkaloids -- 6.6 Indole alkaloids -- 6.7 Ipecac alkaloids -- 6.8 Miscellaneous alkaloids -- 7 Microbial metabolites containing nitrogen -- 7.1 Introduction -- 7.2 Piperidine and pyridine metabolites -- 7.3 Diketopiperazines -- 7.4 Benzodiazepines -- 7.5 Metabolites derived from the tryptophan pathway -- 7.6 Miscellaneous metabolites.

Antibiotics are some of the most widely used drugs. Their release in the environment is of great concern since their consumption is a major factor for antibiotic resistance, one of the most important threats to human health. Their occurrence and fate in agricultural systems have been extensively investigated in recent years. Yet whilst their biotic and abiotic degradation pathways have been thoroughly researched, their biotransformation pathways in plants are less understood, such as in case of trimethoprim. Although trimethoprim has been reported in the environment, its fate in higher plants still remains unknown. A bench-scale experiment was performed and 30 trimethoprim metabolites were identified in lettuce (Lactuca sativa L.), of which 5 belong to phase I and 25 to phase II. Data mining yielded a list of 1018 ions as possible metabolite candidates, which was filtered to a final list of 87 candidates. Molecular structures were assigned for 19 compounds, including 14 TMP metabolites reported for the first time. Alongside well-known biotransformation pathways in plants, additional novel pathways were suggested, namely, conjugation with sesquiterpene lactones, and abscisic acid as a part of phase II of plant metabolism. The results obtained offer insight into the variety of phase II conjugates and may serve as a guideline for studying the metabolization of other chemicals that share a similar molecular structure or functional groups with trimethoprim. Finally, the toxicity and potential contribution of the identified metabolites to the selective pressure on antibiotic resistance genes and bacterial communities via residual antimicrobial activity were evaluated. ; The work presented in this paper is part of a project that has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement no. 675530. ; Peer reviewed

Bacterial Secondary Metabolites: Synthesis and Applications in Agroecosystem presents the structure, properties, and biotechnological applications of bacterial metabolites and their upcoming industrial, pharmaceutical, antimicrobial, and anticancer applications. Chapters cover topics such as the use of lactic acid bacteria as an antifungal and antibacterial agent, bacterial siderophores structure and potential applications, and the role of cyanobacteria metabolites in disease management, amongst others. Plant and agri-food environmental scientists and researchers, graduate, and post-graduate students in related fields will benefit from this reference book which is published as part of the Nanobiotechnology for Plant Protection series

We report herein improved version of the synthesis of hapten based on cholecalciferol and its active metabolite 25-hydroxycholecalcalferol. The methodology of obtaining high-molecular immunogenic conjugates of vitamin D3 derivatives with bovine serum albumin and horseradish peroxidase conjugates for direct ELISA was optimized. Immunisation of rabbits was carried out and polyclonal antibodies to 25-hydroxycholecalceferol were obtained and tested in an enzyme-linked immunosorbent assay. To improve the accuracy of the method, the sample preparation procedure was optimized, including the release of vitamin D3 and its active metabolites from complexes with vitamin D-binding protein.

The authors would like to apologize for omitting a number of contributors from the above publication who share rights to the authorship of this manuscript.

Secondary metabolites are organic molecules of low molecular weight, biosynthesized by any living being using a wide range of biosynthetic pathways, known as secondary metabolism. In evolutionary terms, secondary metabolism is seen as a set of specialized pathways that use a varied and specialized series of enzymes. Secondary metabolism aims to produce molecules with specific functions that promote the adaptability and survival of the species. However, secondary metabolites are not molecules essential to life, as are the lipids, carbohydrates and amino acids involved in basic life functions and produced by the primary metabolism. Terrestrial plants and algae, because they are sessile species, synthesize an admirable structural diversity of secondary metabolites. […]. (excerpt) ; This work was funded by FCT-Fundação para a Ciência e a Tecnologia, the European Union, QREN, FEDER, COMPETE, by funding the cE3c centre (UIDB/00329/2020) and the LAQV-REQUIMTE (UIDB/50006/2020) research units, and funded by the project EthnoHERBS (H2020-MSCA-RISE-2018, No. 823973). ; info:eu-repo/semantics/publishedVersion

Intro -- Foreword -- Preface -- Acknowledgment -- Contents -- Contributors -- About the Editors -- Part I: Antifungal Metabolites (AFM) for Sustainable Agriculture -- Chapter 1: Potential of Streptomyces and Its Secondary Metabolites for Biocontrol of Fungal Plant Pathogens -- 1.1 Introduction -- 1.2 Streptomyces Production of Metabolites for Biological Control -- 1.3 Main Phytopathogenic Fungi -- 1.3.1 Phytopathogenic Microorganism's Control -- 1.3.2 PGPA as Biocontrol Agents (BCAs) -- 1.3.3 Crop Diseases -- 1.4 Production of Enzymes -- 1.5 Volatile Organic Compounds (VOC) -- 1.6 Phytohormone Production -- 1.7 Enhancement of Plant Growth -- 1.7.1 Siderophore Production -- 1.7.2 Phosphate Solubilization -- 1.8 Commercialization, Environmental Effects, and Biosafety of Streptomyces Products -- 1.8.1 Formulation and Inoculation Methods -- 1.9 Conclusion -- References -- Chapter 2: Antifungal Secondary Metabolites Against Blast Fungus Magnaporthe oryzae -- 2.1 Introduction -- 2.2 Plant Infection Mechanism by Magnaporthe oryzae -- 2.3 Biological Control -- 2.4 Effects of Bioactive Natural Products Against Blast Fungus -- 2.5 Mechanisms of Important Bioactive Secondary Metabolites Against Cereal Blast Fungus -- 2.6 Conclusion and Future Perspectives -- References -- Chapter 3: Utilization of Plant Growth-Promoting Bacteria (PGPB) Against Phytopathogens -- 3.1 Introduction -- 3.2 Phytopathogens -- 3.3 Antibiotic Used on Plants to Control Phytopathogens -- 3.4 PGPB for Control of Phytopathogens -- 3.4.1 Mechanistic Insights -- 3.5 Conclusions -- References -- Chapter 4: PGPR in Biofilm Formation and Antibiotic Production -- 4.1 Introduction -- 4.2 Plant-Microbiome Interaction by the Biofilm Formed by PGPR -- 4.3 PGPR and Its Role in Agriculture -- 4.4 Antibiotic Production by PGPR -- 4.4.1 Biosynthesis of Polyketide Group of Antibiotics by PGPR.