Explore the vast range of titles available.

Manfred Göthert, who had served Naunyn-Schmiedeberg’s Arch Pharmacol as Managing Editor from 1998 to 2005, deceased in June 2019. His scientific oeuvre encompasses more than 20 types of presynaptic receptors, mostly on serotoninergic and noradrenergic neurones. He was the first to identify presynaptic receptors for somatostatin and ACTH and described many presynaptic receptors, known from animal preparations, also in human tissue. In particular, he elucidated the pharmacology of presynaptic 5-HT receptors. A second field of interest included ligand-gated and voltage-dependent channels. The negative allosteric effect of anesthetics at peripheral nACh receptors is relevant for the peripheral clinical effects of these drugs and modified the Meyer-Overton hypothesis. The negative allosteric effect of ethanol at NMDA receptors in human brain tissue occurred at concentrations found in the range of clinical ethanol intoxication. Moreover, the inhibitory effect of gabapentinoids on P/Q Ca 2+ channels and the subsequent decrease in AMPA-induced noradrenaline release may contribute to their clinical effect. Another ligand-gated ion channel, the 5-HT 3 receptor, attracted the interest of Manfred Göthert from the whole animal via isolated preparations down to the cellular level. He contributed to that molecular study in which 5-HT 3 receptor subtypes were disclosed. Finally, he found altered pharmacological properties of 5-HT receptor variants like the Arg219Leu 5-HT 1A receptor (which was also shown to be associated with major depression) and the Phe124Cys 5-HT 1B receptor (which may be related to sumatriptan-induced vasospasm). Manfred Göthert was a brilliant scientist and his papers have a major impact on today’s pharmacology.

Recently, the occurrence of candidiasis has increased dramatically, especially in immunocompromised patients. Additionally, their treatment is often ineffective due to the resistance of yeasts to antimycotics. Therefore, there is a need to search for new antifungals. A series of nine newly synthesized thiazole derivatives containing the cyclopropane system, showing promising activity against Candida spp., has been further investigated. We decided to verify their antifungal activity towards clinical Candida albicans isolated from the oral cavity of patients with hematological malignancies and investigate the mode of action on fungal cell, the effect of combination with the selected antimycotics, toxicity to erythrocytes, and lipophilicity. These studies were performed by the broth microdilution method, test with sorbitol and ergosterol, checkerboard technique, erythrocyte lysis assay, and reversed phase thin-layer chromatography, respectively. All derivatives showed very strong activity (similar and even higher than nystatin) against all C. albicans isolates with minimal inhibitory concentration (MIC) = 0.008–7.81 µg/mL Their mechanism of action may be related to action within the fungal cell wall structure and/or within the cell membrane. The interactions between the derivatives and the selected antimycotics (nystatin, chlorhexidine, and thymol) showed additive effect only in the case of combination some of them and thymol. The erythrocyte lysis assay confirmed the low cytotoxicity of these compounds as compared to nystatin. The high lipophilicity of the derivatives was related with their high antifungal activity. The present studies confirm that the studied thiazole derivatives containing the cyclopropane system appear to be a very promising group of compounds in treatment of infections caused by C. albicans. However, this requires further studies in vivo.Key points• The newly thiazoles showed high antifungal activity and some of them — additive effect in combination with thymol.• Their mode of action may be related with the influence on the structure of the fungal cell wall and/or the cell membrane.• The low cytotoxicity against erythrocytes and high lipophilicity of these derivatives are their additional good properties.

Metabolomics is the analysis of endogenous and exogenous low molecular mass metabolites within a cell, tissue, or biofluid of an organism in response to an external stressor. The sub-discipline of environmental metabolomics is the application of metabolomic techniques to analyze the interactions of organisms with their environment. There has been a rapid growth in environmental metabolomics over the past decade. This growth can be attributed to the comprehensive and rapid nature of nontargeted metabolomics and the ability to generate hypotheses involving complex environmental stressors, especially when the mode of action is unknown. Using a wide variety of model organisms, metabolomic studies have detected stress from abiotic factors such as xenobiotic exposure and temperature shifts as well as biotic stressors such as herbivory and competition. Nuclear magnetic resonance (NMR)-based metabolomics has been the dominant analytical platform used for environmental metabolomics studies, owing to its nonselectivity and ease of sample preparation. However, the number of mass spectrometry (MS)-based metabolomic studies is also increasing rapidly, owing to its high sensitivity for the detection of trace levels of metabolites. In this review, we provide an overview of the general experimental design, extraction methods, analytical instrumentation, and statistical methods used in environmental metabolomics. We then highlight some of the recent studies that have used metabolomics to elucidate hitherto unknown biochemical modes of actions of various environmental stressors to both terrestrial and aquatic organisms, as well as identify potential metabolite shifts as early bioindicators of these stressors. Through this, we emphasize the immense potential and versatility of environmental metabolomics as a routine tool for characterizing the responses of organisms to numerous types of environmental stressors.

Combination chemotherapy can increase treatment efficacy and suppress drug resistance. Knowledge of how to engineer rational, mechanism-based drug combinations, however, remains lacking. Although studies of drug activity have historically focused on the primary drug–target interaction, growing evidence has emphasized the importance of the subsequent consequences of this interaction. Bedaquiline (BDQ) is the first new drug for tuberculosis (TB) approved in more than 40 y, and a species-selective inhibitor of the Mycobacterium tuberculosis (Mtb) ATP synthase. Curiously, BDQ-mediated killing of Mtb lags significantly behind its inhibition of ATP synthase, indicating a mode of action more complex than the isolated reduction of ATP pools. Here, we report that BDQ-mediated inhibition of Mtb’s ATP synthase triggers a complex metabolic response indicative of a specific hierarchy of ATP-dependent reactions. We identify glutamine synthetase (GS) as an enzyme whose activity is most responsive to changes in ATP levels. Chemical supplementation with exogenous glutamine failed to affect BDQ’s antimycobacterial activity. However, further inhibition of Mtb’s GS synergized with and accelerated the onset of BDQ-mediated killing, identifying Mtb’s glutamine synthetase as a collateral, rather than directly antimycobacterial, metabolic vulnerability of BDQ. These findings reveal a previously unappreciated physiologic specificity of ATP and a facet of mode-of-action biology we term collateral vulnerability, knowledge of which has the potential to inform the development of rational, mechanism-based drug combinations.

Quinofumelin, a quinoline‐based fungicide, demonstrated potent antifungal activity against Fusarium graminearum, the pathogen responsible for Fusarium head blight (FHB) in wheat. Previously, we elucidated that quinofumelin targets dihydroorotate dehydrogenase (DHODH), an indispensable enzyme in the de novo pyrimidine biosynthesis pathway. To explore its resistance mechanism, five FgDHODHII site‐directed mutants with distinct genotypes were generated using the homologous recombination strategy. Sensitivity assays identified varying resistance levels: FgDHODHII‐A94V remained sensitive to quinofumelin, FgDHODHII‐D155T conferred low‐level resistance, FgDHODHII‐N281A conferred moderate‐level resistance, and FgDHODHII‐V179E/V179D conferred high‐level resistance. Quinofumelin inhibition was reversed by the addition of uridine monophosphate (UMP), uridine or uracil. Although the mutants did not exhibit growth defects, quinofumelin‐resistant mutants displayed reduced sporulation and virulence. Quinofumelin showed cross‐resistance to ipflufenoquin, but no cross‐resistance to other common fungicides (phenamacril, carbendazim, tebuconazole, pydiflumetofen, prothioconazole, fluopyram, benzovindiflupyr, pyraclostrobin and azoxystrobin). Molecular docking, molecular dynamics (MD) simulations and microscale thermophoresis (MST) revealed that D155T, V179E, V179D and N281A mutations altered the binding mode of quinofumelin, resulting in diminished binding affinity. This study provides key insights into its mode of action and resistance mechanism of quinofumelin, facilitating its application in sustainable FHB management. The D155T, V179E, V179D and N281A mutations in FgDHODHII altered the binding mode of quinofumelin, resulting in diminished affinity and a negative correlation between binding affinity and the resistance level of these mutants.

Background The emergence of antibiotic resistant pathogenic bacteria has reduced our ability to combat infectious diseases. At the same time the numbers of new antibiotics reaching the market have decreased. This situation has created an urgent need to discover novel antibiotic scaffolds. Recently, the application of pattern recognition techniques to identify molecular fingerprints in ‘omics’ studies, has emerged as an important tool in biomedical research and laboratory medicine to identify pathogens, to monitor therapeutic treatments or to develop drugs with improved metabolic stability, toxicological profile and efficacy. Here, we hypothesize that a combination of metabolic intracellular fingerprints and extracellular footprints would provide a more comprehensive picture about the mechanism of action of novel antibiotics in drug discovery programs. Results In an attempt to integrate the metabolomics approach as a classification tool in the drug discovery processes, we have used quantitative 1 H NMR spectroscopy to study the metabolic response of Escherichia coli cultures to different antibiotics. Within the frame of our study the effects of five different and well-known antibiotic classes on the bacterial metabolome were investigated both by intracellular fingerprint and extracellular footprint analysis. The metabolic fingerprints and footprints of bacterial cultures were affected in a distinct manner and provided complementary information regarding intracellular and extracellular targets such as protein synthesis, DNA and cell wall. While cell cultures affected by antibiotics that act on intracellular targets showed class-specific fingerprints, the metabolic footprints differed significantly only when antibiotics that target the cell wall were applied. In addition, using a training set of E. coli fingerprints extracted after treatment with different antibiotic classes, the mode of action of streptomycin, tetracycline and carbenicillin could be correctly predicted. Conclusion The metabolic profiles of E. coli treated with antibiotics with intracellular and extracellular targets could be separated in fingerprint and footprint analysis, respectively and provided complementary information. Based on the specific fingerprints obtained for different classes of antibiotics, the mode of action of several antibiotics could be predicted. The same classification approach should be applicable to studies of other pathogenic bacteria.

Pseudomonas aeruginosa is a ubiquitous Gram(−) bacterium, classified as an ESKAPE pathogen with emerging multidrug resistance development and increasing prevalence among hospitals, aquacultures, and foods, which is mostly related to efficient adaptation strategies to conventional antimicrobials. Therefore, there is an urgent need to research P. aeruginosa ’s response to alternative antimicrobial compounds that are promising approaches in combating their survival and pathogenesis. The following study evaluated the transcriptomic response of P. aeruginosa NT06 food-isolate to subinhibitory concentration (subMIC) of rosemary essential oil combined with chlorogenic acid (REO-CGA). REO was obtained by hydrodistillation from dried leaves of Rosmarinus officinalis L. and characterized by GC–MS analysis, indicating 1,8–cineole as the major compound (52.6%). Micro broth dilution method was employed to establish the antimicrobial activity of REO, CGA, and their combination, and subMIC was used to study the growth kinetics during 72 h of incubation. RNA-seq was employed to establish the differentially expressed genes (DEGs), which were functionally annotated using GO terms and KEGG pathways. DEGs were mostly involved in the metabolism of aromatic compounds, energy acquisition, survival under oxygen limitation, spoilage, adaptation, and protection abilities. This study presents the implantation of molecular and bioinformatic approaches to deepen understanding of the REO-CGA mode of action and adaptive strategies of P. aeruginosa food isolate to those antimicrobials.

Abstract Garviecin LG34 produced by Lactococcus garvieae LG34 exhibits wide-spectrum antibacterial activity against both Gram-positive and Gram-negative bacteria. This work aimed at clarifying the antibacterial mode of action of garviecin LG34 against Gram-negative bacterium Salmonella typhimurium. To determine the concentration for the bacteriocin antimicrobial mode experiments, the minimum inhibitory concentration of garviecin LG34 against S. typhimurium CICC21484 was determined as 0.25 mg/ml. Garviecin LG34 decreased the viable count of S. typhimurium CICC21484 and its antibacterial activity was the dose and time dependant. Garviecin LG34 led to the dissipation of transmembrane potential, the rise in the extracellular conductivity, UV-absorbing material at 260 nm, and LDH level of S. typhimurium CICC21484. Scanning electron micrographs results shown that garviecin LG34 cause dramatic deformation and fragmentation including the flagellum shedding, pores formation in surface, and even completely breakage of S. typhimurium cell. Moreover, garviecin LG34 decreased the intracellular ATP level. The results of this study demonstrated that garviecin LG34 can destroy cell structure, increase membrane permeability of S. typhimurium, thereby might be used as biopreservative for treating food borne and salmonellosis resulting from Gram-negative bacterium S. typhimurium. The bacteriocin garviecin LG34 affects Salmonella typhimurium’s cell structure and membrane permeability, which could be exploited as a biopreservative for treating food borne and salmonellosis.

Background The biodegradation of chitin is an important part of the carbon and nitrogen cycles in nature. Speeding up the biotransformation of chitin substrates can not only reduce pollution, but also produce high value-added products. However, this process is strictly regulated by the catalytic efficiency of the chitinolytic machinery. Therefore, it is necessary to study the mode of action and compound mechanisms of different chitin-degrading enzymes in depth to improve the catalytic efficiency of the chitinolytic machinery. Results The thermophilic bacterium Streptomyces sp. F-3 showed comparatively high chitin degradation activities. To elucidate the mechanism underlying chitin hydrolysis, six chitin degradation-related enzymes were identified in the extracellular proteome of Streptomyces sp. F-3, including three chitinases (SsChi18A, SsChi18B, and SsChi18C) from the GH18 family, one GH19 chitinase (SsChi19A), one GH20 β-N-acetylhexosaminidase (SsGH20A), and one lytic polysaccharide monooxygenase (SsLPMO10A) from the AA10 family. All were upregulated by chitin. The heterologously expressed hydrolases could withstand temperatures up to 70 °C and were stable at pH values of 4 to 11. Biochemical analyses displayed that these chitin degradation-related enzymes had different functions and thus showed synergistic effects during chitin degradation. Furthermore, based on structural bioinformatics data, we speculated that the different action modes among the three GH18 chitinases may be caused by loop differences in their active site architectures. Among them, SsChi18A is probably processive and mainly acts on polysaccharides, while SsChi18B and SsChi18C are likely endo-non-processive and displayed higher activity on the degradation of chitin oligosaccharides. In addition, proteomic data and synergy experiments also indicated the importance of SsLPMO10A, which could promote the activities of the hydrolases and increase the monosaccharide content in the reaction system, respectively. Conclusions In this article, the chitinolytic machinery of a thermophilic Streptomyces species was studied to explore the structural basis for the synergistic actions of chitinases from different GH18 subfamilies. The elucidation of the degradation mechanisms of these thermophilic chitinases will lay a theoretical foundation for the efficient industrialized transformation of natural chitin.

Diabetes mellitus is a metabolic disorder that can lead to various complications affecting the heart, kidney, and eye. Several synthetic and natural products have been used for disease management, but the disease still remains a global challenge. The use of plants as an alternative management for diabetes has been on the rise. Regrettably, the comprehensive repository is not available to guide future research in the area of plants with a related mechanism of action for the development of an effective drug. To identify and compile medicinal plants frequently used with proven scientific hypoglycaemic properties and their possible modes of action. This was done through a literature search of scientific databases using search tools like DOAJ, EMBASE, Europe PMC, FSTA, Google Scholar, HubMed, Indian Citation Index, Medline Plus, Merck Index, PubMed, ScienceDirect, Science3open, Science Open, SciFinder, Scirus, Core, Scopus, Semantic Scholar, Shodhganga, and World Wide Science. Search keywords included: medicinal plants, antidiabetics, hypoglycaemic, alpha-amylases/glucosidase inhibition, glucose metabolic enzymes, antihyperglycaemia, insulin secretion/surrogate, β-cell amelioration, phytochemicals, diabetes management, anti-oxidant, and enhance glucose transporters. The study excludes plants used in the management of diseases other than diabetes mellitus. From the search, 611 authenticated medicinal plants with anti-diabetic properties were eligible and grouped according to their reported probable mode of action. Precisely 20.6% of the plants exhibited their anti-diabetic effect via prevention of oxidative stress; 11.6% acted through stimulation of insulin secretion, inhibition of insulin degradation, and reduction of insulin resistance. Also, 10.8% inhibited enzymes of carbohydrate gastrointestinal digestion, 2.8% were postulated to regulate enzymes of glucose metabolism, and 54.2% acted via nonspecific or multiple means, as well as those whose anti-diabetic mode of action was yet to be identified. This study has shown that the exact mechanisms or mode of action of the majority of plants with hypoglycaemic properties are yet to be explored. Scientists would therefore find this paper useful in their future research. This paper may also serve as a potential lead for the easy harmonization of plants with a related mode of action in the drug discovery process targeted at the management of diabetes mellitus. Graphical abstract