Analogues Of Metabolites Research Articles

Tubular bile duct structure mimicking bile duct morphogenesis for prospective in vitro liver metabolite recovery

BackgroundLiver metabolites are used to diagnose disease and examine drugs in clinical pharmacokinetics. Therefore, development of an in vitro assay system that reproduces liver metabolite recovery would provide important benefits to pharmaceutical research. However, liver models have proven challenging to develop because of the lack of an appropriate bile duct structure for the accumulation and transport of metabolites from the liver parenchyma. Currently available bile duct models, such as the bile duct cyst-embedded extracellular matrix (ECM), lack any morphological resemblance to the tubular morphology of the living bile duct. Moreover, these systems cannot overcome metabolite recovery issues because they are established in isolated culture systems. Here, we successfully established a non-continuous tubular bile duct structure model in an open-culture system, which closely resembled an in vivo structure. This system was utilized to effectively collect liver metabolites separately from liver parenchymal cells.ResultsTriple-cell co-culture of primary rat hepatoblasts, rat biliary epithelial cells, and mouse embryonic fibroblasts was grown to mimic the morphogenesis of the bile duct during liver development. Overlaying the cells with ECM containing a Matrigel and collagen type I gel mixture promoted the development of a tubular bile duct structure. In this culture system, the expression of specific markers and signaling molecules related to biliary epithelial cell differentiation was highly upregulated during the ductal formation process. This bile duct structure also enabled the separate accumulation of metabolite analogs from liver parenchymal cells.ConclusionsA morphogenesis-based culture system effectively establishes an advanced bile duct structure and improves the plasticity of liver models feasible for autologous in vitro metabolite-bile collection, which may enhance the performance of high-throughput liver models in cell-based assays.

LC-MS/MS based molecular networking approach for the identification of cocoa phenolic metabolites in human urine

Dietary phenolic compounds are often transformed by gut microbiota prior to absorption. This transformation may modify their structures, producing novel gut flora metabolites associated with numerous health benefits. Traditional mass spectrometry (MS) based approaches for assessing dietary exposure of cocotea (cocoa, coffee and tea) products provided very little information about the modification and fate of dietary phenolics after ingestion, mainly due to limitation of complex sample nature and their data analyses. Mass spectrometry techniques are well-suited to a high-throughput characterization of natural products, however, analyzing MS based data of complex biological matrix is still considered a challenge. In order to overcome such limitations and simplify the analysis of complex MS data, a cocotea based human trial was conducted where MS based molecular networking approach was implemented.To demonstrate the utility of this approach in one of the specific cocotea diets, we have applied it to a diverse collection of human (n = 15) urine samples, who consumed cocoa rich in polyphenols over a 48-h period. This approach illustrated the power of the new strategy, allowing the rapid identification of new analogues of cocoa metabolites after human consumption.Analysis of human urine samples after cocoa consumption revealed (by assignment of unknown metabolites based on the network similarities) that monomeric flavanols are mainly absorbed and transformed directly into their glucuronide and sulfated moieties. Subsequently, the hydroxy and methoxy phenyl-g-velerolactone as well as their smaller metabolites (such as hydroxyphenyl valeric acids, hydroxy and methoxy phenyl propionic acids and their derivates) are indicative of bacterial metabolism of cocoa major flavanols. For the first time, our study exemplifies and highlight the implementation of MS based molecular networking approach in illustrating the tracking of various structural motifs of ingested cocoa phenolics in human based study.

Mitochondrial disorders in neuromuscular pathology

Introduction. With the advent of new drugs — analogues of mitochondrial metabolites, the widespread introduction into practice of research methods for assessing the function of mitochondria in patients with neurological pathology and other diseases becomes relevant. Study aim. To determine the change in the intracellular activity of mitochondrial enzymes (succinate dehydrogenase, α -glycerophosphate dehydrogenase, glutamate dehydrogenase, lactate dehydrogenase) in case of neuromuscular diseases. Materials and methods . We examined 74patients with neuromuscular diseases. The activity of 4 mitochondrial enzymes involved in carbohydrate metabolism (lactate dehydrogenase), amino acid metabolism (glutamate dehydrogenase), fatty acids ( α -glycerophosphate dehydrogenase), and mitochondrial respiratory chain complex II (succinate dehydrogenase) was evaluated. For a cytochemical study of the activity of mitochondrial enzymes in peripheral blood lymphocytes, the method proposed by A.G.E. Pearse as modified by R.P. Narcissov. Results. The greatest changes were revealed in cases with myotonic dystrophy: statistically significant decreases in the average activity value of all studied enzymes ( р <0.05).In cases with hereditary motor-sensory neuropathy of type I the activity of succinate dehydrogenase and glutamate dehydrogenase is reduced ( р <0.05), in cases with type II there are deviations in the activity indicators of mitochondrial enzymes, more pronounced compared with type I, but not statistically significant (p >0.05). In patients with myasthenia gravis, a decrease in the activity of α -glycerophosphate dehydrogenase and glutamate dehydrogenase (p <0.05) was noted. Average values of succinate dehydrogenase and lactate dehydrogenase activity indicators were also reduced (p >0.05). In cases with Landusi-Dejerine myopathy the activity of succinate dehydrogenase, α -glycerophosphate dehydrogenase and glutamate dehydrogenase were reduced, of which only for α -glycerophosphate dehydrogenase p <0.05. In the analysis of each case in groups of patients with the studied pathology, it was shown that in addition to patients with myotonic dystrophy, in which all patients decreased the activity of succinate dehydrogenase, α -glycerophosphate dehydrogenase and glutamate dehydrogenase, in other cases, in some patients, the studied enzyme activity did not change. Conclusion. There are methods for studying these metabolites in plasma. The activity of mitochondrial enzymes is also examined. In cases with neuromuscular diseases, there are violations of the mitochondria. Therefore, it is necessary to consider such patients as metabolic patients and prescribe metabolic, antioxidant therapy to them.

Molecular and Microbial Microenvironments in Chronically Diseased Lungs Associated with Cystic Fibrosis.

To visualize the personalized distributions of pathogens and chemical environments, including microbial metabolites, pharmaceuticals, and their metabolic products, within and between human lungs afflicted with cystic fibrosis (CF), we generated three-dimensional (3D) microbiome and metabolome maps of six explanted lungs from three cystic fibrosis patients. These 3D spatial maps revealed that the chemical environments differ between patients and within the lungs of each patient. Although the microbial ecosystems of the patients were defined by the dominant pathogen, their chemical diversity was not. Additionally, the chemical diversity between locales in the lungs of the same individual sometimes exceeded interindividual variation. Thus, the chemistry and microbiome of the explanted lungs appear to be not only personalized but also regiospecific. Previously undescribed analogs of microbial quinolones and antibiotic metabolites were also detected. Furthermore, mapping the chemical and microbial distributions allowed visualization of microbial community interactions, such as increased production of quorum sensing quinolones in locations where Pseudomonas was in contact with Staphylococcus and Granulicatella, consistent with in vitro observations of bacteria isolated from these patients. Visualization of microbe-metabolite associations within a host organ in early-stage CF disease in animal models will help elucidate the complex interplay between the presence of a given microbial structure, antibiotics, metabolism of antibiotics, microbial virulence factors, and host responses.IMPORTANCE Microbial infections are now recognized to be polymicrobial and personalized in nature. Comprehensive analysis and understanding of the factors underlying the polymicrobial and personalized nature of infections remain limited, especially in the context of the host. By visualizing microbiomes and metabolomes of diseased human lungs, we reveal how different the chemical environments are between hosts that are dominated by the same pathogen and how community interactions shape the chemical environment or vice versa. We highlight that three-dimensional organ mapping methods represent hypothesis-building tools that allow us to design mechanistic studies aimed at addressing microbial responses to other microbes, the host, and pharmaceutical drugs.

The Role of the Phosphorus Atom in Drug Design.

Although the phosphorus atom is found in a variety of oxidation states, most of the phosphorus-containing molecules of pharmacological importance possess phosphorus in the form of phosphonate or phosphinate functional groups, or in a major oxidation state as a phosphate group. The most common occurrence of phosphorus in drugs is either in prodrugs or in compounds for which the phosphorus atom plays a role in the biological activity, such as in modified nucleotides, in metabolically stable analogues of metabolites bearing phosphate groups, and as bioisosteric analogues of carboxyl groups.

Brassinosteroids Promote Growth and Secondary Metabolite Production in Lavandin (Lavandula intermedia Emeric ex Loisel.)

Lavandin (Lavandula x intermedia), a hybrid between L. angustifolia (English lavender) and L. latifolia (spike lavender), is a valuable aromatic and medicinal plant cultivated in the world. Lavandin essential oil with characteristic scent and fragrance properties is mainly used in cosmetics, perfumes and pharmaceutical industries. The objective of this study was to determine the effect of foliar application of 24-epibrassinolide (24-eBL), a brassinosteroid analogue, on growth and secondary metabolite production of lavandin (Lavandula x intermedia var. Super). 24-eBL at 0, 0.75, 1.5 and 2.25 mg/L concentrations was applied to 8 years old plants twice. The highest growth parameters were obtained from the plants applied with 1.5 and 2.25 mg/L of 24-eBL. 24-eBL also increased the total phenolics and essential oil contents. Especially 1.5 mg/L 24-eBL application was the most suitable concentration for total phenolic and essential oil contents. Besides 24-eBL also modified essential oil composition. The percentages of linalyl acetate and 1,8-cineol increased while some of the components such as camphor, borneol, geraniol and lavandulyl acetate decreased with the 24-eBL applications. To conclude, 24-eBL may be a promising compound for use in lavandin cultivation because of its positive effects on plant growth, phenolic content, essential oil content and oil quality.

Exposure to di-2-ethylhexyl terephthalate in the U.S. general population from the 2015–2016 National Health and Nutrition Examination Survey

BackgroundDi-2-ethylhexyl terephthalate (DEHTP) is used as a replacement plasticizer for other phthalates, including di-2-ethylhexyl phthalate (DEHP). Use of consumer products containing DEHTP may result in human exposure to DEHTP. ObjectiveTo assess exposure to DEHTP in a nationally representative sample of the U.S. general population 3 years and older from the 2015–2016 National Health and Nutrition Examination Survey (NHANES). MethodWe quantified two DEHTP metabolites, mono-2-ethyl-5-hydroxyhexyl terephthalate (MEHHTP) and mono-2-ethyl-5-carboxypentyl terephthalate (MECPTP) in 2970 urine samples by using online solid-phase extraction coupled with isotope dilution-high-performance liquid chromatography-tandem mass spectrometry. We used linear regression to examine associations between MEHHTP and MECTPP and several parameters including age, sex, race/ethnicity, and household income. We also compared the MEHHTP and MECPTP results to those of their corresponding DEHP metabolite analogs, namely mono-2-ethyl-5-hydroxyhexyl phthalate (MEHHP) and mono-2-ethyl-5-carboxypentyl phthalate (MECPP). ResultsThe weighted detection frequencies were 96% (MEHHTP) and 99.9% (MECPTP); urinary concentrations of the two metabolites correlated significantly (Pearson correlation coefficient = 0.89, p < 0.0001). MECPTP concentrations were higher than MEHHTP in all age, sex, race/ethnicity groups examined. Furthermore, MECPTP adjusted geometric mean (GM) concentrations were significantly higher in samples collected in the evening than in the morning or afternoon. Females had significantly higher adjusted GM concentrations of MEHHTP and MECPTP than males. We observed no significant associations between the adjusted GM concentrations of the metabolites and race/ethnicity. Both metabolite adjusted GM concentrations increased significantly with household income, and decreased significantly with age. Only household income was significantly associated with the concentrations of MECPP, but not of MEHHP, the two DEHP metabolites. The adjusted GM of the [MEHHTP]:[MECPTP] molar concentrations ratio increased with age, and was significantly higher in samples collected in the morning than in those collected in the afternoon or evening. ConclusionsExposure to DEHTP is widespread in the U.S. general population 3 years and older. These data represent the first U.S. population-based representative background exposure to DEHTP.

MARSI: metabolite analogues for rational strain improvement.

SummaryMetabolite analogues (MAs) mimic the structure of native metabolites, can competitively inhibit their utilization in enzymatic reactions, and are commonly used as selection tools for isolating desirable mutants of industrial microorganisms. Genome-scale metabolic models representing all biochemical reactions in an organism can be used to predict effects of MAs on cellular phenotypes. Here, we present the metabolite analogues for rational strain improvement (MARSI) framework. MARSI provides a rational approach to strain improvement by searching for metabolites as targets instead of genes or reactions. The designs found by MARSI can be implemented by supplying MAs in the culture media, enabling metabolic rewiring without the use of recombinant DNA technologies that cannot always be used due to regulations. To facilitate experimental implementation, MARSI provides tools to identify candidate MAs to a target metabolite from a database of known drugs and analogues.Availability and implementationThe code is freely available at https://github.com/biosustain/marsi under the Apache License V2. MARSI is implemented in Python.Supplementary information Supplementary data are available at Bioinformatics online.

Determination of Fragmentation Schemes and Metabolites of Fluorinated Histone Deacetylase Inhibitors for Use as Positron Emission Tomography Imaging Agents Using HPLC-MS/MS

High performance liquid chromatography coupled with tandem mass spectrometry was developed and validated as a method for the analysis of fluorinated histone deacetylase inhibitors (F-HDACi), and then employed to study their metabolism in biosystems. Four HDACi analogs labeled with the positron emission nuclide 18F constitute a group of potential positron emission tomography imaging agents, which were developed by the Institute of Nuclear Energy Research (INER) and coded as INER-1577 #1, #2, #3, and #4 during animal studies for the diagnosis of dementia. The performance of the method was found to be suitable for the determination of analog #3, and it was employed to determine the structures and fragmentation mechanisms of all four analogs and to study the biotransformations of analogs #3 and #4. The results indicated that the method used for the determination of analog #3 was suitable for determining the abundance of the analogs in chemical and biochemical tests with high precision, accuracy, reproducibility, and recovery. Weaknesses in the chemical bonding of the analogs were found to involve the fluoro, dimethylamino, and benzamide groups in a fragmentation mechanism deduced via tandem mass spectrometry. The metabolites of analogs #3 and #4 in rat liver microsomes and rat plasma were also identified to clarify their characteristic behaviors in biosystems. The major product of analogs #3 in liver microsomes was produced by hydroxylation of the benzylic carbon atom, but in rat plasma the metabolites of analog #3 were produced by hydrolysis of the benzamide group to give a diaminobiphenyl compound with the simultaneous replacement of a fluorine atom by a hydroxyl group. The metabolites of analog #4 in liver microsomes were produced by hydroxylation of the benzylic carbon atom and hydrolysis of the benzamide bond. The results of the studies characterized the chemical and biochemical behaviors of the series F-HADCi analogs.

Two Are Better Than One: Dual Targeting of Riboswitches by Metabolite Analogs

In this issue of Cell Chemical Biology, Wang etal. (2017) examine the effect of the novel synthetic moleculeribocil-C and the natural compound roseoflavin in Gram-positive pathogens. In methicillin-resistant Staphylococcus aureus (MRSA), ribocil-C and roseoflavin target two autonomous riboswitches simultaneously, thereby inhibiting de novo synthesis and uptake of riboflavin.

Glycolysis regulates the expansion of myeloid-derived suppressor cells in tumor-bearing hosts through prevention of ROS-mediated apoptosis

Immunotherapy aiming to rescue or boost antitumor immunity is an emerging strategy for treatment of cancers. The efficacy of immunotherapy is strongly controlled by the immunological milieu of cancer patients. Myeloid-derived suppressor cells (MDSCs) are heterogeneous immature myeloid cell populations with immunosuppressive functions accumulating in individuals during tumor progression. The signaling mechanisms of MDSC activation have been well studied. However, there is little known about the metabolic status of MDSCs and the physiological role of their metabolic reprogramming. In this study, we discovered that myeloid cells upregulated their glycolytic genes when encountered with tumor-derived factors. MDSCs exhibited higher glycolytic rate than their normal cell compartment did, which contributed to the accumulation of the MDSCs in tumor-bearing hosts. Upregulation of glycolysis prevented excess reactive oxygen species (ROS) production by MDSCs, which protected MDSCs from apoptosis. Most importantly, we identified the glycolytic metabolite, phosphoenolpyruvate (PEP), as a vital antioxidant agent able to prevent excess ROS production and therefore contributed to the survival of MDSCs. These findings suggest that glycolytic metabolites have important roles in the modulation of fitness of MDSCs and could be potential targets for anti-MDSC strategy. Targeting MDSCs with analogs of specific glycolytic metabolites, for example, 2-phosphoglycerate or PEP may diminish the accumulation of MDSCs and reverse the immunosuppressive milieu in tumor-bearing individuals.

Quick Activation/Stabilization of a α-Glucosidase-catalyzed Hydrolysis Reaction by Addition of a Betaine-type Metabolite Analogue

To understand the requirement of preincubation of betaine-type analogues with enzymes and/or substrates to activate enzyme reactions, we compared α-glucosidase-catalyzed hydrolysis using the analogue 2-(N,N,N-tri-n-butylammonium)acetate and different mixing protocols. We found that enzyme activation is independent of the mixing protocol used and activation initiates immediately following the addition of the analogue to the reaction. Further analysis revealed that facilitation, ascribed to the temporal stabilization of α-glucosidase, is primarily applicable to the active enzyme and not to the denatured protein.

Increased yield of β-glucosidase-catalyzed hydrolysis reactions in the presence of betaine-type metabolite analog.

β-Glucosidases (EC 3.2.1.21), abundant enzymes distributed in animals, plants and microorganism, has been generating lots of attentions for bioethanol production from cellulosic biomass. In this study, using three different origins of β-glucosidases, glucose productivity of β-glucosidase-catalyzed hydrolysis reactions in the presence of synthetic betaine-type metabolite analog (2-N,N,N-tri-n-butylammonium) acetate, was investigated. By the addition of the analog, the hydrolysis yields for all β-glucosidases was highly improved from 4-13 to 64-100%. To understand the factors affecting on the yield enhancements, the kinetic parameters, inhibition constants of end-product and temporal stability of β-glucosidases were compared. As a result, enhancement of the yields is mainly related to the increase in the temporal stability of β-glucosidases in the presence of the analog. The present findings lead to not only improve the glucose productivity of β-glucosidase-catalyzed hydrolysis reaction toward bioethanol production but also apply to a new stabilization method for various unstable enzymes.

Chemodiversity in the genus Aspergillus.

Isolates of Aspergillus species are able to produce a large number of secondary metabolites. The profiles of biosynthetic families of secondary metabolites are species specific, whereas individual secondary metabolite families can occur in other species, even those phylogenetically and ecologically unrelated to Aspergillus. Furthermore, there is a high degree of chemo-consistency from isolate to isolate in a species even though certain metabolite gene clusters are silenced in some isolates. Genome sequencing projects have shown that the diversity of secondary metabolites is much larger in each species than previously thought. The potential of finding even further new bioactive drug candidates in Aspergillus is evident, despite the fact that many secondary metabolites have already been structure elucidated and chemotaxonomic studies have shown that many new secondary metabolites have yet to be characterized. The genus Aspergillus is cladistically holophyletic but phenotypically polythetic and very diverse and is associated to quite different sexual states. Following the one fungus one name system, the genus Aspergillus is restricted to a holophyletic clade that include the morphologically different genera Aspergillus, Dichotomomyces, Phialosimplex, Polypaecilum and Cristaspora. Secondary metabolites common between the subgenera and sections of Aspergillus are surprisingly few, but many metabolites are common to a majority of species within the sections. We call small molecule extrolites in the same biosynthetic family isoextrolites. However, it appears that secondary metabolites from one Aspergillus section have analogous metabolites in other sections (here also called heteroisoextrolites). In this review, we give a genus-wide overview of secondary metabolite production in Aspergillus species. Extrolites appear to have evolved because of ecological challenges rather than being inherited from ancestral species, at least when comparing the species in the different sections of Aspergillus. Within the Aspergillus sections, secondary metabolite pathways seem to inherit from ancestral species, but the profiles of these secondary metabolites are shaped by the biotic and abiotic environment. We hypothesize that many new and unique section-specific small molecule extrolites in each of the Aspergillus will be discovered.

Significance of anionic functional group in betaine-type metabolite analogs on the facilitation of enzyme reactions

Using synthetic sulfobetaine library, the enzyme activation behavior has been investigated. Comparison of enzyme activation behavior revealed that sulfobetaines equally facilitate enzyme reactions, being consistent with that of carboxybetaines. The subsequent kinetic and solution property analyses clarified that both the kinetic parameter and hydration property changes are identical with those of carboxybetaines, indicating that the difference in the anionic functional group of the betaine structure scarcely affects the enzyme activation. On the other hand, comparison of carboxy- or sulfo-betaines with tetraalkylammonium salts, whose counteranion binds to the ammonium cation intermolecularly, revealed that the activation ability for enzymes of tetraalkylammonium salts is considerably smaller than that of carboxy- or sulfo-betaines. These findings give us a hint to design the useful betaine-type enzyme activators.

A Bioorthogonal Chemical Reporter of Viral Infection.

Pathogen‐selective labeling was achieved by using the novel gemcitabine metabolite analogue 2′‐deoxy‐2′,2′‐difluoro‐5‐ethynyluridine (dF‐EdU) and click chemistry. Cells infected with Herpes Simplex Virus‐1 (HSV‐1), but not uninfected cells, exhibit nuclear staining upon the addition of dF‐EdU and a fluorescent azide. The incorporation of the dF‐EdU into DNA depends on its phosphorylation by a herpes virus thymidine kinase (TK). Crystallographic analyses revealed how dF‐EdU is well accommodated in the active site of HSV‐1 TK, but steric clashes prevent dF‐EdU from binding human TK. These results provide the first example of pathogen‐enzyme‐dependent incorporation and labeling of bioorthogonal functional groups in human cells.

A Bioorthogonal Chemical Reporter of Viral Infection.

Pathogen‐selective labeling was achieved by using the novel gemcitabine metabolite analogue 2′‐deoxy‐2′,2′‐difluoro‐5‐ethynyluridine (dF‐EdU) and click chemistry. Cells infected with Herpes Simplex Virus‐1 (HSV‐1), but not uninfected cells, exhibit nuclear staining upon the addition of dF‐EdU and a fluorescent azide. The incorporation of the dF‐EdU into DNA depends on its phosphorylation by a herpes virus thymidine kinase (TK). Crystallographic analyses revealed how dF‐EdU is well accommodated in the active site of HSV‐1 TK, but steric clashes prevent dF‐EdU from binding human TK. These results provide the first example of pathogen‐enzyme‐dependent incorporation and labeling of bioorthogonal functional groups in human cells.

Enhanced Chromogenic Sensitivity of Horseradish Peroxidase-Catalyzed Oxidative Reactions in the Presence of Betaine-Type Metabolite Analogs

Abstract Horseradish peroxidase (HRP), a well-known oxidase, is frequently used in the diagnostic field as a labeling enzyme, where it amplifies the substrate binding signal of antibodies. Though practical for detecting moderate amounts of substrate, there is strong demand for further development of its sensitivity to detect minuscule quantities of biomarkers. Recently, we found that betaine-type cellular metabolite analogs facilitate enzymatic hydrolysis just by dissolving them into the reaction buffer. In the present study, using the analog (2-(N,N,N-tri-n-butylammonium) acetate) and various colorimetric substrates of HRP, we investigated the activation behavior of HRP. As a result, the analog structure- and concentration-dependently facilitated the various HRP-catalyzed oxidative reactions. Interestingly, the analog facilitated not only the reaction rate but also the chromogenic sensitivity. Kinetic and structural analyses revealed that the increased chromogenic sensitivity is related to the enhancement of the conformational flexibility in the substrate binding site in HRP by addition of the analog, which diminishes the binding affinity between HRP and large substrates. The finding serves to create practical applications of the analogs for increased detection sensitivity of HRP-related clinical agents.

Cryoprotective ability of betaine-type metabolite analogs during freezing denaturation of enzymes.

To evaluate an analog library of betaine-type cellular metabolites, which are naturally found in polar fish for survival in subzero temperatures, for preventing denaturation of enzymes during freezing. Comparison of the cryoprotective ability of reported cryoprotectants, such as dimethylsulfoxide, glycerol, ectoine, hydroxyectoine, and trehalose, with betaine-type analogs using α-glucosidase revealed that analogs introducing C3-C6 alkyl chains into an ammonium cation retained 20 % higher activity than the control cryoprotectants at the same concentration. In particular, the analog possessing triplicate n-butyl chains showed a profound effect. It allowed retention of enzyme activity to 95 % even after 100 freeze-thaw cycles, while addition of the control cryoprotectants decreased the activity to 10-20 %. The cryoprotective ability of betaine-type analogs can be applied not only to α-glucosidase but also other enzymes such as β-glucosidase, alkaline phosphatase, lactose dehydrogenase, sulfatase, and horseradish peroxidase. Synthetic betaine-type metabolite analogs possess practicable cryoprotective ability for various enzymes, and are considerably superior to previously reported cryoprotectants.

(Dis)similar Analogues of Riboswitch Metabolites as Antibacterial Lead Compounds.

The rise of antimicrobial resistance in human pathogenic bacteria has increased the necessity for the discovery of novel, yet unexplored antibacterial drug targets. Riboswitches, which are embedded in untranslated regions of bacterial messenger RNA (mRNA), represent such an interesting target structure. These RNA elements regulate gene expression upon binding to natural metabolites, second messengers, and inorganic ions, such as fluoride with high affinity and in a highly discriminative manner. Recently, efforts have been directed toward the identification of artificial riboswitch activators by establishing high-throughput screening assays, fragment-based screening, and structure-guided ligand design approaches. Emphasis in this review is placed on the special requirements and synthesis of new potential antibiotic drugs that target riboswitches in which dissimilarity is an important aspect in the design of potential lead compounds.