Organic reactions in ionic liquids: ionic liquid-accelerated nucleophilic substitution reaction of alpha-tosyloxyketones with potassium salts of aromatic acids

The room temperature ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]) is used as a ‘green' recyclable alternative to classical molecular solvents for the nucleophilic substitution reaction of a-tosyloxy ketones with potassium salts of aromatic acids. Significant rate enhancement and improved yields have been observed.

Histidine acts as a co-germinant with glycine and taurocholate for Clostridium difficile spores

Aims: It is well established that the bile salt sodium taurocholate acts as a germinant for Clostridium difficile spores and the amino acid glycine acts as a co-germinant. The aim of this study was to determine whether any other amino acids act as co-germinants. Methods and Results: Clostridium difficile spore suspensions were exposed to different germinant solutions comprising taurocholate, glycine and an additional amino acid for 1 h before heating shocking (to kill germinating cells) or chilling on ice. Samples were then re-germinated and cultured to recover remaining viable cells. Only five amino acids out of the 19 common amino acids tested (valine, aspartic acid, arginine, histidine and serine) demonstrated co-germination activity with taurocholate and glycine. Of these, only histidine produced high levels of germination (97·9–99·9%) consistently in four strains of Cl. difficile spores. Some variation in the level of germination produced was observed between different PCR ribotypes, and the optimum concentration of amino acids with taurocholate for the germination of Cl. difficile NCTC 11204 spores was 10–100 mmol l-1. Conclusions: Histidine was found to be a co-germinant for Cl. difficile spores when combined with glycine and taurocholate. Significance and Impact of the Study: The findings of this study enhance current knowledge regarding agents required for germination of Cl. difficile spores which may be utilized in the development of novel applications to prevent the spread of Cl. difficile infection.

Biological fluorination from the sea : discovery of a SAM-dependent nucleophilic fluorinating enzyme from the marine-derived bacterium Streptomyces xinghaiensis NRRL B24674

We thank Prof. David O’Hagan and Dr Qingzhi Zhang (University of St Andrews, UK) for their helpful discussion and for providing the synthetic 50 -FDA sample. This work is supported by National Natural Science Foundation of China (No. 81503086), a starting funding (No. 20140520) from Tianjin University of Science & Technology, a research funding of “1000 Talents Plan” of Tianjin (to LM) and Foundation of Key Laboratory of Industrial Fermentation Microbiology of Ministry of Education and Tianjin Key Lab of Industrial Microbiology (No. 2015IM106)

Quantification of glycine betaine, choline and trimethylamine N-oxide in seawater particulates: Minimisation of seawater associated ion suppression

A liquid chromatography/mass spectrometry (LC/MS, electrospray ionisation) method has been developed for the quantification of nitrogenous osmolytes (N-osmolytes) in the particulate fraction of natural water samples. Full method validation demonstrates the validity of the method for measuring glycine betaine (GBT), choline and trimethylamine N-oxide (TMAO) in particulates from seawater. Limits of detection were calculated as 3.5, 1.2 and 5.9 pg injected onto column (equivalent to 1.5, 0.6 and 3.9 nmol per litre) for GBT, choline and TMAO respectively. Precision of the method was typically 3% for both GBT and choline and 6% for TMAO. Collection of the particulate fraction of natural samples was achieved via in-line filtration. Resulting chromatography and method sensitivity was assessed and compared for the use of both glass fibre and polycarbonate filters during sample collection. Ion suppression was shown to be a significant cause of reduced instrument response to N-osmolytes and was associated with the presence of seawater in the sample matrix

Quantification of glycine betaine, choline and trimethylamine N-oxide in seawater particulates: Minimisation of seawater associated ion suppression

A liquid chromatography/mass spectrometry (LC/MS, electrospray ionisation) method has been developed for the quantification of nitrogenous osmolytes (N-osmolytes) in the particulate fraction of natural water samples. Full method validation demonstrates the validity of the method for measuring glycine betaine (GBT), choline and trimethylamine N-oxide (TMAO) in particulates from seawater. Limits of detection were calculated as 3.5, 1.2 and 5.9 pg injected onto column (equivalent to 1.5, 0.6 and 3.9 nmol per litre) for GBT, choline and TMAO respectively. Precision of the method was typically 3% for both GBT and choline and 6% for TMAO. Collection of the particulate fraction of natural samples was achieved via in-line filtration. Resulting chromatography and method sensitivity was assessed and compared for the use of both glass fibre and polycarbonate filters during sample collection. Ion suppression was shown to be a significant cause of reduced instrument response to N-osmolytes and was associated with the presence of seawater in the sample matrix

Nucleophilic addition of Nitrones to Electron deficient acetylenes and related studies

Nitrones or azomethine-N-oxides are important precursors for the synthesis of several heterocyclic systems. They belong to the allyl anion type 1,3-dipoles and possess unique structural features which make them extraordinarily useful synthons. They behave as 1,3-dipoles in 1,3-dipolar cycloaddition reactions and as electrophiles in reactions with organometallic reagents. These are the two basic reactions given by nitrones. Nitrones also act as ‘spin traps’ in which they react with short-lived radicals to furnish stable nitroxide radicals which can be detected and identified by electron paramagnetic resonance (EPR) spectroscopy. Recently SmI2 catalysed reductive cross-coupling reactions of nitrones have gained significant interest in which the reactions are initiated by single electron transfer (SET) to nitrones. Apart from these reactions, nitrones are also known to participate in reactions which are initiated by the nucleophilic attack of nitrone-oxygen. In our group, we have also explored the nucleophilic character of nitrones through various reactions. The results obtained enabled us to develop a novel two-step one-pot strategy for quinolines and indoles - the heterocycles renowned for their pharmacological applications, from nitrones and electron deficient acetylenes. Using dibenzoylacetylene and phenylbenzoylacetylene as dipolarophiles, we could introduce a desired functional group at a predetermined position of the quinolines or indoles to be synthesised. In this context, the thesis entitled “NUCLEOPHILIC ADDITION OF NITRONES TO ELECTRON DEFICIENT ACETYLENES AND RELATED STUDIES” portrays our attempt to expand the scope of our x novel synthetic protocol using ester functionalised acetylenes: dimethyl acetylenedicarboxylate (DMAD) and methyl propiolate. The thesis is organised in to five chapters. The first chapter briefly describes the different classes of reactions that nitrone functionality can tolerate. The research problem is defined at the end of this chapter. The second chapter describes the synthesis of different nitrones used for the present study. The optimisation and expansion of scope of the novel strategy towards quinoline synthesis is discussed in the third chapter. The fourth chapter portrays the synthesis of indole-3-carboxylates using the novel strategy. In the fifth chapter, the reaction of N-(2,6-dimethylphenyl) and N-(2,4,6-trimethylphenyl)nitrones are discussed. Here we also discuss the mechanistic reinvestigation of Baldwin’s proposal in the isoxazoline-oxazoline rearrangement. The major outcome of the work is given at the end of the thesis. The structural formulae, schemes, tables and figures are numbered chapter-wise since each chapter of the thesis is organized as an independent unit. All new compounds (except two compounds reported in fourth chapter) are fully characterised on the basis of spectral and analytical data and single crystal X-ray analysis on representative examples. Relevant references are included at the end of individual chapters.

Partial molar volumes of glycine and dl-alanine in aqueous ammonium sulfate solutions at 278.15, 288.15, 298.15 and 308.15 K

In this work, the partial molar volumes of glycine and DL-alanine in aqueous solutions of ammonium sulfate at 0.0, 0.1, 0.3, 0.7, and 1.0 mol.kg(-1) are determined between 278.15 and 308.15 K. Transfer volumes were obtained, which are larger for glycine than DL-alanine. On the contrary, the hydration numbers are higher for DL-alanine than glycine, and dehydration of the amino acids is observed with increasing temperature or salt molality. The data suggest that interactions between ion and charged/hydrophilic groups are predominant and, by applying the methodology proposed by Friedman and Krishnan, it was concluded that they are mainly pairwise. A group-contribution scheme has been successfully applied to the pairwise volumetric interaction coefficient. Finally, the dehydration effect on glycine, alanine and serine in the presence of different electrolytes has been rationalized in terms of the charge density and a parameter accounting for the cation's hydration.

Teor de fenólicos totais e crescimento radicular em soja (Glycine max (L.) Merr.) inoculada com as bactérias endofítica e epifítica e sua exposição à ferrugem.

Os compostos fenólicos são formados no metabolismo secundário dos vegetais e estão envolvidos no mecanismo de defesa. O objetivo do trabalho foi avaliar o efeito dos isolados 0G e EN78 na produção de fenólicos totais na soja, frente à exposição à ferrugem da soja (Phakospora pachyrhizi), e no crescimento radicular. O isolado EN78 induziu um aumento no teor de fenólicos totais quando exposto à ferrugem, mesmo antes da manifestação do sintoma. Esse mesmo isolado apresentou eficiência simbiótica com o Biorhizo 10 (Bradyrhizobium elkanii e japonicum), promovendo o desenvolvimento radicular, enquanto que o isolado 0G não influiu no teor de fenólicos totais, mas induziu aumento da biomassa radicular.