Microscale experiments in chemistry - the need of the new millenium 2. Experiments which bring theory closer to laboratories

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Microscale experiments in chemistry - the need of the new millenium 5. Organic qualitative analysis and mixture separation on microscale

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Microscale experiments in chemistry-the need of the new millennium. Part 1. Newer ways of teaching laboratory courses with new apparatus

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Facile method for trimethylsilylation of alcohols using hexamethyldisilazane and ammonium thiocyanate under neutral conditions

A highly efficient method for trimethylsilylation of primary, secondary, tertiary, allylic, and a variety of sugar-derived alcohols using hexamethyldisilazane in the presence of a catalytic amount of ammonium thiocyanate under neutral conditions is reported

Purification and Characterization of an Active Principle, Lawsone, Responsible for the Plasmid Curing Activity of Plumbago zeylanica Root Extracts

Plasmid curing is the process of obviating the plasmid encoded functions such as antibiotic resistance, virulence, degradation of aromatic compounds, etc. in bacteria. Several plasmid curing agents have been reported in literature, however, no plasmid curing agent can eliminate all plasmids from different hosts. Hence, there is always a need for novel plasmid curing agents that can be effectively used for reversal of plasmid encoded functions such as virulence, antibiotic resistance, etc. In the present study, an active principle responsible for the plasmid curing activity was purified from roots of Plumbago zeylanica by bioassay guided fractionation and identified as 2-hydroxy-1,4-naphthoquinone (lawsone), on the basis of spectral and analytical data such as NMR, GCMS, FTIR. Plasmid curing activity of lawsone was observed against reference as well as wild plasmids (pBR322, pRK2013, R136, pUPI281, and pUPI282) residing in a range of hosts. Curing of plasmid was confirmed by agarose gel electrophoresis. MICs of antibiotics against A. baumannii A24 (pUPI281) and E. coli (pRK2013) decreased significantly in presence of lawsone suggesting synergy between lawsone and antibiotics. Lawsone also inhibited transfer of plasmid pRK2013 to E. coli either by transformation or conjugation. Viability assays (MTT) revealed that lawsone was not toxic to mammalian cells. Thus, the present investigation has revealed lawsone as an effective plasmid curing agent capable of suppressing development and spread of antibiotic resistance. Further, lawsone has important application in basic research to identify phenotypes encoded by the plasmids in plasmid curing experiments. To the best of our knowledge this is the first report of plasmid curing activity of lawsone isolated from roots of P. zeylanica

Synthesis of Gold Nanoanisotrops Using Dioscorea bulbifera

Biosynthesis of metal nanoparticles employing plant extracts and thereby development of an environmentally benign process is an important branch of nanotechnology. Here, the synthesis of gold nanoparticles using Dioscorea bulbifera tuber extract (DBTE) as the reducing agent is reported. Field emission scanning electron microscopy (FESEM), energy-dispersive spectroscopy (EDX), X-ray diffraction (XRD), and UV-visible absorption spectroscopy confirmed the reduction of gold ions to AuNPs. The anisotropic nanoparticles consist of a mixture of gold nanotriangles, nanoprisms, nanotrapezoid, and spheres. The kinetics of particle formation was time dependent and was enhanced by the increase of temperature from 6°C to 50°C, the optimum being 50°C. The optimum concentration of chloroauric acid was found to be 1 mM. Complete reduction of the metal ions within 5 hours by DBTE highlights the development of a novel ecofriendly route of biological synthesis of gold nanoparticles. This is the first paper on synthesis of gold nanoparticles using DBTE

Antidiabetic Activity of Gnidia glauca

Diabetes is a metabolic disorder affecting about 220 million people worldwide. One of the most critical complications of diabetes is post-prandial hyper-glycemia (PPHG). Glucosidase inhibitor and α-amylase inhibitors are class of compounds that help in managing PPHG. Low-cost herbal treatment is recommended due to their lesser side effect for treatment of diabetes. Two plants with significant traditional therapeutic potential, namely, Gnidia glauca and Dioscorea bulbifera, were tested for their efficiency to inhibit α-amylase and α-glucosidase. Stem, leaf, and flower of G. glauca and bulb of D. bulbifera were sequentially extracted with petroleum ether, ethyl acetate, and methanol as well as separately with 70% ethanol. Petroleum ether extract of flower of G. glauca was found to inhibit α-amylase significantly (78.56%). Extracts were further tested against crude murine pancreatic, small intestinal, and liver glucosidase enzyme which revealed excellent inhibitory properties. α-glucosidase inhibition provided a strong in vitro evidence for confirmation of both G. glauca and D. bulbifera as excellent antidiabetic remedy. This is the first report of its kind that provides a strong biochemical basis for management of type II diabetes using G. glauca and D. bulbifera. These results provide intense rationale for further in vivo and clinical study

Organic chemistry in capillaries

Capillaries, the simplest, cheapest and most easily accessible tools in the chemistry laboratory are put to several uses such as checking the solubility, detecting a functional group, and performing reactions. These innovative uses of open-ended capillaries reduce the consumption of chemicals, solvents, and reagents and considerably lessen the time required to perform all these functions

Trimethylsilyl triflouromethanesulfonate promoted [3+2] dipolar cycloaddition of nitrones and silylenol ethers: an efficient route to 5-siloxyisoxazolidines

The reaction of silyl enol ethers and nitrones, in the presence of trimethylsilyl trifluoromethanesulfonate, gives 5-siloxyisoxazolidines in excellent yield under fairly mild conditions

Short and efficient synthesis of (2S,3R,4R,5R) and (2S,3R,4R,5S)-tetrahydroxyazepanes via the henry reaction

The Henry reaction with the easily available α-D-xylo-pentodialdose afforded a diastereomeric mixture of nitroaldoses with the α-D-gluco- and β-l-ido-configuration, respectively, in good yield. When n-BuLi was used as the base, the reaction afforded the α-D-gluco-nitroaldose as the only product. The reduction of the nitro group in the α-D-gluco- and β-L-ido-nitroaldoses, removal of the protecting groups and intramolecular reductive cyclo-amination afforded the corresponding (2S,3R,4R,5R) and (2S,3R,4R,5S) tetrahydroxyazepanes