Computational Studies on Selected Macrolides Active against Escherichia coli Combined with the NMR Study of Tylosin A in Deuterated Chloroform

Abstract: Although many antibiotics are active against Gram-positive bacteria, fewer also show activity against Gram-negative bacteria. Here, we present a combination of in silico (electron ion-interaction potential, molecular docking, ADMET), NMR, and microbiological investigations of selected macrolides (14-membered, 15-membered, and 16-membered), aiming to discover the pattern of design for macrolides active against Gram-negative bacteria. Although the conforma-tional studies of 14-membered and 15-membered macrolides are abundant in the literature, 16-membered macrolides, and their most prominent representative tylosin A, have received rela-tively little research attention. We therefore report the complete 1H and 13C NMR assignment of tylosin A in deuterated chloroform, as well as its 3D solution structure determined through mo-lecular modelling (conformational search) and 2D ROESY NMR. Additionally, due to the degra-dation of tylosin A in deuterated chloroform, other species were also detected in 1D and 2D NMR spectra. We additionally studied the anti-bacterial activity of tylosin A and B against se-lected Gram-positive and Gram-negative bacteria

myo-Inositol based fluorescence quenched molecular probes and synthesis of autoinducer-2 (Al-2)

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Radiosynthesis and reactivity of N-[11C]methyl carbamoylimidazole.

N-Methyl carbamoylimidazole is a safe and practical alternative to methyl isocyanate for carbamoylation reactions. We have developed a new chemical route for its synthesis from methyl iodide and applied this to the synthesis of N-[11C]methyl carbamoylimidazole as a new [11C]synthon to radiolabel biomolecules for PET imaging research. N-[11C]methyl carbamoylimidazole was prepared from [11C]methyl iodide in 70-74% radiochemical yield (decay corrected) and can be used in situ for further reaction without purification. The reactivity of N-[11C]methyl carbamoylimidazole was demonstrated in a series of [11C]carbamoylation reactions

Radiosynthesis and reactivity of N-[11C]methyl carbamoylimidazole.

N-Methyl carbamoylimidazole is a safe and practical alternative to methyl isocyanate for carbamoylation reactions. We have developed a new chemical route for its synthesis from methyl iodide and applied this to the synthesis of N-[11C]methyl carbamoylimidazole as a new [11C]synthon to radiolabel biomolecules for PET imaging research. N-[11C]methyl carbamoylimidazole was prepared from [11C]methyl iodide in 70-74% radiochemical yield (decay corrected) and can be used in situ for further reaction without purification. The reactivity of N-[11C]methyl carbamoylimidazole was demonstrated in a series of [11C]carbamoylation reactions