- A Water Soluble Pd2L4 Cage for Selective Binding of Neu5Ac
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The sialic acid N-acetylneuraminic acid (Neu5Ac) and its derivatives are involved in many biological processes including cell-cell recognition and infection by influenza. Molecules that can recognize Neu5Ac might thus be exploited to intervene in or monitor such events. A key obstacle in this development is the sparse availability of easily prepared molecules that bind to this carbohydrate in its natural solvent; water. Here, we report that the carbohydrate binding pocket of an organic soluble [Pd2L4]4+ cage could be equipped with guanidinium-terminating dendrons to give the water soluble [Pd2L4][NO3]16 cage 7. It was shown by means of NMR spectroscopy that 7 binds selectively to anionic monosaccharides and strongest to Neu5Ac with Ka=24 M?1. The cage had low to no affinity for the thirteen neutral saccharides studied. Aided by molecular modeling, the selectivity for anionic carbohydrates such as Neu5Ac could be rationalized by the presence of charge assisted hydrogen bonds and/or the presence of a salt bridge with a guanidinium solubilizing arm of 7. Establishing that a simple coordination cage such as 7 can already selectively bind to Neu5Ac in water paves the way to improve the stability, affinity and/or selectivity properties of M2L4 cages for carbohydrates and other small molecules.
- Schaapkens, Xander,van Sluis, Roy N.,Bobylev, Eduard O.,Reek, Joost N. H.,Mooibroek, Tiddo J.
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- Design, synthesis, and antimicrobial evaluation of hexadentate hydroxypyridinones with high iron(iii) affinity
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A range of hexadentate 3-hydroxypyridin-4-ones (HPOs) with high affinity for iron(III) has been synthesized. The log stability constants of two HPO-iron complexes (logK1) were determined to be over 34, and pFe values of the two HPOs were determined to be over 31. Antimicrobial assay indicated that they are able to markedly inhibit the growth of both Gram-positive and Gram-negative bacteria. Compounds 14a and 14e were found to exhibit the strongest inhibitory activity against Staphyloccocus aureus, Bacillus subtilis, Pseudomonas aeruginosa, and Escherichia coli, with MIC values of 8, 8, 16, and 8 lg/mL, respectively. These results indicate that hexadentate 3-hydroxypyridin-4-ones have potential application as antimicrobial agents, especially in the treatment of wound infection.
- Zhang, Ming-Xia,Zhu, Chun-Feng,Zhou, Ying-Jun,Kong, Xiao-Le,Hider, Robert C.,Zhou, Tao
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p. 659 - 668
(2015/02/19)
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- Branched polycyclic tetrazole systems. 1. Synthesis and structure of 2-(5-tetrazolyl)ethyl derivatives of some CH-, OH-, and NH-acids
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The cycloaddition of dimethylammonium azide to the nitrile groups of 2-cyanoethyl derivatives of CH-, OH-, and NH-acids leads to open-chain branched structures containing terminal NH-tetrazolyl groups. An x-ray diffraction structural analysis of tris[2-(5-tetrazolyl)ethyl]nitromethane revealed steric access of the equivalent NH-tetrazolyl rings of the branched system. In going from the branched nitrile substrates to the corresponding tetrazoles, the PMR spectra show a breakdown in the resolution of the multiplet components, which had not been observed previously for monocyclic 5-substituted tetrazoles. A dependence was found for the 13C NMR chemical shifts on the pKa values, reflecting the NH-addity of the branched polycyclic tetrazoles in water.
- Zubarev,Gurskaya,Zavodnik,Ostrovskii
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p. 1292 - 1298
(2007/10/03)
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