[en] Many biological processes from infection to tumor immune evasion are controlled by cell surface sialylation. To gather further insight into these processes, methods to alter cell surface sialylation are required. One way to achieve this is inhibiting the key enzyme of sialic acid de novo biosynthesis, the intracellular bifunctional UDP-N-acetylglucosamine epimerase/ N-acetylmannosamine kinase (GNE/MNK). Here, we present low molecular weight inhibitors of MNK activity based on picolinic acid derivatives. They were identified in a fragment screening using ¹⁹F NMR and validated in a biochemical inhibition assay followed by a structure-activity relationship analysis and docking. The optimized compound 6-carbamoylpicolinic acid inhibits MNK with a double-digit micromolar affinity. Its low molecular weight (166 Da) renders this picolinic acid derivative an exquisite starting point for the development of high-affinity MNK inhibitors, which may serve as molecular probes or lead candidates in future. (author)

[en] Dipicolinic acid (pyridine-2,6-dicarboxylic acid), labelled with ¹⁴C, has been synthesised, on a miniature scale, starting from formaldehyde-(¹⁴C). The radioactive label was incorporated into the '4' position of the pyridine ring to prevent possible loss of label owing to decarboxylation during experiments. The compound was intended for use in the localisation of dipicolinic acid in bacterial spores. (Author)

[en] The results on the potentiometric studies of the ternary systems: Zn(II)/Cd(II)-8. HQS-HA (where 8-HQS =8-hydroxyqinoline, 5-sulphonic acid; HA= quinaldinic acid (QUINA) or picolinic acid (PIC)) have been discussed. (auth.)

[en] The effect of organic acids on the adsorption of U(VI) onto oxide surfaces (TiO₂(anatase), SiO₂ (amorphous) and Al₂O-3(amorphous)) has been investigated. Two different organic acids, salicylic and picolinic acids, were used. Changes of adsorption ratio of U(VI), which depend on the existence of organic acids in a sample, were measured as a function of pH. Quantities of adsorbed organic acids, which depend on the existence of U(VI) in a sample, were also measured as a function of pH. It is confirmed that the soluble complex formation of U(VI) with organic acids can deteriorate the adsorption of U(VI) onto TiO₂ surface. It is noteworthy that salicylic acid does not affect the adsorption of U(VI) onto SiO₂ surface, however, picolinic acid enhances the adsorption of U(VI) onto SiO₂ surface. The latter effect can be understood by considering the formation of a ternary surface complex on SiO₂ surface, which was confirmed by the co-adsorption of picolinic acid with U(VI) and the change in a fluorescence spectra of U(VI) on surface, In the case of Al₂O-3, organic acids themselves were largely adsorbed onto a surface without deteriorating the adsorption of U(VI). This would support the possibility of a ternary surface complex formation on the Al₂O-3 surface, and an additional spectroscopic study is required.

No abstract available

[en] Reaction between 2-pyridinecarboxylic acid (Hpic) and K₃[Cr(O₂)₄] give complex [Cr(pic)₃].H₂O (1) which is characterized by elemental analysis and spectroscopic methods (FT-IR, Raman) and X-ray crystallography. In the crystal structure of 1, chromium atom with coordinated by three nitrogen and three oxygen atoms has a distorted octahedral geometry. Also a water molecule is incorporated in crystal network. Each water molecule acts as hydrogen bond bridging and connects two adjacent complexes by two O-H···O hydrogen bonds

[en] Luminescence spectroscopy and in particular time resolved luminescence spectroscopy has become most suitable technique to characterize the uranyl species, as uranyl complexes are known to emit green light upon photo irradiation. The characteristic luminescence features originate from uranyl ion have been used to identify the specie and help to understand the complexation behavior of uranyl with various ligands. In this work, luminescence of uranyl (UO_2"2"+) - picolinic acid complex has been studied in aqueous and acetonitrile medium. In aqueous medium, the uranyl luminescence gets quenched when complexed with picolinic acid; whereas, uranyl luminescence is found to be enhanced by picolinic acid in acetonitrile medium. The enhancement is due to the sensitization of uranyl luminescence by picolinate ion. UV-Vis spectroscopy studies revealed the formation of 1:2 type complex of uranyl with picolinate in acetonitrile medium. This enhanced luminescence results in very low detection limit for uranium, namely 0.6 ppb. (author)

No abstract available

[en] The ternary complexes of In(III) with γ-picoline and nicotinic acid have been studied polarographically, in aqueous solution at pH 4.5 ± 0.02 and ionic strength 0.1 (KCl). The reduction of simple ion and its binary and ternary complexes was found to be reversible and diffusion-controlled involving three electrons. A Schaap and Mcmasters treatment of the observed polarographic data revealed the formation of (In-(nico)(γ-pico))²⁺, (In-(nico)₂(γ-pico))⁺ and (In-(nico)(γ-pico)₂)²⁺ ternary complexes with formation constants log β₁₁=3.90, log ^beta_²1=5.58 and log β₁₂=4.00. (author). 8 refs

No abstract available