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Hu proteins are members of the RNA-binding protein (RBP) family and play a pivotal role in the regulation of post-transcriptional processes. Through interaction with selected mRNAs, RBPs regulate their function and stability; as a consequence, RBP dysregulation can cause abnormal translation of key proteins involved in several pathologies. In the past few years, this observation has sparked interest to develop new treatments against these pathologies by using small molecules able to modulate RBP activity. Among the four Hu proteins, we have directed our efforts towards the isoform HuR, which is mainly involved in cancer, inflammation and retinopathy. Aimed at developing compounds able to modulate the stability of HuR-mRNA complexes, in the present work, we applied a biophysical fragment screening by assessing a library of halogen-enriched heterocyclic fragments (HEFLibs) via Surface Plasmon Resonance (SPR) and Saturation Transfer Difference (STD) NMR to select promising fragments able to interact with HuR. One selected fragment and a few commercially available congeners were exploited to design and synthesize focused analogues of compound N-(3-chlorobenzyl)-N-(3,5-dihydroxyphenethyl)-4-hydroxybenzamide (1), our previously reported hit. STDNMR spectroscopy, molecular modeling, and SPR offered further insight into the HuR-small molecule interaction and showed that fragment-based approaches represent a promising and yet underexplored strategy to tackle such unusual targets. Lastly, fluorescence polarization (FP) studies revealed the capability of the new compounds to interfere with the formation of the HuR-mRNA complex. This is, to our knowledge, the first fragment-based campaign performed on the Hu protein class, and one of the few examples in the larger RBP field and constitutes an important step in the quest for the rational modulation of RBPs and related RNA functions by small molecules., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Cancer is the second most important cause of death worldwide. There is always a demand for new anticancer drugs and continuously a wide variety of natural and synthetic compounds were developed by the researchers. Nowadays, a large number of drugs in clinical practice were found to have a high incidence of side effect and multidrug conflict. The development of novel less toxic, low cost and very energetic N-methylpicolinamide-bearing hybrids is a hot research topic in the community of medicinal chemistry. Herein we highlight the current advances in the synthesis of picolinamide-containing heterocyclic compounds as potent anticancer agents. In addition, briefly explore their structure-activity relationship studies for the inspiration of the innovation and development of more potent and effective drugs against various death-causing cancer diseases., (Copyright © 2019 Elsevier Inc. All rights reserved.)

As a man-made additive, chromium picolinate Cr(pic) 3 has become a popular dietary supplement worldwide. In this paper Cr(pic) 3 and its new derivatives Cr(6-CH 3 -pic) 3 (1), [Cr(6-NH 2 -pic) 2 (H 2 O) 2 ]NO 3 (2) and Cr(3-NH 2 -pic) 3 (3) were synthesized, and complexes 1 and 2 were characterized by X-ray crystal structure (where pic=2-carboxypyridine). The relationship between the chemical properties and biotoxicity of these complexes was fully discussed: (1) The dynamics stability of chromium picolinate complexes mainly depends on the CrN bonds length. (2) There is a positive correlation between the dynamics stability, electrochemical potentials and generation of reactive oxygen species through Fenton-like reaction. (3) However, no biological toxicity was observed through MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) and sub-chronic oral toxicity study for these chromium picolinate compounds. Together, our findings establish a framework for understanding the structure-property-toxicity relationships of the chromium picolinate complexes., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Phosphorescent studies of 2-arylimidazole heteroleptic cyclometalated iridium(III) complexes with picolinic acid as the ancillary ligand were made. The observed experimental data reveals that these complexes possess dominantly (3)MLCT and (3)π-π* excited states and the solvent shift of these complexes are interpreted by Reichardt-Dimroth and Marcus solvent functions. The results are consistent with prior assignments on the absorption band to a metal-to-ligand charge transfer excited state associated with chelating ligand. Emission kinetic studies exploited that the radiative transition (k(r)), increases with increasing λ(emi)., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Three novel ligands containing pyridine-2,6-dicarboxylic acid unit, trans-4 -(4'-methoxystyryl) pyridine-2,6-dicarboxylic acid, trans-4-(4'-(dimethylamino)styryl)pyridine-2,6-dicarboxylic acid, and trans-4-(4'-(diphenylamino)styryl)pyridine-2,6-dicarboxylic acid were synthesized and their complexes with Eu(III), Tb(III) ions were successfully prepared. The ligands and the corresponding metal complexes were characterized by means of MS, elemental analysis, IR, (1)H NMR and TG-DTA. The luminescence spectra of Eu(III) and Tb(III) complexes in solid state were studied. The strong luminescence emitting peaks at 615 nm for Eu(III) and 545 nm for Tb(III) can be observed. The applications in cell imaging of the europium and terbium complexes were investigated., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Two novel pyrazole-derived ligands, 3-chloro-6-(3,5-dimethyl-1H-pyrazol-1-yl)picolinic acid (CDPA) and 3-chloro-6-(3,5-dimethyl-1H-pyrazol-1-yl)-N-phenylpicolinamide (CDPP) were prepared by 3,6-dichloropicolinic acid (DCPA). Their complexes with terbium(III) and europium(III) were synthesized. The complexes were characterized by elemental analysis, infrared spectra, (1)H NMR and TG-DTG. Furthermore, the above complexes using 1,10-phenanthroline as a secondary ligand were also synthesized and characterized. The luminescence properties of these complexes in solid state were investigated. The results suggested that Tb(III) complexes exhibit more efficient luminescence than Eu(III) complexes and the fluorescence of the complexes with 1,10-phenanthroline as a secondary ligand was prominently stronger than that of complexes without this ligand., and the three ligand (DCPA), (CDPP) and (CDPA) are excellent sensitizers to Eu(III) and Tb(III) ion., (Copyright (c) 2009 Elsevier B.V. All rights reserved.)

Two chargeless VO(IV) complexes with 3-hydroxypyridine-2-carboxylic acid (H2hpic), [VO(Hhpic-O,O)(Hhpic-O,N)(H2O)].3H2O (1) and the cyclic tetramer [(VO)4(mu-(hpic-O,O',N))4(H2O)4].8H3O (2), have been synthesized and characterized by elemental analysis, mass, infrared, electronic absorption, electron spin resonance (ESR) spectroscopies, and X-ray crystallography. Their coordination structures are similar to each other (and 1 is readily transformed into 2), but are quite different from that of bis(pyridine-2-carboxylato)oxovanadium(IV). The magnetic susceptibility of 2 indicates the presence of a weak ferromagnetic intramolecular interaction between the V atoms at low temperature, in addition to a weak antiferromagnetic intermolecular interaction. The ESR signal of 2 was broad, while 1 showed an eight-line hyperfine splitting pattern due to coupling of the unpaired electron with the 51V nucleus (I=7/2). The ESR spectrum and cyclic voltammogram of 2 clearly show that the cyclic tetramer remains intact in solution. The insulinomimetic activity of 1 and 2 was evaluated by means of in vitro measurements of the inhibition of free fatty acid release from epinephrine-treated isolated rat adipocytes. While 1 exerted higher insulinomimetic activity than VOSO4, the activity of 2 was significantly lower than that of VOSO4. Hence 2 appears to retain its cyclic structure during the in vitro test. These results indicate that the rational ligand design for VO complexes might be a promising approach to obtain superior insulinomimetic activity.

A novel bis(6-ethylpicolinato)(H(2)O)oxovanadium(IV) complex (VO(6epa)(2) x (H(2)O)) was prepared and its structure was revealed by X-ray analysis (space group Pc(#7), a=10.838(2), b=11.148(5), c=16.642(3) A, and Z=2). Because VO(6epa)(2) x (H(2)O) exhibited higher in vitro insulinomimetic activity compared to that of vanadyl sulfate in terms of inhibition of free fatty acid (FFA) release from isolated rat adipocytes in the presence of epinephrine, its in vivo effect on whether the complex has a blood glucose normalizing effect was examined in KK-A(y) mice, a model animal of type 2 diabetes mellitus. VO(6epa)(2) x (H(2)O) was found to normalize the high blood glucose levels of KK-A(y) mice when given intraperitoneally at doses of 49 micromol/kg body weight for the first 4 days and then 39 micromol/kg body weight for 10 days. In addition, VO(6epa)(2) x (H(2)O) improved glucose tolerance ability as examined by the oral glucose test and seemed to have little toxicity in terms of serum parameters. VO(6epa)(2) x (H(2)O) showed higher normoglycemic activity than bis(6-methylpicolinato)oxovanadium(IV) (VO(6mpa)(2)) at the same dose. These results indicated that greater enhancement of the blood glucose normalizing effect in KK-A(y) mice by ethyl substitution compared to methyl substitution may be due to its being more strongly lipophilic.

Using the copper assisted halogen exchange the MAO-B inhibitor Ro 43-0463, N-(2-aminoethyl)-5-iodo-2-pyridinecarboxamide, was labelled with 123I as well as with 125I to allow in vitro and in vivo investigations including SPET with healthy volunteers. Ro 43-0463 is known to inhibit reversibly and specifically MAO-B, having an IC50 of 3 x 10(-8) Mol/L. The labeling in the presence of CuSO4 and ascorbic acid was optimised, varying time (30 to 105 min), precursor concentration (1-3.5 mg) and temperature (130-200 degrees C). The labeling yield ranged between 60 and 70%. Purification was achieved with Lichrosorb RP-18 (5 micron, 250 x 8 mm) and 1.5 mL/min 0.36 M H3PO4/EtOH 97/3 [0.01 M (NH4)2HPO4]. After neutralisation and sterile filtration the final activity concentration ranged between 18.5 and 37 MBq/mL. Biodistribution studies showed a brain to blood ratio greater than 1 within 1 h p.i. The main radiation burden calculated from these animal data is to alimentary and excretory organs and the ovaries. Autoradiography was performed using rat brain slices and 5 nM [125I]Ro 43-0463 in TRIS-buffer pH 7.4 for 90 min at 20 degrees C. Its radioactivity pattern corresponds to the known distribution of MAO-B in the rat brain. By displacement with L-deprneyl the highly specific binding of R0 43-0463 was proven in vitro. SPECT studies with normal volunteers corresponded with the pattern found in autoradiography.

The blood glucose level of rats with streptozotocin (STZ)-induced diabetes has been found to be normalized by administration of vanadyl or vanadate complexes. During our investigations on the development of anti-diabetic vanadyl complexes with various types of coordination mode such as V-O, V-N and V-S, we found that a new bis(picolinato)oxovanadium (IV) complex (VPA) has a strong insulin-mimetic effects as evaluated by an in vitro experiments, in which the inhibition of free fatty acid release in isolated rat adipocytes treated with epinephrine was observed to be similar to that of insulin. VPA was also effective for normalizing the blood glucose level of STZ-induced diabetic rats when given intraperitoneally or orally. The serum glucose level was maintained in the normal range for about 30 days with body weight gain after the end of oral administration of VPA for 14 days. VPA was confirmed to be an orally active and long-term acting insulin-mimetic vanadyl complex to treat insulin-dependent diabetes mellitus (IDDM) in rats.