A novel series of pyrazole derivatives toward biological applications: experimental and conceptual DFT characterization.

A new series of 13 pyrazole-derivative compounds with potential antifungal activity were synthetized with good yields. The series have the (E)-2-((1-(R)-3,5-dimethyl-1H-pyrazol-4-yl)diazenyl)phenol general structure and were characterized by means of X-ray diffraction, UV-Vis, FTIR, 1H-NMR, 13C-NMR, and two-dimensional NMR experiments. This experimental characterization was complemented by DFT simulations. A deep insight regarding molecular reactivity was accomplished employing a conceptual DFT approach. In this sense, dual descriptors were calculated at HF and DFT level of theory and GGV spin-density Fukui functions. The main reactive region within the molecules was mapped through isosurface and condensed representations. Finally, chemical descriptors that have previously shown to be close related to biological activity were compared within the series. Thus, higher values of chemical potential ω and electrophilicity χ obtained for compounds 10, 9, 8, 6 and 7, in this order, suggest that these molecules are the better candidates as biological agents.

Characterization of hydroxymethylpyrimidine phosphate kinase from mesophilic and thermophilic bacteria and structural insights into their differential thermal stability.

The hydroxymethylpyrimidine phosphate kinases (HMPPK) encoded by the thiD gene are involved in the thiamine biosynthesis pathway, can perform two consecutive phosphorylations of 4-amino-5-hydroxymethyl-2-methyl pyrimidine (HMP) and are found in thermophilic and mesophilic bacteria, but only a few characterizations of mesophilic enzymes are available. The presence of another homolog enzyme (pyridoxal kinase) that can only catalyze the first phosphorylation of HMP and encoded by pdxK gene, has hampered a precise annotation in this enzyme family. Here we report the kinetic characterization of two HMPPK with structure available, the mesophilic and thermophilic enzyme from Salmonella typhimurium (StHMPPK) and Thermus thermophilus (TtHMPPK), respectively. Also, given their high structural similarity, we have analyzed the structural determinants of protein thermal stability in these enzymes by molecular dynamics simulation. The results show that pyridoxal kinases (PLK) from gram-positive bacteria (PLK/HMPPK-like enzymes) constitute a phylogenetically separate group from the canonical PLK, but closely related to the HMPPK, so the PLK/HMPPK-like and canonical PLK, both encoded by pdxK genes, are different and must be annotated distinctly. The kinetic characterization of StHMPPK and TtHMPPK, shows that they perform double phosphorylation on HMP, both enzymes are specific for HMP, not using pyridoxal-like molecules as substrates and their kinetic mechanism involves the formation of a ternary complex. Molecular dynamics simulation shows that StHMPPK and TtHMPPK have striking differences in their conformational flexibility, which can be correlated with the hydrophobic packing and electrostatic interaction network given mainly by salt bridge bonds, but interestingly not by the number of hydrogen bond interactions as reported for other thermophilic enzymes. ENZYMES: EC 2.7.1.49, EC 2.7.4.7, EC 2.7.1.35, EC 2.7.1.50.

A new isoxazolic compound acts as alpha7 nicotinic receptor agonist in human umbilical vein endothelial cells.

Recent evidence suggests that the alpha7 nicotinic acetylcholine receptors (alpha7 nAChRs) participate in the development of angiogenesis and could be a new endothelial target for revascularization in therapeutic angiogenesis. It has been shown that in human umbilical vein endothelial cells (HUVECs) alpha7 nAChR agonists increase the intracellular calcium concentration ([Ca2+]i), thus inducing proliferation and vessel formation which are important stages of angiogenesis. In the present study we evaluated the effect of new isoxazole compounds on the cytosolic Ca2+ signal in HUVECs using the fluorescent Ca2+ indicator Fluo-3AM and probing the involvement of alpha7 nAChR by means of pharmacological tools. HUVECs expressed mainly alpha7 nAChR, since there was no significant difference in the increase in [Ca2+]i induced by nicotine, a non-selective nicotinic agonist, in relation to choline, a selective alpha7 nAChR agonist. The increase in [Ca2+]i induced by 1 mM choline was inhibited significantly (p = 0.014) in cells which had been pre-incubated for 15 min with methyllycaconitine (MLA), a selective alpha7 nAChR antagonist. The studied compounds 1, 2, and 3 induced an increase in [Ca2+]i in a dose-dependent manner. Compound 1 at 10 microM induced a greater increase in [Ca2+]i than compounds 2 and 3. The increase in [Ca2+]i induced by compound 1 was significantly inhibited by MLA (p = 0.013) and completely inhibited by mecamylamine, a non-selective nAChR antagonist, indicating that the isoxazolic compound 1 acts as an alpha7 nAChR agonist.

Antifungal activity of tetrahydroquinolines against some phytopathogenic fungi.

Seven synthetic tetrahydroquinolines with different substitution patterns were obtained by an imino Diels-Alder condensation reaction and were evaluated against phytopathogenic fungi. Compounds with a methoxy group showed interesting activity against Cladosporium cladosporoides with a MIC value of 13.75 microg/mL

1-[2-(4-Nitro-phen-yl)-5-(5-phenyl-1,2-oxazol-3-yl)-1,2,3,4-tetra-hydro-quinolin-4-yl]pyrrolidin-2-one monohydrate.

The title compound, C(28)H(24)N(4)O(4)·H(2)O, crystallizes with two organic mol-ecules and two solvent water mol-ecules in the asymmetric unit. The most obvious difference between the mol-ecules is the torsion angles between the isoxazole ring and the benzene and phenyl rings [47.0 (2)/56.4 (2) and 33.3 (2)/11.0 (2)°, respectively]. Another important difference is observed in the rotation of the nitro group with respect to the phenyl groups [3.5 (6) and 31.1 (6)°]. The pyrrolidinone fragment is cis oriented with respect to the 4-nitro-phenyl fragment. In the crystal, mol-ecules are linked into centrosymmetric R(4) (2)(8) and R(4) (4)(20) motifs by O-H⋯O and N-H⋯O inter-actions.

In vitro activity of thienyl-2-nitropropene compounds against Trypanosoma cruzi.

The in vitro activity of four 2-nitropropene derivatives, 1-(3-benzothienyl)-2-nitropropene (N1), 1-(3-thienyl)-2-nitropropene (N2), 1-(5-bromo-2-thienyl)-2-nitropropene (N3) and 1-(4-bromo-2-thienyl)-2-nitropropene (N4), were tested against cultures of the parasite Trypanosoma cruzi. Cytotoxicity studies were performed using Vero cells. The blood trypomastigotes, amastigotes and epimastigotes showed differential degrees of sensitivity towards the four tested compounds; the highest activity against the epimastigotes and blood tripomastigotes was exhibited by N1, followed by N3, N4 and finally N2. In contrast, whereas the compounds N1, N3 and N4 exerted similar magnitudes of activity against amastigotes, N2 was found to be a much less potent compound. According to our results, the compound N1 had the highest level of activity (IC50: 0.6 microM) against epimastigotes.

5-(1-Cyclo-hexen-1-yl)-3-(4-methoxy-phen-yl)isoxazole.

In the title compound, C(16)H(17)NO(2), the isoxazole ring makes a dihedral angle of 14.81 (13)° with the 4-methoxy-phenyl ring. Two atoms of the cyclo-hexene ring are disordered over two almost equally occupied positions [0.526 (13)/0.474 (13)]. The mol-ecular structure features a short intra-molecular C-H⋯O contact.

1-(3-Phenyl-isoxazol-5-yl)cyclo-hexane-1,2-diol.

In the title compound, C(15)H(17)NO(3), there are two mol-ecules in the asymmetric unit wherein the isoxazole rings make dihedral angles of 16.16 (15) and 16.79 (13)° with the benzene rings, and the cyclo-hexane rings adopt chair conformations. In both mol-ecules, the hydroxyl groups of the diol fragments are cis oriented, the O-C-C-O torsion angles being 60.76 (12) and -55.86 (11)°. The two mol-ecules are linked by a strong O-H⋯N hydrogen bond and the crystal packing is stabilized by one O-H⋯N and two O-H⋯O hydrogen bonds. An intra-molecular O-H⋯O hydrogen bond is observed in one of the mol-ecules.

Bennett acceptance ratio method to calculate the binding free energy of BACE1 inhibitors: Theoretical model and design of new ligands of the enzyme.

In recent years, the design, development, and evaluation of several inhibitors of the BACE1 enzyme, as part of Alzheimer's treatment, have gathered the scientific community's interest. Here, a linear regression model was built using binding free energy calculations through the Bennett acceptance ratio method for 20 known inhibitors of the BACE1 enzyme, with a Pearson coefficient of R = 0.88 and R2  = 0.78. The validation of this model was verified employing eight additional random inhibitors, which also gave a linear correlation with R = 0.97 and R2  = 0.93. Furthermore, this linear regression model was also used for proposing the structure of four potential BACE1 inhibitors, and the most active of them gave a theoretical Kd  = 10 nM. However, these molecules have not been synthesized yet. Our team used a total time of more than 800 ns for the Molecular Dynamics to carry out this study, and all the software used were freely available.

Malla suburetral retropúbica (TVT): experiencia clínica y análisis de datos en el Hospital El Carmen de Maipú / Retropubic suburethral mesh (TVT): clinical experience and data analysis at the Hospital El Carmen de Maipú

La incontinencia urinaria de esfuerzo es la pérdida involuntaria de orina durante una maniobra de esfuerzo físico, ejercicio, estornudo o tos. Afecta aproximadamente al 15% de las mujeres de 30-60 años y su prevalencia es del 30-41%. Aunque existen terapias conservadoras para su manejo, muchas pacientes terminarán necesitando cirugía para su resolución. Las mallas suburetrales son alternativas para el manejo quirúrgico, existiendo dos vías de instalación, la transobturadora (TOT o TVT-O) y la retropúbica (del inglés tension-free vaginal tape o TVT), siendo esta última la que presenta mejores resultados y menos complicaciones posoperatorias. Objetivo: evaluar la tasa de efectividad y las complicaciones de la TVT en la Unidad de Piso Pélvico Femenino del Hospital El Carmen de Maipú entre los años 2015 y 2020. Materiales y Métodos: Se obtuvieron 715 registros de pacientes que fueron sometidas a TVT y se logró contactar telefónicamente con el 60,69% de ellas. Resultados: Los resultados muestran una tasa de efectividad del 94,8% y una tasa de complicaciones del 2,3%. Conclusión: Este estudio aporta evidencia local de los resultados posoperatorios en la IOE en pacientes que requirieron la instalación de una malla suburetal retropúbica, demostrando ser una cirugía altamente efectiva y segura.

Stress urinary incontinence is the involuntary loss of urine during physical exertion, exercise, sneezing, or coughing. It affects approximately 15% of women aged 30-60, with a prevalence of 30-41%. Although there are conservative therapies for its management, many patients will eventually require surgery for resolution. Suburethral sling are considered for surgical management, and there are two installation alternatives, transobturator (TOT or TVT-O) and retropubic (tension-free vaginal tape or TVT), with the latter presenting better results and fewer postoperative complications. Objetive: to evaluate effectiveness rate and complications of the TVT in the Female Pelvic Floor Unit of Hospital El Carmen de Maipú between 2015 and 2020. Materials and Methods: A total of 715 patient records were obtained for those who underwent TVT, and 60.69% of them were successfully contacted by telephone. Results: The results show an effectiveness rate of 94.8% and a complication rate of 2.3%. Conclusion: This study provides local evidence for the results of stress urinary incontinence that required the placement of a retropubic suburethral sling, proving to be a highly effective and safe surgery.

Unusual dimerization of a BcCsp mutant leads to reduced conformational dynamics.

Cold shock proteins (Csp) constitute a family of ubiquitous small proteins that act as RNA-chaperones to avoid cold-induced termination of translation. All members contain two subdomains composed of 2 and 3 ß-strands, respectively, which are connected by a hinge loop and fold into a ß-barrel. Bacillus caldolyticus Csp (BcCsp) is one of the most studied members of the family in terms of its folding, function, and structure. This protein has been described as a monomer in solution, although a recent crystal structure showed dimerization via domain swapping (DS). In contrast, other cold shock proteins of the same fold are known to dimerize in a nonswapped arrangement. Hypothesizing that reducing the size of the hinge loop may promote swapping as in several other DS proteins with different folds we deleted two residues from these region (BcCsp∆36-37), leading to a protein in monomer-dimer equilibrium with similar folding stability to that of the wild-type. Strikingly, the crystal structure of BcCsp∆36-37 revealed a nonswapped dimer with its interface located at the nucleic acid-binding surface, showing that the deletion led to structural consequences far from the perturbation site. Concomitantly, circular dichroism experiments on BcCsp∆36-37 demonstrated that binding of the oligonucleotide hexathymidine disrupts the dimer. Additionally, HDXMS shows a protective effect on the protein structure upon dimerization, where the resulting interactions between ligand-binding surfaces in the dimer reduced the extent of exchange throughout the whole protein. Our work provides evidence of the complex interplay between conformational dynamics, deletions, and oligomerization within the Csp protein family. DATABASES: Structural data are available in the Protein Data Bank under accession number 5JX4.

Incontinencia urinaria en el adulto mayor / Urinary incontinence in the elderly

RESUMEN Antecedentes: La incontinencia urinaria (IU) corresponde a la pérdida involuntaria de orina. En la medida en que la población envejece, aumenta su prevalencia y severidad. Objetivo: Describir el impacto de la incontinencia de orina en la población adulto mayor, así como conocer su fisiopatología e implicancias en la calidad de vida. Método: Revisión de la literatura disponible en PubMed, Embase y Medline utilizando los términos "urinary incontinence" y "elderly" entre los años 1990 y 2018. Resultados: La IU en el adulto mayor impacta negativamente en la calidad de vida de esta población, teniendo una multiplicidad de causas subyacentes que implican un tratamiento integral y multidisciplinario de esta patología. Conclusión: Dado el incremento de la edad en la población, conocer y manejar esta patología es importante para el clínico y el especialista para que de esta forma mejore la calidad de vida en este grupo etario.

ABSTRACT Background: Urinary incontinence (UI) is the involuntary loss of urine. The prevalence and severity of this condition increase as population ages. Objective: To describe the impact urinary incontinence in the elderly population, as well as to know its pathophysiology and implications in the quality of life. Method: Review of the literature available in PubMed, Embase and Medline using the keywords "urinary incontinence" and "elderly" between 1990 and 2018. Results: UI in the elderly has a negative impact on their quality of life, having a multiplicity of underlying causes that imply a comprehensive and multidisciplinary treatment of this pathology. Conclusion: Given the age increase in general population, knowing and managing this pathology is important for the clinician and the specialist to improve the quality of life in this age group.

Isoxazoles: synthesis, evaluation and bioinformatic design as acetylcholinesterase inhibitors.

OBJECTIVES: Inhibition of acetylcholinesterase (AChE) is a common treatment for early stages of Alzheimer's disease. In this study, nine isoxazoles derivatives were tested for their in-vitro AChE activity. The molecular docking showed the interaction of the compounds with the active site. METHODS: The isoxazoles were synthesized using 1,3-dipolar cycloaddition in the presence of sodium hypochlorite. They were also isolated and characterized by spectroscopic methods. The in-vitro activity was measured by an adapted version of Ellman's assay. KEY FINDINGS: The isoxazoles are described as inhibitors of AChE. The most potent compound in the series exhibited a moderate inhibitory activity (50% inhibitory concentration = 134.87 µm). The design of new compounds was created by using the RACHEL module of the SYBYL software. CONCLUSIONS: Our research provided enough evidence of the efficacy of isoxazoles as AChE inhibitors. The isoxazoles were synthesized and evaluated as inhibitors of AChE. The docking study based on a novel series of complexes isoxazole with AChE from Electroporus electricus has demonstrated that the ligand bind is similar to the compounds used as reference. To find new candidates with the isoxazole core that act as inhibitors of AChE, part of the structure of the compound 9 was used for de-novo design. Molecular docking models of the ligand-AChE complexes suggest that the compound 10 is located on the periphery of the AChE active site.

Heteroarylisopropylamines as MAO inhibitors.

The in vitro monoamine oxidase inhibitory (MAOI) activities of 11 heteroarylisopropylamines vis-à-vis MAO-A and MAO-B were described and interpreted in terms of possible interactions with the enzyme active site. Molecular dynamics simulations allowed a comparison between the most active MAO-A inhibitor of the series, the 1-(2-benzofuryl)-2-aminopropane, and the specific, analogous MAO-A substrate serotonin.

Charge-transfer interactions in the inhibition of MAO-A by phenylisopropylamines--a QSAR study.

The HOMO energies and the charges on the aromatic carbons of two sets of MAO-A-inhibiting phenylisopropylamines, one containing 4-amino substituents, were calculated by the AM1 method, in order to evaluate the importance of charge-transfer interactions between drug and enzyme. Multiple-linear regressions of the pIC50 values on the calculated descriptors were performed with 33 compounds from the two sets, and separately with each set. A poor correlation was obtained when the two sets were merged, as a result of opposing trends shown by the two separate sets. These opposing trends were reconciled by invoking a partial protonation of the basic 4-amino substituents by a hydrogen-bond-donor fragment of the enzyme. The resulting analysis indicated that electron-rich rings and higher HOMO levels tended to increase activity. This model received support from the evaluation of the IMAO activity of four new phenylisopropylamines.

In vitro activity of thienyl-2-nitropropene compounds against Trypanosoma cruzi

The in vitro activity of four 2-nitropropene derivatives, 1-(3-benzothienyl)-2-nitropropene (N1), 1-(3-thienyl)-2-nitropropene (N2), 1-(5-bromo-2-thienyl)-2-nitropropene (N3) and 1-(4-bromo-2-thienyl)-2-nitropropene (N4), were tested against cultures of the parasite Trypanosoma cruzi. Cytotoxicity studies were performed using Vero cells. The blood trypomastigotes, amastigotes and epimastigotes showed differential degrees of sensitivity towards the four tested compounds; the highest activity against the epimastigotes and blood tripomastigotes was exhibited by N1, followed by N3, N4 and finally N2. In contrast, whereas the compounds N1, N3 and N4 exerted similar magnitudes of activity against amastigotes, N2 was found to be a much less potent compound. According to our results, the compound N1 had the highest level of activity (IC50: 0.6 ìM) against epimastigotes.