Isocyanide Cu(I) complexes with unexpected μ2‐bridging pseudohalides: Synthesis, characterization and catalytic activity towards CuAAC

Three neutral Cu(I) complexes bearing 2,6-dimethylphenyl isocyanide (CNXyl) and different triatomic pseudohalogens (SCN−, OCN− and N3−) as ligands were efficiently synthesized and characterized. The solid-state structures were unambiguously determined through single-crystal X-ray diffraction, revealing unexpected bridging coordination modes in the case of OCN− and N3−. All the complexes were tested for azide-alkyne cycloaddition (CuAAC), showing interesting catalytic activity towards the formation of 1,4-disubstituted-1,2,3-triazoles for the cyanato and the azido Cu(I) complexes. Both species afforded yields above 90% with 0.5 mol% of catalyst at 50°C for 24 h. Several alkynes and azides were tested using the more active azido Cu(I) complex, affording the corresponding triazoles in high yields. The azido Cu(I) complex also induced the intramolecular CuAAC in the presence of dimethyl acetylenedicarboxylate and benzyl bromide/phenylacetylene

3‐(Pyridin‐2‐yl)imidazo[1,5‐a]pyridine (Pyridylindolizine) as Ligand in Complexes of Transition and Main‐Group Metals

Producción CientíficaThe coordination of the easily prepared 3‐(pyridin‐2‐yl)imidazo[1,5‐a]pyridine (pyridylindolizine, Py‐indz) ligand to several metal moieties was studied, and its electronic properties, similar to those of the classical ligands 2,2′‐bipyridine (bipy) and 1,10‐phenanthroline (phen), are reported. The new complexes were prepared and fully characterized by X‐ray crystallography and other typical spectroscopic methods if possible. Paramagnetic complexes [Ni(S2X)2(Py‐indz)] X = P(OEt)2 (1), COEt (2); [Ni(acac)2(Py‐indz)] (3, acac = acetylacetonate); [Ni(Py‐indz)3](PF6)2 (4); [Mn2Cl4(Py‐indz)2] (6); and [MnCl2(Py‐indz)2] (7) have the magnetic moment expected for a metallic cation with two or five unpaired electrons. Diamagnetic complexes show NMR spectra with similar patterns with small differences depending on the complex. [M{S2P(OEt)2}2 (Py‐indz)] M = Zn (8), Cd (9) have pentacoordinate and hexacoordinate structures, respectively. Octahedral tin complexes [SnL4(Py‐indz)] L4 = I4 (10), Cl3Ph (11), and Cl2nBu2 (12) have different behaviors in solution; whereas complex 10 is practically insoluble, complex 11 displays the expected pattern in its NMR spectrum, and complex 12 shows dynamic behavior. The Py‐indz ligand is also able to stabilize copper(I) and forms [Cu(PPh3)2(Py‐indz)]BF4 (13). The synthesis of the carbonyl complexes [MBr(CO)3(Py‐indz)] M = Mn (14), Re (15) and [Mo(CO)4(Py‐indz)] (16) was followed by IR spectroscopy in solution. [RuCl·p‐cym(Py‐indz)]PF6 (17, p‐cym = p‐cymene) has the familiar half‐sandwich “three‐legged piano‐stool” geometry.Ministerio de Economía, Industria y Competitividad (Project CTQ2013- 41067-P

Affinity modulation of photoresponsive hosts for fullerenes: light-gated corannulene tweezers

Producción CientíficaSix azobenzene derivatives bearing polyaromatic fragments have been prepared and their reversible photoisomerization has been assessed. Corannulene-functionalized molecules have demonstrated excellent switchable hosting abilities towards fullerenes in which an interesting range of affinities has been found. The success of this design relies upon the reversible formation and destruction of tweezer-like structures.Ministerio de Economía, Industria y Competitividad (Project CTQ 2013-41067-P

Antiviral activity of ribosome-inactivating proteins

Producción CientíficaRibosome-inactivating proteins (RIPs) are rRNA N-glycosylases from plants (EC 3.2.2.22) that inactivate ribosomes thus inhibiting protein synthesis. The antiviral properties of RIPs have been investigated for more than four decades. However, interest in these proteins is rising due to the emergence of infectious diseases caused by new viruses and the difficulty in treating viral infections. On the other hand, there is a growing need to control crop diseases without resorting to the use of phytosanitary products which are very harmful to the environment and in this respect, RIPs have been shown as a promising tool that can be used to obtain transgenic plants resistant to viruses. The way in which RIPs exert their antiviral effect continues to be the subject of intense research and several mechanisms of action have been proposed. The purpose of this review is to examine the research studies that deal with this matter, placing special emphasis on the most recent findings.Junta de Castilla y León - (Grant VA033G19

Copper Complexes in the Promotion of Aldol Addition to Pyridine-2-carboxaldehyde: Synthesis of Homo- and Heteroleptic Complexes and Stereoselective Double Aldol Addition

Producción CientíficaCuCl2·2H2O and Cu(ClO4)2·6H2O are able to promote aldol addition of pyridine-2-carboxaldehyde (pyca) with acetone, acetophenone, or cyclohexenone under neutral and mild conditions. The general and simple one-pot procedure for the aldol addition to Cu(II) complexes accesses novel Cu complexes with a large variety of different structural motifs, from which the aldol-addition ligand can be liberated by treatment with NH3. Neutral heteroleptic complexes in which the ligand acts as bidentate, or homoleptic cationic complexes in which the ligand acts as tridentate can be obtained depending on the copper salt used. The key step in these reactions is the coordination of pyca to copper, which increases the electrophilic character of the aldehyde, with Cu(ClO4)2 leading to a higher degree of activation than CuCl2, as predicted by DFT calculations. A regio- and stereoselective double aldol addition of pyca in the reaction of Cu(ClO4)2·6H2O with acetone leads to the formation of a dimer copper complex in which the novel double aldol addition product acts as a pentadentate ligand. A possible mechanism is discussed. The work is supported by extensive crystallographic studies.2019-12-312019-12-31Ministerio de Economía, Industria y Competitividad (Project CTQ 2013-41067-P

Killing cancer cells by targeting the EGF receptor

Producción CientíficaIn this issue of Cancer Biology & Therapy, Bachran et al. analyze the effect of two chimeric toxins (SE and SA2E) consisting of the epidermal growth factor (EGF) and the plant protein toxin saporin towards an oral squamous cell carcinoma cell line (BHY) as well as on primary oral squamous cell carcinoma (OSCC) tumour cells

Removal of Phenolic Compounds from Water Using Copper Ferrite Nanosphere Composites as Fenton Catalysts

The authors affiliated to the University of Jaén (Department of Inorganic and Organic Chemistry) acknowledge financial support from the Spanish Ministry of Economy, Industry and Competitiveness and from FEDER (Project CTQ2016-80978-C2-1-R). L. Mateus thanks the Asociación Universitaria Iberoamericana de Postgrado (AUIP) and University of Jaén for their grant and financial support.Copper ferrites containing Cu+ ions can be highly active heterogeneous Fenton catalysts due to synergic effects between Fe and Cu ions. Therefore, a method of copper ferrite nanosphere (CFNS) synthesis was selected that also permits the formation of cuprite, obtaining a CFNS composite that was subsequently calcined up to 400 °C. Composites were tested as Fenton catalysts in the mineralization of phenol (PHE), p-nitrophenol (PNP) and p-aminophenol (PAP). Catalysts were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and magnetic measurements. Degradation of all phenols was practically complete at 95% total organic carbon (TOC) removal. Catalytic activity increased in the order PHE < PNP < PAP and decreased when the calcination temperature was raised; this order depended on the electronic effects of the substituents of phenols. The as-prepared CFNS showed the highest catalytic activity due to the presence of cubic copper ferrite and cuprite. The Cu+ surface concentration decreased after calcination at 200 °C, diminishing the catalytic activity. Cuprite alone showed a lower activity than the CFNS composite and the homogeneous Fenton reaction had almost no influence on its overall activity. CFNS activity decreased with its reutilization due to the disappearance of the cuprite phase. Degradation pathways are proposed for the phenols.This research was funded by Spanish Ministry of Economy, Industry and Competitiveness and FEDER (grant number CTQ2016-80978-C2-1-R), Asociación Universitaria Iberoamericana de Postgrado (AUIP) and University of Jaén

Modelos de enseñanza-aprendizaje. Un modelo de aplicación del Aprendizaje Basado en Problemas (ABP) en odontología infantil

Entre las diferentes técnicas de Enseñanza-Aprendizaje utilizadas en las ciencias biomédicas, una de las que mayor popularidad ha adquirido en las últimas décadas es el “Aprendizaje Basado en Problemas” (ABP), considerado un hito en la educación médica. Como ocurre en otros sistemas, el ABP está centrado en el alumno y pretende fomentar un tipo de aprendizaje auto-dirigido. De sus principales virtudes se destaca que favorece el desarrollo de cierto tipo de competencias como la toma de decisiones, el razonamiento crítico, o el trabajo en equipo. Buena parte del el éxito de una actividad basada en el ABP radica en la planificación de la misma. Los principales factores que deben tenerse en cuenta y detallar son: - la delimitación de los objetivos a alcanzar - la selección del/los problemas sobre los que se trabajará - la definición de las reglas de la actividad - determinar el tiempo en el que deberá darse solución al problema A lo largo del siguiente capítulo se detallan cada uno de estos aspectos y se relata una modelo de experiencia educativa inspirada en el ABP. El objetivo de la actividad es poner al alumno frente a situaciones clínicas infrecuentes en la consulta de Odontología Infantil en la Licenciatura/Grado de Odontología pero que son situaciones relativamente cotidianas para un odontólogo general/odontopediatra. Se pretende fomentar la integración de conocimientos de odontología infantil, la responsabilidad colectiva y la toma de decisiones clínicas simulando las condiciones a las que los alumnos se van a enfrentar una vez graduados. Para ello se diseñaron una serie de situaciones clínicas en un paciente virtual. A lo largo de todo el curso académico se realizaron distintas sesiones en las que se facilitaba a los alumnos una serie de datos clínicos (historia clínica, fotos, radiografías) y se les planteaban una serie de preguntas: diagnóstico, plan de tratamiento justificado, etc. que deberían responder en 15 minutos. Los alumnos participaron por equipos en base a los boxes en los que realizaban sus prácticas clínicas pero sólo uno del equipo respondía a las preguntas en cada jornada. A medida que transcurrían las diferentes sesiones clínicas se fue haciendo pública las respectivas calificaciones y el acumulado hasta ese momento de forma que los alumnos podían ir viendo sus progresos en relación al resto de la clase. Para fomentar la implicación en la actividad se estableció un “pódium” con los boxes que obtuvieron una mejor puntuación al acabar el curso académico, que además vieron recompensado su buen hacer con un incremento en su calificación final en la asignatura. La opinión de los alumnos respecto a la actividad fue muy positiva, y un buen complemento para la formación teórico-práctica recibida respecto a Odontología Infantil

Antibiotic Prophylactic Regimens for Infective Endocarditis in Patients Undergoing Dental Procedures

Up to date causal relationship has been demonstrated between dental manipulations and the onset of infective endocarditis (IE). However, since 1955, numerous expert committees have proposed antibiotic prophylaxis (AP) to prevent bacteraemia of oral origin. Controversy regarding the efficacy of AP prior to the dental procedures has intensified in recent years because of the lack of conclusive evidence on its efficacy for the prevention of IE and on its cost-effectiveness, as well as the possibility of allergic reactions and the emergence of antibiotic resistance. Accordingly, AP is now maintained exclusively for patients at highest risk and who require the manipulation of the gingival or periapical regions of the teeth or perforation of the oral mucosa. In the context of a restrictive policy, the National Institute for Health and Clinical Excellence (NICE) of the United Kingdom published a new guideline in 2008 stating that “AP against IE is not recommended for persons undergoing dental procedures”, regardless of risk status and of the nature of the procedure to be performed. The NICE guideline has generated further controversy, and expert committees in other countries continue to publish prophylactic regimens for the prevention of IE secondary to dental procedures. In this chapter, we discuss the principal guidelines currently applicable in Europe, the USA and Australia, and we draw particular attention to the need for randomised clinical trials

Conjugative DNA Transfer From E. coli to Transformation-Resistant Lactobacilli

Lactic acid bacteria (LAB) belonging to the genus classically known as Lactobacillus, recently split into 25 different genera, include many relevant species for the food industry. The well-known properties of lactobacilli as probiotics make them an attractive model also for vaccines and therapeutic proteins delivery in humans. However, scarce tools are available to accomplish genetic modification of these organisms, and most are only suitable for laboratory strains. Here, we test bacterial conjugation as a new tool to introduce genetic modifications into many biotechnologically relevant laboratory and wild type lactobacilli. Using mobilizable shuttle plasmids from a donor Escherichia coli carrying either RP4 or R388 conjugative systems, we were able to get transconjugants to all tested Lactocaseibacillus casei strains, including many natural isolates, and to several other genera, including Lentilactobacillus parabuchneri, for which no transformation protocol has been reported. Transconjugants were confirmed by the presence of the oriT and 16S rRNA gene sequencing. Serendipitously, we also found transconjugants into researcher-contaminant Staphylococcus epidermidis. Conjugative DNA transfer from E. coli to S. aureus was previously described, but at very low frequencies. We have purified this recipient strain and used it in standard conjugation assays, confirming that both R388 and RP4 conjugative systems mediate mobilization of plasmids into S. epidermidis. This protocol could be assayed to introduce DNA into other Gram-positive microorganisms which are resistant to transformation.FUNDING: Work in ML lab was supported by the grant BIO2017-87190-R from the Spanish Ministry of Science and Innovation. Work in MÁ lab was funded by the Spanish State Research Agency (AEI) and the European Regional Development Fund (FEDER) (AGL2016-78708-R, AEI/FEDER, EU). DG-H was a recipient of a predoctoral appointment from the University of Cantabria. RM-C received an ErasmusC traineeship grant