Enzymatic and solid-phase synthesis of new donepezil-based L- and D-glutamic acid derivatives and their pharmacological evaluation in models related to Alzheimer's disease and cerebral ischemia

Supplementary data associated with this article can be found in the online version, at http://dx.doi.org/10.1016/j.ejmech.2017.02. 034. These data include MOL files and InChiKeys of the most important compounds described in this article.Previously, we have described N-Bz-L-Glu[NH-2-(1-benzylpiperidin-4-yl)ethyl]-O-nHex (IQM9.21, L-1) as an interesting multifunctional neuroprotective compound for the potential treatment of neurodegenerative diseases. Here, we describe new derivatives and different synthetic routes, such as chemoenzymatic and solid-phase synthesis, aiming to improve the previously described route in solution. The lipase-catalysed amidation of L- and D-Glu diesters with N-benzyl-4-(2-aminoethyl)piperidine has been studied, using Candida antarctica and Mucor miehei lipases. In all cases, the α-amidated compound was obtained as the main product, pointing out that regioselectivity was independent of the reacting Glu enantiomer and the nature of the lipase. An efficient solid-phase route has been used to produce new donepezil-based L- and D-Glu derivatives, resulting in good yield. At micromolar concentrations, the new compounds inhibited human cholinesterases and protected neurons against toxic insults related to Alzheimer's disease and cerebral ischemia. The CNS-permeable compounds N-Cbz-L-Glu(OEt)-[NH-2-(1-benzylpiperidin-4-yl)ethyl] (L-3) and L-1 blocked the voltage-dependent calcium channels and L-3 protected rat hippocampal slices against oxygen-glucose deprivation, becoming promising anti-Alzheimer and anti-stroke lead compounds.This work was supported by the Spanish Ministry of Economy and Competitiveness (MINECO, grants SAF2015-64948-C2-1-R and SAF2012-31035) and Consejo Superior de Investigaciones Científicas (CSIC, grant PIE-201580E109) to M.I.R.-F; Instituto de Salud Carlos III (Miguel Servet contract and projects CP11/00165 and PI14/00372), European Commission - Marie Curie Actions FP7 (FP7- People-2012-CIG-322156), Bayer AG, From Targets to Drugs (grant 2015-03-1282) and Fundacion FIPSE (grant 12-00001344-15) to R.L.; Spanish Ministry of Economy and Competitiveness (SAF2015- 63935) to M.G.L.; and Spanish Ministry of Education (fellowship for Master Studies) to L.M.Peer Reviewe

Antifungal effect of Pegylated Graphene Oxide and Silver Nanoparticles against Candida albicans

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Dibenzo[1,4,5]thiadiazepine: A hardly-known heterocyclic system with neuroprotective properties of potential usefulness in the treatment of neurodegenerative diseases

In this work we describe a new family of dibenzo[1,4,5]thiadiazepines (2-12) that showed an interesting in vitro biological profile, namely neuroprotective and antioxidant properties, as well as blockade of cytosolic calcium entry. They showed no cytotoxic effects and the majority were predicted as CNS-permeable compounds. In human neuroblastoma cells they displayed good neuroprotective properties against mitochondrial oxidative stress which, in many cases, almost reached the full protection (>90%) when compounds were incubated with cells 24 h before the addition of toxic stressors. In co-incubation conditions these figures were smaller, although some compounds maintained an interesting level of neuroprotection, higher than 50%. Four selected compounds (2, 5, 8, and 11) were found to be effective antioxidant agents by sequestering mitochondrial radical oxygen species (ROS). Moreover, compound 2 showed a remarkable calcium-channel modulating activity. The interest of these compounds is increased by the fact that dibenzo[1,4,5]thiadiazepine is a barely known structure that is not difficult to synthesize and presents very few described derivatives, opening a new and broad line of research in Medicinal Chemistry. © 2014 Elsevier Inc. All rights reserved.Peer Reviewe

Rheological Properties of Different Graphene Nanomaterials in Biological Media

Carbon nanomaterials have received increased attention in the last few years due to their potential applications in several areas. In medicine, for example, these nanomaterials could be used as contrast agents, drug transporters, and tissue regenerators or in gene therapy. This makes it necessary to know the behavior of carbon nanomaterials in biological media to assure good fluidity and the absence of deleterious effects on human health. In this work, the rheological characterization of different graphene nanomaterials in fetal bovine serum and other fluids, such as bovine serum albumin and water, is studied using rotational and microfluidic chip rheometry. Graphene oxide, graphene nanoplatelets, and expanded graphene oxide at concentrations between 1 and 3 mg/mL and temperatures in the 25–40 °C range were used. The suspensions were also characterized by transmission and scanning electron microscopy and atomic force microscopy, and the results show a high tendency to aggregation and reveals that there is a protein–nanomaterial interaction. Although rotational rheometry is customarily used, it cannot provide reliable measurements in low viscosity samples, showing an apparent shear thickening, whereas capillary viscometers need transparent samples; therefore, microfluidic technology appears to be a suitable method to measure low viscosity, non-transparent Newtonian fluids, as it is able to determine small variations in viscosity. No significant changes in viscosity are found within the solid concentration range studied but it decreases between 1.1 and 0.6 mPa·s when the temperature raises from 25 to 40 °C

Old phenothiazine and dibenzothiadiazepine derivatives for tomorrow’s neuroprotective therapies against neurodegenerative diseases

From an in-house library of compounds, five phenothiazines and one dibenzothiadiazepine were selected to be tested in neuroprotective and cholinergic assays. Three of them, derived from the N-alkylphenothiazine, the N-acylaminophenothiazine, and the 1,4,5-dibenzo[b,f]thiadiazepine system, protected human neuroblastoma cells against oxidative stress generated by both exogenous and mitochondrial free radicals. They could also penetrate the CNS, according to an in vitro bloodebrain barrier model, and an N-acylaminophenothiazine derivative behaved as a selective inhibitor of butyrylcholinesterase. Free radical capture and/or promotion of antioxidant protein biosynthesis are mechanisms that can be implicated in their neuroprotective actions. Due to their excellent pharmacological properties and the fact that they were not biologically explored in the past, one N-acylaminophenothiazine and one 1,4,5-dibenzo[b,f]thiadiazepine have been selected to develop two new series that are currently in progressThis work is dedicated to our dear colleagues Prof. Carlos Corral (deceased) and Dr. Jaime Lissavetzky, which conducted the first syntheses of these compounds. The authors gratefully acknowledge the financial support of Spanish Ministry of Science and Innovation MICINN (projects SAF2006-01249, SAF2009-13015-C02-01, and SAF2009-12150), Community of Madrid (Programa de Actividades de I þ D entre Grupos de Investigación en Biociencias, project S-SAL/0275/2006), and the Institute of Health Carlos III (Red RENEVAS, RETICS-RD06/0026). The fellowships to G.C.G.-M. and M.P.A. from CSIC and MICINN respectively, are also acknowledged.Peer reviewe

Neuroprotective and Cholinergic Properties of Multifunctional Glutamic Acid Derivatives for the Treatment of Alzheimer’s Disease

Novel multifunctional compounds have been designed, synthesized, and evaluated as potential drugs for the treatment of Alzheimer’s disease (AD). With an L-glutamic moiety as a suitable biocompatible linker, three pharmacophoric groups were joined: (1) anN-benzylpiperidine fragment selected to inhibit acetylcholinesterase by interacting with the catalytic active site (CAS), (2) an N-protecting group of the amino acid, capable of interacting with the acetylcholinesterase (AChE)-peripheral anionic site (PAS) and protecting neurons against oxidative stress, and (3) a lipophilic alkyl ester that would facilitate penetration into the central nervous system by crossing the blood-brain barrier. At submicromolar concentration, they inhibit AChE and butyrylcholinesterase (BuChE) of human origin, displace the binding of propidium iodide from the PAS of AChE, and could thus inhibit Aβ aggregation promoted by AChE. They also display neuroprotective properties against mitochondrial free radicals, show low toxicity, and could be able to penetrate into the CNS.The authors gratefully acknowledge the financial support of SpanishMinistry of Science and Innovation (projects SAF 2006-01249, SAF 2006-08540, and SAF- 2006-03589), Comunidad de Madrid (Programa de Actividades de IþD entre Grupos de Investigación en Biociencias, project S-SAL/0275/2006), and the Spanish Ministry of Health (Instituto de Salud Carlos III) RETICS-RD06/0026, and Agencia Laín Entralgo. The fellowships to M.P.A. and G.C.G.-M. from MEC and CSIC, respectively, are also acknowledgedPeer reviewe

Comportamiento reológico de suspensiones de nanotubos de carbono con Aplicaciones biomédicas

[EN]: The rheological behaviour of different carbon nanotubes suspensions in the dilute regime was evaluated. Suspensions of commercial multi-walled carbon nanotubes without functionalization, multi-walled carbon nanotubes oxidized in our laboratory with nitric acid under reflux for 24 hours and commercial multi-walled carbon nanotubes functionalized with carboxylic groups were studied. The study was performed in two dispersing media: water and fetal bovine serum (FBS). The results were compared with those obtained in previous work carried out for suspensions of single-walled carbon nanotubes (SWCNTs) to understand the influence of the structure of carbon nanotubes on the rheological properties when a biological medium is present. Structural characterization was performed with different techniques: XRD, IR, TGA, TEM, SEM and AFM. For the colloidal characterization, the zeta potential of the suspensions was determined at pH values between 4 and 9, our range of interest being between pH = 6-8, close to physiological pH. The measurements were done for different concentrations of suspensions (1, 1.5, 3 mg/mL) and temperature of 25, 30 and 37 °C.[ES]: Se estudió el comportamiento reológico de diferentes suspensiones de nanotubos de carbono en régimen diluido. Se estudiaron suspensiones de nanotubos de carbono de paredes múltiples comerciales sin funcionalización, nanotubos de carbono de paredes múltiples oxidados en nuestro laboratorio con ácido nítrico a reflujo durante 24 horas y nanotubos de carbono de paredes múltiples comerciales funcionalizados con grupos carboxílicos. El estudio se realizó en dos medios dispersantes: agua y suero fetal bovino (FBS). Los resultados se compararon con los obtenidos en trabajos previos realizados para suspensiones de nanotubos de carbono de pared simple (SWCNTs) con el fin de comprender la influencia de la estructura de los nanotubos de carbono en las propiedades reológicas en presencia de un medio biológico. La caracterización estructural se realizó con diferentes técnicas: XRD, IR, TGA, TEM, SEM y AFM. Para la caracterización coloidal, se determinó el potencial zeta de las suspensiones a valores de pH comprendidos entre 4 y 9, siendo nuestro rango de interés entre pH = 6-8, cercanos al pH fisiológico. Las medidas reológicas se realizaron para diferentes concentraciones de las suspensiones (1, 1.5 y 3 mg/ mL), y temperatura de 25, 30 and 37 °C

Production, physiological response, and calcium and magnesium balance of lactating Holstein cows fed different sources of supplemental magnesium with or without ruminal buffer

The objective of this study was to evaluate the effects of dietary replacement of magnesium oxide (MgO) with calcium-magnesium hydroxide [CaMg(OH)2] and its interaction with ruminal buffer (sodium sesquicarbonate) supplementation on production, Ca and Mg balance, and overall physiological response of mid-lactation Holstein dairy cows. Sixty cows averaging 40.5 ± 7.0 kg of milk/d were used. Treatments were assigned following a 2 × 2 factorial arrangement: (1) MgO, (2) MgO + buffer, (3) CaMg(OH)2, or (4) CaMg(OH)2 + buffer. Diets were formulated to have 16.5% of crude protein, 1.82 Mcal/kg of net energy for lactation, 0.67% Ca, 0.39% P, and 0.25% Mg, all on a dry matter (DM) basis. Treatments were individually top dressed. Milk production, composition, and DM intake were evaluated. A subsample of 20 cows were randomly selected for the evaluation of Ca and Mg balance, blood gases, and electrolytes. Ruminal fluid was also collected for evaluation of pH and Ca and Mg solubility. Effects of Mg source, buffer, and the interaction Mg source × buffer were analyzed through orthogonal contrasts. An interaction of Mg source × buffer was found for DM intake and feed efficiency, in which cows fed CaMg(OH)2 had a similar feed efficiency regardless of ruminal buffer inclusion; however, when cows were fed MgO, the inclusion of buffer reduced feed efficiency. No effects on body weight and milk yield were observed. Buffer addition tended to increase the concentrations of fat, protein, and solids-not-fat, without affecting the yields of these milk components. Magnesium source and buffer did not affect ruminal fluid, blood, urine, or fecal pH; however, buffer supplementation increased urinary pH. Treatment with CaMg(OH)2 increased blood concentration of HCO3 −, total CO2, and base excess compared with cows fed MgO. No differences were observed in the ruminal solubility of Ca and Mg or on milk or urinary Ca and Mg excretion. Greater plasma Mg concentration was observed for animals fed MgO compared with cows fed CaMg(OH)2; however, both sources were above the threshold recommended in the literature for dairy cows. Also, a reduction in fecal Mg excretion was observed in animals fed CaMg(OH)2. In summary, we provide evidence that CaMg(OH)2 could replace MgO without affecting performance, overall physiological response, or Ca and Mg balance of mid-lactating dairy Holstein cows.UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Agroalimentarias::Centro de Investigación en Nutrición Animal (CINA)UCR::Vicerrectoría de Docencia::Ciencias Agroalimentarias::Facultad de Ciencias Agroalimentarias::Escuela de Zootecni