Antiviral activity of myricetin glycosylated compounds isolated from Marcetia taxifolia against chikungunya virus.

The chikungunya virus (CHIKV) has produced epidemic outbreaks of significant public health impact. The clinical symptoms of this disease are fever, polyarthralgia, and skin rash, generally self-limiting, although patients may develop a chronic disabling condition or suffer lethal complications. Unfortunately, there is no specific treatment or vaccine available. Thus, the search for effective therapies to control CHIKV infection is an urgent need. This study evaluated the antiviral activity of flavonoids isolated from Marcetia taxifolia by in vitro and in silico analysis. Cytotoxicity of compounds was determined by MTT assay and viral load was assessed in cell substrates supernatants by plaque-forming and RT-qPCR assays. Selected molecules were analyzed by molecular docking assays. Myricetin 3-rhamnoside (MR) and myricetin 3-(6-rhamnosylgalactoside) (MRG) were tested for antiviral assays and analyzed by the TCID50 method and RT-qPCR. MR exhibited dose-dependent antiviral activity, reducing viral titer at concentrations of 150-18.8 µg/mL by at least 1-log. Similarly, MRG showed a significant decrease in viral titer at concentrations of 37.5, 9.4, and 2.3 µg/mL. RT-qPCR analysis also displayed a substantial reduction of CHIKV RNA for both flavonoids. Furthermore, molecular docking of the selected flavonoids proposed the nsP3 macrodomain as a possible target of action. Our study reveals that MR and MRG could be considered promising anti-CHIKV therapeutic agents. Molecular modeling studies showed MR and MRG ligands with a high affinity for the N-terminal region of the nsP3 macrodomain, postulating them as a potential target of action for the CHIKV control.

Termoquímica computacional: en la búsqueda de la precisión química

Introducción: La termoquímica computacional es un campo de gran interés por sus diversas aplicaciones en diferentes campos de la química. En la actualidad, con el avance en el desarrollo de los supercomputadores se pueden emplear diversas metodologías que emplean cálculos de estructura electrónica para estimar valores termodinámicos con errores ~ 1,0 kcal/mol en comparación con los datos experimentales. Metodología: En este artículo se describen brevemente los principales métodos compuestos empleados en la termoquímica computacional como la serie de Petersson, los métodos Weizmann, el modelo HEAT y con especial énfasis en las teorías Gaussian-n. Aplicaciones: Diversas aplicaciones de la termoquímica computacional se presentan en este trabajo tales como el estudio de la reactividad y las estabilidades de nuevos derivados de compuestos químicos con potencialidades como fármacos, estudios de contaminantes en la química de la atmosfera donde se estiman valores importantes de entalpias de formación sobre compuestos derivados del gas de efecto invernadero SF6, estudios de compuestos derivados del petróleo de potencial importancia como nuevos combustibles y el desarrollo de explosivos con estimaciones energéticas de las entalpias de disociación de enlace y de combustión de nuevos compuestos orgánicos. Conclusiones: La termoquímica computacional es una herramienta actual para resolver problemas de la química donde la experimentación es difícil y con un alto costo económico. Se espera en un futuro que esta área desarrolle nuevos métodos y códigos computacionales que permitan estudiar sistemas moleculares de gran tamaño importantes en otras áreas de las ciencias como la física, la biología, ciencias de los materiales, entre otros.

Introdução: A termoquímica computacional é uma área de grande interesse devido às suas diversas aplicações em diferentes campos da química. Hoje em dia, com o avanço no desenvolvimento de supercomputadores, várias metodologias podem ser utilizadas que utilizam cálculos de estrutura eletrônica para estimar valores termodinâmicos com erros de ~ 1,0 kcal/mol em comparação com os dados experimentais. Metodologia: Este artigo descreve resumidamente os principais métodos compostos usados em termoquímica computacional, como a série Petersson, os métodos de Weizmann, o modelo HEAT e com especial ênfase nas teorias Gaussianas-n. Aplicações: Várias aplicações da termoquímica computacional são apresentadas neste trabalho tais como o estudo da reatividade e estabilidades de novos derivados de compostos químicos com potencial como drogas, estudos de poluentes em química atmosférica onde valores importantes de entalpias são estimados de treinamento em compostos derivados do gás de efeito estufa SF6, estudos de compostos derivados do petróleo com potencial importância como novos combustíveis e o desenvolvimento de explosivos com estimativas energéticas das entalpias de dissociação de ligações e combustão de novos compostos orgânicos. Conclusões: A termoquímica computacional é uma ferramenta atual para resolver problemas de química onde a experimentação é difícil e com alto custo econômico. Espera-se que no futuro esta área desenvolva novos métodos e códigos computacionais que permitam estudar grandes sistemas moleculares importantes em outras áreas da ciência como física, biologia, ciência dos materiais, entre outras.

SUMMARY Introductión: Computational thermochemistry is an area of great interest for its various applications in many different fields of chemistry. With the increase of the computational power readily available, it is currently possible to use various calculation based on the electronic structure methods for estimate thermodynamic properties with an error on the order of ~1.0 kcal/mol, which is comparable to experimental values. Methodology: In this work we briefly describe the main composite methods such as Petersson series, the Weizmann methods the HEAT model and with special focus on the Gaussian-n theories. Applications: Various applications of computational thermochemistry are presented in this work such as the study of reactivity and stabilities of new derivatives of chemical compounds with potential use as drugs, studies of pollutants in atmospheric chemistry where important values of enthalpies are estimated of training on compounds derived from the greenhouse gas SF6, studies of compounds derived from petroleum of potential importance as new fuels and the development of explosives with energy estimates of the enthalpies of bond dissociation and combustion of new organic compounds. Conclusions: Computational thermochemistry is a current tool to solve chemistry problems where experimentation is difficult and with a high economic cost. It is expected in the future that this area will develop new methods and computational codes that allow studying large molecular systems important in other areas of science such as physics, biology, materials science, among others.

Experimental and theoretical study of the mechanism and rate constants of the sequential 5-exo-trig spirocyclization involving vinyl, aryl and N-alkoxyaminyl radicals.

In this research the sequential generation and cyclization of N-alkoxyaminyl radicals to produce 1-azaspiro[4.4]nonane, a prominent scaffold in organic and medicinal chemistry, was studied. Competition experiments in benzene at 80 °C with brominated oxime ethers using Bu3SnH as chain transfer and AIBN as the initiator generated vinyl or aryl radicals which were captured by oxime ethers, allowing approximate 5-exo-trig cyclization constants at 4.6 × 108 s-1 and 9.9 × 108 s-1 respectively to be established. Similar results were obtained by kinetic studies using the transition state theory (TST) from ab initio calculations with density functional theory (DFT) using the M06-2X, B3LYP, mPW1PW91 and TPSSh functionals in combination with the 6-311+G(d, p) basis set. Additionally, it was found that the 5-exo-trig cyclization of the N-alkoxyaminyl radical onto CC double bonds is a reversible process whose constants were determined to be in the range of 6.2 × 100 s-1 and 3.5 × 106 s-1 at 80 °C, depending on the nature of the substituents. The calculation of the radical stabilization energy (RSE) shows that the N-alkoxyaminyl radical is a very stable species and its reactivity in the addition on alkenes is governed by its nucleophilic character and the stability of the carbon-centered radical formed after cyclization. The reduction constant of the N-alkoxyaminyl radical with Bu3SnH in the gas phase at 80 °C was also estimated to be 3.4 × 100 M-1 s-1 through computational calculations. This information facilitates the rational planning of cascades and other methodologies applied to the construction of carbocyclic and aza-heterocyclic compounds.

Structural parameters and physicochemical data from quantum chemical calculations of the peroxyacyl nitrate derivatives RC(O)O2NO2.

This article present the structural parameters and physicochemical data (ΣD 0, ΔH°f,298K and ΔG°f,298K ) of the methoxyformyl peroxynitrate CH3OC(O)O2NO2 (MoPAN), peroxypropionyl nitrate CH3CH2C(O)O2NO2 (PPN), peroxyacryloyl nitrate CH2CHC(O)O2NO2 (APAN), peroxy-n-butyryl nitrate CH3(CH2)2C(O)O2NO2 (PnBN), peroxycrotonyl nitrate CH3(CH=CH)C(O)O2NO2 (CPAN), peroxyisobutyryl nitrate (CH3)2CHC(O)O2NO2 (PiBN), peroxymethacryloyl nitrate CH2=C(CH3)C(O)O2NO2 (MPAN) and peroxy-n-valeryl nitrate CH3(CH2)3C(O)O2NO2 (PnVN) peroxyacyl nitrate derivatives. The equilibrium structures have been performed using the B3LYP and M06-2X functionals combined with the 6-311++G(3df,3pd) basis set. The physicochemical data were calculated using several Gn methods, G3B3, G3MP2B3, G4 and G4MP2. Computational calculations were carried out with GAUSSIAN09 program.

Screening for Interacting Proteins with Peptide Biomarker of Blood-Brain Barrier Alteration under Inflammatory Conditions.

Neurodegenerative diseases are characterized by increased permeability of the blood-brain barrier (BBB) due to alterations in cellular and structural components of the neurovascular unit, particularly in association with neuroinflammation. A previous screening study of peptide ligands to identify molecular alterations of the BBB in neuroinflammation by phage-display, revealed that phage clone 88 presented specific binding affinity to endothelial cells under inflammatory conditions in vivo and in vitro. Here, we aimed to identify the possible target receptor of the peptide ligand 88 expressed under inflammatory conditions. A cross-link test between phage-peptide-88 with IL-1ß-stimulated human hCMEC cells, followed by mass spectrometry analysis, was used to identify the target of peptide-88. We modeled the epitope-receptor molecular interaction between peptide-88 and its target by using docking simulations. Three proteins were selected as potential target candidates and tested in enzyme-linked immunosorbent assays with peptide-88: fibronectin, laminin subunit α5 and laminin subunit ß-1. Among them, only laminin subunit ß-1 presented measurable interaction with peptide-88. Peptide-88 showed specific interaction with laminin subunit ß-1, highlighting its importance as a potential biomarker of the laminin changes that may occur at the BBB endothelial cells under pathological inflammation conditions.

Inverse Molecular Docking Study of NS3-Helicase and NS5-RNA Polymerase of Zika Virus as Possible Therapeutic Targets of Ligands Derived from Marcetia taxifolia and Its Implications to Dengue Virus.

Dengue and Zika are two mosquito-borne diseases of great impact on public health around the world in tropical and subtropical countries. DENV and ZIKV belong to the Flaviviridae family and the Flavivirus genus. Currently, there are no effective therapeutic agents to treat or prevent these pathologies. The main objective of this work was to evaluate potential inhibitors from active compounds obtained from Marcetia taxifolia by performing inverse molecular docking on ZIKV-NS3-helicase and ZIKV-NS5-RNA polymerase as targets. This computational strategy is based on renormalizing the binding scores of the compounds to these two proteins, allowing a direct comparison of the results across the proteins. The crystallographic structures of the ZIKV-NS3-helicase and ZIKV-NS5-RNA-polymerase proteins share a great similarity with DENV homologous proteins. The P-loop active site of the crystallographic structure of ZIKV-NS3-helicase presents a high percentage of homology with the four dengue serotypes. It was found that most ligands of the active compounds (5,3'-dihydroxy-3,6,7,8,4'-pentamethoxyflavone (5DP); 5-hydroxy-3,6,7,8,3',4'-hexamethoxyflavone (5HH); myricetin-3-O-rhamnoside (M3OR)) from Marcetia taxifolia had a better affinity for ZIKV-NS3-helicase than for ZIKV-NS5-RNA polymerase, as indicated by the negative multiple active site correction (MASC) score, except for M3RG that showed a higher affinity for ZIKV-NS5-RNA polymerase. On the other hand, the AutoDock Vina scores showed that M3OR had the highest score value (-9.60 kcal/mol) and the highest normalized score (1.13) against ZIKV-NS3-helicase. These results in silico demonstrated that the nonstructural proteins NS3-helicase and NS5-RNA polymerase, which share similar molecular structures between the selected viruses, could become therapeutic targets for some bioactive compounds derived from Marcetia taxifolia.

Thermochemistry and UV spectroscopy of alkyl peroxynitrates.

High level ab initio calculations and multiconfigurational methods have been used to characterize the equilibrium structures, vibrational frequencies, enthalpies of formation, and UV-vis spectra of alkyl peroxynitrates R-OONO(2) (R = H, CH(3), C(2)H(5), C(3)H(7)). Excellent agreement with the experimental enthalpy of formation is obtained for HOONO(2) warranting similar accuracy for the rest of compounds for which values are inexistent or measured indirectly. The spectra obtained by MS-CASPT2/CASSCF calculations are very similar in all the species, showing a broad band below 200 nm with a shoulder due to pipi* transitions and a tail at approximately 250 nm due to weak npi* transitions on the NO(2) group.