Thymidine is known as a progenitor of nucleosides that have significant biological activity. The widening importance of nucleoside derivatives as unrivaled potential antimicrobial and therapeutic agents has attracted contemplation to the synthesis of thymidine derivatives. In the present study, thymidine was treated with various acyl halides to produce 5'-O-acyl thymidine derivatives by direct acylation method with an excellent yield. To obtain newer products for antimicrobial assessment studies, the 5'-O-thymidine derivatives were further modified into three series of 3'-O-acyl thymidine derivatives containing a wide variety of functionalities in a single molecular framework. The chemical structures of the newly synthesized compounds were elucidated by analyzing their physicochemical, elemental, and spectroscopic data. Additionally, the X-ray powder diffraction (XRD) of these acylated products was studied. For the computational investigation, we have selected eight synthesized thymidine derivatives, which have notable antibacterial activity, and performed molecular docking against bacterial lectin protein FimH of Escherichia coli (4XO8) to suggest a potent inhibitor against bacterial function. Molecular docking was performed using AutoDock Vina to calculate the binding affinities and interactions between the antibacterials and the FimH E. coli (4XO8). It was found that the selected thymidine derivatives have strongly interacted mainly with Tyr48, Tyr137, Asp140, Arg98, Gln133, Phe 1, Asn23, Asn135, Lys76, Asp47, Ile13, and Ile52 residues. In silico pharmacokinetic properties were also predicted to search their absorption, metabolism, excretion, and toxicity. This computational examination showed that these thymidine derivatives might be used as potential inhibitors against the promising antibacterial activity for future studies.
Editorial for the Special Issue. Guest Editors, Special Issue: Dedicated to Heterogenous Catalysis Research done by Mexican Groups Prof. Juan C. Fierro-Gonzalez, Instituto Tecnologico de Celaya, Departamento de Ingenieria Quimica, Grupo de Catalisis Heterogenea, Celaya, Guanajuato, Mexico, jcfierro@iqcelaya.itc.mx Prof. J. Noe Diaz de Leon Hernandez, Centro de Nanociencias y Nanotecnologia, Departamento de Nanocatalisis, Universida Nacional Autonoma de Mexico, noejd@cnyn.unam.mx
A convenient pathway to obtain 3 beta-hydroxy-6-oxo-5 alpha-steroids from 3 beta-acetoxy Delta(5)-steroids is reported; the methodology was applied to the synthesis of laxogenin (7), substance that behaves as a plant growth hormone. This is an alternative way to produce an important functionality found in many examples of naturally occurring steroids. The developed procedure uses inexpensive reagents and can be carried out in four steps. The oxidizing and acidic steps used in this methodology did not affect the labile spiroketal side chain present in diosgenin (16).
Editorial for the Special Issue. Guest Editors, Special Issue: Mexican Academics Overseas, Journal of the Mexican Chemical Society Dr. Gabriel Merino, Investigador 3-E, Centro de Investigacion y de Estudios Avanzados Merida, Km. 6 Antigua Carr. Merida - Progreso, 97310 Merida, Yucatan, Mexico, gmerino@cinvestav.mx Dr. Javier Vela, Professor of Chemistry, Iowa State University, 2438 Pammel Dr. Ames, IA 50011, USA, vela@iastate.edu
This review discusses the concept of polypharmacology in drug discovery and development. The relationship between polyphar-macology and polypharmacy, drug repurposing, combination of drugs and in vivo testing are discussed. Modern applications of polypharma-cology and polypharmacy in epigenetic and antiviral drug development are described as examples. A survey of modern methodologies to design and develop multiple-target ligands is presented with a special focus on computational-based methods. These approaches include, but are not limited to, target fishing, proteochemometric modeling, data mining of side effects of drugs, and computer-aided drug repurposing.
Topological insulator Bi2Se3 becomes superconductor when it is intercalated with copper. In this work, we present our studies related to the electronic and structural characterization of CuxBi2Se3 with Cu variation from x = 0.11 to 0.20. We show structural and chemical studies performed via X-ray diffraction and photoelectron spectroscopy. Cu insertion modifies the Bi and Se binding energies and induces superconductivity in the compound.
Tuberculosis (TB) is a great cause of morbidity and mortality around the world. The increasing incidence of multidrug-resistant (MDR) Mycobacterium tuberculosis and co-infection TB-AIDS led to the need to develop new TB drugs, and plants could be a source of them. The hexane extract of Citrus sinensis with anti-TB activity was analyzed by GC-MS. This analysis showed the presence of 40 volatile components, including monoterpenes (81.74%), sesquiterpenes (1.32%), fatty acids (1.15%), and some other oxygenated non-aromatic compounds (15.73%). Some identified compounds were tested against M. tuberculosis H37Rv, and one clinical isolated MDR M. tuberculosis strain. Results showed that palmitic acid, decanal, caryophyllene oxide, and cis-limonene oxide contributed to the anti-TB activity of hexane extract of C. sinensis peel.
Thermodynamic parameters (Delta H degrees, Delta G degrees, Delta S degrees) and the activation energy (Delta Es) were calculated to explain the limiting equivalent conductance (Lambda(0)) and ion association constant (K-A) of s-acetylthiocholine halides and perchlorate in acetonitrile at different temperatures by using conductance measurements. It has been evaluated by using Fuoss-Onsager equation. It is evident that the values of (Lambda(0)) increase regularly with increase in temperature. For all salts of s-acetylthiocholine, (Lambda(0)) indicates less solvation or higher mobility of the ions in all solvent systems studied. The free energy change Delta G degrees values are negative for all salts (Br-, I-and ClO4-). Clearly strengthening to interionic association at higher temperatures is largely caused by a decrease in the permitivity of the solvent. The positive values of (Delta H degrees) for three salts (Br-, I- and ClO4-) show that the association processes are endothermic in nature. Entropy change (Delta S degrees) values are positive for all salts indicate the randomness of ions in all solvent systems studied.
A new chelating ligand, 5,5-dimethyl-2-(2-(3-nitrophenyl)hydrazono)cyclohexane-1,3-dione (L), and four transition metal complexes were synthesized. The ligand and its complexes were characterized by IR, H-1 and C-13-NMR spectra, elemental analyses, magnetic susceptibility, mass spectra, UV-Vis. and thermogravimetry-differential thermal analysis (TGA-DTA). The metal complexes showed different geometric structures. Antibacterial tests of the ligand and complexes were also done. The Zn(II) complexes showed antibacterial activity against Staphylococcus aureus ATCC-25923 at middle level. The optical properties of the ligand and its complexes were extensively investigated by optical measurements. The average transmittance value of the ligand was the highest value, while the average transmittance value of the [CuL2(NO3)(2)]center dot 6H(2)O complex was the lowest value. The optical band gap of the ligand, [(Zn)(2)L(OH)(4)]center dot 2DMF, [ZnL(NO3)(2)(H2O)(2)]center dot 5H(2)O, [CuL2(OAc)]center dot OAc center dot 3.5H(2)O and [CuL2(NO3)(2)]center dot 6H(2)O complexes were calculated and 3.121 eV, 2.180 eV, 1.551 eV, 2.489 eV and 1.556 eV values were found, respectively. The complexes decreased the optical band gap of the ligand. The optical band gap value of the [ZnL(NO3)(2)(H2O)(2)]center dot 5H(2)O complex is the lowest value. The optical band gap value of the ligand is the highest value. The complexes decrease the angle of incidence of the ligand, while complexes increase the angle of refraction of the ligand. The electric susceptibility of the ligand decreases with its complexes.
In the 70’s decade Prof. Ei-Ichiro-Ochiai wrote an introductory book on Bioinorganic Chemistry, emphasizing that although the term “inorganic” signifies “not related to organism”, at that time there were some findings indicating that the so called inorganic elements and its compounds played an important role in living organisms. At that time Prof. Williams wrote the book The metals of life. Biochemists and inorganic chemists began to identify the relevance of metal compounds in some of the most important biological processes in several organisms. The study of biochemical functions with more precise analytical techniques allows the identification of metals in proteins and enzymes. Furthermore it was identified that prosthetic groups in proteins were coordination compounds such as, the iron porphyrine in hemoglobin. Another important area in bioinorganic chemistry is Metals in Medicine, after the discovery of cytotoxicity activity of the Cis-dichloro, diamine platinum (II) compound and its uses as an antineoplastic drug. The present issue is dedicated to this field of chemistry, especially in this year that every coordination chemists celebrate the 100th Anniversary of the Nobel Prize awarded to Alfred Werner for the establishment of the bases of coordination chemistry. The content of the present issue reflects the appeal of the field, since it brought together a review on DNA/ metallic compounds covering from experimental to theoretical approaches plus 11 articles, contributed from recognized authors from 8 countries, covering a number of specialties such as biomimetic compounds, coordination compounds with several biological activities, anticancer, antiparasitaries, antidiabetics drugs and several other topics related to medicinal inorganic chemistry.
Simple transfer across the water/nitrobenzene interface of three model quaternary ammonium cations: Tetramethylammonium (TMA + ), Choline (Ch + ) and Tetrabutylammonium (TBA + ), was fol- lowed by Square Wave Voltammetry (SWV) which constitutes a more sensitive approach to ionic quantification compared to other conven- tional techniques. A linear and reproducible response was observed in the range of 10 to 100 µM. Detection limits obtained by the ULA-2 method were 5.9, 10.7 and 13.8 µM for the mentioned ions, respec- tively. The simultaneous and independent analysis of two ions with different hydrophilic characters such as TBA + and Ch + is achieved by direct inspection of the resulting voltammograms after background subtraction. We report the particular effect of temperature in the SWV response studied in the range from 288 K to 313 K. The differential peak current shows a significant linear increase with increasing tem- peratures while background currents show no variation, thus turning the combined enhancement of using a differential pulse method at an optimal temperature into a significant option for quaternary ammo- nium ion quantitative analysis.
Coffee phenols were identified, quantified and correlated with antioxidant activity determined by the ABTS •+ (2,2'-azino- bis(3-ethylbenzothiazoline-6-sulphonic acid)) and DPPH • (2,2-diphe- nyl -1-picrylhydrazyl radical) assays. Melanoidins (Maillard reaction products) were determined for green and processed coffee. For green Arabica beans and its products, results suggest that roasting decreases antioxidant activity. However, torrefacto roasted coffee showed greater antioxidant activity than Caracoli beans. Instant coffee showed greater antioxidant activity than green Robusta beans by both assays. A high correlation was found between antioxidant activity and melanoidins, total phenols, caffeic acid, and caffeine.
This paper studies and determines the dispersion properties (Jg, Eg and Db), kinetics parameters and hydrodynamics of the process and its effect on the recovery of silver contained in spent diluted fixers by techniques of ion flotation in columns. The experimental results show silver recoveries of 97 % using sodium isopropyl xanthate (SIX) 0.06 g·L -1 and 0.04 g·L -1 of frother, at a Jg of 1.0 cm·s -1 and Jl of 0.72 cm·s -1 . Xanthate-promoter combinations do not improve the separa- tion; however, recoveries of 91.5% are achieved. The control of pH at 6.0 during the ion flotation of silver helps to improve the separation, compared to pH values of 7.0 and 8.0. The kinetic constant of appar- ent flotation k (min -1 ) maintains a linear behavior with the recovery and the dispersion properties, until reaching a slope change in the plot of Eg Vs Jg, where the system changes bubble flow regime, from homogeneous to turbulent.
In this work the synthesis, characterization and evaluation of a novel sorbent material used for the solid-phase extraction of tita- nium (IV) from hydrochloric acid medium is described. The material was prepared by the sol-gel route incorporating bis(2-ethylhexylphos- phoric acid) (D2EHPA) as extractant within a polymeric matrix based on polysiloxanes and characterized through FTIR-ATR, XRD, 29 Si and 31 P NMR, TGA and DSC. In studies of titanium sorption and desorption in batch mode several factors related with the extraction and back-extraction operations were evaluated, such as: contact time, titanium concentration, nature and composition of the aqueous media, and extractant concentration in the sorbent. The maximum sorption was observed at 30 min of contact time in a 1 mol L -1 HCl + 0.1% KCl medium, while the maximum desorption was observed at 60 min in a 1.5 mol L -1 H2SO4 + 20% v/v H2O2 medium when titanium concentra- tion was 70 mg L -1 . Under optimal conditions the recovered percent of titanium was nearly 90%. In addition, the characterization of the extraction equilibrium was performed. The selectivity of the method was studied adding Al(III), Fe(III) and V(V) to the extraction medium. A high selectivity for Ti over Al and Fe was observed, even at high concentrations of the interferents; 50% of Ti, only 7% of Fe, 3% of Al and less than 1% of V were recovered under the established conditions. The method was finally applied for titanium recovery from a certified fly ash sample generated from a municipal incineration plant.
Novel chiral glycinate derivatives (S)-6 and (S)-7 contain- ing the a-phenylethyl group, were prepared and studied as potential precursors of enantiopure a-substituted-a-amino acids. In particu- lar, the alkylation of enolate (S)-7-Li showed substantial (78:22 dr) stereoinduction by the N-(1-phenylethyl)benzamide chiral auxiliary. Addition of DMPU showed no appreciable effect upon the diastere- oselectivity.
Some biochemical properties and purification of linamarase enzyme from Lactobacillus delbrueckii NRRL B-763 were studied. The crude enzyme was used to detoxify cassava flour cyanide and samples of 150 µm particle size treated with the crude enzyme showed a reduction from 2.1 mg HCN/10g sample to 0.11 mg HCN/10 g sample after 20 h (95% reduction). Untreated control samples of 0.5 mm particle size showed a reduction from 2.1mg HCN/10 g sample to 1.98 mg HCN/10 g sample after 40 h (5.7% reduction). The enzyme was purified 33 fold with a 40% yield through a series of four steps namely, ammonium sulphate precipitation, acetone precipitation, ion exchange chromatography and gel filteration chromatograrphy using Sephadex G-200. The purified enzyme showed maximum activity at pH 4.5. The enzyme showed 100% stability at the pH range of 5.0 and 6.0. Maximum activity of the enzyme was observed at a temperature of 50 o C and maximum stability at a temperature range of 40 and 50 o C. The approximate enzyme molecular weight was estimated to be 56
Preparation of quinolinyl-3-oxopropanoic acid 2 was accomplished by hydrolysis of pyranoquinolinedione 1 in aqueous alkaline medium. The chemical behavior of this beta-keto acid 2 towards nitrosation, coupling with a diazonium salt, esterification, condensation with 2,2-dimethoxyethanamine, hydrazinolysis, Knoevenagel condensation with isatine, salisyaldehyde, 3-formylquinolones, and 3-formylchromone, was investigated. Also many of the products of these reactions were found obtainable using either pyranoquinolinedione 1 or beta-keto acid 2, under the same conditions.
