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  • Open access
  • 82 Reads
Computational Model for Multiplex Assay of Drug Immunotoxicity in Macrophage - Study of the Anti-Microbial G1 using Flow Cytometry
The development of in vitro cytotoxicity assays has been driven by the need to rapidly evaluation of potential toxicity of large numbers of compounds, to reduce animal experimentation, and to save time and material resources. The large number of experimental results reported by different groups worldwide has lead to the accumulation of huge amounts of ontology-like data in large public databases as in ChEMBL. Conversely, many drugs have been assayed only for some selected tests. In this context, High-throughput multi-target Quantitative Structure-Activity (High-throughput mt-QSAR) techniques may become an important tool to rationalize drug discovery process. In this work, we train and validate by the first time mt-QSAR model using TOPS-MODE approach to calculate drug molecular descriptors and the software STATISTICA to seek a Linear Discriminant Analysis (LDA) function. This model correctly classifies 8,258 out of 9,000 (Accuracy = 91.76%) multiplexing assay endpoints of 7903 drugs (including both train and validation series). Each endpoint correspond to one out of 1418 assays, 36 molecular and cellular targets, 46 standard type measures, in two possible organisms (human and mouse). After that, we determined experimentally, by the first time, the values of EC50 = 21.58 μg/mL and Cytotoxicity = 23.6 % for the anti-microbial / anti-parasite drug G1 over Balb/C mouse peritoneal macrophages using flow cytometry. In addition, the model predicts for G1 only 7 positive endpoints out 1,251 cytotoxicity assays (0.56% of probability of cytotoxicity in multiple assays). Both experimental and theoretical results point to a low macrophage cytotoxicity of G1. The results obtained are very important because they complement the toxicological studies of this important drug. This work opens a new door for the "in silico" multiplexing screening of large libraries of compounds.
  • Open access
  • 137 Reads
Synthesis and Reactions of New Tellurium-Substituted Terpenyl Compounds
In recent years, chalcogenides were widely used as efficient reagents and catalysts to create new carbon-oxygen, carbon-nitrogen and carbon-carbon bonds. Our previous research was focused on developing effective methods for the synthesis of new optically active organosulfur and organoselenium compounds derived from monoterpenes. Satisfying results prompted us to synthesize tellurium analogues. We have developed new methodologies for the synthesis of terpene ditellurides, tellurides, methyl terpenyl tellurides, and phenyl terpenyl tellurides from p-menthane, carane and pinane systems. The synthesis was based on the reaction of sodium telluride, sodium ditelluride, sodium benzenetellurolate, and sodium methanetellurolate with terpene tosylates, chlorides and epoxides. Additionally, terpene tellurides were converted in situ to telluronium ylides, and were used as reagents in asymmetric epoxydation. The best selectivity of epoxidation reaction was achieved for dicaranyl telluride.
  • Open access
  • 168 Reads
Antioxidant Activity and Total Phenolics of Plants Used in Traditional Medicine in Ecuador
Medicinal plants are organisms that are naturally endowed with chemical compounds (secondary metabolites) with properties of high therapeutic value, yielding advances in the development of synthetic drugs with physiological action beneficial to humans (ref). The use of these plants has an ancient origin in different cultures around the world and their preparation is basically in the form of extracts and teas. Medicinal plants that have a significant amount of phenolic compounds are of great interest since these compounds are attributed various activities; the most relevant is antioxidant activity, which is important in countering oxidative stress (Huie, 2002). Oxidative stress arises mainly as consecuence of the overproduction of free radicals due to inbalance in production of antioxidants by the cells (Emilien et al, 2000). Natural products especially from plant sources have the ability to reduce oxidative stress by acting as antioxidant (Irshad et al, 2012), therefore, in this work we determined the total content of phenolic compounds and antioxidant activity was evaluated of six plants used in traditional medicine for Ecuadorian indigenous ethnicities. The species collected in this study were: Potalia amara, Salvia corrugata Vahl, Ilex guayusa Loes, Scoparia dulcis, Monnina sp and Alternanthera porrigens.
  • Open access
  • 92 Reads
Formation of a Flavin-Linked Cysteine
The deposition of Amyloid beta peptides (Aβ) in the formation of amyloid fibrils is believed to be causally linked to Alzheimer's disease. A short Aβ fragment (KLVFF; Aβ16-20) can bind full-length Aβ. The Aβ recognition peptide including KLVFF was attached with hydrophilic groups, and then the product altered the Aβ aggregation pathways and inhibited Aβ toxicity (Tjernberg, L. O. et al. J. Biol. Chem. 1996, 271, 8545-8548. ). Since flavins is widely known as biological oxidation reagents, the flavin-linked KLVFF is likely to directly hydroxylate aggregated Aβ fibrils and then disrupt the aggregated Aβ fibril. 2-Aminoethanethiol derivatives, such as cysteine, is reacted with aldehydes, and five-membered heterocyclic ring is formed via formation of imine. Since formylmethylflavin (FMF) contains aldehyde group, FMF is likely to bind cysteine. Then, the peptides containing Aβ recognition region and cysteine, such as CKLVFF, also can be attached with FMF to form the flavin-linked KLVFF. The preliminary experiment of this reaction, the reaction between FMF and cysteine, was investigated. FMF (2.84 mg, 10 μmol) was suspended in phosphate buffer (pH 7, 10 ml), and cysteine (2.42 mg, 20 μmol) was added. The suspension was stirred at 65ºC for 1h. As a result, FMF was completely reacted, and flavin-linked cystein were detected using HPLC and ESI-MS.
  • Open access
  • 103 Reads
Microwave Assisted Transesterification of β-Cyclodextrin
From several decades microwave assisted synthesis is known to speed up many reactions and processes. Better yield, shortening in the reaction time and easy set-up are also the one of the most important factors on this case. In opposite there is also a lot of processes known in which enzymes or whole microorganisms are inactivated by action of electromagnetic field with microwave frequencies. In some cases however it was shown that microwaves may also activate the enzymatic transformations influencing enzyme/reagent fitting or protein conformation. The phenomenon has also been observed in case of some carbohydrates. According to that in presented study enzymatic transesterification of β-cyclodextrin using vinyl esters of long chain carboxylic acids has been presented. All the reactions were performed at microwaves and in conventional conditions. Lipase from porcine pancreas was used as a biocatalyst. Reactions were carried out in DMSO or DMF as solvents using fatty acids vinyl esters as acyl donors (vinyl stearate and and vinyl laurate respectively). After the reaction the products were precipitated from the solution in several stages. Products were analyzed according to overall yield and degree of substitution. The structure of the obtained esters was investigated by means of FTIR spectroscopy. As a result the conclusion may be drowning out that microwaves induced processes by means of better yield and higher degree of substitution. The shortening in the reaction time was also observed and process looks promising as an alternative way for introducing acyl donors into carbohydrate molecules howevere further, detailed study on the transesterification should be done. The Polish State Committee supported the research for  Scientific Research Grant No. N312 331240
  • Open access
  • 111 Reads
Iodine-Catalysed Synthesis of a Novel Meso-Substituted Dipyrromethane and its Evaluation as a Cation Chemosensor
In recent years, meso-substituted dipyrromethanes have been frequently explored as potential ion sensors. Some of these compounds exhibit very interesting photophysical properties, which can be triggered in the presence of some ions and display chromogenic and/or fluorescence changes. However, most common methods for the synthesis of these molecules can be laborious and time-consuming, requiring a great excess of pyrrole and a tightly controlled atmosphere. Recently, a new method based on molecular iodine-catalysis has been proposed as a fast, inexpensive and good-yielding procedure with reduced reaction times. Using molecular iodine as a catalyst withdraws the requirement of strong and expensive acid-catalysts, such as TFA. Here we report the synthesis and characterization of a dipyrromethane functionalised with an arylthiophene bridge, by using the iodine catalytic method. The compound was obtained in the solid state in 60% yield. Evaluation of the chemosensory ability in the presence of several cations showed both chromogenic and fluorescent response, with Fe3+, Cu2+, Hg2+ and Cr3+ among the most easily detected ions.
  • Open access
  • 140 Reads
PhSZn-Halides: New Green Thiolates
A new class of bench-stable and odorless zinc thiolates can be prepared by insertion of the elemental zinc into a sulfur-halogen bond. The reulting reagents were used for the regio- and stereoselective thiolysis of epoxides in "on-water" conditions as well as in the solvent free synthesis of thioesters starting from the corresponding acyl halides. A comparison with the reactivity of the selenium analogues will be discussed.This communnication is dedicated to Prof. Lorenzo Testaferri in the occasion of his retirement