Indole-substituted 2,4-diamino-5,8-dihydropyrido[2,3-d]pyrimidines from one-pot process and evaluation of their ability to bind dopamine receptors

A series of novel 7-indole substituted 2,4-diamino-5,8-dihydropyrido[2,3-d]pyrimidine analogous to the 2,4-diaminopteridine core were synthesized by the three-component one-pot cyclocondensation between 2,4,6-triaminopyrimidine, 3-(2-cyanoacetyl)indole and aromatic aldehydes. The reactions, which exhibited good performance, proceeded in EtOH using indium (III) chloride as catalyst under microwave irradiation, in short reaction times. On the basis of certain structural similarity of these compounds with known ligands of the D2 dopamine receptors (D2DR), the study of these compounds as possible ligands of dopamine D2 and D1 receptors was carried out. Three of them showed moderate affinity to D2-DR since the Ki D1/D2 ratio reached values of 40, 65 and 31 for compounds 4c, 4k and 4j, respectively. Finally, molecular modeling studies revealed stronger molecular interactions of such derivatives with the D2DR than with D1DR, what agrees with the experimental data, and gives an additional support to the observed selectivity to the D2DR.     

Use of p-toluenesulfonic acid for the controlled grafting of alkoxysilanes onto silanol containing surfaces: preparation of tunable hydrophilic, hydrophobic, and super-hydrophobic silica

The modification of Aerosil 200 has been carried out using methoxysilanes in toluene reflux, with p-toluenesulfonic acid as the catalyst. Both trimethoxyalkyl silanes (methyl, ethyl, propyl, butyl, hexyl, octyl, and octadecyl) and trialkylmethoxy silanes (trimethyl and dimethyloctyl) have been used. The surface has been studied by 29Si NMR, 13C NMR, elemental analysis, thermogravimetry, water contact angle, and BET analysis. When incorporating trimethoxysilanes, a plateau of modification was achieved after 1 h of reflux, while when using trialkylmethoxy silanes, a longer time of about 7 h was required. The average number of molecules incorporated in both cases has been well above those reported by other authors in similar reactions and in much shorter times. Depending on the modification agent and on the experimental conditions, the resulting organosilicas are in seven cases superhydrophobic, in three cases hydrophobic, and in two cases hydrophilic. Two structural origins for superhydrophobicity have been identified in these samples: almost complete disappearance of water accessible surface silanols (smallest methoxysilanes) and shielding of would-be water accessible surface silanols by long aliphatic tails. These features can be very precisely controlled.     

Microwave-assisted headspace single-drop microextration of chlorobenzenes from water samples

A one-step and in-situ sample preparation method used for quantifying chlorobenzene compounds in water samples has been developed, coupling microwave and headspace single-drop microextraction (MW-HS-SDME). The chlorobenzenes in water samples were extracted directly onto an ionic liquid single-drop in headspace mode under the aid of microwave radiation. For optimization, a Plackett-Burman screening design was initially used, followed by a mixed-level factorial design. The factors considered were: drop volume, aqueous sample volume, stirring speed, ionic strength, extraction time, ionic liquid type, microwave power and length of the Y-shaped glass-tube. The optimum experimental conditions found from this statistical evaluation were: a 5 μL microdrop of 1-hexyl-3-methylimidazolium hexafluorophosphate exposed for 20 min to the headspace of a 30 mL aqueous sample, irradiated by microwaves at 200 W and placed in a 50 mL spherical flask connected to a 25 cm Y-shaped glass-tube. Under the optimised experimental conditions, the response of a high performance liquid chromatographic system was found to be linear over the range studied and with correlation coefficients ranging between 0.9995 and 0.9999. The method showed a good level of repeatability, with relative standard deviations varying between 2.3 and 8.3% (n = 5). Detection limits were found in the low μg L⁻¹ range varying between 0.016 and 0.039 μg L⁻¹. Overall, the performance of the proposed method demonstrated the favourable effect of microwave sample irradiation upon HS-SDME. Finally, recovery studies from different types of environmental water samples revealed that matrix had little effect upon extraction.     

Colored inks analysis and differentiation: a first step in artistic contemporary prints discrimination

Prints are the most popular artistic technique. Due to their manufacturing procedure, they are also one of the most frequently falsified types of artwork. In terms of their economic and historic value, the chemical analysis and characterisation of coloured inks and their principal constituent materials (pigments), together with the historical and aesthetic information available in the Catalogues Raisonées, are important tools in distinguishing originals from non-original prints.The chemical characterisation and discrimination of coloured inks has test in this study. Analysis using Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) and X-ray diffraction (XRD) has been done on blue pigments and inks, due to this colour is one of the most representative for the presence of organic and inorganic materials in their composition. Conclusion obtained for this colour would demonstrate the capability of the approach when it is applied to any other coloured set of inks.     

Dominance relations and ranking of units by using interval number ordering with cross-efficiency intervals

This paper proposes an approach to the cross-efficiency evaluation that considers all the optimal data envelopment analysis (DEA) weights of all the decision-making units (DMUs), thus avoiding the need to make a choice among them according to some alternative secondary goal. To be specific, we develop a couple of models that allow for all the possible weights of all the DMUs simultaneously and yield individual lower and upper bounds for the cross-efficiency scores of the different units. As a result, we have a cross-efficiency interval for the evaluation of each unit. Existing order relations for interval numbers are used to identify dominance relations among DMUs and derive a ranking of units based on the cross-efficiency intervals provided. The approach proposed may also be useful for assessing the stability of the cross-efficiency scores with respect to DEA weights that can be used for their calculation.     

Isolation of the new anacardic acid 6-[16'Z-nonadecenyl]-salicylic acid and evaluation of its antimicrobial activity against Streptococcus mutans and Porphyromonas gingivalis

A new anacardic acid, 6-[16'Z-nonadecenyl]-salicylic acid (1), along with seven known compounds, 6-[8'Z-pentadecenyl] salicylic acid (15:1 anacardic acid) (2), 6-nonadecenyl salicylic acid (anacardic acid 19:0) (3), 6-pentadecyl salicylic acid (anacardic acid 15:0) (4), masticadienonic acid (5), 3α-hydroxymasticadienonic acid (6), 3-epi-oleanolic acid (7) and β-sitosterol, were isolated from the bark of Amphipterygium adstringens using a bioassay-guided fractionation method. The structure of the new compound (1) was elucidated by spectroscopic data interpretation. The known compounds (2-7) were identified by comparison of their spectroscopic data with reported values in the literature. Compounds 1-4 exhibited antibacterial activity against Streptococcus mutans and Porphyromonas gingivalis with minimum inhibitory concentrations ranging from 7 to 104?μg?mL and from 12 to 126?μg?mL, respectively.     

Decarboxylative coupling reactions: a modern strategy for C-C-bond formation

This critical review examines transition metal-catalyzed decarboxylative couplings that have emerged within recent years as a powerful strategy to form carbon-carbon or carbon-heteroatom bonds starting from carboxylic acids. In these reactions, C-C bonds to carboxylate groups are cleaved, and in their place, new carbon-carbon bonds are formed. Decarboxylative cross-couplings constitute advantageous alternatives to traditional cross-coupling or addition reactions involving preformed organometallic reagents. Decarboxylative reaction variants are also known for Heck reactions, direct arylation processes, and carbon-heteroatom bond forming reactions.     

Development of a cellular biosensor for the detection of 2,4,6-trichloroanisole (TCA)

2,4,6-trichloroanisole (TCA) is a microbial metabolite formed from chlorophenols through the activity of several natural fungal strains present on the cork oak bark. TCA is the primary compound responsible for the mousty/mould off-odour known as “cork taint” present in cork stoppers, wine, water and alcoholic beverages. Chromatographic and electrochemical methods are currently used for the determination of TCA, however its detection at low concentrations remains a technical challenge. The aim of this study was the development of a rapid novel biosensor system based on the Bioelectric Recognition Assay (BERA). The sensor measured the electric response of cultured membrane-engineered fibroblast cells suspended in an alginate gel matrix due to the change of their membrane potential in the presence of the analyte. Membrane-engineered cells were prepared by osmotic insertion of 0.5 μg/l of specific TCA antibodies into the membrane of the cells. The BERA-based sensor was able to detect TCA in a few minutes (3-5 min) at extremely low concentrations (10⁻¹ ppt), thus demonstrating higher sensitivity than the human sensory threshold. In addition, the assay was quite selective against other haloanisoles and halophenols structurally related to or co-occurring with TCA. Finally the sensor was tested against real white wine samples from cork soaks. At this real test, the BERA sensor was able to detect TCA from cork soaks rapidly (3-5 min) at very low concentrations (1.02-12 ng/l), covering the whole range for the detection threshold for wines (1.4-10 ng/l). Therefore, this novel biosensor offers new perspectives for ultra-rapid, ultra-sensitive and low-cost monitoring of TCA presence in cork and wine and possibly also other food commodities.