Scielo RSS <![CDATA[Química Nova]]> http://www.scielo.br/rss.php?pid=0100-404220170005&lang=es vol. 40 num. 5 lang. es <![CDATA[SciELO Logo]]> http://www.scielo.br/img/en/fbpelogp.gif http://www.scielo.br <![CDATA[HPLC-DAD PROFILE OF PHENOLIC COMPOUNDS, CYTOTOXICITY, ANTIOXIDANT AND ANTI-INFLAMMATORY ACTIVITIES OF THE AMAZON FRUIT <em>Caryocar villosum</em>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-40422017000500483&lng=es&nrm=iso&tlng=es Piquiá (Caryocar villosum - Caryocaraceae) is a native fruit from the Amazon region rich in bioactive substances. Fruit pulp extracts were analyzed by HPLC, together with extracts obtained from fruit pulp industry residual parts, byproducts such as husks (shells) and seeds. Extracts were prepared with two ethanolic solvent systems. Phenolic substances ellagic and gallic acids were detected with standards and quantified by HPLC. Cytotoxic, antioxidant and anti-inflammatory activities in vitro were also evaluated. Shell extracts showed free radicals scavenger capacity in ABTS (IC50: 3.93 ± 0.12 µg mL-1) and DPPH models (IC50: 7.81 ± 0.34 µg mL-1), low cytotoxicity in human fibroblasts, but high at tumor strains, and also a high anti-inflammatory potential observed by the inhibition of nitric oxide production. At low concentrations (20 µg mL-1), excellent antioxidant activities were verified in cellular assays, with percentages of 70.69 ± 2.77%, 79.89 ± 6.50% and 79.48 ± 8.6% for shell, pulp and seed extracts, respectively. With this set of results, C. villosum fruit extracts become a high potential raw material to be used in pharmaceutical and cosmetic applications. <![CDATA[THE SYMMETRY BREAKING PHENOMENON IN 1,2,3-TRIOXOLENE AND C<sub>2</sub>Y<sub>3</sub>Z<sub>2</sub> (Z= O, S, Se, Te, Z= H, F) COMPOUNDS: A PSEUDO JAHN-TELLER ORIGIN STUDY]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-40422017000500491&lng=es&nrm=iso&tlng=es 1,2,3-Trioxolene (C2O3H2) is an intermediate in the acetylene ozonolysis reaction which is called primary ozonide intermediate. The symmetry breaking phenomenon were studied in C2O3H2 and six its derivatives then oxygen atoms of the molecule are substituted by sulphur, selenium, tellurium (C2Y3H2) and hydrogen ligands are replaced with fluorine atoms (C2Y3F2). Based on calculation results, all seven C2Y3Z2 considered in the series were puckered from unstable planar configuration with C2v symmetry to a Cs symmetry stable geometry. The vibronic coupling interaction between the 1A1 ground state and the first excited state 1B1 via the (1A1+1B1) ⊗b1 pseudo Jahn-Teller effect problem is the reason of the breaking symmetry phenomenon and un-planarity of the C2Y3 ring in the C2Y3Z2 series. <![CDATA[EVALUATION OF TRACE ELEMENTS RELEASING FROM SOILS TREATED WITH RETORTED OIL SHALE]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-40422017000500496&lng=es&nrm=iso&tlng=es Soils that had received successive applications of retorted oil shale (ROS) in an experiment under field conditions were used in this study, aiming to evaluate the availability of trace elements. In the batch tests, we observed that toxic elements present in the ROS are not desorbed from the matrix in significant amounts to contaminate soil and groundwater. The element Ca represents the greatest nutrient contribution, which has high mobility and ease release into the soil solution. Concerning the results obtained from the soil extracts analysis; we observed that the undesirable elements released into the extracts are not directly related to the presence of ROS in the soil samples. Comparing the behavior of soil samples with and without ROS it is possible to infer that many of the trace elements are derived from soil constituents, from previous fertilizer and pesticides applications. The study suggested that the ROS can be used as a soil conditioner for agricultural purposes without adding harmful elements to the environment. <![CDATA[SELECTIVE SYNTHESIS OF PEG-MONOESTER USING CESIUM HETEROPOLY ACID AS HETEROGENEOUS CATALYST]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-40422017000500506&lng=es&nrm=iso&tlng=es Esterification of oleic acid with polyethylene glycol 600 (PEG-600) to produce polyethylene glycol monooleate (PEG-monooleate) and polyethylene glycol dioleate (PEG-dioleate) as by-product has been studied in the presence of heterogeneous acid catalysts, i.e. cesium heteropoly acid (Cs HPA). The results are compared with those obtained from a classical homogeneous acid catalyst; p-toluene sulphonic acid (p-TSA). The reaction was conducted under nitrogen flow with vigorous stirring at 130 ºC and 150 ºC. The catalyst loading kept at 4% and the reaction was monitored at 1, 3, 7 and 24 hours. Reaction samples were analyzed using high performance liquid chromatography (HPLC) equipped with evaporative light scattering detector (ELSD). The results obtained showed that Cs HPAs exhibit 100% selectivity of PEG-monooleate from the first hour until 24 hours. However, this does not happen with homogeneous p-TSA, where formation of by-product; PEG-dioleate is observed in the initial stage. It is also showed that the mole ratio is the most important parameter not only to produce high yield of monoester but also to maintain it along the reaction. Chemical and physical properties of catalysts were characterized using Thermal Gravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), Fourier Tranmittance Infra-Red (FTIR), ammonia temperature programmed desorption (NH3-TPD) and X-ray Diffraction (XRD). <![CDATA[ÍNDICES DE PODER ELECTROFÍLICO GLOBAL Y LOCAL PARA EL ESTUDIO TEÓRICO DE LA REACTIVIDAD QUÍMICA: APLICACIÓN A DERIVADOS CARBONILO α,β-INSATURADOS]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-40422017000500513&lng=es&nrm=iso&tlng=es In this study two new global descriptors for chemical reactivity are proposed, namely the electrophilic power and nucleophilic power. These have been developed by performing the normalization of the local electrophilic power and local nucleophilic power respectively, which were recently proposed elsewhere. In particular, the usefulness of both global and local electrophilic power was evaluated by studying the chemical reactivity of six series of α,β-unsaturated carbonyl compounds whose experimental reactivity measures toward the nucleophile glutathione are available. It was observed in the majority of the cases the global and local electrophilic powers work as better than the popular global and local electrophilicity indices, respectively. <![CDATA[EVALUATION OF HYDROGEN PRODUCTION FROM ANAEROBIC CO-DIGESTION OF ORGANIC SOLID WASTE AND RESIDUAL GLYCEROL FROM BIODIESEL PRODUCTION]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-40422017000500523&lng=es&nrm=iso&tlng=es The anaerobic co-digestion of solid organic waste with residual glycerol from biodiesel production (1% v v-1) for hydrogen production was investigated by means of the Biochemical Hydrogen Potential (BHP). The specific hydrogen production from co-digestion with and without glycerol corresponded to 140 mL H2 g VS-1 and 87,3 mL H2 g VS-1 removed, respectively, while the maximum specific H2 production rate was found to be 14.26 e 8.57 mL H2 g VS h-1, respectively. Co-digestion of solid organic waste with glycerol enhanced hydrogen production and reduced the fermentation lag phase in around 4 hours. The dominant metabolite product of the anaerobic fermentation was butyric acid. The results revealed that co-digestion of organic water and glycerol is promising and can potentially be used to maximize energy production while contributing to the management and treatment of these wastes. <![CDATA[METAL OXIDES FROM LIKE-HYDROTALCITES MATERIALS MODIFIED WITH Ga<sup>3+</sup> AS CATALYSTS FOR ETHYL BIODIESEL SYNTHESIS]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-40422017000500528&lng=es&nrm=iso&tlng=es Summary: The synthesis of like-hydrotalcites materials (layered double hydroxides - LDHs) with molecular formula MgxM3+y(CO3)(OH)16·4H2O in different ratios Mg2+/M3+ where M3+ is Al3+, Ga3+ or both was carried out by the coprecipitation method to be applied in the transesterification reactions for synthesis of ethyl biodiesel from soybean oil and ethanol. The reactions were processed for 12 hours at 120 ºC at a molar ratio oil/ethanol (1/20) with 20% (m/m) of the catalyst in relation to the oil mass, and the products were quantified by GC-FID. With the introduction of Ga3+ in the solid, some physicochemical characteristics of LDHs were kept based in the data from X-ray pattern diffraction (XRD), vibrational spectrometry (ATR-FTIR), and scanning electron microscopy (SEM), but changes from thermogravimetric analysis (TGA), superficial area (BET), and the acidity/basicity properties were observed. Typical hydrotalcite with Mg2+/M3+ = 3 was used as reference material and reach 45.1% of biodiesel conversion. Although the best conversion result (77.6%) was reached from the solid without Ga3+ and with Mg2+/M3+ ratio 4/1, there is an interesting correlation between the catalytic activities and the physicochemical properties of the solids with Ga3+ and their respective homologous materials as discussed in this work. <![CDATA[NEW HYBRIDS BASED ON IRON (III) OXYHYDROXIDE AND GOLD NANOPARTICLES (AuNPs / FeOOH) as CATALYSTS FOR THE REDUCTION OF ORGANIC ENVIRONMENTAL POLLUTANTS]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-40422017000500534&lng=es&nrm=iso&tlng=es A new δ-FeOOH supported nano-Au catalyst was prepared by a facile method using HAuCl4 as the gold source and NaBH4 as the reducing agent. The samples (denoted as AuNPs/FeOOH) were characterized by means of X-ray diffraction (XRD), UV-vis and infrared spectroscopies and scanning electron microscope (SEM). The obtained characterization data confirmed the formation of Au nanoparticles on the δ-FeOOH matrix surface. SEM observations showed that Au nanoparticles have a spherical morphology and good dispersion with a narrow size distribution on the surface of iron (III) oxyhydroxide. The catalyst exhibits significantly high catalytic activity for hydrogenation of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) at room temperature. The high performance obtained can be attributed to the specific characteristics of the nanostructure of the catalyst of nano-Au deposited on the external surface of δ-FeOOH, including plenty of oxygen-containing groups of δ-FeOOH for anchoring AuNPs. Moreover, the catalytic activity increased when the AuNPs content in the δ-FeOOH support. The AuNPs-based δ-FeOOH hybrids are interesting catalysts for hydrogenation of nitrophenols to aminophenols. <![CDATA[ENZYMATIC SYNTHESIS OF ISOPENTYL CAPRYLATE USING FUSEL OIL AS FEEDSTOCK]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-40422017000500541&lng=es&nrm=iso&tlng=es Four commercial lipase preparations immobilized by covalent attachment on epoxy-polysiloxane-β-cyclodextrin were tested as potential biocatalysts to mediate the esterification reaction of isopentanol with caprylic acid in solvent-free medium. Among them, the immobilized lipase from Rhizopus oryzae was the most active biocatalyst, attained ester conversion higher than 80% in 24 h, being selected for subsequent tests using fusel oil as source of isopentanol. An experimental design was performed and the analysis of the results revealed that the formation of the isopentyl caprylate was strongly influenced by the variable molar ratio at 95% of confidence level. The proposed mathematical model allowed predicting that the excess of caprylic acid (molar ratio fusel oil to acid of 1:1.5) and reaction temperature of 45 ºC favor the reaction to attain high ester conversion. Sensory evaluation of the flavors profile in relation to all the components involved in the reaction (caprylic acid, fusel oil and esters) showed that the formed esters had distinct aromas from the starting materials, confirming that the changes in flavors occurred before and after esterification reactions. <![CDATA[CHEMICAL CONTRIBUTION TO THE WASTEWATER MANAGEMENT PLAN OF HEALTH SERVICES]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-40422017000500548&lng=es&nrm=iso&tlng=es In this study were analyzed the main lines of health care waste at the Hospital of the Federal University of Paraná (HC/UFPR), performing an inventory that aims from awareness, characterization, until a viable wastewater treatment proposal for the institution. In this context, were emphasized physical and chemical analyses parameters, inorganic species following the legislation, as well as some chemical analysis used as support for the investigation of the environmental standard of hospital wastewater. The UFPR Clinical Hospital has a health care waste management plan, which is focused on the issue of solid waste. Thus, there are no policies, procedures and specific supervision for managing wastewater, which causes the waste to be disposed directly in the sewage network. At work in question was the physicochemical characterization, inorganic species other relevant chemical species and toxicological analysis of four collection points. Depending on the physical and chemical parameters, phenols and monitored toxicological analysis, one realizes that the hospital sewage characteristics are different from domestic sewage, which in principle suggests the need for special treatment. In this work, the behavior of the wastewater points of HC/UFPR against three types of treatment. The tests performed by the method of activated carbon, Fenton and photoFenton process. <![CDATA[CHEMICAL MODIFICATION OF COMMON MELON PECTIN (<em>CUCUMIS MELO</em> VAR. ACIDULUS)]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-40422017000500554&lng=es&nrm=iso&tlng=es Melon is one of the most widely consumed fruits in the world. In Brazil, 60% of the production is for domestic consumption, with these fruits deemed to be of lower commercial value. For the first time, pectin has been extracted from this species of melon. So the extraction of this polysaccharide can be used as an alternative to increase the value of the fruit, improving profits in the domestic market where it can be used in many industries. The goal of this study is to determine, quantify, characterize and chemically modify by sulfation pectin from common melon for eventual application as an antithrombotic agent. The acidic, basic and neutral extractions yielded an average of 11%, 14% and 8% respectively. The FTIR spectrum revealed that pectin has a low degree of esterification (DE). The bands which appeared at 833 cm-1 and 1251 cm-1 can be attributed to the vibrations of C-O-S and S=O respectively, showing that the material was sulfated. The 13C NMR spectrum showed consistent carbon galacturonic acid peaks and agrees with the FTIR data and elemental analysis for the sulfation of pectin. The molecular weight (MW) determined by GPC was 7.7 x 105 g mol-1, consistent with pectin. <![CDATA[STRATEGIES AND MATERIALS USED IN HETEROGENEOUS PHOTOCATALYSIS APPLIED TO HYDROGEN GENERATION THROUGH WATER PHOTOLYSIS]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-40422017000500561&lng=es&nrm=iso&tlng=es Among the various technologies for the production of hydrogen fuel, heterogeneous photocatalysis is one of the most promising, especially with the use of semiconductors, notably TiO2. However, the use of TiO2 is limited by hindrances for the photolysis of water, such as wide bandgap, a less negative conduction band reduction potential as compared to that of hydrogen evolution and the high electron/hole recombination rate. Deactivation of the semiconductor can be avoided by the addition of electron-rich compounds (sacrificial reagents) which react irreversibly with the hole, leading to a higher quantum efficiency. Another strategy is the Z scheme. In this system, two different photocatalysts (or photosystems) are combined using a suitable redox mediator. Furthermore, the bandgap can be adjusted by doping with transition metal oxides, with control of metal oxide valence band using p-orbitals of an anion, or s-orbitals of p-block metal ions, or by spectral sensitization. In view of these questions, the purpose of this review article is to describe and discuss recent studies that use a variety of materials for the photocatalytic generation of hydrogen. <![CDATA[POTENTIAL MOLECULAR TARGETS FOR ANTITUBERCULOSIS DRUG DISCOVERY]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-40422017000500572&lng=es&nrm=iso&tlng=es Tuberculosis (TB) is an infectious disease caused by mycobacteria from the Mycobacterium genus, mainly by Mycobacterium tuberculosis (MTB). The World Health Organization (WHO) aims to reduce the number of TB cases worldwide in the coming years. Nevertheless, the increasing number of multidrug-resistant (MDR-TB) and extensive-drug resistance (XDR-TB) strains, and the ineffectiveness of the current treatment in latent tuberculosis are challenges to be overcome. In this review, we will demonstrate the recent advances in the tuberculosis drug discovery, focusing the research of new molecular targets in the Mycobacterium tuberculosis. Among the promising targets described herein, we highlight those, which act in different pathways in the mycobacteria, such as energy metabolism, cell wall biosynthesis, DNA synthesis, iron metabolism and transport through membranes. Furthermore, bioactive compounds discovered using phenotypic assays screening and validated through genetic approaches are also presented. <![CDATA[METHOD VALIDATION FOR HS-SPME / GC-MS FOR DETERMINATION OF CARBARYL IN BLOOD PLASMA]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-40422017000500586&lng=es&nrm=iso&tlng=es The aim this research is to develop a HS-SPME/GC-MS method to analyze the carbaryl in blood plasma samples of the rural workers, who live round the perimeter of Chapada do Apodi-CE. This was achieved by chromatographic signal of the 1-naftol, degradation product of carbaryl with the intention of evaluating the degree of exposure of the workers to pesticides, causing chromosome abnormalities as already evidence in appropriate literature. Three different types of covered SPME fibers were tested and a full factorial design with central point in two levels. The variables optimized were temperature and ionic strength and temperature was the response in the design. Study was undertaken to determinate the equilibrium time. The thermal degradation of carbaryl in SPME headspace was analyzed by 1H-NMR. Proposed method achieved low limits of detection and quantification (1.5 and 5 ng mL-1, respectively) with good precision and accuracy, using the method of weighted least squares. However, the proposed method can be considered a good alternative way of monitoring carbaryl in blood plasma by analytical signal of 1-naftol. None of the plasma analyzed presented a concentration of 1-naftol compound higher than limit of detection of the method proposed here. <![CDATA[USE OF GOLD NANORODS FOR THE DEVELOPMENT OF PRACTICAL CLASSES IN NANOTECHNOLOGY]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-40422017000500594&lng=es&nrm=iso&tlng=es A gold nanoparticles functionalization experiment was conducted in a biotechnology summer course at UFOP as a model for the introduction of the laboratory practice in nanotechnology for postgraduate courses in the areas of chemistry and biotechnology. The gold nanorods were synthesized by the seed method and then, functionalized with anti-IL-6 antibodies using the reagents EDAC/NHS and polyethyleneimine (PEI). This nanocompound was tested against the binding with the specific antigen (IL-6) and changes in the longitudinal plasmon absorption spectrum showed the coupling efficiency, which was also verified by the decrease in zeta potential. The experiment was satisfactory, with a positive feedback from participants, and could be implemented in nanotechnology practical classes from postgraduate courses, as a way for improve education in the emergent area of nanobiotechnology. <![CDATA[THE VISCOUNT OF BARBACENA AND JOSÉ ÁLVARES MACIEL: CONNECTION IN SCIENCE AND DISCONNECTION IN POLITICS]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-40422017000500602&lng=es&nrm=iso&tlng=es These two men were former natural philosophy students from the University of Coimbra. Barbacena finished in 1775 and obtained a doctorate in 1776, whereas Maciel graduated in 1785 and then did scientific and industrial work in Portugal and England. The Viscount was a founder member of the Lisbon Academy of Sciences in 1779, and its secretary for 9 years. Both came to Brazil in 1788, when the Viscount was named Governor of Minas Gerais. Insofar as gold production was falling drastically, the Governor-to-be saw in Maciel the right person to start a comprehensive survey of the mineral potential of his domain. Soon after their arrival their lives parted. Without leaving his scientific pursuits, Maciel became embroiled in the planned uprising known as Inconfidência Mineira and was arrested in late 1789. His promising scientific career was aborted at the age of 29 and he was sentenced to exile in Africa. His despondency contributed to an early death at 43. The Viscount’s fate is also gloomy, for in Brazil he is hardly remembered today for any devotion to science, but mainly as the harsh persecutor of patriots.