Compostos de platina em quimioterapia do câncer

The vast majority of clinically used antitumor drugs are either synthetic or natural product based organic compounds. In this review we describe different aspects, such as structure-activity relationships, mechanism of action, clinical uses and possible future prospects, of the platinum antitumor complexes, a distinct class of antitumor agents.

Substâncias enantiomericamente puras (SEP): a questão dos fármacos quirais

The thalidomide disaster, in the 60,s, is the most painful reminder of the importance of chirality for biological activity. After this episode, much attention has been devoted to study the correlations between toxicological and pharmacological properties and chirality. Actualy, to get a licence for a new chiral drug in EUA, European community and Japan, it is necessary to study the biological properties of each enatiomer independently. This article presents an overview about the importance of the chirality of organic compounds and its relationships with biological activity, asymmetric synthetic methodologies and market.

Determinação dos hidrocarbonetos saturados e policíclicos aromáticos presentes no material particulado da atmosfera amazônica

It was identified and quantified several organic compounds in the atmosphere of a site into Amazon Basin with high impact of biomass burning emission. It was important to know the particulate matter composition with respect to n-alkanes and PAH associated with the particulate matter because they provided indication on the main sources contributing to airborne particles, the contribution of natural vs. man-made emission and the aging of the particles. The main classes of compounds observed were n-alkanes, PAH and nitro-PAH. It was observed the formation of nitro-PAH from photochemical reactions. The aerosol mass concentration is mainly associated with fluoranthene, pyrene and benzo(ghi)perylene. Environmental and direct emissions samples (flaming and smoldering) were collected and analysed.

Especiação de Arsênio - uma revisão

This paper provides a review on separation methods and analytical techniques for the determination of several species of organic and inorganic arsenic in different matrices. Arsenic is an element whose speciation is of particular interest due to the great variation of toxicity levels exhibited for its different chemical forms. Arsenic (III) and As (V) are the most toxic species while organic compounds such as arsenobetaine (AsB), produced by methylation of inorganics species (carcinogenics) are relatively less toxic, hence the great importance of arsenic speciation in the determination of the degree of contamination of an environmental or biological system.

Oxidações catalíticas e eletrocatalíticas de substratos orgânicos. O cério como oxidante

This paper reviews the catalytic and electrocatalytic oxidation of organic compounds using cerium (IV) salts. Direct and indirect methods and those using modified electrodes are described.

The wide synthetic versatility of five membered rings containing phosphorus

The chemistry of cyclopentadiene rings has been widely studied. This review article deals with a similar chemistry of new compounds containing from 1 to 5 phosphorus atoms on the ring substituting the carbon atoms. The neutral rings containing one, two and three phosphorus atoms can be used as building blocks for the synthesis of new organic compounds containing phosphorus. These rings plus the anionic ones also show great potential as ligands in coordination chemistry. The aim of this article is to show how important this new area is and how diverse the chemistry related to a single type of ring can be.

Estado da arte da cromatografia gasosa de alta resolução e alta temperatura

The developments in stationary phase synthesis and capillary column technology, have opened new perspectives in analysis of high molecular mass compounds (³600 daltons) and thermolabile organic compounds by High Temperature High Resolution Gas Chromatography (HT-HRGC). HT-HRGC is a new analytical borderline and its application to the analysis of high molecular mass compounds is still in its infancy. The apolar and medium polar gum phases can now be operated at temperatures up to 400-480ºC, being used for the analysis of n-alcanes up to C-100, lipids, oligosaccharides, industrial resins, polyglycerols, cyclodextrins, porphyrins, etc. This technique should play a leading role as a powerful tool, for many different analysis types, in multidisciplinary fields of Science.

Interações entre corantes e argilas em suspensão aquosa

Adsorption of cationic dyes on clays can be used as a model for the interactions between organic compounds and these minerals. Cationic dyes like methylene blue are used to study these interactions because of the spectroscopic changes observed when their molecules are adsorbed on clay surfaces. Depending on the structure and layer charge of the clay particles several processes may occur, like adsorption of dye monomers and aggregates on the external and internal surfaces of the clay tactoids, migration towards internal surfaces, protonation, etc. Under certain conditions the deaggregation-aggregation of the clay particles are accelerated trapping dye species during these processes. A general scheme is proposed for the processes occurring between clays and dyes in aqueous suspensions, which can be used to explain the behaviour of specific systems.

Origem e implicações dos ácidos carboxílicos na atmosfera

A general overview about the ambient levels of low molecular weight carboxylic acids and their possible emission sources, as well as the implication of them in the atmosphere is presented. Carboxylic acids are considered to be one of the dominant classes of organic compounds found in the atmosphere in a variety of phases, such as in rainwater, snow and ice, on aerosol particles and gas phase. They may be originated from biogenic and anthropogenic direct emissions and by photochemical reaction in situ. Emission sources and formation mechanisms of organic acids in the atmosphere are discussed.

Métodos de extração e/ou concentração de compostos encontrados em fluidos biológicos para posterior determinação cromatográfica

When organic compounds present in biological fluids are analysed by chromatographic methods, it is generally necessary to carry out a prior sample preparation due the high complexity of this type of sample, especially when the compounds to be determinated are found in very low concentrations. This article describes some of the principal methods for sample preparation in analyses of substances present in biological fluids. The methods include liquid-liquid extraction, solid phase extraction, supercritical fluid extraction and extraction using solid and liquid membranes. The advantages and disadvantages of these methods are discussed.

Filmes poliméricos ultrafinos produzidos pela técnica de automontagem: preparação, propriedades e aplicações

The self-assembly technique is a powerful tool to fabricate ultrathin films from organic compounds aiming at technological applications in molecular electronics. This relatively new approach allows molecularly flat films to be obtained on a simple and cheap fashion from various types of material, including polyelectrolytes, conducting polymers, dyes and proteins. The resulting multilayer films may be fabricated according to specific requirements since their structural and physical properties may be controlled at the molecular level. In this review we shall comment upon the evolution of preparation methods for ultrathin films, the process of adsorption and their main properties, as well as some examples of technological applications of layer-by-layer or self-assembled films.

Estudo de compostos orgânicos em lixiviado de aterros sanitários por EFS e CG/EM

The main purpose of this work was the qualitative study of organic compounds in landfill leachate. The samples were collected from a sanitary landfill located at Gravataí, a southern Brazilian city, that receive both, industrial and domestic refuse. The samples were submitted to solid phase extraction (SPE) with XAD-4 resin as the stationary phase. The instrumental analysis was performed by Gas Chromatography with a Mass Spectrometry Detector (GC/MSD). The compounds achieved in the SPE extracts were tentatively identified by the GC/MS library. It was found several oxygen and nitrogen compounds like carboxylic acids, ketones, amines and amides. Sulfur compounds and phthalate esters are also identified.

Descoloração e degradação de poluentes orgânicos em soluções aquosas através do processo fotoeletroquímico

Organic compounds responsible for the color of wastewaters are usually refractory to biological digestion. In this paper the photo-assisted electrolysis process is used for color removal from three of the most colored wastewaters, which are daily generated in large amounts: the E1 bleach Kraft mill effluent, a textile reactive dye effluent and a landfill leachate. Electrolysis was carried out at 26,5 mA cm-2 in a flow reactor in which the anode surface was illuminated by a 400 W high pressure Hg bulb. In all experiments 70-75% of color reduction was observed which was also followed by a net organic load oxidation.

Redução de poluentes de efluentes das indústrias de papel e celulose pela floculação/coagulação e degradação fotoquímica

The abatement of recalcitrant lignin macromolecules from effluents of pulp and paper industry was investigated by combined process. Flocculation and coagulation with aluminum sulfate and natural polyelectrolytes extracted from cactus Cereus peruvianus were used in the first step. After separation of solid residues by filtration, the photochemical methods using TiO2 as catalyst were employed for photocatalytic degradation of lignin compounds from solution. The abatement of lignin compounds after flocculation and coagulation was 46%, and after the overall process, the pollutants reduction observed were 66%. The remaining organic compounds may be removed by any biological treatment.

Compostos orgânicos em sedimentos marinhos: uma viagem ao fundo do Oceano Atlântico Norte

The present study investigates the origin and distribution of several classes of organic compounds present in recently deposited abyssal sediments in the North East Atlantic Ocean. Six cores were sampled (multicorer) along 20ºW longitude as part of the UK's Biogeochemical Ocean Flux Study (BOFS). The sediments underlie diverse water columns, ranging from the Iceland Basin, an area of high primary productivity but presumed low aeolian inputs, to an area off West Africa characterized by oligotrophic and upwelling waters and high aeolian input. Concentration of predominantly marine (e.g. sterols and alkenones) and terrestrial (n-alkanes) compounds showed remarkable changes along the transect.