Terpenos com atividade inseticida: uma alternativa para o controle químico de insetos

Many substances from different sources have been used by men for decades to control insects. After the 2nd World War, the use of inorganic compounds have declined drastically and natural products, as well as synthetic derivatives, have been widely used instead. The search for natural alternatives have improved the development of bench top bioassays and an array of synthetic approaches for known and novel natural products that shows relevant activities as feeding supressors and deterrents. The studies concerning mode of action and environmental impact of these substances, that may be biodegradable and selective for undesired insects, had led to the evaluation and discovery of a number of molecules, mostly terpenoids and alkaloids, that are well reported as candidates for inseticidal compounds that could be an effective alternative for insects control with a lower impact on human health, household animals and the environment.

Aplicação da CLAE para determinação do ácido 10-Hidróxi-2-decenóico (10-HDA) em geléia real pura e adicionada a mel brasileiro

The aim of this paper was to determine the 10-HDA in pure royal jelly and products containing royal jelly, using HPLC methodology. 10-HDA is the natural indicator of the presence of royal jelly in products and also gives the authenticity of pure royal jelly. The chromatographic conditions used were: isocratic system, C18-H column, auto sampler, diode array UV-VIS detector (225 nm), mobile phase with methanol/water (45:55), pH= 2.5 and a-naphtol as internal standard. The results obtained using laboratory samples for pure royal jelly were 2.37%, varying from 0.15% for honey with 10% of royal jelly to 2.10% for honey with 90% of royal jelly respectivelly. For commercial products, the 10-HDA content varied from no detectable to 0.026%. The recovery test presented a minumum of 100.44% The detection limit was 45.92 ng/mL and the quantification limit was 76.53 ng/mL.

Eletrodeposição de irídio em tubo de grafite como modificador químico permanente em espectrometria de absorção atômica

A tubular electrochemical flow-cell for iridium deposition on the inner surface of pyrolytic graphite tube for permanent chemical modification is proposed. A transversal heated graphite tube was used as working electrode, a cylindrical piece of graphite inserted into the graphite tube as auxiliary electrode, and a micro Ag/AgCl(sat) as reference electrode. Iridium solution in 1.0 mol L-1 HCl, flowing at 0.55 mL min-1 for 60 min was used to perform the electrochemical modification. The applied potential to the flow-cell was - 0.700 V vs Ag/AgCl. Scanning electron microscopy images were taken for thermal and electrochemical modified graphite surface in order to evaluate the iridium distribution. Selenium hydride trapping was used to verify the performance of the proposed permanent chemical modifier.

Determinação de corantes artificiais por cromatografia líquida de alta eficiência (CLAE) em pó para gelatina

Synthetic dyes were determined by high performance liquid chromatography in 76 samples of regular jelly and diet jelly powders, of several flavors produced by seven different manufacturers. Three sample of each product, from different batches, were analyzed. The same qualitative composition was observed for products of the same flavor from different manufacturers, but the quantitative composition varied markedly from one manufacturer to the other. There were no or few significant differences between batches from a given manufacturer, demonstrating good quality control in the use of these additives by the food industry. None of the samples exceeded the limit stipulated by Brazilian legislation.

Validação de metodologia analítica para doseamento de soluções de lapachol por CLAE

Lapachol is a naphthoquinone found in several species of the Bignoniaceae family possessing mainly anticancer activity. The present work consists of the development and validation of analytical methodology for lapachol and its preparations. The results here obtained show that lapachol has a low quantification limit, that the analytical methodology is accurate, reproducible, robust and linear over the concentration range 0.5-100 µg/mL of lapachol.

Laboratório químico-prático do Rio de Janeiro: primeira tentativa de difusão da Química no Brasil (1812- 1819)

Until the present date, historians of science have described inaccurately the first laboratory created in Brazil for establishing and divulging Chemistry, namely the "Laboratório Químico-Prático do Rio de Janeiro". During recent research carried out in the Arquivo do Museu Imperial (Petrópolis, RJ), I localized a document entitled "Ensaio histórico analítico das operações do Laboratório Químico-Prático do Rio de Janeiro", which allowed me to gain the relevant information to correct some of the observations made in the first chronicles.

A formação do Químico

Training of highly qualified personnel is the most transversal axis among those identified in the document "Mobilizing Axes in Chemistry", published by SBQ, in 2002, which demands to deep the discussions, initiated in the symposium "The Chemist's Education", whose main objective was to discuss the repercussions of that training in the teaching and in the industrial section. After the publication of an initial paper, a couple of meetings and workshops held in Rio de Janeiro, in December 2003, involving the national chemist community, discussed the "The role of the graduate degrees in the Chemist's Education" and "The Chemist's Education", and confirmed the need to invest in the formation of qualified human resources in profusion and in all levels. Actions to be taken were delineated. Presently, the graduate programs in Chemistry are showing expressive results. However, although these professionals are mostly absorbed by the academy (the absorption of the industry is less significant), only a few programs give special attention to the didactical and pedagogical training. The regional decentralization is actually a tendency in most programs, but the interaction academy-economic activities is still a challenge. It is necessary to establish with the industrial section, the highly qualified professional's profile in Chemistry that the industry can absorb. The undergraduation is growing in number and quality, however still excessively concentrated in the Southeast area. The national "Curricula Guidelines" for Chemistry Courses, through its flexible approach, propitiate the integral, interdisciplinary (non compartmentalized) and critical-reflexive training of the professionals as citizens and as entrepreneurs. However, deficiencies are still recognized. The evaluation system of undergraduate courses has been able to identify the most fragile modalities of courses and other indicators. It was also verified that Brazilian chemistry industry absorbs minimally the highly qualified professionals, which is attributed to the fact that the Federal Council of Chemistry is vertically organized and does not recognize the graduate degrees as professional qualification. In the conclusion, it stands out, among other aspects, the importance of the effective implantation of the national curricula guidelines, bringing out courses whose didactical and pedagogical projects may offer a solid formation in Chemistry, but comprehensive and general enough to enable the Chemistry professionals to develop varied skills.

Constituintes polares das folhas de Machaonia brasiliensis (Rubiaceae)

Chemical investigation of the MeOH extract of the leaves of Machaonia brasiliensis (Rubiaceae) resulted in the isolation and identification of 3beta-O-beta-glucopyranosyl stigmasterol, 3beta-O-beta-glucopyranosyl sitosterol, secologanoside, 7-O-beta-glucopyranosyl quercetagetin, 4,5-O-dicaffeoylquinic acid and 5-O-caffeoylquinic acid. The structures of these compounds were established by spectroscopic analysis, including 2D NMR experiments. The chemotaxonomic relevance of the isolation of secologanoside is discussed.

Estudo químico e perfil cromatográfico das cascas de Aspidosperma parvifolium A. DC. ("pau-pereira")

Four known alkaloids, uleine, epiuleine, apparicine and desmethyluleine, besides the isoprenoids lupeol and stigmasterol were isolated from the stem bark of Aspidosperma parvifolium. Their identification was based on spectroscopic analysis (UV, IR, ¹H-NMR, 13C-NMR, MS). The chromatographic profile of the ethanolic extract was obtained by HPLC and uleine, epiuleine and apparicine were identified in the extract.

Estudo eletroquímico e químico-quântico da oxidação do antidepressivo tricíclico amitriptilina

This work presents the electrochemical and quantum chemical studies of the oxidation of the tricyclic antidepressant amitriptyline (AM) employing a carbon-polyurethane composite electrode (GPU) in a 0.1 mol L-1 BR buffer. The electrochemical results showed that the oxidation of AM occurs irreversibly at potentials close to 830 mV with the loss of one electron and one proton and is controlled by reagent and product adsorption. According to the PM3 results, the atom C16 is the region of highest probability for the oxidation of AM since it has the largest charge variation.

Saponinas triterpênicas de Tocoyena brasiliensis Mart. (Rubiaceae)

The present communication reports the isolation and identification of four triterpenoid saponins from the chloroform extract of the leaves of Tocoyena brasiliensis: 3-O-beta-D-quinovopyranosyl quinovic acid, 3-O-beta-D-quinovopyranosyl cincholic acid, 3-O-beta-D-glucopyranosyl quinovic acid and the 28-O-beta-D-glucopyranosyl ester derivative of quinovic acid as binary mixtures, respectively. From the ethanol extract a flavonoid identified as ramnazin-3-O-rutinoside was obtained. The structures of these compounds were assigned by data analysis of 1D and 2D NMR spectrometry and comparison with data recorded in the literature for these compounds.

Triterpenóides pentacíclicos das folhas de Terminalia brasiliensis

Eleven oleanane, ursane and lupane-type triterpenes were isolated from the leaves of Terminalia brasiliensis Camb, daturadiol (3b,6beta-dihydroxy-olean-12-ene), 3beta-hydroxy-30-norlupan-20-one, lupenone, beta-amyrenone, alpha-amyrenone, lupeol, beta-amyrin, alpha-amyrin, betulin, erythrodiol and uvaol, in addition to squalene, sitosterol and alpha-tocopherol. The structures of these compounds were identified by ¹H and 13C NMR spectral analysis and comparison with literature data.

A graduação em química: um novo químico para uma nova era

The discussions sponsored by the Brazilian Chemical Society, over the past five years, intending to produce a chemistry agenda with perspectives and needs for the next decade for the country, have involved the national chemistry community and several related sectors of Brazilian society. Chemistry education has been the theme throughout these discussions. It is known that the low level of basic and secondary education and the recent increase in high school courses and institutions adversely affect the quality of undergraduate teaching. The recent national "Curriculum Guidelines" for Chemistry Courses, through their flexible approach, encourage the integral, interdisciplinary (non compartmentalized) and critical-reflexive training of professionals as citizens and as entrepreneurs. However, deficiencies are still recognized. The system of undergraduate course evaluation has identified the most fragile modalities of the courses and other indicators. Also, it has been verified that the Brazilian chemistry industry absorbs only minimally the highly qualified professionals, which is attributed to the fact that the Federal Council of Chemistry is vertically organized and does not recognize the graduate degrees as professional qualifications. In conclusion, the importance of the effective implantation of the national curriculum guidelines is apparent, among other aspects, highlighting courses whose didactical and pedagogical projects may offer a solid formation in Chemistry. However, at the same time the guidelines are comprehensive and general enough to enable the chemistry professionals to develop varied skills.

Inovação tecnológica e produção no setor químico

Innovation is the main tool for competitiveness and growth in the chemical sector and the main factors for innovation activities in industry as well as the innovation dynamics are discussed in this paper. Success indicators of innovation in Oxiteno are the following: 54% of the current production derives from RD&E projects, 11% of the gross margin in the internal market is due to new products, the company is a technology licensor, holding 17 patents and keeping a strong participation in the production and service sales in the high technology catalysts area, beyond its core petrochemicals and surfactants area.