O sistema globalmente harmonizado de classifica����o e rotulagem de produtos qu��micos (GHS): uma introdu����o para sua aplica����o em laborat��rios de ensino e pesquisa acad��mica

The present article provides an overview of the Globally Harmonised System of Classification, Labelling and Packaging of Chemicals (GHS) and its implementation in Brazil. Although Classification and Packaging is beyond the scope of the responsibility of academic chemists, labelling of chemicals used in academic laboratories will be required by the competent authorities to ensure the safety of students and staff. Therefore, academic teachers and researchers responsible should be familiarised with the GHS principles outlined here and at least be able to label, by applying these principles, mixtures of substances previously classified by the competent authorities.

Produtos qu��micos perigosos utilizados em laborat��rios de ensino: proposta e exemplos para indica����o de seus perigos no r��tulo

Typically hundreds of different chemical products stored in small flasks which cannot accommodate labels large enough to bear all information required by the Globally Harmonised System of Classification, Labelling and Packaging of Chemicals (GHS) are used in academic laboratories. To overcome this restriction Brazilian legislation permits communication of the dangers of chemical products to trained laboratory workers/students by alternative means. Here we describe an alternative label system, developed by the German Social Accident Insurance (DGUV), which allows hazard communication to trained workers/students via a labelling system, using pictograms and highly condensed hazard statements to alert about dangerous chemical products.

Explorando produtos naturais microbianos nas fronteiras da Qu��mica e da Biologia

The chemistry of natural products has been remarkably growing in the past few decades in Brazil. Aspects related to the isolation and identification of new natural products, as well as their biological activities, have been achieved in different laboratories working on this subject in the country. More recently, the introduction of new molecular biology tools has strongly influenced the research on natural products, mainly those produced by microorganisms, creating new possibilities to assess the chemical diversity of secondary metabolites. This paper describes some ideas on how the research on natural products can have a considerable input from molecular biology in the generation of chemical diversity. We also explore the role of microbial natural products in mediating interspecific interactions and their relevance to ecological studies. Examples of the generation of chemical diversity are highlighted by using genome mining, mutasynthesis, combinatorial biosynthesis, metagenomics, and synthetic biology, while some aspects of microbial ecology are also discussed. The idea to bring up this topic is linked to the remarkable development of molecular biology techniques to generate useful chemicals from different organisms. Here, we focus mainly on microorganisms, even though similar approaches have also been applied to the study of plants and other organisms. Investigations in the frontier of chemistry and biology require interactions between different areas, characterizing the interdisciplinarity of this research field. The necessity of a real integration of chemistry and biology is pivotal to finding correct answers to a number of biological phenomena. The use of molecular biology tools to generate chemical diversity and control biosynthetic pathways is largely explored in the production of important biologically active compounds. Finally, we briefly comment on the Brazilian organization of research in this area, the necessity of new strategies for the graduation programs, and the establishment of networks as a way of organization to overcome some of the problems faced in the area of natural products.

A Import��ncia da determina����o anal��tica de intermedi��rios reativos e de seus produtos de rea����es com biomacromol��culas: uma mini revis��o

Metabolic reactive intermediates can react with biomolecules such as DNA and proteins to produce adducts. Recently, research has shown that such adducts can act as precursors of some chronic diseases (cancer, Parkinson's, immunologic system diseases, etc.), and their determination is important because they are biomarkers of undesirable health effects. These compounds are produced at very low concentrations, but the development and dissemination of sensitive new analytical tools, especially those based on chromatography coupled to other analytical instruments, make such determinations possible. This mini review is focused on the formation of reactive intermediates, their reaction with biomolecules, and the importance of their determination.

Software para simula����o de mecanismo de supress��o da luminesc��ncia: modelo cin��tico de Stern-Volmer

A software that includes both Stochastic and Molecular Dynamics procedures has been developed with the aim of visualizing the Stern-Volmer kinetic mechanism of dynamic luminescence quenching. The software allows the student to easily simulate and graphically visualize the molecular collisions, the molecular speed distributions, the luminescence decay curves, and the Stern-Volmer graphs. The software named "SternVolmer" is written for the FreeBASIC compiler and can be applied to dynamic systems where luminescent molecules, during their excited state lifetimes, are able to collide with quenching molecules (collisional quenching). The good agreement found between the simulations and the expected results shows that this software can be used as an effective teaching aid for the study of luminescence and kinetic decay of excited states.

Resson��ncia: desenvolvimento, utiliza����o e avalia����o de um software educacional

Resonance is a useful concept that shows how electrons are shared between two or more atoms and allows a prediction of the chemical reactivity and relative stability of reagents, intermediates, and products. An educational software that enables interactive exploration of the concepts related to resonance and thereby facilitates its understanding was developed. The software was field-tested, and an evaluation questionnaire concerning the software as an educational tool was answered by the students and professors involved in the test. The results led to the conclusion that the developed computer application can be characterized as an auxiliary tool that assists teachers in their lectures and students in their learning process.

An��lise dos produtos de degrada����o do esfenvalerato por SBSE/CLAE-UV/DAD utilizando planejamento fatorial fracion��rio

A simple procedure based on stir bar sorptive extraction and high-performance liquid chromatography-ultraviolet/photodiode array detection (SBSE/LC-UV/PAD) to determine intermediates and by-products of esfenvalerate is described. The influence of organic modifier, ionic strength, extraction time, temperature and pH were simultaneously evaluated by using a factorial experimental design. The utilization of different organic solvents and desorption times were also investigated to establish the optimal conditions for SBSE liquid desorption. Among the ten different peaks (intermediates and by-products) detected after degradation of esfenvalerate, eight (including 3-phenoxybenzoic acid and 3-phenoxybenzaldehyde) were successfully extracted by SBSE under the optimized conditions.

Determina����o da atividade antitr��ptica em prote��nas de produtos do amendoim isoladas por cromatografia de afinidade

The peanut is an oleaginous plant of high nutritional value, a source of protein and a trypsin inhibitor. Trypsin inhibitors are proteins present in the vegetable kingdom, considered anti-nutritional factors for animals. However, there have been several recent reports about their heterologous and beneficial effects on human health. These important effects have been the focus of studies investigating these inhibitors in foods. The aim of the present study was to isolate and determine the estimated molecular mass and specific inhibitory activity, for trypsin in the Japanese peanut, peanut butter, and peanut nougat using the techniques of precipitation with ammonium sulfate and affinity chromatography on trypsin - Sepharose CNBr 4B. The techniques used in this study were efficient for isolating the protein inhibitors with antitryptic specific activity of 694 UI mg-1, 823 UI mg-1 and 108 UI mg-1 for the Japanese peanut, peanut nougat, and peanut butter, respectively. The techniques featured high selectivity of the adsorbent, with consequent efficiency in isolation, given the low amount of dosed proteins and specific antitryptic activity presented by the products studied. The various health-related benefits show the importance of detecting and isolating efficient trypsin inhibitors in foods, taking into account the health claims attributed to the vegetable and its high consumption by humans.

CHEMOSTAT, UM SOFTWARE GRATUITO PARA AN��LISE EXPLORAT��RIA DE DADOS MULTIVARIADOS

The objective of this work was to develop a free access exploratory data analysis software application for academic use that is easy to install and can be handled without user-level programming due to extensive use of chemometrics and its association with applications that require purchased licenses or routines. The developed software, called Chemostat, employs Hierarchical Cluster Analysis (HCA), Principal Component Analysis (PCA), intervals Principal Component Analysis (iPCA), as well as correction methods, data transformation and outlier detection. The data can be imported from the clipboard, text files, ASCII or FT-IR Perkin-Elmer “.sp” files. It generates a variety of charts and tables that allow the analysis of results that can be exported in several formats. The main features of the software were tested using midinfrared and near-infrared spectra in vegetable oils and digital images obtained from different types of commercial diesel. In order to validate the software results, the same sets of data were analyzed using Matlab© and the results in both applications matched in various combinations. In addition to the desktop version, the reuse of algorithms allowed an online version to be provided that offers a unique experience on the web. Both applications are available in English.

Eclos��o e mortalidade de Meloidogyne exigua em extratos e em produtos naturais

A eclos��o e mortalidade de juvenis de segundo est��dio (J2) de Meloidogyne exigua foram avaliadas em extratos aquosos de urucum-colorau (Bixa orellana), cravo-da-��ndia (Syzygium aromaticum), canela (Cinnamomum zeylanicum), pimenta-do-reino (Piper nigrum), gengibre (Zingiber officinale), salsa (Petroselium crispum), soro de leite, solu����o nutritiva hidrop��nica, solu����o aquosa de cloreto de s��dio (NaCl) e a����car (sacarose), fermento biol��gico e probi��tico (Controlmix��). O soro de leite e os extratos de canela, fermento biol��gico e cloreto de s��dio causaram 100% de mortalidade (P<0,05) ap��s 24 h do contato dos J2 com os extratos. Mortalidade acima de 50% tamb��m ocorreu nos extratos de cravo-da-��ndia e no probi��tico. Os demais materiais testados foram estatisticamente iguais �� ��gua (P<0,05). A eclos��o foi avaliada durante 16 dias de imers��o dos ovos de M. exigua nos extratos. Comparando os valores da ��rea abaixo da curva de progresso da eclos��o, observou-se que, exceto o a����car e a solu����o hidrop��nica, todos os extratos e produtos testados inibiram a eclos��o (P<0,01) dos J2 de M. exigua. Entre todos os extratos e produtos testados, maior inibi����o (P<0,01) da eclos��o ocorreu no soro de leite, probi��tico, canelaecravo-da-��ndia, destacando-se o soro de leite e o extrato de canela que assim como inibiram a eclos��o tamb��m foram altamente t��xicos aos juvenis.

Avalia����o de produtos alternativos para controle da requeima do tomateiro

Em condi����es de campo, avaliaram-se produtos alternativos no manejo da requeima do tomateiro (Lycopersicon esculentum), causada por Phytophthora infestans, em tr��s experimentos (E). Compararam-se, em E1, extratos de: [pimenta (Capsicum chinense) + pimenta-do-reino (Piper nigrum) + cravo (Syzygium aromaticum) + a��afr��o-da-��ndia (Curcuma longa) + alho (Allium sativum)]; (pimenta-do-reino + cravo + alho); e (cravo + a��afr��o-da-��ndia + alho); em E2, ��leo de nim (Azadirachta indica) (0,5%); leite (20%); e calda bordalesa; e em E3, preparado homeop��tico obtido de tecido de tomateiro com requeima (dinamiza����o C30); mistura ��gua-etanol; e calda bordalesa. Em E1, os extratos e a testemunha n��o diferiram quanto �� severidade na metade da epidemia (Y50), severidade final (Ym��x), ��rea abaixo da curva de progresso (AACPD) e taxa de progresso da doen��a (r). Em E2, Y50 com ��leo de nim (3%) e calda bordalesa (1%) n��o diferiram; Ym��x foi maior com ��leo de nim (44%) que com calda bordalesa (14%); leite n��o reduziu Ym��x; r e AACPD foram menores com ��leo de nim (0,161 e 533, respectivamente) que na testemunha (0,211 e 1186, respectivamente) e semelhantes ��queles com calda bordalesa (0,156 e 130, respectivamente); r e AACPD foram similares nos tratamentos leite e testemunha. Em E3, Y50, Ym��x, AACPD e r com a mistura ��gua-etanol e preparado homeop��tico foram similares aos da testemunha. A calda bordalesa foi o tratamento mais eficiente no controle da requeima, e o ��leo de nim foi promissor. No manejo da doen��a em sistemas alternativos de produ����o, �� necess��rio integrar pr��ticas, para se potencializarem os efeitos individualizados.

Avalia����o de produtos alternativos no controle da ferrugem do cafeeiro

Objetivou-se neste trabalho avaliar produtos org��nicos quanto ao efeito protetor e indutor de resist��ncia �� ferrugem do cafeeiro (Hemileia vastatrix), comparando-se com fungicidas sist��micos. O trabalho foi desenvolvido em casa-de-vegeta����o, utilizando-se mudas de cafeeiro cv. Catua�� Vermelho 144. Foram avalidados como indutores de resist��ncia extratos foliares, suspens��es de con��dios f��ngicos e de c��lulas bacterianas, fertilizantes foliares, hipocloritos e acibenzolar-S-methyl (ASM). O delineamento experimental utilizado foi em blocos casualizados com tr��s repeti����es, sendo que cada parcela experimental foi constitu��da de cinco mudas de caf�� perfazendo um total de 15 mudas por tratamento. Os experimentos foram repetidos duas vezes com resultados semelhantes. Quando avaliado o efeito protetor, a maioria dos compostos reduziu o n��mero de p��stulas e a ��rea foliar com ferrugem em compara����o �� testemunha 1 (��gua). Extratos de folhas de caf��, obtidos pelo processo aquoso e extratos de sementes de Azadirachta indica ('neem") obtidos pelo processo de extra����o com metanol apresentaram prote����o similar, mas nunca superior a epoxiconazole + piraclostrobin. Extratos aquosos de folhas de caf��, ASM, Bacillus subtilis e Pseudomonas putida reduziram a infec����o causada por H. vastatrix em mais de 77 %.

Determina����o de paracetamol em produtos farmac��uticos empregando um sistema de an��lise por inje����o em fluxo com gera����o de ��cido nitroso

O uso do ��cido nitroso para determina����o de paracetamol (acetoaminofenol) em formula����es s��lidas e l��quidas empregando um sistema de an��lise por inje����o em fluxo �� descrito. A determina����o da droga foi realizada pela rea����o do paracetamol com ��cido nitroso gerado em linha e o produto dessa rea����o foi monitorado em 430 nm em meio alcalino. A curva anal��tica apresentou uma faixa de concentra����o de paracetamol variando entre 9,7x10-5 a 6,2x10-3 mol L-1 com um limite de detec����o de 2,5x10-5 mol L-1. Os desvios padr��o relativos foram menores que 2% para solu����es contendo 1,2x10-4 e 2,8x10-4 mol L-1 de paracetamol (n=10) e uma freq����ncia de amostragem de 60 determina����es por hora foram obtidos. Os resultados da determina����o de paracetamol nas formula����es farmac��uticas obtidas pelo procedimento em fluxo proposto est��o em boa concord��ncia com os resultados obtidos utilizando-se o procedimento da Farmacop��ia Americana a um n��vel de confian��a de 95% e dentro de uma faixa aceit��vel de erro.