Phosphoenolpyruvate carboxykinase (PEPCK) is a ubiquitous enzyme found in all known groups of organisms, acting in the reversible conversion of oxaloacetate (OAA) to phosphoenolpyruvate (PEP) in the presence of divalent metal ion, and dependent of adenosine 5’-triphosphate (ATP) or guanosine-5’-triphosphate (GTP). PEPCK is an important enzyme in the metabolism of some organisms, such as Trypanosoma cruzi, being suggested as a potential drug target to treat Chagas’ disease. Its catalytic activity is, classically, measured by coupled assays. Herein, a direct assay by liquid chromatography-tandem mass spectrometry (LC-MS/MS) capable of quantifying PEP, in co-elution with OAA by the differentiation obtained by the mass spectra, is reported. The developed assay was used throughout the purification protocol in order to measure the activity of PEPCK of T. cruzi, which was expressed in Escherichia coli. The purified enzyme was kinetically characterized by the developed method with Michaelis-Menten constant (KMapp) values of 96 ± 4 and 275 ± 18 µmol L-1 to OAA and ATP as substrates, respectively. The developed assay was also used for ligand screening and proved to be able to identify very low inhibitions for small molecules (50 µmol L-1).

Os etenoditioacetais polarizados são conhecidos como importantes intermediários em muitos processos de síntese. Neste trabalho, reporta-se a anelação livre de metal de transição de 1,1-bis(tiometil)-2-nitroetileno com hidroxilalquilaminas e alquildiaminas. Esta metodologia permite a síntese direta de N-heterociclos tais como imidazolidinas, oxazolidinas e benzoxazóis sob irradiação de micro-ondas. Estes compostos foram avaliados como inibidores da acetilcolinesterase usando um reator capilar contendo a enzima imobilizada acoplado a um espectrômetro de massas.

Polarized ketene dithioketals have been recognized as useful building blocks in many synthetic operations. In this work, a transition-metal-free annulations of 1,1-bis(thiomethyl)-2-nitroethylene with hydroxylalkylamines or alkyldiamines have been reported. This methodology provides a directed approach to N-heterocycles, e.g., imidazolidines, oxazolidines and benzoxazoles under microwave conditions. These compounds were evaluated as acetylcholinesterase inhibitors by using an enzyme immobilized capillary reactor-tandem mass spectrometry.

A lagarta parda Thyrinteina arnobia (Lepidoptera: Geometridae), é considerada no Brasil uma importante praga de plantas nativas, como Psidium guajava, e exóticas, como espécies de Eucalyptus. Neste trabalho é relatado o isolamento dos componentes feromonais de T. arnobia, através de técnicas de extração de glândulas e micro-extração em fase sólida (SPME) de fêmeas virgens. As amostras coletadas foram analisadas por cromatografia a gás acoplada a um detector eletroantenográfico (CG-EAD) e espectrometria de massas (CG-EM). Foram observadas duas respostas eletroantenográficas em antenas de machos de T. arnobia e as análises por CG-EM sugeriram a estrutura do 3,4-epoxi-6,9-eneicosadieno como componente majoritário. A síntese racêmica deste epoxidieno foi realizada em 10 etapas com rendimento global de 28%. Foram também sintetizados os quatro estereoisômeros do epoxidieno a partir dos respectivos epoxiálcoois enantiomericamente enriquecidos.

The eucalyptus brown-looper Thyrinteina arnobia (Lepidoptera: Geometridae) is considered an important pest in Brazilian native plants, e.g. Psidium guajava, and exotic plants, such as Eucalyptus species. In this work we describe the isolation of the pheromone components of T. arnobia, using glands extract and solid phase micro extraction (SPME) of virgin females. The samples were analyzed by gas chromatography with an electroantennographic detector (GC-EAD), and mass spectrometry (GC-MS). Two reproducible electroantennographic responses were elicited in the male antenna of T. arnobia and one of them was identified as 3,4-epoxy-6,9-heneicosadiene by CG-MS. The racemic synthesis of this epoxydiene was carried out in 10 steps and 28% overall yield. The four stereoisomers of the epoxydiene were also synthesized employing the corresponding enantiomeric enriched epoxyalcohols.

Insecticidal activity of essential oils of Pelargonium graveolens, Lippia alba and compounds geraniol, linalool, 1,8-cineole, limonene, carvone, citral and Azamax® were evaluated against Spodoptera frugiperda. Topical application assay showed essential oil of P. graveolens has acute toxicity against Spodoptera frugiperda larvae (third instar) with LD50 1.13 µg/mg per insect and LD90 2.56 µg/mg per insect. Three essential oils of L. alba also exhibited insecticidal activity with LD50 ranging from 1.20 to 1.56 µg/mg per insect and LD90 from 2.60 to 3.75 µg/mg per insect. Geraniol, linalool, carvone and citral caused significant mortality of 30, 90, 84 and 64% respectively, compared to negative control. The bioinsecticide, Azamax®, caused lower mortality than the compounds of the essential oils.

Neste trabalho, o emprego de cloreto férrico como um eficiente catalisador em reações de glicosilação de açúcares na presença de álcoois alílicos e propargílicos é descrito. Os glicosídios correspondentes foram obtidos com rendimentos de moderados a bons. Este novo procedimento apresenta maior seletividade quando comparado a métodos clássicos encontrados na literatura. As principais características desse método simples incluem condições de reação não perigosas, quantidade de catalisador baixa, bom rendimento e seletividade anomérico elevada.

In this work, the use of ferric chloride as an efficient catalyst in glycosylation reactions of sugars in the presence of allyl and alkynyl alcohols is described. The corresponding glycosides were obtained with moderate to good yields. This new procedure presented greater selectivity when compared to classic methods found in the literature. Principal features of this simple method include non-hazardous reaction conditions, low-catalyst loading, good yields and high anomeric selectivity.

A composição dos voláteis emitidos por diferentes árvores é usada com sucesso como marcador em uma grande variedade de estudos, como a quimiotaxonomia. A caracterização dos voláteis emitidos por diferentes espécies de Pinus provou ser uma ferramenta importante para entender o processo de seleção de plantas hospedeiras por insetos herbívoros. Os voláteis dos galhos de cinco espécies de Pinus (P. caribaea, P. elliottii, P. maximinoi, P. patula e P. taeda) foram coletados por aeração e analisados por cromatografia gasosa com detector de ionização de chama (GC-FID), utilizando colunas de fase não-polar e quiral, e espectrometria de massas (GC-MS) com analisador de quadrupolo. A composição relativa foi usada para análises de componentes principais (PCA) e de agrupamento hierárquico (HCA) para a discriminação das cinco espécies.

The composition of the volatiles emitted by different trees has been successfully used as a marker in a wide variety of studies, such as chemotaxonomy. Characterization of the volatiles emitted by different species of Pinus has proven to be an important tool to understand the process of host-tree selection by herbivorous insects. The volatiles present in samples of the branches of five species of Pinus (P. caribaea, P. elliottii, P. maximinoi, P. patula and P. taeda) were collected by aeration, and the contents analyzed by gas chromatography using a flame ionization detector (GC-FID), applying non-polar and chiral column phases, and mass spectrometry (GC-MS) using a quadrupole mass analyzer. The relative composition of the different volatiles was used to perform a discriminant analysis among the five pine species, by means of cluster (HCA) and principal component (PCA) analyses.

Neste trabalho nós apresentamos uma revisão sobre a síntese em fase sólida de metabólitos secundários, tais como alcalóides, poliaminas, esteróides, terpenos e flavonóides, descritos na literatura a partir de 2000. Um número considerável de rotas sintéticas elegantes e desafiadoras, usando suportes sólidos, será discutido.

In this manuscript, we disclose solid-phase organic syntheses (SPOS) of small-molecules of some secondary metabolites, such as alkaloids, polyamines, steroids, terpenes, and flavonoids, described in the literature since 2000. A number of elegant, efficient and challenging syntheses on solid support will be presented.

Neste trabalho nós relatamos o uso de microondas como fonte de energia para promover a síntese de uma série de nitroeteno N,S-acetais com bons rendimentos. Estes compostos são intermediários muito úteis para a síntese de sistemas heterocíclicos nitrogenados

In this paper we report the use of microwaves as heat source to promote the synthesis of a series of nitroketene N,S-acetals with good to excellent isolated yields. These compounds are very useful intermediates for synthesizing nitrogen-containing heterocycles.

Nesse trabalho é relatada a síntese de uma série de ácidos N-aril antranílicos inéditos, com bons a excelentes rendimentos, empregando irradiação de microondas como fonte de aquecimento para promover a reação de acoplamento de Ullmann entre ácidos antranílicos e brometos de arila contendo grupos substituintes doadores ou aceptores de elétrons.

In this paper we report the synthesis of a series of novel N-aryl anthranilic acids, with good to excellent yields, employing microwaves as heat source to promote the Ullmann coupling between anthranilic acids and aryl bromides possessing electron donating or withdrawing groups.

The essential oils from the leaves of six species of the Baccharis genus (B. dracunculifolia, B. microdonta, B. regnelli, B. schultzii, B. trimera, and B. uncinella), collected in the "Campos de Altitude" of the Atlantic Forest (SP), were extracted using hydrodistillation procedures and analyzed by GC and GC/MS. There was a predominance of sesquiterpenes in all studied oils as b-elemene in B. dracunculifolia and B. regnelli, a-humulene in B. trimera, g-gurjunene in B. schultzii, bicyclogermacrene in B. regnelli, d-cadinene in B. regnelli and B. uncinella, spathulenol in B. schultzii, caryophyllene oxide in B. microdonta and guaiol in B. uncinella. However, a high amount of monoterpenes was also observed in B. uncinella (a-pinene), B. regnelli (d-car-3-ene) and B. schultzii (limonene). The chemical compounds of the essential oils of B. schultzii, B. regnelli and B. microdonta are described for the first time in this work.

A oxidação de mono-fenóis à para-benzoquinonas é assunto de interesse contínuo devido à existência de inúmeros produtos naturais contendo esta unidade estrutural. As para-benzoquinonas possuem reatividade química importante como agentes oxidantes e como dienófilos na reação de Diels-Alder. Usualmente nós preparamos as para-benzoquinonas pela reação de oxidação dos respectivos mono-fenóis com oxigênio molecular e catalisada por [CoII(salen)]. Porém, foi necessário estudar estas oxidações utilizando-se outros oxidantes. Nós apresentamos aqui nossos resultados sobre esta importante reação de oxidação com uma variedade de oxidantes, utilizando onze mono-fenóis como substratos. Os oxidantes utilizados foram cobalto, níquel, cobre e vanádio derivados com alguns ligantes do tipo salen. Também foram estudados peróxido de hidrogênio, OXONE®, dimetil dioxirano e ácido iodoxibenzóico.

The oxidation of mono-phenols to para-benzoquinones is of continuing interest due to the existence of numerous natural products containing this structural unit. The chemical reactivity of para-benzoquinones is also noteworthy, as oxidants and dienophiles in the Diels-Alder reaction. We have used for quite some time now, molecular oxygen and catalysis with [CoII(salen)] as the oxidation procedure, but felt the need for other oxidants and conditions to be of use with different phenol substrates. We now present our results on this important oxidation with a variety of oxidants, using eleven mono-phenols as substrates. The oxidants tested are cobalt, nickel, copper and vanadyl metals, with a selection of different salen type ligands. Completing this study we also investigated the use of hydrogen peroxide, OXONE®, dimethyl dioxirane and iodoxybenzoic acid.

Nesta revisão estão descritas as sínteses de feromônios de insetos desenvolvidas e publicadas por grupos de pesquisa brasileiros, e tem por objetivo apresentar o estado da arte desta área de pesquisa no país e fornecer uma informação rápida sobre as moléculas já sintetizadas e metodologias empregadas. As sínteses estão apresentadas em ordem cronológica, exceto quando se trata de diferentes metodologias para a mesma molécula.

This review describes the syntheses of insect pheromones developed and published by Brazilian research groups and aims to present the state of the art of this area in the country, and also to serves as a quick view of the already synthesized molecules and employed methodology. The syntheses are presented in chronological order, except when they refer to different approaches for the same molecule.

A lagarta-parda, Thyrinteina arnobia, causa grandes prejuízos à cultura do eucalipto, destacando-se como o principal lepidóptero desfolhador; portanto, medidas alternativas de controle são necessárias. Neste trabalho foi avaliada, pela técnica de eletroantenografia (EAG), a interação dos voláteis dos óleos essenciais de sete espécies de Eucalyptus, frente às antenas de fêmeas e de machos de T. arnobia. Foram também identificados 28 compostos voláteis bioativos contidos no óleo essencial de E. grandis, utilizando a detecção eletroantenográfica acoplada à cromatografia a gás (CG-EAD). Estes resultados indicam que CG-EAD é uma ferramenta muito útil na triagem de compostos bioativos presentes em extratos de plantas e sugerem que T. arnobia utiliza vários destes terpenos como sinais para encontrar seu hospedeiro.

Eucalyptus is frequently attacked by the Brazilian eucalyptus brown looper, Thyrinteina arnobia. This caterpillar is regarded as the main lepidopterous pest of Eucalyptus and yet no practical and environmentally acceptable method of control currently exists. Electroantennographic techniques (EAG) have never before been used to detect semiochemicals that affect the behavior of T. arnobia. Thus, in this work, the ability of T. arnobia males and females to detect volatile essential oils of seven Eucalyptus species was investigated by EAG. We demonstrated that T. arnobia antennal olfactory system clearly showed differential sensitivity to several compounds, by coupled gas chromatography-electroantennographic detection (GC-EAD). Twenty-eight compounds were identified that elicited responses in T. arnobia, indicating that GC-EAD analysis may well be a useful means of screening active plant extracts for compounds that contribute to the observed behavior of this defoliator. The results also suggest that this species uses several volatile cues to find its host.

A doença de Chagas, causada pelo Trypanosoma cruzi, é endêmica em 15 países na América Latina. Neste trabalho uma coleção de 38 cumarinas foi preparada em solução e testada frente à enzima gliceraldeído-3-fostafo-desidrogenase (gGAPDH) do T. cruzi. A rota sintética foi baseada na condensação de Knoevenagel de diferentes 2-hidroxibenzaldeídos com ácido de Meldrum ou malonato de etila, seguido de O-alquilação e/ou reação de transesterificação. Dentre as cumarinas preparadas, os melhores resultados obtidos para inibir 50% da atividade catalítica da enzima foram entre 80 e 130 µM.

Chagas' disease, caused by Trypanosoma cruzi, is endemic in 15 countries in Latin America. In this work a library of 38 coumarins was prepared in solution phase and evaluated against T. cruzi glycolytic enzyme glyceraldehyde-3-phosphate-dehydrogenase (gGAPDH). The synthetic route was based on the Knoevenagel condensation of different 2-hydroxybenzaldehydes with Meldrum's acid or diethyl malonate, followed by O-alkylation and/or transesterification reactions. Among the prepared coumarins, the best values obtained to inhibit 50% of the enzymatic activity range from 80 to 130 µM.

The use of pheromones in integrated pest management has been increasing in the last years due to environmental concern. This development is accompanied by the search for simple, efficient and less aggressive synthetic methodologies for the preparation of pheromones. One of these methodologies includes microbiological reactions, more specifically biocatalytic reduction of carbonyl compounds using baker's yeast (Saccharomyces cerevisiae). This review presents the use of baker's yeast as an easy and cheap alternative to obtain enantiomerically enriched compounds employed in the synthesis of pheromones.