Fungi and bacteria are well-known pathogens for plants, fruits, and animals, including humans. In this context, the prospection of antimicrobial agents is crucial to provide new alternatives for the treatment of microbial diseases. Hence, selenium- and tellurium-containing compounds are underexploited and herein, antimicrobial activity of several organochalcogenated compounds was evaluated against Gram-negative and Gram-positive bacteria and fungi. A direct comparison between Se- and Te-containing compounds was performed, as well as structure-activity relationship studies. Among assayed compounds, secondary Se-amines LQ16 and LQ20 and secondary Te-amine LQ28 showed excellent results against a variety of fungi, while primary Te-amine LQ10 demonstrated promising results against bacteria. These results suggest organoselenides and organotellurides may be used for the development of new antimicrobial agents.

The ozonolysis reaction is widely used in the academy and in industry. The first reports about the existence of the ozone molecule were made over 200 years ago. Several ideas and assumptions were made to understand the chemical properties of the ozone molecule and the ozonolysis mechanism. The intent of this paper is not to be an extensive review about ozone chemistry or ozonolysis reactions, but to highlight how the rational process was developed and how conclusions were drawn at a time with limited instrumentation.

Several organic chemistry labs in Brazil suffers from the absence of a safe method to extrude sodium wire, used to obtain anhydrous solvents such as THF or ethyl ether. This technical note presents the assembly instructions for a sodium wire press, similar to the one that has been used for the past four years in our laboratory without any maintenance.

A resposta comportamental de machos e fêmeas adultos de Pseudopiazurus obesus (Boheman, 1838) (Coleoptera: Curculionidae) a várias fontes de odores foi avaliada em um olfatômetro de tubo em Y. Insetos machos e fêmeas foram significativamente mais atraídos para uma combinação dos voláteis emitidos pelos machos da espécie e pela planta hospedeira, sugerindo a existência de um feromônio de agregação produzido pelos machos. Análises comparativas dos voláteis emitidos pelos machos e fêmeas revelaram três compostos macho-específicos, em uma relação de 77:14:9, dando suporte químico às observações comportamentais. (1R,2S)-(+)-Grandisal e (1R,2S)-(+)-grandisol foram identificados como sendo os compostos majoritário e intermediário, respectivamente, enquanto que a estrutura química do componente minoritário, que parece ser um novo derivado do grandisol, ainda necessita ser determinada. Estes três compostos são os principais candidatos a feromônio na espécie.

The behavioral responses of adult male and female Pseudopiazurus obesus (Boheman, 1838) (Coleoptera: Curculionidae) to several odour sources were evaluated in a Y-tube olfactometer. Males and females insects were significantly more attracted to a combination of volatiles released by males of the species and host plant, suggesting the existence of a male-produced aggregation pheromone. Comparative analysis of the volatiles released by males and females revealed three male-specific compounds, in a ratio of 77:14:9, providing a chemical support to the behavioral observations. (1R,2S)-(+)-Grandisal and (1R,2S)-(+)-grandisol were identified as the major and intermediate compounds, respectively, while the chemical structure of the minor compound, that seems to be a new grandisol derivative, still remains to be determined. These three compounds are the most important pheromone candidates in the species.

In this work we show how to build a piece of equipment for depositing thin films by the dip-coating process, using inexpensive components easily found on the market. This equipment allows us to control the dipping and pulling velocity at which the substrate is put in the film precursor solution, two very important parameters for obtain thin films. This article discusses the construction of the mechanical and electric parts of the equipment, a simple method to interface it to a computer and the development of the software to control the dip-coating parameters.

O composto (S)-2-metil-4-octanol (1) é produzido especificamente pelos machos da broca da cana-de-açúcar Sphenophorus levis, e sua atividade biológica está aparentemente associada ao comportamento de agregação da espécie. Desenvolveu-se neste trabalho uma nova metodologia sintética para a preparação deste composto, utilizando-se o D-manitol (2) como material de partida, tendo-se o (R)-gliceraldeído acetonídeo (4) como intermediário chave. Através de análises cromatográficas de um acetil derivado do produto final, empregando-se colunas quirais, estabeleceu-se um excesso enantiomérico de 99,5%. O composto (1) já foi previamente identificado como componente do feromônio de agregação de uma grande variedade de espécies de curculionídeos.

(S)-2-Methyl-4-octanol (1) is a male-specific compound released by the sugarcane weevil Sphenophorus levis, being its biological activity associated with the aggregation behaviour of the species. Continuing our studies on the chemical ecology of this species, this work describes an expeditious synthesis of alcohol (1), starting from the easily available D-mannitol (2), in a route that employ the known (R)-glyceraldehyde acetonide (4) as key intermediate. GC analysis of an acetyl derivative of the final product, using a chiral stationary phase column, revealed an enantiomeric excess of 99.5%. Compound (1) has been identified as component of the male-produced aggregation pheromone in several curculionid species.

A introdução de um grupamento equivalente ao ânion carboximetil a enonas e nitroalquenos através da reação de adição 1,4 do cianocuprato da 2,4,4-trimetil-2-oxazolina 3, resulta numa metodologia interessante para a síntese de produtos naturais como (±)-metil jasmonato (1) e (±)-baclofen (2).

Introduction of a synthon equivalent to a carboxymethyl anion to enones and nitroalkenes, through a 1,4-addition reaction of 2,4,4-trimethyl-2-oxazoline cyanocuprate 3, proved to be an interesting methodology for the synthesis of natural products such as (±)-methyl jasmonate (1) and (±)-baclofen (2).

Os percevejos Euschistus heros e Piezodorus guildinii (Heteroptera: Pentatomidae) são importantes pragas da cultura da soja no Brasil. Uma característica marcante nestas espécies é o fato de que ambas se utilizam das mesmas estruturas químicas como feromônios sexuais, ou seja, os ésteres metílicos 2,6,10-trimetildodecanoato de metila (1) (minoritário) e o 2,6,10-trimetiltridecanoato de metila (2). No intuito de se verificar a exata função biológica destas estruturas e melhor entender o sistema de comunicação de cada espécie, realizou-se a síntese do componente minoritário 1 juntamente com um composto análogo, o 2,6,10-trimetiltetradecanoato de metila (3). Tais compostos serão submetidos a testes em laboratório, juntamente com o componente majoritário 2, já previamente sintetizado.

The stink bugs Euschistus heros and Piezodorus guildinii (Heteroptera: Pentatomidae) are economically important soybean pests in Brazil. An intriguing characteristic of these species is the fact that they use the same chemical compounds as sex pheromone, e.g., methyl 2,6,10-trimethyldodecanoate (1) (minor) and methyl 2,6,10-trimethyltridecanoate (2). In order to investigate the specific biological function of these molecules and to increase the knowledge of the communication system of each species, we have synthesized the minor component 1 and an analogue compound, methyl 2,6,10-trimethyltetradecanoate (3). These compounds will be tested on indoor bioassay, in addition with the previously synthesized major component 2.

Os compostos utilizados pelo percevejo da soja Piezodorus guildinii como feromônio de alarme foram caracterizados através da análise da composição química das secreções da glândula metatorácica dos insetos adultos. Além dos hidrocarbonetos característicos, (E)-2-hexenal e (E)-4-oxo-2-hexenal foram detectados como constituintes majoritários. Tais compostos já foram previamente descritos como feromônio de alarme em outras espécies de pentatomídeos.

The compounds utilized by the soybean stink bug Piezodorus guildinii as alarm pheromone were characterized by analysis of the chemical composition of the metathoracic scent gland secretions from adult bugs. In addition to characteristic hydrocarbons, (E)-2-hexenal and (E)-4-oxo-2-hexenal were detected as major constituents. These compounds were previously described as alarm pheromone in several other pentatomid species.