NEWSLETTER 25

Annals of the Brazilian Academy of Sciences

AABC - Volume 90 (1 Suppl. 1) - April 2018

With great pleasure I would like to advertise the special volume “Brazil: Frontiers of Chemical Sciences” that was organized by the colleague Frank Crespilho (Instituto de Química de São Carlos, USP, São Paulo). A total of 16 exceptional papers reviewing different aspects of chemistry were published in this issue of the AABC. All are part of a project that started in 2016, with the purpose to produce special volumes in commemoration of the centenary of the Brazilian Academy of Sciences.

The topics addressed in the papers of this issue show a great variation, ranging from flow analysis to enzymatic reactions, passing through the discussion of bioeconomy of natural Brazilian products and carbon dioxide cycle involving enzymatic action and nanoparticles.

I would also like to call your attention to the editorial by Dr. Crespilho – a very inspiring text.

Many thanks to Dr. Crespilho and all authors who have contributed to this volume. We all hope that the high quality of the contributions will inspire others also to submit equally great papers to the AABC.

Please keep in mind that since 2000, all papers published by the AABC can be downloaded free of charge at the SciELO site and previous editions of the Newsletter are available at the ABC website.

We are now inviting you to scroll through the text and click on the title of the article that interests you!

Alexander W. A. Kellner
Editor-in-Chief

BRAZIL: FRONTIERS OF CHEMICAL SCIENCES 

1 - Carbon dioxide/methanol conversion cycle based on cascade enzymatic reactions supported on superparamagnetic nanoparticles
Authors: Caterina G.C. Marques Netto, Leandro H. Andrade and Henrique E. Toma

Carbon dioxide/methanol conversion cycle is a joint work by the Laboratories of Nanotechnology (USP), Biocatalysis (USP) and Biomimetic Chemistry (UFSCar),  based on cascade reactions performed by three sequential enzymes immobilized on superparamagnetic nanoparticles,  showing good conversion efficiencies under recyclable and sustainable conditions, allowing a rational use of this global warming gas.

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2 - The long and successful journey of electrochemically active amino acids. From fundamental adsorption studies to potential surface engineering tools
Authors: André H.B. Dourado, Fabián C. Pastrián and Susana I. Córdoba de Torresi

The electrochemical activity of proteins has been known since the beginning of electrochemistry. Along the history, this behavior was attributed to 5 among the 23 amino acids, called electroactive amino acids group, composed by L-Tryptophan, L-Tyrosine, L-Histidine, L-Methionine and L-Cysteine. Despite the big amount of studies about their electrochemical behavior, mechanisms about their oxidations are still controversial. This work compiles the most remarkable publications about the all five molecules and, in the case of L-Cysteine, its adsorption behavior is object of deep investigation. Finally, these molecules are presented as surface engineering tools for the synthesis of controlled nanoparticles.

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3 - Enzymes immobilized in Langmuir-Blodgett films: Why determining the surface properties in Langmuir monolayer is important?
Author: Luciano Caseli

The immobilization of enzymes in Langmuir-Blodgett (LB) films is a recent approach to produce biosensors with enhanced properties. Commonly, the conformation of enzymes can be determined by the environmental conditions and the LB technique allows for easily manipulation of chemical composition, morphology and thickness of the film. In this sense, an outline of papers that report the immobilization of enzymes as LB films since the 1980’s have shown the evolution of this strategy. In general, the surface properties of the floating monolayer prepared previously are important to determine the efficiency of the device, including thermodynamic, morphological, rheological and molecular aspects.

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4 - From Medicinal Chemistry to Human Health: Current Approaches to Drug Discovery for Cancer and Neglected Tropical Diseases
Authors: Leonardo G. Ferreira, Glaucius Oliva and Adriano D. Andricopulo

Ligand- and structure-based drug design are pivotal approaches to the knowledge-based pharmaceutical industry. The success of these strategies depends on a fine convergence of experimental and computational methods to overcome the outstanding challenges enclosed in modern drug development. In this scenario, cutting edge research on life-threatening conditions such as neglected tropical diseases and cancer has been conducted. By participating in international initiatives for drug discovery, the Laboratório de Química Medicinal e Computacional (LQMC) of the Universidade de São Paulo has contributed to the progress in the development of new lead compounds for these diseases. The laboratory has applied different strategies in medicinal chemistry, molecular and structural biology, along with computational approaches, such as bio- and chemo-informatics to generate high-quality preclinical candidates able to progress into the drug development chain.

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5 - Brazilian Bioluminescent Beetles: Reflections on Catching Glimpses of Light in the Atlantic Forest and Cerrado
Authors: Etelvino J.H. Bechara and Cassius V. Stevani

Bioluminescence – visible and cold light emission by living organisms – is a worldwide and multicolored phenomenon described in terrestrial and marine environments since ancient times. It emerged discontinuously along evolution over 30 times, probably as an adaptive response against oxygen toxicity and was appropriated for courtship, predation, camouflage and communication. The biological light results from the oxidation of a substrate (luciferin) by oxygen, catalyzed by an enzyme (luciferase), yielding the product in the fluorescent state. This review focuses on luminescent beetles – Lampyridae (fireflies), Elateridae (click-beetles) and Phenogodidae (railroad-worms), of which the chemistry, color modulation and technological applications are discussed.

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6 - Chemistry Inspired by the Colors of Fruits, Flowers and Wine
Authors: Frank H. Quina and Erick L. Bastos

Studies of two classes of natural plant pigments, the anthocyanins and the betalains, as well as of the pyranoanthocyanin pigments formed from anthocyanins during the maturation of red wine are reviewed. These two pigments are responsible for most of the red, purple and blue colors of fruits and flowers and anthocyanins are pyranoanthocyanins for the color of red wines. As part of our diet, they confer a number of important health benefits. Our systematic studies of these pigments are providing a deeper understanding of their often complex chemisty and photochemistry and the relationship of these to their biological roles.

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7 - Activity and Stability of Dispersed Multi Metallic Pt-based Catalysts for CO Tolerance in Proton Exchange Membrane Fuel Cell Anodes
Authors: Ayaz Hassan and Edson A. Ticianelli

The CO poisoning effect and insufficient stability usually encountered when the Pt based supported catalysts are employed in the anode of proton exchange membrane fuel cell (PEMFC) can be efficiently improved by modifying their properties by the addition of ad-metal or by the modification of the catalyst substrate. Here we obtained a two-fold enhancement in H₂ oxidation current and sufficient gain in stability, when PtMo/C heat treated at 600 °C  is applied as catalyst in the anode fed with H₂ containing 100 ppm CO, as compared to PtMo/C catalyst. Almost similar results are obtained, when Pt is supported on Mo₂C/C and WC/C supports and the resultant Pt/Mo₂C/C and Pt/WC/C catalysts are employed in the anode.  Besides, the activity and stability are also improved with PtMoRu/C and PtMoRuFe/C as anode catalysts, which are obtained by incorporating Ru and Fe as third and fourth element in the PtMo/C catalyst. 

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8 - Controlled synthesis of noble metal nanomaterials: motivation, principles, and opportunities in nanocatalysis
Authors: Rafael S. Geonmonond, Anderson G.M. da Silva and Pedro H.C. Camargo

Metal nanoparticles are of paramount importance in nanoscience. Their properties are strongly dependent on size, shape, and composition, for example. Therefore, synthetic control over these parameters paves the way for optimized performances. Nevertheless, the level of synthetic control in terms of straightforwardness and robustness still remains challenging and restricted to a few systems. In this review, the fundamentals of solution-phase synthesis of metal nanoparticles are discussed, emphasizing definitions, motivations, theories, and established strategies. As a proof-of-concept example in terms of applications, we discuss how the controlled synthesis of metal nanoparticles influences their catalytic and optical properties.

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9 - Sunlight-driven water splitting using hematite nanorod photoelectrodes
Author: Flavio L. Souza

Direct conversion of solar energy into chemical energy (hydrogen and oxygen) by using seawater and sunlight irradiation might be a most economical approach to provide clean and sustainable energy for supplying the global demand. In this context, iron oxide based-material with columnar morphology rises as a promising design for developing low-cost and efficient photoelectrochemical devices. This brief review gives critical aspects and novel perspective of the latest advances on use of columnar hematite electrodes designed by an easy and scalable chemical route originally named as Purpose-Built Method (PBM), including the recent record on the field.

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10 - The potential contribution of the natural products from Brazilian biodiversity to bioeconomy
Authors: Marilia Valli, Helena M. Russo and Vanderlan S. Bolzani

The development of our society has been based on the use of biodiversity, especially for medicines and nutrition. Brazil is the nation with the largest biodiversity in the world accounting for more than 15% of all living species. Considering the chemical and biological diversity of Brazil, this review highlights the Brazilian natural products that were successfully used to develop new products and the value of secondary metabolites from Brazilian biodiversity with potential application for new products and technologies.

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11- New trends in plasmonic (bio)sensing
Authors: Jorge R. Mejía-Salazar, Sabrina A. Camacho, Carlos J.L.  Constantino and Osvaldo N.  Oliveira Junior

Early detection of diseases such as Cancer and Alzheimer enormously increases the likelihood of a successful treatment. This need has motivated multidisciplinary research efforts in physics, with chemical and biological concepts for ultrasensitive probing of biological molecules. In particular, the excitation of surface plasmon polaritons, i.e., coupled oscillations of light and electrons on a metal/dielectric interface, has been explored owing to their ability for fast, real-time analysis of biomolecular interactions. In the paper, we provide an overview of recent results to improve the sensing abilities of plasmonic biosensing platforms, also giving a perspective for developments in the near future. 

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12- Solid-phase extractions in flow analysis
Authors: Fábio R.P. Rocha, Alex D. Batista, Wanessa R. Melchert and Elias A.G. Zagatto

Solid-phase extraction (SPE) is a worldwide-recognized strategy for improving analytical sensitivity and selectivity. Its mechanization in flow analysis (FA) reduces the probability of systematic errors and contamination risks, leading to improved precision, increased sample throughput, and low reagent consumption. These aspects are in consonance with the Green Chemistry concept. Consequently, analytical procedures exploiting SPE-FA have undergone amazing development, as emphasized in this review, which discusses historical aspects, main cornerstones, system design and recent applications. Emphasis is given to analyte separation/concentration, sample clean-up and release of sorbed chemical species involving both packed  (e.g. mini-columns, cartridges and disks) or fluidized particles.

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13- Advances in enzyme bioelectrochemistry
Authors: Andressa R. Pereira, Graziela C. Sedenho, João C.P. de Souza and Frank N. Crespilho

The review entitled “Advances in enzyme bioelectrochemistry” includes the main theoretical and practical aspects of bioelectrochemistry of redox proteins. It describes the advances in the utilization of enzymes in films and the development of new materials, such as metal nanoparticles, flexible carbon fibers, and graphene. Besides, it is describing the development of new methodologies and in situ techniques, which allows to obtain molecular-level detail, contributing to the elucidation of fundamental aspects of electron transfer in biomolecules and bioelectrocatalytic mechanisms. Moreover, some examples related to the enzymatic biosensors and biofuel cells that have been developing in the last years are discussed.

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14- Traditional and New methods for the Preparation of Diazocarbonyl Compounds
Authors: Antonio C.B. Burtoloso, Patrícia B. Momo and Graziele L. Novais

The chemistry of diazocarbonyl compounds has shown, over the years, several important applications in organic synthesis. This class of compounds is capable to perform different types of transformations, leading to the synthesis of many structures with diverse functionalities. This review will cover the traditional methods to synthesize diazocarbonyl compounds, as well as the new and safer procedures to prepare them.

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15- Organic Synthesis: New Vistas in the Brazilian Landscape
Authors: Ronaldo A. Pilli and Francisco F. de Assis

The current Brazilian scenario reveals a promising future for the chemical sciences as well as trained and talented young generation of chemists has come to play over the last decades. Out of the promising areas covered in this overview, catalysis, green chemistry and methodology development stand out as the more productive ones but in the years to come academic and industrial laboratories have to share their expertise on these and other areas, such as scalability, methodology and total syntheses, if the promise they hold is to be realized.

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16- Enzymatic reactions involving the heteroatoms from organic substrates
Authors: Caterina G.C. Marques Netto, Davyson J. Palmeira, Patrícia B. Brondani and  Leandro H. Andrade

Synthetic procedures involving the assimilation or transformation of heteroatom-containing molecules into organic compounds are common reactions employed in several organic processes. However, there is a demand for the synthesis of relevant hetero-organic derivatives, with special attention to environmental-friendly reactions, such as the biocatalyzed transformations. In the last years, several new methodologies were developed to obtain heteroatom-containing molecules by the use of enzymes. Therefore, it is recognized that this field is receiving significant attention in different areas of research. Herein, we describe the historical background along with the progress of biocatalyzed reactions involving the heteroatom from hetero-organic substrates.

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Annals of the Brazilian Academy of Sciences
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