Arlan de Assis Gonsalves

DESENVOLVIMENTO DE FÁRMACOS POR HIBRIDAÇÃO MOLECULAR: UMA AULA PRÁTICA DE QUÍMICA MEDICINAL USANDO COMPRIMIDOS DE PARACETAMOL E SULFADIAZINA E A FERRAMENTA VIRTUAL SciFinder ®

Medicinal Chemistry is a multidisciplinary discipline and the discovery of new bioactive molecules is one of its objectives. Molecular Hybridization (MH) is a strategy of rational design of new prototypes, where the lead compound is produced through an adequate fusion of pharmacophoric sub-unities. Undergraduate laboratory experiments for Medicinal Chemistry education with a focus on MH are scarce. Therefore, the present paper describes a practice class for some undergraduate courses (Pharmacy, Chemistry and/or Chemical Engineering) involving drug development and MH that can be performed at low cost. In this work, alternative materials such as paracetamol and sulfadiazine tablets were used to engage students attention and to contextualize important concepts of MH. The experiment describes the synthesis of a new compound involving the azo coupling between an aromatic amine (sulfadiazine) and a phenol (paracetamol) to show undergraduate students a practical example of MH. In this case, SciFinder® - a search website of the American Chemical Society - was also demonstrated and utilized as a search tool in the proposed experimental class.

Síntese do 4-((5-acetamido-2-hidroxifenil) diazenil) benzenossulfônico, um Azobenzeno Derivado do Acetaminofeno, e Avaliação do seu Potencial como Indicador de Valor de pH

Strong absorption and bright colours of the azobenzene have attracted attention for the development of chemical sensors of this class of compounds, such as acid-base indicators. The present work describes the synthesis of a derivative of the drug acetaminophen, the azobenzene 4 - ((5-acetamido-2-hydroxyphenyl) diazenil) benzenesulfonic, and evaluation of the potential of this as a pH value indicator. The azobenzene was obtained in 77% yield and low cost, and shown to be a promising pH value indicator with good solubility in water, readily distinguishable color change in the zone turning, wide range of usable concentration and pK a values calculated: 9,072; 9,322 e 9,265. Thus it can be used as pH value indicator of basic band, and the results may contribute to the development of new synthetic compounds with acid-base indicator activity with low production cost.

Synthesis of Vanillin Derivatives and Evaluation as Photoprotective Agents against the UVB Radiation

Este trabalho descreve a sintese e determinacao do fator de protecao solar (FPS) de formulacoes de protetor solar contendo dois filtros quimicos derivados da vanilina. As sinteses alcancaram rendimentos de 85% e 60% para obtencao do derivado 1 (4-(4-hidroxi-3-metoxifenil)-3-buten-2-ona) e derivado 2 (4-[4-(acetiloxi)-3-metoxifenil]-3-buten-2-ona), respectivamente. Formulacoes contendo os filtros quimicos sintetizados, na concentracao de 5,0%(m/m), apresentaram atividade de fotoprotecao UVB in vitro iguais a: derivado 1 (FPS 8,5 ± 0,2) e derivado 2 (FPS 12,2 ± 0,9). Tais valores foram superiores a formulacao contendo benzofenona-3 (FPS 6,9 ± 0,6) na mesma concentracao.

Acetilcolinesterase - AChE: Uma Enzima de Interesse Farmacológico

A acetilcolinesterase (AChE) tem uma importância inquestionavel para o adequado funcionamento das sinapses colinergicas presentes em nosso sistema nervoso central e periferico, fato que torna esta enzima um alvo atraente para o desenvolvimento de novas drogas. Neste contexto, o conhecimento das metodologias que podem ser empregadas para avaliar a atividade enzimatica da AChE e um fator importante para o sucesso de pesquisas cientificas relacionadas a esta enzima. Desta forma, o presente trabalho inicialmente trata da AChE e de moleculas capazes de inibir ou reativar este catalisador biologico. Na segunda parte do artigo sao explanados os fundamentos de diferentes metodologias utilizadas para se determinar a atividade enzimatica da AChE, desde as mais simples e de baixo custo, ate os metodos que necessitam de maiores investimentos em reagentes e equipamentos. Com esta revisao, os autores fornecem aos pesquisadores algumas alternativas para a realizacao de experimentos envolvendo a determinacao da atividade da AChE, de forma que os mesmos possam avaliar e eleger o metodo mais adequado para seus respectivos ensaios.

Tamarindus Shell: Caracterization and Adsorption Studies of Methylene Blue and Chromium(VI) Using Finite Batch Technique

This work describes the use of tamarindus shell as an alternative adsorbent for the removal of methylene blue and chromium(VI) species from aqueous solutions. The adsorbent at unmodified form was used in sorption studies. The solid was characterized by MEV, BET and BJH. Acidic functional groups on the surface of the adsorbent were seen by FTIR, Boehm’s titration and pHPCZ. The results showed that the kinetic equilibrium was reached after 120 and 180 min for the dye and the metal respectively. The kinetic data were better fitted to pseudo-first order for dye adsorption and to pseudo-second order for metal adsorption. The change points in sorption stages (rapid and slow phase) were defined by the MCVP parameter using Hung’s algorithm. The effects of pH and ionic strength on adsorption capacity were also studied.

Contextualizando reações ácido-base de acordo com a teoria protônica de Brönsted-Lowry usando comprimidos de propranolol e nimesulida

This paper reports the use of alternative materials for teaching experimental chemistry. In this context, nimesulide and propranolol tablets were used to teach chemical concepts about acid-base reactions according to Bronsted-Lowry protonic Theory. Important topics of Organic, Analytical and Pharmaceutical Chemistry were discussed, such as purification by acid-base extraction, solubility of organic compounds in aqueous solutions, buffers, the dissociation constant (pKa), potentiometric titration and ionization of drugs in biological fluids. The purification of propranolol and nimesulide from tablets produced yields of 75% and 90%, respectively. The experimental values of pKa for both drugs were in agreement with those from the literature.