Cleônia Roberta Melo Araújo

Diferentes estratégias para a reticulação de quitosana

One of the most important aspects of chitosan derivatization depends on the crosslinking of their polymeric chains. This chemical strategy may confer new properties to those derivatives, which can be used to enhance their biotechnological applications. So far, this work aims to discuss some strategies related to the crosslinking of chitosan focusing on reagents, reaction mechanisms and properties/applications of the crosslinked derivatives in several fields of science.

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.

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.