This work describes the synthesis, molecular structure, and packaging of the compounds 6-bromo-2,3-dimethoxybenzaldehyde (6-BRB) and 5-bromo-2,3-dimethoxybenzaldehyde (5 BRB). Characterization in the solid-state was carried out by X-ray diffraction, and the analysis of the interactions was described by the Hirshfeld surface, which helps in understanding the effect of replacing the bromine position in the aromatic ring. Both compounds (6-BRB and 5-BRB) crystallized in the space group P21/c and are stabilized with C-HO interactions, but only the 6-BRB has a halogen-type interaction. Theoretical calculations, carried out by the density functional theory at the CAM-B3LYP/6-311++G(d,p) level of theory in gas phase, provided information on their electronic properties. The geometric properties were compared to experimental data, and the analyses of the frontier molecular orbitals and the molecular electrostatic potential (MEP) maps were obtained to predict the physical-chemical properties. The supramolecular arrangements were analyzed throughout complexation interactions and corrected by counterpoise method. Hyperconjugation energies were employed to examine the stability of the intermolecular interactions of the compounds. The interaction intensities were determined through the topological parameters obtained through the quantum theory of atoms in molecules model.

Derivatives of the thiazolidine-2,4-dione core represent a heterocyclic class with several correlated properties. In this context, the synthesis of structural analogues of these bioactive substances becomes attractive in the field of medicinal chemistry. These analogues act as antimicrobial agents against Gram-positives pathogens. The present work aimed to synthesize 10 different derivatives of 5-arylidene-thiazolidine-2,4-dione, employing urea as the catalyst in a solvent-free reaction medium, with yields that ranged from 45 to 99%. The compounds obtained were submitted to an antimicrobial assay against S. aureus ATCC 29213. Two compounds presented minimum inhibitory concentration of 62.5 and 32.5 µg mL-1 and minimum bactericidal concentration < 500 µg mL-1, demonstrating their antibacterial potential. Principal component analysis was carried out to discriminate the compounds in active and inactive classes. Four geometric and electronic molecular descriptors were required to completely discriminate the compounds. The selected descriptors can guide us in designing new 5-arylidene-thiazolidine-2,4-dione derivatives with enhanced activity.

O presente trabalho descreve as atividades antibacterianas e antifúngicas de diversas chalconas obtidas diretamente através da condensação aldólica tipo Claisen-Schmidt das quais se determinou a concentração inibitória mínima frente a diferentes microrganismos (bactérias Gram-positivas e Gram-negativas e fungos). Estruturas no estado sólido cristalino de sete chalconas foram determinadas por análise de difração de raios X (XRD). Estudos quimiométricos foram realizados com intuito de identificar uma potencial relação entre estrutura e atividade.

The present work describes the antibacterial and antifungal activities of several chalcones obtained by a straight Claisen-Schmidt aldol condensation determined by the minimal inhibitory concentration against different microorganisms (Gram-positive and Gram-negative bacteria and fungi). Solid state crystal structures of seven chalcones were determined by X-ray diffraction (XRD) analysis. Chemometric studies were carried out in order to identify a potential structure-activity relationship.

Com o objetivo de relacionar os descritores geométricos e eletrônicos dos derivados análogos da rutaercarpina com a atividade biológica contra o câncer do sistema nervoso central (CNS), cálculos de química quântica molecular em nível B3LYP/6-31(d) e análise estatística foram realizados para os 21 derivados análogos da rutaecarpina. Dos 86 descritores moleculares calculados, 5 foram selecionados na construção do modelo de análises de componentes principais (PCA). A componente PC1, a qual responde por 46,11% da variância total dos dados, foi capaz sozinha de discriminar completamente os compostos em duas classes: ativos e inativos. Todos os descritores moleculares selecionados pelo modelo PCA são parâmetros eletrônicos. A análise de agrupamento hierárquico (HCA) foi também aplicada aos descritores selecionados pelo modelo PCA. Baseado nos 5 descritores selecionados é possível sugerir novos derivados ativos da rutaercarpina para serem sintetizados. Além disso, um modelo de mínimos quadrados parciais para análise discriminante (PLS-DA) supervisionado foi construído e aplicado com sucesso na discriminação dos análogos à rutaercarpina, o qual foi validado usando um conjunto independente de compostos.

In order to relate the geometric and electronic descriptors of the rutaecarpine analogous to their biological activity against cancer of the central nervous system (CNS), molecular quantum chemical calculations at B3LYP/6-31(d) level and statistical analysis were carried out for 21 rutaecarpine analogous. Out of the 86 molecular descriptors calculated, 5 were selected to build the principal component analysis (PCA) model. The PC1 component that accounts for 46.11% of the total variance of the data was alone able to discriminate completely the compounds into two classes: active and inactive. All molecular descriptors selected by PCA model are electronic parameters. The hierarchical cluster analysis (HCA) was also applied on the selected descriptors. Based on the 5 electronic descriptors selected, it is possible to suggest new compounds to be synthesized with activity against CNS cancer. In addition to that, a supervised partial least squares discriminant analysis (PLS-DA) model was built and successfully applied to discriminate rutaecarpine analogues, being validated through an independent test set and considered robust to overfitting.

Métodos quimiométricos (estatísticos) são empregados para classificar um conjunto de compostos derivados de neolignanas com atividade biológica contra a Paracoccidioides brasiliensis. O método AM1 (Austin Model 1) foi utilizado para calcular um conjunto de descritores moleculares (propriedades) para os compostos em estudo. A seguir, os descritores foram analisados utilizando os seguintes métodos de reconhecimento de padrões: Análise de Componentes Principais (PCA), Análise Hierárquica de Agrupamentos (HCA) e o método de K-vizinhos mais próximos (KNN). Os métodos PCA e HCA mostraram-se bastante eficientes para classificação dos compostos estudados em dois grupos (ativos e inativos). Três descritores moleculares foram responsáveis pela separação entre os compostos ativos e inativos: energia do orbital molecular mais alto ocupado (E HOMO), ordem de ligação entre os átomos C1'-R7 (L14) e ordem de ligação entre os átomos C5'-R6 (L22). Como as variáveis responsáveis pela separação entre compostos ativos e inativos são descritores eletrônicos, conclui-se que efeitos eletrônicos podem desempenhar um importante papel na interação entre receptor biológico e compostos derivados de neolignanas com atividade contra a Paracoccidioides brasiliensis.

Chemometric (statistical) methods are employed to classify a set of neolignan compounds with activity against Paracoccidioides brasiliensis. The AM1 (Austin Model 1) method was used to calculate a set of molecular descriptors (properties) of the neolignan compounds under study. The descriptors were further analyzed using Principal Components Analysis (PCA), Hierarchical Cluster Analysis (HCA) and K-Nearest Neighbor (KNN) chemometric methods. The PCA and HCA methods were quite efficient to classify the compounds into two groups (active and inactive) and three descriptors were found to be important in the classification: the highest occupied molecular orbital energy (E HOMO), the bond order between C1'-R7 atoms (L14) and the bond order between C5' -R6 atoms (L22). The three variables responsible for the separation between active and inactive compounds are all electronic descriptors, therefore we can conclude that electronic effects should have an important role when one is trying to understand the activity of neolignan compounds against Paracoccidioides brasiliensis.

Um conjunto de dezoito compostos de neolignanas com atividade antiesquistossomose foi estudado com o método semi-empírico PM3 e outros métodos teóricos com o intuito de avaliar algumas propriedades (variáveis ou descritores) moleculares selecionadas e correlacioná-las com a atividade biológica. Análise exploratória dos dados (análise de componentes principais, PCA, e análise hierárquica de agrupamentos, HCA), análise discriminante (DA) e o método KNN foram utilizados na obtenção de possíveis correlações entre os descritores calculados e a atividade biológica em questão e na predição da atividade antiesquistossimose de algumas moléculas teste. Os descritores moleculares responsáveis pela separação entre os compostos ativos e inativos foram: energia de hidratação (HE), refratividade molecular (MR) e carga sobre o átomo C19 (Q19). Estes descritores fornecem informações a respeito do tipo de interação que pode ocorrer entre os compostos e seu respectivo receptor biológico. Após a construção do modelo para compostos ativos e inativos, os métodos PCA, HCA, DA e KNN foram empregados em um estudo de predição. Foram estudados 10 novos compostos e somente 5 deles foram classificados como ativos contra esquistossomose.

A set of eighteen neolignan derivative compounds with anti-schistosomiasis activity was studied by using the quantum mechanical semi-empirical method PM3 and other theoretical methods in order to calculate selected molecular properties (variables or descriptors) to be correlated to their biological activities. Exploratory data analysis (principal component analysis, PCA, and hierarchical cluster analysis, HCA), discriminant analysis (DA) and the Kth nearest neighbor (KNN) method were employed for obtaining possible relationships between the calculated descriptors and the biological activities studied and predicting the anti-schistosomiasis activity of new compounds from a test set. The molecular descriptors responsible for the separation between active and inactive compounds were: hydration energy (HE), molecular refractivity (MR) and charge on the C19 carbon atom (Q19). These descriptors give information on the kind of interaction that can occur between the compounds and their respective biological receptor. The prediction study was done with a new set of ten derivative compounds by using the PCA, HCA, DA and KNN methods and only five of them were predicted as active against schistosomiasis.