Francisco Jaime Bezerra Mendonça Junior

Synthesis of 1,2,3-triazole derivatives and in vitro antifungal evaluation on Candida strains.

1,2,3-Triazoles have been extensively studied as compounds possessing important biological activities. In this work, we describe the synthesis of ten 2-(1-aryl-1H-1,2,3-triazol-4-yl)propan-2-ols via copper catalyzed azide alkyne cycloaddition (CuAAc or click chemistry). Next thein vitro antifungal activity of these ten compounds was evaluated using the microdilution broth method against 42 isolates of four different Candida species. Among all tested compounds, the halogen substituted triazole 2-[1-(4-chlorophenyl)-1H-(1,2,3)triazol-4-yl]propan-2-ol, revealed the best antifungal profile, showing that further modifications could be done in the structure to obtain a better drug candidate in the future.

Evidence for the involvement of descending pain-inhibitory mechanisms in the attenuation of cancer pain by carvacrol aided through a docking study

AIMS The present study evaluated the carvacrol (CARV) effect on hyperalgesia and nociception induced by sarcoma 180 (S180) in mice. MAIN METHODS Carvacrol treatment (12.5-50mg/kgs.c.) once daily for 15days was started 24h after injection of the sarcoma cells in the hind paw (s.c.). Mice were evaluated for mechanical sensitivity (von Frey), spontaneous and palpation-induced nociception, limb use and tumor growth on alternate days. CARV effects on the central nervous system were evaluated through immunofluorescence for Fos protein. Molecular docking studies also were performed to evaluate intermolecular interactions of the carvacrol and muscimol, as ligands of interleukin-10 and GABAA receptors. KEY FINDINGS CARV was able to significantly reduce mechanical hyperalgesia and spontaneous and palpation-induced nociception, improve use paw, decrease the number of positively marked neurons in lumbar spinal cord and activate periaqueductal gray, nucleus raphe magnus and locus coeruleus. CARV also caused significant decreased tumor growth. Docking studies showed favorable interaction overlay of the CARV with IL-10 and GABAA. SIGNIFICANCE Together, these results demonstrated that CARV may be an interesting option for the development of new analgesic drugs for the management of cancer pain.

Self-organizing maps of molecular descriptors for sesquiterpene lactones and their application to the chemotaxonomy of the Asteraceae family.

The Asteraceae, one of the largest families among angiosperms, is chemically characterised by the production of sesquiterpene lactones (SLs). A total of 1,111 SLs, which were extracted from 658 species, 161 genera, 63 subtribes and 15 tribes of Asteraceae, were represented and registered in two dimensions in the SISTEMATX, an in-house software system, and were associated with their botanical sources. The respective 11 block of descriptors: Constitutional, Functional groups, BCUT, Atom-centred, 2D autocorrelations, Topological, Geometrical, RDF, 3D-MoRSE, GETAWAY and WHIM were used as input data to separate the botanical occurrences through self-organising maps. Maps that were generated with each descriptor divided the Asteraceae tribes, with total index values between 66.7% and 83.6%. The analysis of the results shows evident similarities among the Heliantheae, Helenieae and Eupatorieae tribes as well as between the Anthemideae and Inuleae tribes. Those observations are in agreement with systematic classifications that were proposed by Bremer, which use mainly morphological and molecular data, therefore chemical markers partially corroborate with these classifications. The results demonstrate that the atom-centred and RDF descriptors can be used as a tool for taxonomic classification in low hierarchical levels, such as tribes. Descriptors obtained through fragments or by the two-dimensional representation of the SL structures were sufficient to obtain significant results, and better results were not achieved by using descriptors derived from three-dimensional representations of SLs. Such models based on physico-chemical properties can project new design SLs, similar structures from literature or even unreported structures in two-dimensional chemical space. Therefore, the generated SOMs can predict the most probable tribe where a biologically active molecule can be found according Bremer classification.

Chemometric studies on potential larvicidal compounds against Aedes aegypti.

The mosquito Aedes aegypti (Diptera, Culicidae) is the vector of yellow and dengue fever. In this study, chemometric tools, such as, Principal Component Analysis (PCA), Consensus PCA (CPCA), and Partial Least Squares Regression (PLS), were applied to a set of fifty five active compounds against Ae. aegypti larvae, which includes terpenes, cyclic alcohols, phenolic compounds, and their synthetic derivatives. The calculations were performed using the VolSurf+ program. CPCA analysis suggests that the higher weight blocks of descriptors were SIZE/SHAPE, DRY, and H2O. The PCA was generated with 48 descriptors selected from the previous blocks. The scores plot showed good separation between more and less potent compounds. The first two PCs accounted for over 60% of the data variance. The best model obtained in PLS, after validation leave-one-out, exhibited q(2) = 0.679 and r(2) = 0.714. External prediction model was R(2) = 0.623. The independent variables having a hydrophobic profile were strongly correlated to the biological data. The interaction maps generated with the GRID force field showed that the most active compounds exhibit more interaction with the DRY probe.

Molecular Modeling and Physicochemical Properties of Supramolecular Complexes of Limonene with α- and β-Cyclodextrins

This study evaluated three different methods for the formation of an inclusion complex between alpha- and beta-cyclodextrin (α- and β-CD) and limonene (LIM) with the goal of improving the physicochemical properties of limonene. The study samples were prepared through physical mixing (PM), paste complexation (PC), and slurry complexation (SC) methods in the molar ratio of 1:1 (cyclodextrin:limonene). The complexes prepared were evaluated with thermogravimetry/derivate thermogravimetry, infrared spectroscopy, X-ray diffraction, complexation efficiency through gas chromatography/mass spectrometry analyses, molecular modeling, and nuclear magnetic resonance. The results showed that the physical mixing procedure did not produce complexation, but the paste and slurry methods produced inclusion complexes, which demonstrated interactions outside of the cavity of the CDs. However, the paste obtained with β-cyclodextrin did not demonstrate complexation in the gas chromatographic technique because, after extraction, most of the limonene was either surface-adsorbed by β-cyclodextrin or volatilized during the procedure. We conclude that paste complexation and slurry complexation are effective and economic methods to improve the physicochemical character of limonene and could have important applications in pharmacological activities in terms of an increase in solubility.

Antileishmanial activity of new thiophene-indole hybrids: Design, synthesis, biological and cytotoxic evaluation, and chemometric studies.

In the present work, thirty-two hybrid compounds containing cycloalka[b]thiophene and indole moieties (TN5, TN5 1-7, TN6, TN6 1-7, TN7, TN7 1-7, TN8, TN8 1-7) were designed, synthesized and evaluated for their cytotoxic and antileishmanial activity against Leishmania amazonensis promastigotes. More than half of the compounds (18 compounds) exhibited significant antileishmanial activity (IC50 lower than 10.0μg/L), showing better performance than the reference drugs (tri- and penta-valent antimonials). The most active compounds were TN8-7, TN6-1 and TN7 with respective IC50 values of 2.1, 2.3 and 3.2μg/mL. Demonstrating that all of the compounds were less toxic than the reference drugs, even at the highest evaluated concentration (400μg/mL), no compound tested presented human erythrocyte cytotoxicity. Compound TN8-7s effectiveness against a trivalent antimony-resistant culture was demonstrated. It was observed that TN8-7s antileishmanial activity is associated with DNA fragmentation of L. amazonensis promastigotes. Chemometric studies (CPCA, PCA, and PLS) highlight intrinsic solubility/lipophilicity, and compound size and shape as closely related to activity. Our results suggest that hybrid cycloalka[b]thiophene-indole derivatives may be considered as lead compounds for further development of new drugs for the treatment of leishmaniasis.

Comparative computational studies of 3,4-dihydro-2,6-diaryl-4-oxo-pyrimidine-5-carbonitrile derivatives as potential antinociceptive agents.

In this study, the antinociceptive properties of 3,4-dihydro-2,6-diaryl-4-oxo-pyrimidine-5-carbonitrile derivatives 5a–i at doses of 25 and 50 mg/kg were evaluated in mice, using the abdominal constriction test. Molecular modeling studies were also performed using density functional theory calculations. These data provided information about the electrostatic and ionization potentials and were used to compare the antinociceptive activity of the title compounds. The most active compounds were 3,4-dihydro-2-(4-chlorophenyl)-6-(4-methoxyphenyl)-4-oxo-pyrimidine-5-carbonitrile (5b) and 3,4-dihydro-2,6-diphenyl-4-oxo-pyrimidine-5-carbonitrile (5i), which inhibited the number of abdominal constrictions, at 50 mg/kg dose, in 88.6% and 88% of the sample, respectively. A preliminary SAR study demonstrated that halogen replacement in the phenyl rings of the compounds under study reduces the antinociceptive activity. DFT calculations showed that there is a high correlation between the ionization potentials and the analgesic properties of the compounds. It was found that compounds with a positive ionization potential (compounds 5b and 5i) were found to be the best analgesic drugs in this series.

Docking and PLS Studies on a Set of Thiophenes RNA Polymerase Inhibitors Against Staphylococcus aureus

Staphylococcus aureus lives in commensalism with the majority of the population, being recognized as an important pathogen in patients with chronic liver diseases and can cause a deadly infection. The use of antibiotics as rifampin for the chemotherapy of infections caused by S. aureus has resulted in the selection of mutants with resistance. In an attempt to combat resistant strains new research is continuously conducted, as example searching new biological targets or new inhibitors such as tiophenes derivatives that can inhibit the RNA polymerase enzyme. This work investigated the set of tiophenes, selected from of literature and with RNA polymerase enzyme inhibitory activity of S. aureus. After seeking further information on existing scientific literature, the compounds under study were applied the methodologies of PLS, docking and calculation of Molecular Interaction Fields (MIFs) using Pentacle and VolSurf programmes. In addition, a comparison was made with two tiophenes synthesized in our laboratory and which have been tested against the bacteria. Docking studies showed that active compounds had more interactions with the amino acids on active site when compared with rifampicin. The best model obtained in PLS, considering two LVs (latent variables), after leave-one-outvalidation, exhibited the statistical parameters qcv(2) = 0.68 and r(2) = 0.85. External prediction model presented a rext(2) = 0.67. The obtained model through PLS analyses was able to predict the behavior of compounds synthesized by us. So we extract structural features important for the activity of these compounds. In this paper, first we discussed the topics: S. aureus, tiophenes, RNA polymerase, docking and QSAR methodologies. Then we have selected a series of 56 tiophenes from literature, which have their biological activity tested against the RNA polymerase enzyme of S. aureus. The compounds were subsequently carried out for Partial Least Squares (PLS) Analysis.

Sesquiterpene Lactones with Anti-Hepatitis C Virus Activity Using Molecular Descriptors

Hepatitis C is a worldwide public health problem. The available therapies are limited by their partial effectiveness and with meaningful side-effects. Sesquiterpene lactones (SLs) are a group of natural products with a wide variety of chemical structures and biological activities associated. There are few studies about the influence of the molecular structure of SLs for the anti-hepatitis C virus activity. In the present work, SLs are investigated in a subgenomic RNA replicon assay system and were analyzed using multiple linear regression along with self-organizing maps with DRAGON descriptors in order to identify the structural requirements for their biological activity and to predict the inhibitory potency of SLs. Characteristics such as stereochemistry and electronic effects demonstrated to be important for their anti-HCV activity, and the SOM produced a clear separation betwenn active and inactive compounds. Therefore, it is possible to use this map as a filter for virtual screening to predict the anti-HCV activity of SLs.

Computer-Aided Drug Design Studies in Food Chemistry

In silico methods or computer-aided drug design (CADD) studies, which involve an understanding of molecular interactions from both a qualitative and quantitative point of view, are increasingly being used in both industrial and academic settings. Analysis of the molecular structure of a given system allows relevant information to be extracted, and the potential of bioactive compounds to be predicted. In silico tools used in medicinal chemistry include chemometric methods, structure–activity relationships (SAR), mole cular modeling, and quantitative structure–activity relationships (QSAR), which correlate the structural or property descriptors of compounds to several types of biological activities. This chapter will report some studies to show how computational chemistry can be used to predict important chemical structure information and how these techniques can be applied in food research.