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Two-dimensional bond-based bilinear indices and linear discriminant analysis are used in this report to perform a quantitative structure-activity relationship study to identify new trypanosomicidal compounds. A data set of 440 organic chemicals, 143 with antitrypanosomal activity and 297 having other clinical uses, is used to develop the theoretical models. Two discriminant models, computed using bond-based bilinear indices, are developed and both show accuracies higher than 86% for training and test sets. The stochastic model correctly indentifies nine out of eleven compounds of a set of organic chemicals obtained from our synthetic collaborators. The in vitro antitrypanosomal activity of this set against epimastigote forms of Trypanosoma cruzi is assayed. Both models show a good agreement between theoretical predictions and experimental results. Three compounds showed IC50 values for epimastigote elimination (AE) lower than 50 μM, while for the benznidazole the IC50 = 54.7 μM which was used as reference compound. The value of IC50 for cytotoxicity of these compounds is at least 5 times greater than their value of IC50 for AE. Finally, we can say that, the present algorithm constitutes a step forward in the search for efficient ways of discovering new antitrypanosomal compounds., (Copyright © 2015 Elsevier Masson SAS. All rights reserved.)

Chagas disease chemotherapy, currently based on only two drugs, nifurtimox and benznidazole, is far from satisfactory and therefore the development of new antichagasic compounds remains an important goal. On the basis of antichagasic properties previously described for some 1,2-disubstituted 5-nitroindazolin-3-ones (21, 33) and in order to initiate the optimization of activity of this kind of compounds, we have prepared a series of related analogs (22-32, 34-38, 58 and 59) and tested in vitro these products against epimastigote forms of Trypanosoma cruzi. 2-Benzyl-1-propyl (22), 2-benzyl-1-isopropyl (23) and 2-benzyl-1-butyl (24) derivatives have shown high trypanocidal activity and low unspecific toxicity. Other indazole derivatives with different substitution patterns (1-substituted 3-alkoxy-1H-indazoles and 2-substituted 3-alkoxy-2H-indazoles), arising from the synthetic procedures used to prepare the mentioned indazolinones, have moderate to low effectiveness. The exploration of SAR information using the concept of an activity landscape has been carried out with SARANEA software. We have also searched for structural similarities between 225 known antiprotozoan drugs and compound 22. The results confirm that compounds 22-24 constitute promising leads and that 5-nitroindazolin-3-one system is a novel anti-T. cruzi scaffold which may represent an important therapeutic alternative for the treatment of Chagas disease., (Copyright © 2012 Elsevier Masson SAS. All rights reserved.)

Two-dimensional bond-based linear indices and linear discriminant analysis are used in this report to perform a quantitative structure-activity relationship study to identify new trypanosomicidal compounds. A database with 143 anti-trypanosomal and 297 compounds having other clinical uses, are utilized to develop the theoretical models. The best discriminant models computed using bond-based linear indices provides accuracies greater than 90 for both training and test sets. Our models identify as anti-trypanosomals five out of nine compounds of a set of already-synthesized substances. The in vitro anti-trypanosomal activity of this set against epimastigote forms of Trypanosoma cruzi is assayed. Both models show a perfect agreement between theoretical predictions and experimental results. The compounds identified as active ones show more than 98% of anti-epimastigote elimination (AE) at a concentration of 100 μg/mL. Besides, three compounds show more than 70% of AE at a concentration of 10 μg/mL. Finally, compounds with the best "activity against epimastigote forms/unspecific cytotoxicity" ratio are evaluated using an amastigote susceptibility assay. It should be noticed that, compound Va7-71 exhibit a 100% of intracellular amastigote elimination and shows similar activity when compared to a standard trypanosomicidal as nifurtimox. Finally, we can emphasize that, the present algorithm constitutes a step forward in the search for efficient ways of discovering new anti-trypanosomal compounds., (Copyright © 2011 Elsevier Masson SAS. All rights reserved.)

The synthesis and potent antiprotozoal activity of 14-hydroxylunularin, a natural hydroxybibenzyl bryophyte constituent is reported. 14-hydroxylunularin was highly active in vitro assays against culture and intracellular forms of Leishmania spp. and Trypanosoma. cruzi, in absence of cytotoxicity against mammalian cells. Preliminary structure-activity relationship studies showed that the reported bioactivity depends on hybridization at the carbon-carbon bridge, position and number of free hydroxy group on the aromatic rings. The reported results were also in agreement with the in silico prediction using Non-Stochastic Quadratic Fingerprints-based algorithms. The same compound also showed antiprotozoal activity in Leishmania spp. infected mice by oral and subcutaneous administration routes, with an optimal treatment of a daily subcutaneous administration of 10 mg/kg of body weight for 15 days. This study suggested that 14-hydroxylunularin may be chosen as a new candidate in the development of leishmanicidal therapy.