Microwave-assisted solid-phase synthesis of nicotinyl hydrazones for use in radiochemistry of technetium-99m

We report a new method for efficient and rapid synthesis of HYNIC-hydrazone derivatives using microwaveassisted solid-phase. In comparison to the conventional heating procedure, microwave irradiation considerably accelerated the formation of HYNIC analogues. The synthesis time and efforts are significantly reduced in the present method, without side product formation. We proved that the HYNIC-hydrazone clustering can be directly labeled with technetium without exposing the free hydrazine group. Therefore, this is a useful tool to obtain HYNIC-bioconjugates for use in 99mTc radiochemistry

Compreendendo as formas sólidas de 5E-(feniletenil)benzofuroxano com diferente atividade anti-T. cruzi in vivo

5E-Phenylethenylbenzofuroxan (5PhEBfx) was reported as an excellent anti-Chagas drug candidate. However, its oral bioavailability was affected by the crystallization process. Two samples exhibiting variable in vivo activity was investigated: a thin yellow powder (5PhEBfx-Y) and orange needles (5PhEBfx-O). X-ray powder diffraction, differential scanning calorimetry, vibrational spectroscopy, optical and electron scanning microscopies were applied to investigate both solid forms in order to correlate the solid-state properties with the variable bioavailability of 5PhEBfx. It was observed that 5PhEBfx-Y have a better solubility and consequently higher bioavailability when compared with 5PhEBfx-O. This result suggests that the difference of activity between these two 5E-Phenylethenylbenzofuroxanes could be associated with the solid forms, which also cause the coloration variation.CAPESFINEPInstituto de Pesquisa e Desenvolvimento Institucional (IPDI)FUNCAPPrograma Sul-Americano de Apoio às Atividades de Cooperação em Ciência e Tecnologia (PROSUL) - CNPqDrugs for Neglected Diseases initiative (DNDi

In vivo anti-chagas vinylthio-, vinylsulfinyl-, and vinylsulfonylbenzofuroxan derivatives

New benzofuroxans were developed and studied as antiproliferative Trypanosoma cruzi agents. Compounds displayed remarkable in vitro activities against different strains, Tulahuen 2, CL Brener and Y. Its unspecific cytotoxicity was evaluated using human macrophages being not toxic at a concentration at least 8 times, and until 250 times, that of its T. cruzi IC50. Some biochemical pathways were studied, namely parasite respiration, cysteinyl active site enzymes and reaction with glutathione, as target for the mechanism of action. Not only T. cruzi respiration but also Cruzipain or trypanothione reductase were not affected, however the most active derivatives, the vinylsulfinyl- and vinylsulfonyl-containing benzofuroxans, react with glutathione in a redox pathway. Furthermore, the compounds showed good in vivo activities when they were studied in an acute murine model of Chagas' disease. The compounds were able to reduce the parasite loads of animals with fully established T. cruzi infections. © 2007 American Chemical Society.Peer Reviewe

Identification of Thioredoxin Glutathione Reductase Inhibitors That Kill Cestode and Trematode Parasites

Parasitic flatworms are responsible for serious infectious diseases that affect humans as well as livestock animals in vast regions of the world. Yet, the drug armamentarium available for treatment of these infections is limited: praziquantel is the single drug currently available for 200 million people infected with Schistosoma spp. and there is justified concern about emergence of drug resistance. Thioredoxin glutathione reductase (TGR) is an essential core enzyme for redox homeostasis in flatworm parasites. In this work, we searched for flatworm TGR inhibitors testing compounds belonging to various families known to inhibit thioredoxin reductase or TGR and also additional electrophilic compounds. Several furoxans and one thiadiazole potently inhibited TGRs from both classes of parasitic flatworms: cestoda (tapeworms) and trematoda (flukes), while several benzofuroxans and a quinoxaline moderately inhibited TGRs. Remarkably, five active compounds from diverse families possessed a phenylsulfonyl group, strongly suggesting that this moiety is a new pharmacophore. The most active inhibitors were further characterized and displayed slow and nearly irreversible binding to TGR. These compounds efficiently killed Echinococcus granulosus larval worms and Fasciola hepatica newly excysted juveniles in vitro at a 20 µM concentration. Our results support the concept that the redox metabolism of flatworm parasites is precarious and particularly susceptible to destabilization, show that furoxans can be used to target both flukes and tapeworms, and identified phenylsulfonyl as a new drug-hit moiety for both classes of flatworm parasites

Garbage in, garbage out: how reliable training data improved a virtual screening approach against SARS-CoV-2 MPro

Introduction: The identification of chemical compounds that interfere with SARS-CoV-2 replication continues to be a priority in several academic and pharmaceutical laboratories. Computational tools and approaches have the power to integrate, process and analyze multiple data in a short time. However, these initiatives may yield unrealistic results if the applied models are not inferred from reliable data and the resulting predictions are not confirmed by experimental evidence.Methods: We undertook a drug discovery campaign against the essential major protease (MPro) from SARS-CoV-2, which relied on an in silico search strategy –performed in a large and diverse chemolibrary– complemented by experimental validation. The computational method comprises a recently reported ligand-based approach developed upon refinement/learning cycles, and structure-based approximations. Search models were applied to both retrospective (in silico) and prospective (experimentally confirmed) screening.Results: The first generation of ligand-based models were fed by data, which to a great extent, had not been published in peer-reviewed articles. The first screening campaign performed with 188 compounds (46 in silico hits and 100 analogues, and 40 unrelated compounds: flavonols and pyrazoles) yielded three hits against MPro (IC50 ≤ 25 μM): two analogues of in silico hits (one glycoside and one benzo-thiazol) and one flavonol. A second generation of ligand-based models was developed based on this negative information and newly published peer-reviewed data for MPro inhibitors. This led to 43 new hit candidates belonging to different chemical families. From 45 compounds (28 in silico hits and 17 related analogues) tested in the second screening campaign, eight inhibited MPro with IC50 = 0.12–20 μM and five of them also impaired the proliferation of SARS-CoV-2 in Vero cells (EC50 7–45 μM).Discussion: Our study provides an example of a virtuous loop between computational and experimental approaches applied to target-focused drug discovery against a major and global pathogen, reaffirming the well-known “garbage in, garbage out” machine learning principle

Microwave-assisted solid-phase synthesis of a 1,2-disubstituted benzimidazole library by using a phosphonium linker

An efficient and rapid microwave-assisted solid-phase method for the synthesis of 5-methyl-1,2-disubstituted benzimidazoles derivatives has been developed. The phosphonium linker, obtained by reaction between polymer-supported triphenylphosphine and 4-fluoro-3-nitrobenzyl iodide, underwent aromatic substitution with primary amines, followed by one-pot reaction with aldehydes in the presence of SnCl2·2H 2O, yielded the benzimidazole system under microwave irradiation. The final products were released from the resin with NaOH under microwave irradiation and were obtained in high purity and good overall yield. © 2013 HeteroCorporation.Peer Reviewe

Green Conditions for Passerini Three-Component Synthesis of Tocopherol Analogues

A Passerini three-component reaction of a furoxan aldehyde, phenylethylisocyanide, and trolox derivatives under green conditions are reported. The Passerini reaction to obtain tocopherol mimetics can be efficiently carried out either solvent-free or in aqueous conditions under microwave irradiation, which are standards of green chemistry and characteristic of an ideal synthesis