Phenolic chalcones as agents against Trichomonas vaginalis.

Trichomonas vaginalis, a flagellated and anaerobic protozoan, is a causative agent of trichomoniasis. This disease is among the world's most common non-viral sexually transmitted infection. A single class drug, nitroimidazoles, is currently available for the trichomoniasis treatment. However, resistant isolates have been identified from unsuccessfully treated patients. Thus, there is a great challenge for a discovery of innovative anti-T. vaginalis agents. As part of our ongoing search for antiprotozoal chalcones, we designed and synthesized a series of 21 phenolic chalcones, which were evaluated against T. vaginalis trophozoites. Structure-activity relationship indicated hydroxyl group plays a role key in antiprotozoal activity. 4'-Hydroxychalcone (4HC) was the most active compound (IC50 = 27.5 µM) and selected for detailed bioassays. In vitro and in vivo evaluations demonstrated 4HC was not toxic against human erythrocytes and Galleria mellonella larvae. Trophozoites of T. vaginalis were treated with 4HC and did not present significant reactive oxygen species (ROS) accumulation. However, compound 4HC was able to increase ROS accumulation in neutrophils coincubated with T. vaginalis. qRT-PCR Experiments indicated that 4HC did not affect the expression of pyruvate:ferredoxin oxidoreductase (PFOR) and ß-tubulin genes. In silico simulations, using purine nucleoside phosphorylase of T. vaginalis (TvPNP), corroborated 4HC as a promising ligand. Compound 4HC was able to establish interactions with residues D21, G20, M180, R28, R87 and T90 through hydrophobic interactions, π-donor hydrogen bond and hydrogen bonds. Altogether, these results open new avenues for phenolic chalcones to combat trichomoniasis, a parasitic neglected infection.

A new complex of silver(I) with probenecid: Synthesis, characterization, and studies of antibacterial and extended spectrum ß-lactamases (ESBL) inhibition activities.

This article describes the in vitro antibacterial and ß-lactamase inhibition of a novel silver(I) complex with the sulfonamide probenecid (Ag-PROB). The formula Ag2C26H36N2O8S2·2H2O for the Ag-PROB complex was proposed based on elemental analysis. High-resolution mass spectrometric studies revealed the existence of the complex in its dimeric form. Infrared, nuclear magnetic resonance spectroscopies and Density Functional Theory calculations indicated a bidentate coordination of probenecid to the silver ions by the oxygen atoms of the carboxylate. In vitro antibacterial activities of Ag-PROB showed significant growth inhibitory activity over Mycobacterium tuberculosis, S. aureus, and P. aeruginosa PA01biofilm-producers, B. cereus, and E. coli. The Ag-PROB complex was active over multi-drug resistant of uropathogenic E. coli extended spectrum ß-lactamases (ESBL) producing (EC958 and BR43), enterohemorrhagic E. coli (O157:H7) and enteroaggregative E. coli (O104:H4). Ag-PROB was able to inhibit CTX-M-15 and TEM-1B ESBL classes, at concentrations below the minimum inhibitory concentration for Ag-PROB, in the presence of ampicillin (AMP) concentration in which EC958 and BR43 bacteria were resistant in the absence of Ag-PROB. These results indicate that, in addition to ESBL inhibition, there is a synergistic antibacterial effect between AMP and the Ag-PROB. Molecular docking results revealed potential key residues involved in interactions between Ag-PROB, CTX-M-15 and TEM1B, suggesting the molecular mechanism of the ESBL inhibition. The obtained results added to the absence of mutagenic activity and low cytotoxic activity over non-tumor cell of the Ag-PROB complex open a new perspective for future in vivo tests demonstrating its potential of use as an antibacterial agent.

Synthesis and Anti-Mycobacterium tuberculosis Activity of Imidazo[2,1-b][1,3]oxazine Derivatives against Multidrug-Resistant Strains.

The emergence of multidrug-resistant strains of M. tuberculosis has raised concerns due to the greater difficulties in patient treatment and higher mortality rates. Herein, we revisited the 2-nitro-6,7-dihydro-5H-imidazo[2,1-b][1,3]oxazine scaffold and identified potent new carbamate derivatives having MIC90 values of 0.18-1.63 µM against Mtb H37Rv. Compounds 47-49, 51-53, and 55 exhibited remarkable activity against a panel of clinical isolates, displaying MIC90 values below 0.5 µM. In Mtb-infected macrophages, several compounds demonstrated a 1-log greater reduction in mycobacterial burden than rifampicin and pretomanid. The compounds tested did not exhibit significant cytotoxicity against three cell lines or any toxicity to Galleria mellonella. Furthermore, the imidazo[2,1-b][1,3]oxazine derivatives did not show substantial activity against other bacteria or fungi. Finally, molecular docking studies revealed that the new compounds could interact with the deazaflavin-dependent nitroreductase (Ddn) in a similar manner to pretomanid. Collectively, our findings highlight the chemical universe of imidazo[2,1-b][1,3]oxazines and their promising potential against MDR-TB.

Computational Strategies Targeting Inhibition of Helicobacter pylori and Cryptococcus neoformans Ureases.

Helicobacter pylori and Cryptococcus ssp. are pathogenic ureolytic microorganisms that cause several disorders in the host organism and, in severe cases, lead to death. Both infections have the urease enzyme as a key virulence factor since they use its ability to produce ammonia to soften the inhospitable pH to which they are subjected. In this review, we describe two ureases as possible molecular targets for drug discovery and provide insights for developing potent inhibitors against ureases from these pathogenic microorganisms through computer-aided drug discovery approaches, such as structure-based drug design (SBDD) and structure-activity relationship (SAR). The SAR studies have indicated several essential subunits and groups to be present in urease inhibitors that are critical for inhibitory activity against H. pylori or Cryptococcus spp. Since the threedimensional structure of C. neoformans urease has yet to be determined experimentally, the plant urease of Canavalia ensiformis was used in this study due to its structural similarity. Therefore, in the SBDD context, FTMap and FTSite analyses were performed to reveal characteristics of the urease active sites in two protein data bank files (4H9M, Canavalia ensiformis, and 6ZJA, H. pylori). Finally, a docking-based analysis was performed to explore the best inhibitors described in the literature to understand the role of the ligand interactions with the key residues in complex ligand-urease stabilization, which can be applied in the design of novel bioactive compounds.

Pharmacophore Mapping Combined with dbCICA Reveal New Structural Features for the Development of Novel Ligands Targeting α4ß2 and α7 Nicotinic Acetylcholine Receptors.

The neuronal nicotinic acetylcholine receptors (nAChRs) belong to the ligand-gated ion channel (GLIC) group, presenting a crucial role in several biological processes and neuronal disorders. The α4ß2 and α7 nAChRs are the most abundant in the central nervous system (CNS), being involved in challenging diseases such as epilepsy, Alzheimer's disease, schizophrenia, and anxiety disorder, as well as alcohol and nicotine dependencies. In addition, in silico-based strategies may contribute to revealing new insights into drug design and virtual screening to find new drug candidates to treat CNS disorders. In this context, the pharmacophore maps were constructed and validated for the orthosteric sites of α4ß2 and α7 nAChRs, through a docking-based Comparative Intermolecular Contacts Analysis (dbCICA). In this sense, bioactive ligands were retrieved from the literature for each receptor. A molecular docking protocol was developed for all ligands in both receptors by using GOLD software, considering GoldScore, ChemScore, ASP, and ChemPLP scoring functions. Output GOLD results were post-processed through dbCICA to identify critical contacts involved in protein-ligand interactions. Moreover, Crossminer software was used to construct a pharmacophoric map based on the most well-behaved ligands and negative contacts from the dbCICA model for each receptor. Both pharmacophore maps were validated by using a ROC curve. The results revealed important features for the ligands, such as the presence of hydrophobic regions, a planar ring, and hydrogen bond donor and acceptor atoms for α4ß2. Parallelly, a non-planar ring region was identified for α7. These results can enable fragment-based drug design (FBDD) strategies, such as fragment growing, linking, and merging, allowing an increase in the activity of known fragments. Thus, our results can contribute to a further understanding of structural subunits presenting the potential for key ligand-receptor interactions, favoring the search in molecular databases and the design of novel ligands.

The Emergence of the New P.4 Lineage of SARS-CoV-2 With Spike L452R Mutation in Brazil.

The emergence of several SARS-CoV-2 lineages presenting adaptive mutations is a matter of concern worldwide due to their potential ability to increase transmission and/or evade the immune response. While performing epidemiological and genomic surveillance of SARS-CoV-2 in samples from Porto Ferreira-São Paulo-Brazil, we identified sequences classified by pangolin as B.1.1.28 harboring Spike L452R mutation, in the RBD region. Phylogenetic analysis revealed that these sequences grouped into a monophyletic branch, with others from Brazil, mainly from the state of São Paulo. The sequences had a set of 15 clade defining amino acid mutations, of which six were in the Spike protein. A new lineage was proposed to Pango and it was accepted and designated P.4. In samples from the city of Porto Ferreira, P.4 lineage has been increasing in frequency since it was first detected in March 2021, corresponding to 34.7% of the samples sequenced in June, the second in prevalence after P.1. Also, it is circulating in 30 cities from the state of São Paulo, and it was also detected in one sample from the state of Sergipe and two from the state of Rio de Janeiro. Further studies are needed to understand whether P.4 should be considered a new threat.

Alzheimer's Disease: Related Targets, Synthesis of Available Drugs, Bioactive Compounds Under Development and Promising Results Obtained from Multi-target Approaches.

We describe herein the therapeutic targets involved in Alzheimer's disease as well as the available drugs and their synthetic routes. Bioactive compounds under development are also exploited to illustrate some recent research advances on the medicinal chemistry of Alzheimer's disease, including structure-activity relationships for some targets. The importance of multi-target approaches, including some examples from our research projects, guides new perspectives in search of more effective drug candidates. This review comprises the period between 2001 and early 2020.

Computational studies, design and synthesis of Pd(II)-based complexes: Allosteric inhibitors of the Human Topoisomerase-IIα.

Herein, a robust docking protocol was developed by using a low-cost workflow to highlight the modulation at ATPase domain from Human Topoisomerase-IIα (TOP2A) towards four novel Pd(II)-complexes bearing N,S-donor ligands. In vitro TOP2A inhibition assay confirmed the ability of them to prevent the enzyme functions into concentration ranging at 6.25-25µM. These results exhibited more effectivity than anticancer agent etoposide (35µM) and merbarone (40-50µM). The compounds were screened via Resazurin assay against MCF-7, MDA-MB-231 (Human breast), DU-145 (Human prostate), A549 (Human lung) and Cal27 (Human tongue) tumor cell lines revealing great cytotoxic effects, primarily to MCF-7 (IC50=1.81-4.46µM). As well, 1-4 exhibited their selectivity index (SI) higher than cisplatin against HEK-293 (human kidney) normal cells, at least 11.6-fold (SI1-4=1.4-5.0; SIcis=0.12). Further, Red Blood Cell hemolytic test suggested in vitro non-toxic character for compound 4, previously evaluated as the most effective TOP2A inhibitor.

Phthalimide Derivatives with Bioactivity against Plasmodium falciparum: Synthesis, Evaluation, and Computational Studies Involving bc 1 Cytochrome Inhibition.

We describe herein the design and synthesis of N-phenyl phthalimide derivatives with inhibitory activities against Plasmodium falciparum (sensitive and resistant strains) in the low micromolar range and noticeable selectivity indices against human cells. The best inhibitor, 4-amino-2-(4-methoxyphenyl)isoindoline-1,3-dione (10), showed a slow-acting mechanism similar to that of atovaquone. Enzymatic assay indicated that 10 inhibited P. falciparum cytochrome bc 1 complex. Molecular docking studies suggested the binding mode of the best hit to Qo site of the cytochrome bc 1 complex. Our findings suggest that 10 is a promising candidate for hit-to-lead development.

MAOS and medicinal chemistry: some important examples from the last years.

This review aims to highlight microwave-assisted organic synthesis as applied to medicinal chemistry in the last years, showing some reactions performed under microwave irradiation for the synthesis of distinct structurally molecules of biological interest, divided into the following groups: antineoplastics, anti-inflammatory, antimicrobial agents, antivirals, agents for the treatment of neglected diseases and central nervous system-acting prototypes.

Microwave-assisted synthesis and structure-activity relationships of neuroactive pyrazolo[3,4-b]pyrrolo[3,4-d]pyridine derivatives.

We described herein the optimization of the synthetic methodology exploited to obtain the pyrazolo[3,4-b]pyrrolo[3,4-d]pyridine sedative prototype 1a and novel analogues designed by successive molecular simplifications. By applying microwave irradiation during the hetero Diels-Alder key-step to obtain the heterotricyclic scaffold, under solvent-free conditions, we were able to obtain the desired compounds in drastically shorter times and better yields. Additionally, in vivo evaluation of the sedative effects of these heterocyclic derivatives showed that 1a and the novel structurally-related analogue 1e were the most efficient compounds to impair the locomotor activity in mice at the dose of 10micromol/kg.

Sedation and antinociception induced by a new pyrazolo[3,4-b]pyrrolo[3,4-d]pyridine derivative (LASSBio-873) is modulated by activation of muscarinic receptors.

New substances designed for the treatment of anxiety have previously been synthesized, which resulted in the identification of four new pyrazolo[3,4-b]pyrrolo[3,4-d]pyridine derivatives structurally designed by using zolpidem as lead compound. Among them, LASSBio-873 was the most potent to produce analgesic, sedative and hypnotic effects. Thus, we investigated the possible mechanisms involved in LASSBio-873-induced sedation, as well as its effects on different models of inflammatory pain. LASSBio-873 (4 mg/kg) reduced locomotor activity of mice in the open field test from 205.2+/-25.6 to 87.6+/-16.2 movements/min. Atropine, a non-selective muscarinic antagonist, prevented the LASSBio-873-induced sedation and increased locomotor activity to 192.9+/-30.2 movements/min. In the formalin test, LASSBio-873 (4 mg/kg) significantly reduced the duration of nociceptive behavior during the inflammatory phase, reducing the control reactivity from 197.6+/-14.5s to 84.4+/-10.3s. Carrageenan reduced the latency for the animal reaction from 5.1+/-0.2s (control) to 2.1+/-0.3s which was completely reverted by LASSBio-873 (6 mg/kg) to 5.6+/-0.6s. Atropine prevented the LASSBio-873-induced antinociceptive and antihyperalgesic activities, indicating the interference of the cholinergic system. LASSBio-873 is a novel prototype of drug that modulates muscarinic activity and could be used for neuropsychiatric and cognitive disorders and other conditions associated to acute and chronic pain.