Marcos Paulo Oliveira Almeida

The phenomenon of antimicrobial resistance (AMR) can occur naturally through spontaneous mutation without major damage; however, the overuse and misuse of antimicrobials is responsible for millions of deaths annually. The development of new drugs is an expensive and slow process, while repositioning active substances to different biological activities is a cheaper and faster option. The aim of this study was to evaluate the possibility of repositioning 640 known chemical compounds provided by the Medicines for Malaria Venture organization for antibacterial and antibiofilm activities against multidrug-resistant Staphylococcus aureus (ATCC and clinical isolated) and Escherichia coli (ATCC and clinical isolated), their cytotoxicity, and prediction of interaction sites between compounds and bacteria. MMV020752 and MMV1578884 against S. aureus ATCC and MMV1579850 against E. coli ATCC presented the lowest minimum inhibitory concentration (MIC) of 0.019 μM. MMV1578884 presented the lowest minimum inhibitory concentration of biofilm (MICB50) of 0.0095 μM and the lowest inhibitory concentration (IC50) of 0.019 μM against S. aureus ATCC. MMV1578884, MMV1580854, MMV027339, and MMV1634081 maintain the viability of HFF cells above 100% at 10 and 20 μM, and their interactions with bacteria occur in lipid and protein regions. It is concluded that drugs already available on the market or in more advanced clinical stages can be repositioned for other targets, even other microorganisms.

Congenital toxoplasmosis, caused by the obligatory intracellular apicomplexan protozoan Toxoplasma gondii, can lead to severe complications during pregnancy, including fetal malformations and spontaneous abortion. In the present study, the anti-T. gondii effects of the natural flavonoid quercetin were evaluated using in vitro, ex vivo, and in silico models. Cell viability and intracellular proliferation of the parasite were determined via colorimetric assays. The lipid droplet assay was analyzed using Nile Red staining, the antioxidant and oxidative stress parameters were determined by biochemical assays, and the cytokine levels were quantified by immunoassays. Our results demonstrated that non-cytotoxic concentrations of quercetin (CC₅₀ > 100 μM) significantly inhibited parasite proliferation (IC₅₀ = 14.10 ± 2.83 μM; SI > 7.09) in an irreversible manner. Quercetin impairs parasite adhesion, invasion, and reinfection capacity. In parallel, quercetin reduced lipid droplet accumulation, restored antioxidant balance by modulating redox biomarkers, and regulated cytokine production, notably increasing IL-4, IL-6, and IL-8 levels. Corroborating the in vitro findings, quercetin significantly reduced T. gondii proliferation in human placental villous explants while preserving tissue architecture and viability. In silico analyses revealed that quercetin binds to the active site of T. gondii hypoxanthine-guanine phosphoribosyltransferase (TgHGPRT) and exhibits favorable pharmacokinetic and drug-likeness properties.

Congenital toxoplasmosis remains a significant therapeutic challenge within the spectrum of Toxoplasma gondii infections is estimated about 190,000 cases per year, with a considerable infection rate worldwide (ca. 29%). This study describes the synthesis and pharmacological evaluation of compound 1, a furanocarboxamide derivative. Compound 1 was synthesized through a four-step route with a 64% global yield. To mimic congenital infection, the compound was evaluated against Toxoplasma gondii in placental cells, demonstrating a half maximal inhibitory concentration (IC50) of 2.91 ± 0.12 mM. Given the phylogenetic proximity within the Apicomplexa phylum, compound 1 was also tested against chloroquine-resistant Plasmodium falciparum, showing potent activity (IC50 of 2.04 ± 1.37 µM). Conversely, evaluation against Trypanosoma cruzi revealed low potency (IC50 of 44.12 ± 0.79 µM) suggesting a more specific profile for apicomplexan parasites. ADME (adsorption distribution metabolism, excretion, and toxicity) profiling indicated high permeability but highlighted pharmacokinetic challenges, including high lipophilicity, low aqueous solubility, and low metabolic stability. To explore the mechanism of action, a computational study was conducted using molecular docking against twenty-six essential Toxoplasma gondii enzymes. Molecular dynamics (MD) simulations of the top eight candidates identified TgCDPK1, PKA, and the cytochrome bc1 complex as the most promising targets. Overall, this work establishes compound 1 as a promising hit for congenital toxoplasmosis and malaria, providing a clear roadmap for future hit-to-lead optimization to overcome its current pharmacokinetic limitations.

Background/Objectives: Toxoplasma gondii, an obligate intracellular parasite, poses a major global health concern owing to its potential for congenital transmission, particularly during pregnancy. Current pharmacological treatments, including spiramycin and pyrimethamine, exhibit limitations in both efficacy and safety, underscoring the need for novel therapeutic strategies. In this study, we investigated the antiparasitic potential of BthTX-II, an Asp49 phospholipase A₂ (PLA₂) isolated from Bothrops jararacussu venom, in human trophoblast cells (BeWo) and third-trimester human placental explants infected with T. gondii. Methods: In vitro assays were performed using BeWo cells infected with T. gondii tachyzoites and treated with non-cytotoxic concentrations of BthTX-II (3.125, 1.56, and 0.78 µg/mL). An ex vivo model employing third-trimester human placental villous explants was used under similar conditions. Parasite proliferation, adhesion, and invasion were assessed alongside host immune response modulation. Results: Our findings demonstrate that BthTX-II reduces T. gondii proliferation in BeWo cells at all tested non-cytotoxic concentrations. The toxin also significantly impaired parasite adhesion and invasion while modulating host immune response by upregulating interleukin (IL)-6, IL-8, and macrophage migration inhibitory factor (MIF), and downregulating vascular endothelial growth factor—potentially disrupting parasite proliferation. In placental villous explants, BthTX-II (1.56 μg/mL) reduced T. gondii proliferation and modulated IL-8, MIF, and tumour necrosis factor-alpha levels without compromising tissue viability. Conclusions: These findings highlight BthTX-II as a potential candidate in toxoplasmosis treatment. Further investigation should focus on its dual role in limiting parasite development and modulating immune responses at the maternal–fetal interface.

Toxoplasma gondii is a globally distributed protozoan parasite and a major cause of congenital infections, particularly in South America. Current therapies for congenital toxoplasmosis are limited by toxicity, long treatment regimens, and suboptimal efficacy, highlighting the urgent need for safer and more effective alternatives. In this study, we evaluated the antiparasitic effects of crude ethanolic extract of Brazilian Red Propolis (BRP) and its isolated compounds, focusing on 7-O-methylvestitol, in human trophoblast (BeWo) cells and third-trimester placental explants. Both BRP and 7-O-methylvestitol significantly reduced T. gondii adhesion, invasion, and intracellular replication, without compromising host cell viability. Ultrastructural analyses revealed irreversible parasite damage, and cytokine profiling demonstrated immunomodulatory effects, with enhanced production of interleukin (IL)-6, IL-8, and macrophage migration inhibitory factor (MIF) in BeWo cells and downregulation of IL-6, MIF, and tumor Necrosis Factor (TNF) in infected placental villi. Notably, 7-O-methylvestitol reproduced and, in some assays, surpassed the antiparasitic activity of BRP, suggesting it as a key bioactive constituent responsible for the therapeutic potential of the extract. These findings support the identification of 7-O-methylvestitol as a promising lead compound for structure-based drug design and repositioning strategies, advancing the development of novel, safe, and targeted therapies against congenital toxoplasmosis.

Congenital Chagas disease (CCD) is caused when Trypanosoma cruzi crosses the placental barrier during pregnancy and reaches the fetus, which can lead to serious consequences in the developing fetus. Current treatment is carried out with nifurtimox or benznidazole, but their effectiveness is limited, and they cause side effects, requiring the search for new therapeutic strategies. In this sense, many studies have demonstrated the potential of different compounds of the Copaifera genus in the control of parasitic diseases. Here, we aimed to evaluate the effect of oleoresin (OR) and leaf hydroalcoholic extract (LHE) of Copaifera multijuga on Trypanosoma cruzi infection in human villous trophoblast cells (BeWo line) and human placenta explants. Treatment with both compounds reduced invasion, proliferation, and release of trypomastigotes. Furthermore, OR and LHE affected the trypomastigotes and amastigote morphology, compromising their ability to invade and proliferate in BeWo cells, respectively. Also, treatment with OR decreased ROS production in infected BeWo cells, while LHE induced an increase. In addition, both compounds induced pro-inflammatory and anti-inflammatory cytokine production. In human placental explants, both compounds also decreased T. cruzi infection, in addition to inducing the production of pro-inflammatory cytokines. Thus, both OR and LHE of C. multijuga control T. cruzi infection at the human maternal–fetal interface, highlighting the possible therapeutic potential of these compounds for the treatment of CCD.