Reposicionamento de fármacos: análise antiproliferativa e ultraestrutural desencadeada por fármacos e compostos da covid-box disponibilizada pela medicines for malaria venture contra taquizoítos de Toxoplasma gondii

Abstract

Despite the medical significance of toxoplasmosis, the availabil ity of drugs for its treatment is limited. Additionally, the resistance of some parasite strains to certain treatments poses an additional challenge. The current standard treatment, which consists of a combination of pyrimethamine and sulfadiazine, is effective only in the acute phase of the disease and is often associated with significant adverse effects, which can lead to treatment interruption. Therefore, it is crucial to explore new therapeutic options for toxoplasmosis. In this study, we conducted a screening of drugs and compounds contained in the Covid-Box with the aim of identifying potential treatments for toxoplasmosis. The Covid-Box is an initiative of the Medicines for Malaria Venture (MMV), dedicated to developing treatments for malaria and providing a library of promising drugs and compounds with potential for the treatment of neglected diseases. This library contains 160 drugs and compounds, already marketed or in development, with known or predicted activity against SARS-CoV-2. To evaluate the efficacy of these drugs and compounds against T. gondii, in vitro assays were performed using NHDF (Neonatal Human Dermal Fibroblasts) cells infected with taquizoites of the RH strain and treated with the drugs at a concentration of 1 μM. After seven days of treatment, the anti-T. gondii activity was evaluated by measuring the total area of the wells of the plates with monolayers of infected and treated NHDF cells using ImageJ software. From this analysis, we identified 23 drugs and compounds from the Covid-Box that inhibited the RH strain taquizoites of T. gondii by more than 70%. Most of these compounds showed IC50 values below 0.1 µM, with Cicloheximide and (-) - Anisomicin standing out, which presented IC50 values of 0.02 μM. Cell viability assays demonstrated that these compounds are not toxic at active concentrations against the parasite, being highly selective for T. gondii. Additionally, in silico analysis, most of the selected drugs met the ideal pharmacological parameters, complying with Lipinski's rules (1997) and Veber et al. criteria. (2002). To better understand the mode of action of these drugs, we investigated changes in the ultrastructu re of T. gondii after treatment with six selected drugs from in vitro and in silico assays, using transmission electron microscopy. The main changes observed in the morphology of the parasites included modifications in cell division and in vital organelles for the parasite's survival, such as the endoplasmic reticulum, the Golgi complex, and the rhoptries.