Drug Repurposing Based on Protozoan Proteome: In Vitro Evaluation of In Silico Screened Compounds against Toxoplasma gondii

Abstract

Toxoplasma gondii is a protozoan that infects up to a third of the world’s population. This parasite can cause serious problems, especially if a woman is infected during pregnancy, when toxoplasmosis can cause miscarriage, or serious complications to the baby, or in an immunocompromised person, when the infection can possibly affect the patient’s eyes or brain. To identify potential drug candidates that could counter toxoplasmosis, we selected 13 compounds which were pre-screened in silico based on the proteome of T. gondii to be evaluated in vitro against the parasite in a cell-based assay. Among the selected compounds, three demonstrated in vitro anti-T. gondii activity in the nanomolar range (almitrine, bortezomib, and fludarabine), and ten compounds demonstrated anti-T. gondii activity in the micromolar range (digitoxin, digoxin, doxorubicin, fusidic acid, levofloxacin, lomefloxacin, mycophenolic acid, ribavirin, trimethoprim, and valproic acid). Almitrine demonstrated a Selectivity Index (provided by the ratio between the Half Cytotoxic Concentration against human foreskin fibroblasts and the Half Effective Concentration against T. gondii tachyzoites) that was higher than 47, whilst being considered a lead compound against T. gondii. Almitrine showed interactions with the Na+/K+ ATPase transporter for Homo sapiens and Mus musculus, indicating a possible mechanism of action of this compound.

Repurposing the Medicines for Malaria Venture’s COVID Box to discover potent inhibitors of Toxoplasma gondii, and in vivo efficacy evaluation of almitrine bismesylate (MMV1804175) in chronically infected mice

“…In a previous study [24], eight compounds from the COVID Box, which had undergone an in silico screening based on the proteome of T. gondii, were in vitro evaluated against the parasite. Among these compounds, anti-T. gondii activity at the nanomolar range, along with selective activity, was observed only for almitrine.…”

“…Furthermore, testing this compound against other experimental models of toxoplasmosis would be worthwhile. Based on a molecular docking previously performed [24] almitrine is a strong candidate to bind the Na + / K + ATPase transporter as part of their mechanisms of action. However, further studies are needed to confirm this hypothesis as a possible mechanism of anti-T. gondii action.…”

Anti-Toxoplasma gondii screening of MMV pandemic response box and evaluation of RWJ-67657 efficacy in chronically infected mice

“…Moreover, previous researches have showcased the potential of compounds provided by the 'Medicines for Malaria Venture' (MMV) organization for repositioning in the context of toxoplasmosis (Boyom et al, 2014;Spalenka et al, 2018;Cajazeiro et al, 2022;Dos Santos et al, 2023). In this study, the aim was to identify potential compounds from the MMV Pandemic Response Box (PRB) and explore their repositioning against toxoplasmosis using in silico, in vitro and in vivo approaches.…”

Medicines for Malaria Venture Pandemic Box In Vitro Screening Identifies Compounds Highly Active against the Tachyzoite Stage of Toxoplasma gondii

“…Spalenka et al (2018) and Radke et al (2018) identified, respectively, 25 and 82 Pathogen Box compounds that inhibit T. gondii replication [ 20 , 21 ]. Cajazeiro et al (2022) and Santos et al (2023) demonstrated the activity of COVID Box compounds against T. gondii [ 22 , 23 ]. Pandemic Box compounds were not previously available in Malaria or Pathogen Boxes.…”