In Vitro Evaluation of Anti-Parasitic Activities of Quinolone-Coumarin Hybrids Derived from Fluoroquinolones and Novobiocin Against Toxoplasma gondii

Purpose Toxoplasmosis is caused by the parasite Toxoplasma gondii ( T. gondii ). In immunocompetent individuals, the infection is often asymptomatic; however, in expectant mothers and those with immune system deficiencies, complications may arise. Consequently, there is a need for new drugs that cause minimal damage to host cells. The purpose of this study was to investigate the in vitro antiparasitic efficacy of quinolone–coumarin hybrids QC1–QC12 , derived from quinolone antibacterials and novobiocin, against T. gondii . Methods The derivatives were compared with novobiocin and ciprofloxacin during testing, with pyrimethamine used as a positive control. We conducted the MTT assay to examine the anti-toxoplasmic effects of the test compounds and novobiocin. Evaluation included the infection and proliferation indices, as well as the size and number of plaques, based on the viability of both healthy and infected cells. Results The in vitro assays revealed that QC1, QC3, QC6 , and novobiocin, with selectivity indices (SIs) of 7.27, 13.43, and 8.23, respectively, had the least toxic effect on healthy cells and the highest effect on infected cells compared to pyrimethamine (SI = 3.05). Compared to pyrimethamine, QC1, QC3, QC6 , and novobiocin Without having a significant effect on cell viability, demonstrated a significant effect on reducing in both infection index and proliferation index, in addition to reducing the quantity and dimensions of plaques ( P