Acridones Are Highly Potent Inhibitors of Tachyzoites.

Acridone derivatives, which have been shown to have and activity against spp, inhibit proliferation at picomolar concentrations. Using enzymatic assays, we show that acridones inhibit both cytochrome and dihydroorotate dehydrogenase and identify acridones that bind preferentially to the Q site of cytochrome . We identify acridones that have efficacy in a murine model of systemic toxoplasmosis.

Targeted Structure-Activity Analysis of Endochin-like Quinolones Reveals Potent Qi and Qo Site Inhibitors of Toxoplasma gondii and Plasmodium falciparum Cytochrome bc and Identifies ELQ-400 as a Remarkably Effective Compound against Acute Experimental Toxoplasmosis.

Cytochrome bc inhibitors have been broadly studied as human and veterinary medicines and agricultural fungicides. For the most part, cytochrome bc inhibitors compete with ubiquinol at the ubiquinol oxidation (Qo) site or with ubiquinone at the quinone reduction (Qi) site. 4(1 H)-Quinolones with 3-position substituents may inhibit either site based on quinolone ring substituents.