Chemotherapeutics for Toxoplasma gondii: Molecular Biotargets, Binding Modes, and Structure-Activity Relationship Investigations.

Toxoplasmosis, an infectious zoonotic disease caused by the apicomplexan parasite Toxoplasma gondii (T. gondii), is a major worldwide health problem. However, there are currently no effective options (chemotherapeutic drugs or prophylactic vaccines) for treating chronic latent toxoplasmosis infection. Accordingly, seeking more effective and safer chemotherapeutics for combating this disease remains a long-term and challenging objective. In this paper, we summarize possible molecular biotargets, with an emphasis on those that are druggable and promising, including, without limitation, calcium-dependent protein kinase 1, bifunctional thymidylate synthase-dihydrofolate reductase, and farnesyl diphosphate synthase. Meanwhile, as important components of medicinal chemistry, the binding modes and structure-activity relationship profiles of the corresponding inhibitors were also illuminated. We anticipate that this information will be helpful for further identification of more effective chemotherapeutic interventions to prevent and treat zoonotic infections caused by T. gondii.

Design, synthesis, biological evaluation and molecular docking study on peptidomimetic analogues of XK469.

XK469 is identified as a potent quinoxaline antineoplastic agent based on its significant clinical efficacy. It probably exerts its activity via DNA topoisomerase II (topo II) inhibition. To obtain more effective antineoplastic agents, a spectrum of peptidomimetic-type quinoxaline analogues of XK469 was herein designed, synthesized, and evaluated. Few compounds (e.g. 13a and 13b) exhibited obvious cytotoxicity indicated by in vitro anti-proliferative assay. SAR investigation revealed that introducing of hydrophobic tert-butylamine or dodecylamine moiety at the 3-position of quinoxaline core is favorable for achieving a better anti-proliferative potency, while peptidomimetic derivatives only yielded moderate cytotoxicity. Compounds with improved anti-proliferative activities also demonstrated decent anti-metastatic potencies comparable with that of doxorubicin (Doxo) based on in vivo mouse model study. The topo II-mediated kinetoplast DNA (kDNA) decatenation assay as well as molecular docking studies implicated that these compounds tend to be potent topo II inhibitors. Overall, compounds 13a and 13b, 13b in particular, standed out from various assessments and might be promising candidates for further chemical optimization.