CoMFA analysis of tgDHFR and rlDHFR based on antifolates with 6-5 fused ring system using the all-orientation search (AOS) routine and a modified cross-validated r(2)-guided region selection (q(2)-GRS) routine and its initial application

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.

Perspective on current and emerging drugs in the treatment of acute and chronic toxoplasmosis

No new drugs for treatment of toxoplasmosis have been approved in over 60 years, despite the burden of toxoplasmosis on human society. The small selection of effective drugs is limited by important side effects, often limiting patient use. This perspective highlights promising late-stage drug candidates in the treatment of toxoplasmosis. Presently, drugs target the tachyzoite form of the parasite Toxoplasma gondii responsible for the acute infection but do not eradicate the tissue cyst form underlying chronic infection. Pyrimethamine - the first-line and only approved drug for treatment of toxoplasmosis in the United States - inhibits parasite DNA synthesis by inhibiting dihydrofolate reductase (DHFR). Two novel DHFR inhibitors with improved potency and selectivity for parasite DHFR over human DHFR are in clinical-stage development. One of the most advanced and promising therapeutic targets, demonstrating potential to treat both acute and chronic toxoplasmosis, is the calcium-dependent protein kinase 1 (CDPK1) which plays an essential role in the intracellular replicative cycle of the parasite, and has no direct mammalian homolog. Two CDPK1 inhibitor programs have identified potent and selective lead series, demonstrating acceptable systemic and CNS exposure, and in vivo efficacy in animal models of acute and chronic infection. Physicians need a better arsenal of parasiticidal drugs for the treatment of toxoplasmosis, particularly those active against tissue cysts.

Review of Experimental Compounds Demonstrating Anti-Toxoplasma Activity

Toxoplasma gondii is a ubiquitous apicomplexan parasite capable of infecting humans and other animals. Current treatment options for T. gondii infection are limited and most have drawbacks, including high toxicity and low tolerability. Additionally, no FDA-approved treatments are available for pregnant women, a high-risk population due to transplacental infection. Therefore, the development of novel treatment options is needed. To aid this effort, this review highlights experimental compounds that, at a minimum, demonstrate inhibition of in vitro growth of T. gondii When available, host cell toxicity and in vivo data are also discussed. The purpose of this review is to facilitate additional development of anti-Toxoplasma compounds and potentially to extend our knowledge of the parasite.

Dihydrofolate reductase as a therapeutic target for infectious diseases: opportunities and challenges

Infectious diseases caused by parasites continue to take a massive toll on human health in the poor regions of the world. Filling the anti-infective drug-discovery pipeline has never been as challenging as it is now. The organisms responsible for these diseases have interesting biology with many potential biochemical targets. Inhibition of metabolic enzymes has been established as an attractive strategy for anti-infectious drug development. In this field, dihydrofolate reductase (DHFR) is an important enzyme in nucleic and amino acid synthesis and an extensively studied drug target over the past 50 years. The challenges for novel DHFR inhibition-based chemotherapeutics for the treatment of infectious diseases are now focused on overcoming the resistance problem as well as cost–effectiveness. Each year, the large number of literature citations attest the continued popularity of DHFR. It becomes truly the ‘enzyme of choice for all seasons and almost all reasons’. Herein, we summarize the opportunities and challenges in developing novel lead based on this target.