Novel acyl carbamates and acyl / diacyl ureas show in vitro efficacy against Toxoplasma gondii and Cryptosporidium parvum

Abstract

Toxoplasma gondii and Cryptosporidium parvum are protozoan parasites that are highly prevalent and opportunistically infect humans worldwide, but for which completely effective and safe medications are lacking. Herein, we synthesized a series of novel small molecules bearing the diacyl urea scaffold and related structures, and screened them for in vitro cytotoxicity and antiparasitic activity against T. gondii and C. parvum . We identified one compound (GMG-1-09), and four compounds (JS-1-09, JS-2-20, JS-2-35 and JS-2-49) with efficacy against C. parvum and T. gondii , respectively, at low micromolar concentrations and showed appreciable selectivity in human host cells. Among the four compounds with efficacy against T. gondii , JS-1-09 representing the diacyl urea scaffold was the most effective, with an anti- Toxoplasma IC 50 concentration (1.21 μM) that was nearly 53-fold lower than its cytotoxicity IC 50 concentration, indicating that this compound has a good selectivity index. The other three compounds (JS-2-20, JS-2-35 and JS-2-49) were structurally more divergent from JS-1-09 as they represent the acyl urea and acyl carbamate scaffold. This appeared to correlate with their anti- Toxoplasma activity, suggesting that these compounds’ potency can likely be enhanced by selective structural modifications. One compound, GMG-1-09 representing acyl carbamate scaffold, depicted in vitro efficacy against C. parvum with an IC 50 concentration (32.24 μM) that was 14-fold lower than its cytotoxicity IC 50 concentration in a human intestinal cell line. Together, our studies unveil a series of novel synthetic acyl/diacyl urea and acyl carbamate scaffold-based small molecule compounds with micromolar activity against T. gondii and C. parvum that can be explored further for the development of the much-needed novel anti-protozoal drugs.

Activity of (1-benzyl-4-triazolyl)-indole-2-carboxamides against Toxoplasma gondii and Cryptosporidium parvum

“…Both of the 1-adamantyl counterparts 9a (JS-2-19) and 9b (JS-2-31) showed activity only against T. gondii . This result is consistent with our previous report that showed some 1- and 2-adamantyl benzoyl carbamates to selectively inhibit the growth of T. gondii with comparable IC 50 indices ( Li et al, 2020 ). Extension of the project to the synthesis of (1-adamantyl)-4-phenyl-triazoles provided compounds 11a (JS-2-40) and 11b (JS-2-41) with the latter derivative being the most potent compound against T. gondii .…”

“…As such, we allowed 2 h for the establishment of infection in this study. Furthermore, the 2–4 h time point has been used by many research groups (including ours) in the recent past to assess the in vitro effect of compounds on these parasites before and after invasion of host cells ( Jumani et al, 2019 ; Woolsey et al, 2019 ; Funkhouser-Jones et al, 2020 ; Li et al, 2020 ; Ma et al, 2020 ; Murakoshi et al, 2020 ). When the cultures were analyzed at 72 h post-infection, five compounds (JS-2-22, 27, 28, 30 and 44) were found to have concentration-dependent activity of reducing C. parvum growth and proliferation, regardless of whether treatment started immediately or 2 h after infection of host cells ( Fig.…”

Past, current, and potential treatments for cryptosporidiosis in humans and farm animals: A comprehensive review

“…Modern drug-discovery projects utilize either a phenotype-based or target-based screening approach to identify lead candidate compounds for further development. Cryptosporidium drug discovery programs in the recent past have mostly used phenotypic screening methods to successfully discover or repurpose compounds with in vitro and in vivo activity against the parasite ( Love et al., 2017 ; Jumani et al., 2018 ; Lunde et al., 2019 ; Li et al., 2020 ; Khan et al., 2022a ). However, such an approach invariably results in the identification of candidate compounds that are difficult to optimize as their MMOA and structure-activity relationships (SAR) are generally unknown.…”