Small Molecule Inhibitors of Metabolic Enzymes Repurposed as a New Class of Anthelmintics

Abstract

The enormous prevalence of infections caused by parasitic nematodes worldwide, coupled to the rapid emergence of their resistance to commonly used anthelmintic drugs, presents an urgent need for the discovery of new drugs. Herein, we have identified several classes of small molecules with broad spectrum activity against these pathogens. Previously, we reported the identification of carnitine palmitoyltransferases (CPTs) as a representative class of enzymes as potential targets for metabolic chokepoint intervention that was elucidated from a combination of chemogenomic screening and experimental testing in nematodes. Expanding on these previous findings, we have discovered that several chemical classes of known small molecule inhibitors of mammalian CPTs have potent activity as anthelmintics. Cross-clade efficacy against a broad spectrum of adult parasitic nematodes was demonstrated for multiple compounds from different series. Several analogs of these initial hit compounds were designed and synthesized. The compounds we report represent a good starting point for further lead identification and optimization for development of new anthelmintic drugs with broad spectrum activity and a novel mechanism of action.

Rapid determination of nematode cell and organ susceptibility to toxic treatments

“…However, the limited selection of efficacious anthelmintics and emerging pathogen resistance to anthelmintics ( Sangster et al, 2018 ) identifies a need to expand the selection of drugs available for therapy and control of parasitic nematodes. A surge in research to increase the limited arsenal of available anthelmintic compounds has stemmed from several advances, including expanding parasite multi-omics resources, technological advances in biologic screening methods, access to expanding small molecule inhibitor libraries, and enhanced computational methods that integrate biologic data with large knowledge bases related to both drug and inhibitor compounds (examples include ( Taylor et al, 2013 ; Tyagi et al, 2018 ; Tyagi et al, 2019 ; Jasmer et al, 2020 )). These omics-driven approaches have proven quite effective in identifying small molecule inhibitors that are toxic to parasitic nematodes and have multiple applications to anthelmintic research.…”

Drug Screening for Discovery of Broad-spectrum Agents for Soil-transmitted Nematodes

“…Out of the 39 drugs that hit adult hookworms, 32 that were readily available for repurchase were tested against whipworms at final concentrations of 100 µM (0.75% DMSO), a dose based on the efficacy of known anthelmintics against T . muris adults in vitro and based on previous drug screens 36,52,96 . Pararosaniline pamoate was unavailable from commercial sources instead pararosaniline hydrochloride was purchased and tested against whipworm adults and the following in vivo experiments.…”

A highly expressed intestinal cysteine protease of Ancylostoma ceylanicum protects vaccinated hamsters from hookworm infection

“…Hookworms were hand-picked into individual wells of a 96-well plate (two hookworms per well) containing 50 μL of HCM with 50% heat-inactivated fetal bovine/calf serum [44] replaced by hamster serum (mHCM: 49.5% RPMI 1640 Medium containing L-glutamine without Phenol Red Indicator [Thermo Fisher]; 49.5% hamster serum; 1% 100X PSG [100 U/mL penicillin; 100 μg/mL streptomycin; 0.292 mg/mL L-glutamine; Thermo Fisher]). Each hamster serum group included three wells (two hookworms/well for a total of six hookworm adults scored per group), and the average motility for the three wells was calculated using a standard 3–0 motility index assay (3 = highly motile; 2 = less motile; 1 = motile only when stimulated by touch; 0 = immotile) [45–47]. Motility was monitored for 76 hr (once per day).…”