High-throughput screening of more than 30,000 compounds for anthelmintics against gastrointestinal nematode parasites

Abstract

Gastrointestinal nematodes (GINs) are amongst the most common parasites of humans, livestock, and companion animals. GIN parasites infect 1-2 billion people worldwide, significantly impacting the growth, health, and vitality of hundreds of millions of children, pregnant women, and adult workers in developing countries, thereby perpetuating poverty. The cost and losses associated with GIN infections in human and veterinary health are estimated to be hundreds of billions of dollars worldwide. Two benzimidazoles with suboptimal efficacy are currently used to treat GINs in humans as part of mass drug administrations, with many additional instances of lower-than-normal efficacy and possible resistance. Many livestock and companion animal GINs are resistant to multiple classes of anthelmintic drugs used today. Thus, new anthelmintics are urgently needed. However, screening methods for new anthelmintics using human GINs typically have a low throughput. Here, using our novel screening pipeline that starts with human hookworm parasites, we screened 38,293 conditions in duplicate representing 30,238 unique small molecules from a wide range of compound libraries, including generic diversity, repurposing, natural derivatives, mechanism of action, and multiple target-focused libraries (e.g., targeting kinases, GPCRs, and neuronal proteins). We identified 55 compounds with broad-spectrum activity against adult stages of two evolutionary divergent GINs, hookworms (Ancylostoma ceylanicum) and whipworms (Trichuris muris). Based on known databases, the targets of these 55 compounds were predicted in nematode parasites. One novel scaffold from the diversity set library, F0317-0202, showed good activity (≥~11% Relative motility) against both GINs. To better understand this novel scaffold's structure-activity relationships (SAR), we screened 28 analogs and created SAR models highlighting chemical and functional groups required for broad-spectrum activity. These studies validate our new and efficient screening pipeline at the level of tens of thousands of compounds and provide an important set of new GIN-active compounds for developing novel and broadly-active anthelmintics.