Using UHPLC-MS profiling for the discovery of new sponge-derived metabolites and anthelmintic screening of the NatureBank bromotyrosine library

A Screening of 10,240 NatureBank Fractions Identifies Nematicidal Activity in Agelasine-Containing Extracts from Sponges

Nematode infections affect a fifth of the human population, livestock, and crops worldwide, imposing a burden to global public health and economies, particularly in developing nations. Resistance to commercial anthelmintics has increased over the years in livestock infections and driven the pursuit for new drugs. We herein present a rapid, cost-effective, and automated assay for nematicide discovery using the free-living nematode Caenorhabditis elegans to screen a highly diverse natural product library enriched in bioactive molecules. Screening of 10,240 fractions obtained from extracts of various biological sources allowed the identification of 7 promising hit fractions, all from marine sponges. These fractions were further assayed for nematicidal activity against the sheep nematode parasite Haemonchus contortus and for innocuity in zebrafish. The most active extracts against parasites and innocuous toward vertebrates belong to two chemotypes. High-performance liquid chromatography (HPLC) coupled with nuclear magnetic resonance (NMR) revealed that the most abundant compound in one chemotype is halaminol A, an aminoalcohol previously identified in a small screen against H. contortus. Terpene-nucleotide hybrids known as agelasines predominate in the other chemotype. This study reinforces the power of C. elegans for nematicide discovery from large collections and the potential of the chemical diversity derived from marine invertebrate biota.

Model nematodes as a practical innovation to promote high throughput screening of natural products for anthelmintics discovery in South Asia: Current challenges, proposed practical and conceptual solutions

With the increasing prevalence of anthelmintic resistance in animals recorded globally, and the threat of resistance in human helminths, the need for novel anthelmintic drugs is greater than ever. Most research aimed at discovering novel anthelmintic leads relies on high throughput screening (HTS) of large libraries of synthetic small molecules in industrial and academic settings in developed countries, even though it is the tropical countries that are most plagued by helminth infections. Tropical countries, however, have the advantage of possessing a rich flora that may yield natural products (NP) with promising anthelmintic activity. Focusing on South Asia, which produces one of the world's highest research outputs in NP and NP-based anthelmintic discovery, we find that limited basic research and funding, a lack of awareness of the utility of model organisms, poor industry-academia partnerships and lack of technological innovations greatly limit anthelmintics research in the region. Here we propose that utilizing model organisms including the free-living nematode Caenorhabditis elegans, that can potentially allow rapid target identification of novel anthelmintics, and Oscheius tipulae, a closely related, free-living nematode which is found abundantly in soil in hotter temperatures, could be a much-needed innovation that can enable cost-effective and efficient HTS of NPs for discovering compounds with anthelmintic/antiparasitic potential in South Asia and other tropical regions that historically have devoted limited funding for such research. Additionally, increased collaborations at the national, regional and international level between parasitologists and pharmacologists/ethnobotanists, setting up government-industry-academia partnerships to fund academic research, creating a centralized, regional collection of plant extracts or purified NPs as a dereplication strategy and HTS library, and holding regional C. elegans/O. tipulae-based anthelmintics workshops and conferences to share knowledge and resources regarding model organisms may collectively promote and foster a NP-based anthelmintics landscape in South Asia and beyond.

Natural products as anthelmintics: safeguarding animal health

Covering literature to December 2022This review provides a comprehensive account of all natural products (500 compounds, including 17 semi-synthetic derivatives) described in the primary literature up to December 2022, reported to be capable of inhibiting the egg hatching, motility, larval development and/or the survival of helminths (i.e., nematodes, flukes and tapeworms). These parasitic worms infect and compromise the health and welfare, productivity and lives of commercial livestock (i.e., sheep, cattle, horses, pigs, poultry and fish), companion animals (i.e., dogs and cats) and other high value, endangered and/or exotic animals. Attention is given to chemical structures, as well as source organisms and anthelmintic properties, including the nature of bioassay target species, in vivo animal hosts, and measures of potency.