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.

Phytochemical analysis and gastroprotective effect of Stellaria media (L.) Vill. methanolic extract on piroxicam-induced gastric ulcer in Wistar rats

Stellaria media L. has traditionally been used to treat inflammatory and gastrointestinal ailments. This study aimed to phytochemically characterize the S. media extract and explore its anti-ulcer efficacy against piroxicam-induced stomach lesions in Wistar rats. Phytochemical analysis was performed and antioxidant capacity of extract was determined using 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. In vivo, piroxicam (30mg/kg) was administered to induce gastric ulceration. Gastro protective effect of S. media extract was observed at 150, 300 and 450mg/kg, respectively. While omeprazole (20mg/kg) was used as a conventional anti-ulcer drug. After oral treatment for 14 days, stomach acidic secretions, ulcerogenic indices, hematological markers and oxidative stress parameters were assessed along with histological examination. The existence of polyphenol contents in S. media extract was confirmed in correlation to a marked DPPH inhibition (IC50 27.94µg/mL). S. media extract resulted in a dose-dependent elevation in gastric pH while a decrease in acid volume, acidity and ulceration. Also, S. media extract administration restored the impaired hematological markers (RBCs, Hb, WBCs and PLTs) and decreased oxidative stress by reducing oxidants (TOS and MDA) while raising antioxidants (TAC and CAT). Furthermore, gastric histological results corroborated the aforementioned findings. Conclusively, S. media could provide a promising protective effect against drug-induced gastric ulceration.

Atypical (RIO) protein kinases from Haemonchus contortus--promise as new targets for nematocidal drugs

Almost nothing is known about atypical kinases in multicellular organisms, including parasites. Supported by information and data available for the free-living nematode, Caenorhabditis elegans, and other eukaryotes, the present article describes three RIO kinase genes, riok-1, riok-2 and riok-3, from Haemonchus contortus, one of the most important parasitic nematodes of small ruminants. Analyses of these genes and their products predict that they each play critical roles in the developmental pathways of parasitic nematodes. The findings of this review indicate prospects for functional studies of these genes in C. elegans (as a surrogate) and opportunities for the design of a novel class of nematode-specific inhibitors of RIO kinases. The latter aspect is of paramount importance, given the serious problems linked to anthelmintic resistance in parasitic nematode populations of livestock.