Parasitic nematodes cause a wide range of diseases in animals, including humans. However, the efficacy of existing anthelmintic drugs, commonly used to treat these infections, is waning due to the increasing prevalence of drug resistance in nematode populations. This growing challenge underscores the urgent need to discover and develop novel nematocidal drugs that target new molecular pathways. In the present study, 13 novel derivatives of benzhydroxamic acid (OMKs) were designed and synthesized. Their anthelmintic activity was tested in the parasitic nematode Haemonchus contortus (barber's pole worm) and the free-living nematode Caenorhabditis elegans and potential toxicity assessed in mammalian models. Compound OMK211 showed the most promising results. It decreased viability and motility of larval and adult stages of both nematode species and of both drug-sensitive and drug-resistant strains of H. contortus at micromolar concentrations with the highest efficacy in H. contortus adult males (IC50 ∼ 1 μM). Moreover, OMK211 was not toxic in mammalians cells in vitro and in mice in vivo. Consequently, thermal proteome profiling analysis was used to infer the putative molecular target of OMK211 in H. contortus. The results revealed C2-domain containing protein A0A6F7Q0A8, encoded by gene HCON_00184,900, as an interacting partner of OMK211. Using advanced structural prediction and docking tools, this protein is considered an interesting putative molecular target of new nematocidal drugs as its orthologs are present in several nematodes but not in mammals. In conclusion, novel derivatives of benzhydroxamic acid represent a promising new class of potential anthelmintics, which deserve further testing.

• Keywords
• Drug development, Drug resistance, Nematodes, New anthelmintics,
• MeSH
• Anthelmintics * pharmacology   chemistry   MeSH
• Antinematodal Agents * pharmacology   chemistry   chemical synthesis   MeSH
• Caenorhabditis elegans * drug effects   MeSH
• Haemonchus * drug effects   MeSH
• Haemonchiasis drug therapy   parasitology   MeSH
• Hydroxamic Acids * pharmacology   chemistry   chemical synthesis   MeSH
• Larva drug effects   MeSH
• Mice MeSH
• Animals MeSH
• Check Tag
• Male MeSH
• Mice MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Anthelmintics * MeSH
• Antinematodal Agents * MeSH
• Hydroxamic Acids * MeSH

Carbonyl-reducing enzymes (CREs) catalyse the reduction of carbonyl groups in many eobiotic and xenobiotic compounds in all organisms, including helminths. Previous studies have shown the important roles of CREs in the deactivation of several anthelmintic drugs (e.g., flubendazole and mebendazole) in adults infected with the parasitic nematode Haemonchus contortus, in which the activity of a CRE is increased in drug-resistant strains. The aim of the present study was to compare the abilities of nematodes of both a drug-susceptible strain (ISE) and a drug-resistant strain (IRE) to reduce the carbonyl group of flubendazole (FLU) in different developmental stages (eggs, L1/2 larvae, L3 larvae, and adults). In addition, the effects of selected CRE inhibitors (e.g., glycyrrhetinic acid, naringenin, silybin, luteolin, glyceraldehyde, and menadione) on the reduction of FLU were evaluated in vitro and ex vivo in H. contortus adults. The results showed that FLU was reduced by H. contortus in all developmental stages, with adult IRE females being the most metabolically active. Larvae (L1/2 and L3) and adult females of the IRE strain reduced FLU more effectively than those of the ISE strain. Data from the in vitro inhibition study (performed with cytosolic-like fractions of H. contortus adult homogenate) revealed that glycyrrhetinic acid, naringenin, mebendazole and menadione are effective inhibitors of FLU reduction. Ex vivo study data showed that menadione inhibited FLU reduction and also decreased the viability of H. contortus adults to a similar extent. Naringenin and mebendazole were not toxic at the concentrations tested, but they did not inhibit the reduction of FLU in adult worms ex vivo.

• Keywords
• Anthelmintics, Strongyloides, drug biotransformation, helminths, inhibitors,
• MeSH
• Anthelmintics * pharmacology   therapeutic use   MeSH
• Haemonchus * MeSH
• Glycyrrhetinic Acid * pharmacology   MeSH
• Larva MeSH
• Mebendazole pharmacology   therapeutic use   MeSH
• Vitamin K 3 pharmacology   MeSH
• Animals MeSH
• Check Tag
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Anthelmintics * MeSH
• flubendazole MeSH Browser
• Glycyrrhetinic Acid * MeSH
• Mebendazole MeSH
• Vitamin K 3 MeSH

Most drugs used in the treatment of helminthiasis in humans and animals have lost their efficacy due to the development of drug-resistance in helminths. Moreover, since anthelmintics, like many pharmaceuticals, are now recognized as hazardous contaminants of the environment, returning to medicinal plants and their products represents an environmentally friendly way to treat helminthiasis. The goal of the present study was to test the anthelminthic activity of methanol extracts of eight selected European ferns from the genera Dryopteris, Athyrium and Blechnum against the nematode Haemonchus contortus, a widespread parasite of small ruminants. Eggs and adults of H. contortus drug-susceptible strain ISE and drug-resistant strain WR were isolated from experimentally infected sheep. The efficacy of fern extracts was assayed using egg hatch test and adults viability test based on ATP-level measurement. Among the ferns tested, only Dryopteris aemula extract (0.2 mg/mL) inhibited eggs hatching by 25% in comparison to control. Athyrium distentifolium, Dryopteris aemula and Dryopteris cambrensis were effective against H. contortus adults. In concentration 0.1 mg/mL, A. distentifolium, D. aemula, D. cambrensis significantly decreased the viability of females from ISE and WR strains to 36.2%, 51.9%, 32.9% and to 35.3%, 27.0%, 23.3%, respectively in comparison to untreated controls. None of the extracts exhibited toxicity in precise cut slices from ovine liver. Polyphenol's analysis identified quercetin, kaempferol, luteolin, 3-hydroxybenzoic acid, caffeic acid, coumaric acid and protocatechuic acid as the major components of these anthelmintically active ferns.

• Keywords
• ATP-assay, Athyrium, Dryopteris, Natural anthelmintics, medicinal plants, nematodes,
• MeSH
• Anthelmintics * pharmacology   therapeutic use   MeSH
• Haemonchus * MeSH
• Helminthiasis * MeSH
• Ferns * MeSH
• Larva MeSH
• Humans MeSH
• Sheep Diseases * drug therapy   parasitology   MeSH
• Sheep MeSH
• Plant Extracts pharmacology   MeSH
• Veterinary Drugs * pharmacology   MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Anthelmintics * MeSH
• Plant Extracts MeSH
• Veterinary Drugs * MeSH

As a widely distributed parasitic nematode of ruminants, Haemonchus contortus has become resistant to most anthelmintic classes, there has been a major demand for new compounds against H. contortus and related nematodes. Recent phenotypic screening has revealed two compounds, designated as BLK127 and HBK4, that are active against H. contortus larvae. The present study was designed to assess the activity of these compounds against H. contortus eggs and adults, hepatotoxicity in rats and sheep, as well as biotransformation in H. contortus adults and the ovine liver. Both compounds exhibited no inhibitory effect on the hatching of eggs. The benzyloxy amide BLK127 significantly decreased the viability of adults in sensitive and resistant strains of H. contortus and showed no hepatotoxic effect, even at the highest concentration tested (100 µM). In contrast, HBK4 had no impact on the viability of H. contortus adults and exhibited significant hepatotoxicity. Based on these findings, HBK4 was excluded from further studies, while BLK127 seems to be a potential candidate for a new anthelmintic. Consequently, biotransformation of BLK127 was tested in H. contortus adults and the ovine liver. In H. contortus, several metabolites formed via hydroxylation, hydrolysis and glycosidation were identified, but the extent of biotransformation was low, and the total quantity of the metabolites formed did not differ significantly between the sensitive and resistant strains. In contrast, ovine liver cells metabolized BLK127 more extensively with a glycine conjugate of 4-(pentyloxy)benzoic acid as the main BLK127 metabolite.

• Keywords
• ATP, drug development, drug metabolism, drug resistance, nematodes, new anthelmintics,
• Publication type
• Journal Article MeSH