Nematocidal Effects of a Coriander Essential Oil and Five Pure Principles on the Infective Larvae of Major Ovine Gastrointestinal Nematodes In Vitro

Abstract

The anthelmintic effects of extracted coriander oil and five pure essential oil constituents (geraniol, geranyl acetate, eugenol, methyl iso-eugenol, and linalool) were tested, using larval motility assay, on the third-stage larvae (L3s) of Haemonchus contortus, Trichostrongylus axei, Teladorsagia circumcincta, Trichostrongylus colubriformis, Trichostrongylus vitrinus and Cooperia oncophora. Coriander oil and linalool, a major component of tested coriander oil, showed a strong inhibitory efficacy against all species, except C. oncophora with a half maximal inhibitory concentration (IC50) that ranged from 0.56 to 1.41% for the coriander oil and 0.51 to 1.76% for linalool. The coriander oil and linalool combinations conferred a synergistic anthelmintic effect (combination index [CI] <1) on larval motility comparable to positive control (20 mg/mL levamisole) within 24 h (p < 0.05), reduced IC50 values to 0.11–0.49% and induced a considerable structural damage to L3s. Results of the combined treatment were validated by quantitative fluorometric microplate-based assays using Sytox green, propidium iodide and C12-resazurin, which successfully discriminated live/dead larvae. Only Sytox green staining achieved IC50 values comparable to that of the larval motility assay. The cytotoxicity of the combined coriander oil and linalool on Madin–Darby Canine Kidney cells was evaluated using sulforhodamine-B (SRB) assay and showed no significant cytotoxic effect at concentrations < 1%. These results indicate that testing essential oils and their main components may help to find new potential anthelmintic compounds, while at the same time reducing the reliance on synthetic anthelmintics.

Cell Death and Transcriptional Responses Induced in Larvae of the Nematode Haemonchus contortus by Toxins/Toxicants with Broad Phylogenetic Efficacy

“…Consequently, the relationship between motility and detection of cell death is complex, and the combination of responses related to immotility, PI detected cell death and cells affected, and larval stage investigated produced unique profiles for each given NIT. The data extends findings on correlation between PI labeling and motility for H. contortus larvae [ 11 ], and indicate that information gained from the PI cell death assay adds substantial information to that obtainable from motility assays alone.…”

“…Thus, new tools and biological knowledge related to cellular effects of experimental toxins may promote advances in anthelmintic research on H. contortus . Although PI has been used in a general application to monitor anthelmintic effects on H. contortus larvae [ 11 ], resolution of individual cells and organs relative to cell death outcomes and nuances of a system to do so have not.…”

Novel High-Throughput Fluorescence-Based Assay for the Identification of Nematocidal Compounds That Target the Blood-Feeding Pathway

“…Secondly, the assay utilizes fluorescent measurements of parasite viability via cell/cuticle permeability that are readily scalable, compared with traditional, imagebased measurements of worm motility, as an assessment of nematocidal activity. Compared to other methods [35,36], the screen we detail here also has no requirement for pre-staining or counterstaining larvae making it simple and cheap to implement, and it can be scaled down to 40 L3 per well, allowing for large number of compounds to be screened with the same parasite batch.…”

“…Many other viability dyes are available on the market, and some have already been reported to exhibit utility for helminth viability assays [18,33]. Sytox Green has recently been reported as a viability dye for nematodes by us as well as others [19,35,36] and was chosen for the current study based on the absence of toxicity to N. brasiliensis, and on its spectrum and brightness, which allows it to be used in an assay in which the medium contains large quantities of the naturally autofluorescent protein, haemoglobin. Haemoglobin is present in two forms: oxygenated and deoxygenated, each with a different absorption spectrum, and we found that the presence of lysed RBCs interfered with the excitation and emission wavelengths of other viability dyes reported in the literature (such as propidium iodide, data not shown) [41].…”

Pharmacological characterization of geraniol in sheep and its potential use in the control of gastrointestinal nematodes

“…The in vitro mortality effect of GNL against the model Caenorhabditis elegans was demonstrated with a LC 50 of 14 µg/mL ( Abdel-Rahman et al., 2013 ). Furthermore, GNL was found to reduce larval motility of Haemonchus contortus, Trichostrongylus axei and Teladorsagia circumcincta by 82%, 90% and 94% , respectively ( Helal et al., 2020 ). These promising findings highlight the pharmacological challenge of studying the potential of GNL as a useful tool for treating gastrointestinal parasites in ruminants.…”