In Vitro Anthelmintic Activity of Four Plant-Derived Compounds against Sheep Gastrointestinal Nematodes

Evaluating anthelmintic, anti-platelet, and anti-coagulant activities, and identifying the bioactive phytochemicals of Amaranthus blitum L

BACKGROUND

Highlighting affordable alternative crops that are rich in bioactive phytoconstituents is essential for advancing nutrition and ensuring food security. Amaranthus blitum L. (AB) stands out as one such crop with a traditional history of being used to treat intestinal disorders, roundworm infections, and hemorrhage. This study aimed to evaluate the anthelmintic and hematologic activities across various extracts of AB and investigate the phytoconstituents responsible for these activities.

METHODS

In vitro anthelmintic activity against Trichinella spiralis was evaluated in terms of larval viability reduction. The anti-platelet activities were assessed based on the inhibitory effect against induced platelet aggregation. Further, effects on the extrinsic pathway, the intrinsic pathway, and the ultimate common stage of blood coagulation, were monitored through measuring blood coagulation parameters: prothrombin time (PT), activated partial thromboplastin time (aPTT), and thrombin time (TT), respectively. The structures of isolated compounds were elucidated by spectroscopic analysis.

RESULTS

Interestingly, a previously undescribed compound (19), N-(cis-p-coumaroyl)-ʟ-tryptophan, was isolated and identified along with 21 known compounds. Significant in vitro larvicidal activities were demonstrated by the investigated AB extracts at 1 mg/mL. Among tested compounds, compound 18 (rutin) displayed the highest larvicidal activity. Moreover, compounds 19 and 20 (N-(trans-p-coumaroyl)-ʟ-tryptophan) induced complete larval death within 48 h. The crude extract exhibited the minimal platelet aggregation of 43.42 ± 11.69%, compared with 76.22 ± 14.34% in the control plasma. Additionally, the crude extract and two compounds 19 and 20 significantly inhibited the extrinsic coagulation pathway.

CONCLUSIONS

These findings extend awareness about the nutritional value of AB as a food, with thrombosis-preventing capabilities and introducing a promising source for new anthelmintic and anticoagulant agents.

Utilisation of indigenous knowledge to control gastrointestinal nematodes in Southern Africa

Gastrointestinal nematodes (GIN) exacerbate the impact of droughts on the survival of cattle. The inadequacies of the conventional system make it increasingly important to explore indigenous knowledge (IK) to create drought-tolerant and GIN resilient herds. The objective of the study was to assess the indigenous strategies for controlling GIN during droughts. Face-to-face interviews with experts on IK were conducted to give insight into the importance, methods and ranking of GIN control. The experts identified 86 cattle that were used to test their assertions. The control methods used were identifying cattle that were susceptible to high GIN loads using predisposing factors, diagnosis of GIN burdens using faecal appearance, and treatment using phytotherapy. Experts ranked predisposing factors as the most critical control strategy and identified body condition, class, sex, coat colour, pregnancy status and lactation status as predisposing factors to high GIN burdens. Thin, older, dark-coloured cattle, as well as pregnant and lactating cows, were considered susceptible to GIN. However, pregnancy status, coat colour and sex were significantly associated with high GIN burdens. Cows were 2.6 times more likely to have high GIN burdens than bulls. Dark-coloured cattle were 3.5 times more likely to have high GIN burdens than light-coloured ones, and the likelihood of pregnant cows was 4.9 times higher than non-pregnant cows. A dark-coloured pregnant cow was extremely susceptible to high GIN burdens. In conclusion, knowledge of predisposing factors informs selection decisions when purchasing foundation stock. Cattle that are susceptible to high GIN loads are prioritised during droughts or culled where resources are scarce.

Control of gastrointestinal helminths in small ruminants to prevent anthelmintic resistance: the Italian experience

Helminth infections are ubiquitous in grazing ruminants and cause significant costs due to production losses. Moreover, anthelmintic resistance (AR) in parasites is now widespread throughout Europe and poses a major threat to the sustainability of modern ruminant livestock farming. Epidemiological data on the prevalence and distribution of gastrointestinal nematodes, cestodes and liver- and rumen-flukes in Italian small ruminants are outdated and fragmentary. However, anthelmintics are commonly used to control these infections and often without prior diagnosis. Compared to other European countries, few reports of AR in small ruminants against levamisole, ivermectin and benzimidazoles have been published in Italy, but recent studies suggest that this phenomenon is spreading. Increased and integrated research efforts in developing innovative approaches to control helminth infections and AR are needed and must be tailored to the peculiarities of each context in order to be effectively implemented. This manuscript provides an overview on helminth prevalence and distribution, sustainable treatment strategies and integrated control approaches in small ruminants in Italy. The implementation of targeted treatments and targeted selective treatments is discussed based on different parameters, such as fecal egg count, degree of anaemia (FAMACHA© method), milk production and body condition score. In addition, several Italian studies have also investigated the implementation of alternative strategies such as the use of different natural bioactive compounds or genetic selection for resistance and resilience to helminth infections. These concrete solutions for helminth management in small ruminant farms in the country are reported and discussed, representing a valid example for other Mediterranean countries.

Intestinal Obstruction for Anisakiasis: Surgical and Physical Therapy Treatment

Anisakiasis, a zoonotic disease that can lead to small intestine obstruction, has seen a significant rise in Spain. The country has become the first in Europe with an annual incidence of 8000 cases, primarily due to the popularity of consuming exotic dishes of undercooked or raw fish and the impact of climate change. The clinical presentation of anisakiasis can mimic symptoms of acute appendicitis or intestinal obstruction, leading to potential misdiagnosis. This case report describes a 37-year-old patient with no significant medical history who presented abdominal distension and intense pain in the right lower quadrant. The patient underwent surgery and received physiotherapy treatment, including therapeutic exercises and pulsed-pressure myofascial vacuum therapy, to facilitate functional recovery. The increasing incidence of anisakiasis in Spain underscores the need to consider it in the differential diagnosis of digestive diseases, given the high consumption of poorly prepared or raw fish in the region.

Current Landscape of Methods to Evaluate Antimicrobial Activity of Natural Extracts

Natural extracts have been and continue to be used to treat a wide range of medical conditions, from infectious diseases to cancer, based on their convenience and therapeutic potential. Natural products derived from microbes, plants, and animals offer a broad variety of molecules and chemical compounds. Natural products are not only one of the most important sources for innovative drug development for animal and human health, but they are also an inspiration for synthetic biology and chemistry scientists towards the discovery of new bioactive compounds and pharmaceuticals. This is particularly relevant in the current context, where antimicrobial resistance has risen as a global health problem. Thus, efforts are being directed toward studying natural compounds' chemical composition and bioactive potential to generate drugs with better efficacy and lower toxicity than existing molecules. Currently, a wide range of methodologies are used to analyze the in vitro activity of natural extracts to determine their suitability as antimicrobial agents. Despite traditional technologies being the most employed, technological advances have contributed to the implementation of methods able to circumvent issues related to analysis capacity, time, sensitivity, and reproducibility. This review produces an updated analysis of the conventional and current methods to evaluate the antimicrobial activity of natural compounds.

In vitro evaluation of the effects of methanolic plant extracts on the embryonation rate of Ascaridia galli eggs

The present study aims to find efficient alternatives to synthetic anthelmintics among ethno-veterinary herbs. Ascaridia galli eggs isolated from the worm uterus were exposed in vitro to methanolic extracts (ME) of nine plant species such as Achillea millefolium (AM), Artemisia absinthium (AA), Artemisia vulgaris (AV), Cicerbita alpina (CA), Cichorium intybus (CI), Inula helenium (IH), Origanum vulgare (OV), Tanacetum vulgare (TV), Tanacetum parthenium (TP). Flubendazole (FL), 0.5% formalin with dimethylsulfoxide and Petri dishes without the addition of reagents were used as positive, negative and untreated control respectively. The effects of the different ME at concentrations 0.500, 0.325, 0.200 mg/ml were assessed on the embryonic development (ED) of the eggs in duplicate. Logit analysis was used to calculate EC₅₀ values. A generalized linear mixed model, having plant species and concentration as fixed effect and day as repeated measure, was used to determine differences in ED. Estimated EC₅₀ was the lowest for FL at 0.11 mg/ml. CA and TV followed with 0.27 mg/ml and 0.32 mg/ml. ED for FL was significantly lower (25%) than that of CA (47%). The analysis showed 0.5 mg/ml of the ME of CA and TV significantly affected the ED at 35% and 42% inhibitions respectively. The ED for all ME showed similar pattern i.e., relatively higher efficacy in the first experimental week compared to the rest of the experimental period. The effect from all multicomponent extracts is time and dose dependent. The plants have promising results in inhibiting ED, contributing to the identification of alternative anthelmintic treatments.

In Vitro Anthelmintic Activity of Sea Buckthorn (Hippophae rhamnoides) Berry Juice against Gastrointestinal Nematodes of Small Ruminants

Gastrointestinal nematodes are one of the major threats in small ruminant breeding. Their control is difficult due to the development of anthelmintic resistance, and the search for new molecules endowed with anthelmintic activity (AH) is considered a priority. In this context, we evaluated the in vitro AH activity of two commercial sea buckthorn (Hippophae rhamnoides) berry juices, namely SBT and SBF. The in vitro evaluation was based on the egg-hatch test and larval exsheathment assay at different concentrations. Data were statistically analysed, and the EC₅₀ was calculated. Chemical analyses were performed to evaluate the total polyphenol content of the juices and chemical profile of the most represented compounds. The role of the polyphenolic fraction in the anthelmintic activity of the juices was also assessed. At the highest concentrations, the activity of SBT was high in both tests and comparable to that observed in the thiabendazole-treated positive controls, while SBF showed a lower efficacy. Glycosylated isorhamnetin and quercetin were the most represented polyphenolic compounds in both juices. In conclusion, both H. rhamnoides berry juices tested in this study showed interesting anthelmintic properties in vitro.

In silico prediction of flavan-3-ol as a bioactive compound of Calophyllum macrophyllum as a potential drug against angiostrongylus eosinophilic meningitis

Background and Aim:

Angiostrongylus eosinophilic meningitis is caused by larvae of the rat lungworm Angiostrongylus cantonensis. It manifests as meningitis, radiculitis, cranial nerve abnormalities, and encephalitis, which can be fatal. A flavan-3-ol compound isolated from the bark of Calophyllum macrophyllum Scheff. has several medicinal properties, including antioxidant, anti-inflammatory, antidiabetic, and antibacterial activities. This compound is stronger than other types of flavan-3-ols such as catechin. This study aimed to identify the hydroxylation pattern of this flavan-3-ol compound and evaluated its potential as an anti-meningitis drug, using an in silico approach through pharmacophore and molecular docking methods.

Materials and Methods:

Pharmacokinetic and toxicological data were analyzed and supported by the server http://www.swissadme.ch/index.php and https://tox-new.charite.de/protox_II/index.php. The hydroxylation pattern of the flavan-3-ol compound was identified using shear reagents (MeOH, NaOH, NaOAc, HCl, and AlCl₃). The CviR receptor (pdb id.3QP5) was used in the in silico approach, and seven ligands were downloaded from PubChem in “SMILES” format.

Results:

The spectroscopic analysis conducted using the shear reagents confirmed that the flavan-3-ol compound has a “p-diOH” pattern on the cinnamoyl ring. Pharmacophore analysis revealed this compound “hit” with pharmacophore features, and molecular docking analysis showed that this compound has a strong affinity with both receptors.

Conclusion:

The flavan-3-ol compound is a potential drug candidate for meningitis caused by pathogenic bacteria and the worm A. cantonensis. This result was supported by the pharmacokinetic profile, which had a very low toxicity level to the host. However, further investigation is required to confirm the data in vitro and in vivo.

Anthelmintic Effect of Leucaena leucocephala Extract and Its Active Compound, Mimosine, on Vital Behavioral Activities in Caenorhabditis elegans

Helminth infections continue to be a neglected global threat in tropical regions, and there have been growing cases of anthelmintic resistance reported towards the existing anthelmintic drugs. Thus, the search for a novel anthelmintic agent has been increasing, especially those derived from plants. Leucaena leucocephala (LL) is a leguminous plant that is known to have several pharmacological activities, including anthelmintic activity. It is widely known to contain a toxic compound called mimosine, which we believed could be a potential lead candidate that could exert a potent anthelmintic effect. Hence, this study aimed to validate the presence of mimosine in LL extract and to investigate the anthelmintic effect of LL extract and mimosine on head thrashing, egg-laying, and pharyngeal pumping activities using the animal model Caenorhabditis elegans (C. elegans). Mimosine content in LL extract was confirmed through an HPLC analysis of spiking LL extract with different mimosine concentrations, whereby an increasing trend in peak heights was observed at a retention time of 0.9 min. LL extract and mimosine caused a significant dose-dependent increase in the percentage of worm mortality, which produced LC50s of 73 mg/mL and 6.39 mg/mL, respectively. Exposure of C. elegans to different concentrations of LL extract and mimosine significantly decreased the head thrashing, egg-laying, and mean pump amplitude of pharyngeal pumping activity. We speculated that these behavioral changes are due to the inhibitory effect of LL extract and mimosine on an L-type calcium channel called EGL-19. Our findings provide evidential support for the potential of LL extract and its active compound, mimosine, as novel anthelmintic candidates. However, the underlying mechanism of the anthelmintic action has yet to be elucidated.

First Report of Multiple Drug-resistant Gastrointestinal Nematodes of Sheep in Arbat District, Sulaymaniyah, Iraq Detected By in Vivo and in Vitro Methods

Introduction

The control of gastrointestinal nematodes (GINs) in small ruminants is principally dependent on anthelmintic therapy, which encounters the rising problem of anthelmintic resistance (AR) development. Veterinarians reported anthelmintic failure in several sheep farms in Arbat District, Sulaymaniyah, northern Iraq, which called for a systematic study about the efficacy of three commonly used drugs: albendazole, ivermectin, and levamisole.

Material and Methods

A faecal egg count reduction test (FECRT) was conducted to elucidate the anthelmintics’ efficacies, with coprocultures to determine the GINs parasitising sheep in the study area. Larval development assays (LDAs) were conducted to determine the drugs’ median inhibitory concentrations (IC₅₀).

Results

The FECRT revealed that AR was widespread to all three drugs, and ivermectin was the least effective, reducing the faecal egg counts (FECs) by 50.5% to 57.1%. The coprocultures revealed that the GIN genera of sheep in Arbat District were Trichostrongylus, Nematodirus, and Trichuris, and the resistance was mainly due to Trichostrongylus species. The mean IC₅₀ of albendazole, ivermectin, and levamisole were 0.073 ng/mL, 7.97 ng/mL, and 1.43 ng/mL, respectively.

Conclusion

This study is the first Iraqi report of AR confirmed by both in vivo FECRT and in vitro LDA methods.

Improving stool sample processing and pyrosequencing for quantifying benzimidazole resistance alleles in Trichuris trichiura and Necator americanus pooled eggs

BACKGROUND

There is an urgent need for an extensive evaluation of benzimidazole efficacy in humans. In veterinary science, benzimidazole resistance has been mainly associated with three single-nucleotide polymorphisms (SNPs) in the isotype-1 β-tubulin gene. In this study, we optimized the stool sample processing methodology and resistance allele frequency assessment in Trichuris trichiura and Necator americanus anthelmintic-related SNPs by pyrosequencing, and standardized it for large-scale benzimidazole efficacy screening use.

METHODS

Three different protocols for stool sample processing were compared in 19 T. trichiura-positive samples: fresh stool, egg concentration using metallic sieves with decreasing pore size, and egg concentration followed by flotation with saturated salt solution. Yield of each protocol was assessed by estimating the load of parasite DNA by real-time PCR. Then, we sequenced a DNA fragment of the β-tubulin gene containing the putative benzimidazole resistance SNPs in T. trichiura and N. americanus. Afterwards, resistant and susceptible-type plasmids were produced and mixed at different proportions, simulating different resistance levels. These mixtures were used to compare previously described pyrosequencing assays with processes newly designed by our own group. Once the stool sample processing and the pyrosequencing methodology was defined, the utility of the protocols was assessed by measuring the frequencies of putative resistance SNPs in 15 T. trichiura- and 15 N. americanus-positive stool samples.

RESULTS

The highest DNA load was provided by egg concentration using metallic sieves with decreasing pore size. Sequencing information of the β-tubulin gene in Mozambican specimens was highly similar to the sequences previously reported, for T. trichiura and N. americanus, despite the origin of the sample. When we compared pyrosequencing assays using plasmids constructs, primers designed in this study provided the most accurate SNP frequencies. When pooled egg samples were analysed, none of resistant SNPs were observed in T. trichiura, whereas 17% of the resistant SNPs at codon 198 were found in one N. americanus sample.

CONCLUSIONS

We optimized the sample processing methodology and standardized pyrosequencing in soil-transmitted helminth (STH) pooled eggs. These protocols could be used in STH large-scale screenings or anthelmintic efficacy trials.

In vitro anthelmintic activity of an aqueous extract of Glycyrrhiza glabra and of glycyrrhetinic acid against gastrointestinal nematodes of small ruminants

This study evaluated the in vitro anthelmintic activity of a liquorice (Glycyrrhiza glabra) root aqueous extract and of glycyrrhetinic acid at 30, 10, 5, 1, and 0.5 mg/mL against sheep gastrointestinal nematodes (GINs), using the egg hatch test (EHT), the larval development test (LDT), and the larval migration inhibition test (LMIT). The compounds were applied on a mixture of GIN eggs and larvae, mainly Trichostrongylus spp. and Teladorsagia/Ostertagia spp. Cytotoxicity assays were also performed. In the EHT, both candidates showed significant concentration-dependent efficacy and were significantly more effective (p < 0.001) at the highest concentrations (30 and 10 mg/mL) than the lowest ones. In the LDT, only G. glabra showed a concentration-dependent effect (R2 = 0.924), but glycyrrhetinic acid (R2 = 0.910) had significantly higher efficacy than G. glabra root extract. Moreover, the efficacy of glycyrrhetinic acid at 30, 10, and 5 mg/mL was significantly higher (p < 0.001) than at lower concentrations. In the LMIT, G. glabra showed concentration-dependent efficacy (R2 = 0.971), while considerably reduced efficacy was observed for glycyrrhetinic acid (R2 = 0.855) at the lowest concentrations. These data suggest that the two compounds may have different mechanisms of action. In the LMIT, the 50% lethal concentration (LC50) of glycyrrhetinic acid (~5.12 mg/mL) was > 2.0-fold lower when compared to G. glabra (12.25 mg/mL). Analysis and previous findings indicated low toxicity for both compounds. The results obtained encourage in vivo studies aimed at evaluating the potential use of the tested compounds as natural de-wormers in ruminants.

Unravelling the anthelmintic bioactives from Jasminum grandiflorum L. subsp. Floribundum adopting in vitro biological assessment

ETHNOPHARMACOLOGICAL RELEVANCE

Jasminum grandiflorum L. is a medicinal plant widely used in the traditional system of Medicine as an anthelmintic in ringworm infections, for treating ulcers, stomatitis, skin diseases, and wounds.

AIM OF THE STUDY

The emergence of resistance by different parasites to currently used chemicals has been reported. There are increasing needs for more effective and safer parasiticides. Therefore, the current study was designed to investigate the methanolic extract of the aerial parts of J. grandiflorum subsp. Floribundum (JGTE) to confirm its traditional uses as anthelmintic through a bioassay-guided fractionation and isolation of the active components with anthelmintic activity.

MATERIALS AND METHODS

The JGTE was partitioned into dichloromethane (DCM-F) and n-butanol (BuOH-F) fractions. The JGTE, fractions, and the isolated compounds were tested in vitro for their anthelmintic activity using two nematodes; one larval stage of cestode and one arthropod. Four major compounds were isolated from the most active fraction (BuOH-F) including two flavonoids and two secoirridoid glycosides, identified as kaempferol-3-O-neohesperoside (1), rutin (2), oleuropein (3), and ligstroside (4).

RESULTS

Among the isolated compounds from most active fraction (BuOH-F), rutin (2) displayed the highest anthelmintic activity in a dose-dependent activity with IC₅₀ of 41.04 μg/mL against H. muscae adult worm, followed by ligstroside (4) with IC₅₀ of 50.56 μg/mL.

CONCLUSIONS

These findings could advocate the traditional use of J. grandiflorum L. and provide further insight into the anthelmintic activity of flavonoids.

Combating Parasitic Nematode Infections, Newly Discovered Antinematode Compounds from Marine Epiphytic Bacteria

Parasitic nematode infections cause debilitating diseases and impede economic productivity. Antinematode chemotherapies are fundamental to modern medicine and are also important for industries including agriculture, aquaculture and animal health. However, the lack of suitable treatments for some diseases and the rise of nematode resistance to many available therapies necessitates the discovery and development of new drugs. Here, marine epiphytic bacteria represent a promising repository of newly discovered antinematode compounds. Epiphytic bacteria are ubiquitous on marine surfaces where they are under constant pressure of grazing by bacterivorous predators (e.g., protozoans and nematodes). Studies have shown that these bacteria have developed defense strategies to prevent grazers by producing toxic bioactive compounds. Although several active metabolites against nematodes have been identified from marine bacteria, drug discovery from marine microorganisms remains underexplored. In this review, we aim to provide further insight into the need and potential for marine epiphytic bacteria to become a new source of antinematode drugs. We discuss current and emerging strategies, including culture-independent high throughput screening and the utilization of Caenorhabditis elegans as a model target organism, which will be required to advance antinematode drug discovery and development from marine microbial sources.

Chemical characterization and in vitro biological activity of Cymbopogon citratus extracts against Haemonchus spp. and Trichostrongylus spp. nematodes from sheep

Medicinal plants have been the focus of several studies due to their nematicide properties which can be used to control nematodes in sheep. No study has examined the morphological effects of Cymbopogon citratus on nematodes. Thus, this study evaluated the chemical composition, nematicidal activity and effects of C. citratus extracts on the morphology of eggs and infective larvae (L3) of sheep. Aqueous and methanolic extracts and fractions of C. citratus were obtained and analysed in vitro. The C. citratus extracts were effective against Haemonchus spp. and Trichostrongylus spp. larvae and eggs. Ten fractions were obtained from C. citratus, six of which had high ovicidal activity at 1000 μg mL-1, and two fractions had high activity at all tested concentrations. The phytochemical analysis identified the presence of compounds such as terpenoids, various ketones, esters, and fatty acids. The ultrastructural analysis showed deformations of the cuticle and wilting along the body of the nematodes at all concentrations. The muscular layer, intestinal cells and the mitochondria profile showed damage compared to the typical pattern. Ultra-thin sections of eggs treated with methanolic fractions of C. citratus presented modifications. This study showed the biological activity and effects of C. citratus on the gastrointestinal nematodes in sheep.

In Vitro Anthelmintic Evaluation of Gliricidia sepium, Leucaena leucocephala, and Pithecellobium dulce: Fingerprint Analysis of Extracts by UHPLC-Orbitrap Mass Spectrometry

In the present work, the anthelmintic activity (AA) of ethanolic extracts obtained from Gliricidia sepium, Leucaena leucocephala, and Pithecellobium dulce was evaluated using the third-stage-larval (L₃) exsheathment inhibition test (LEIT) and egg hatch test (EHT) on Haemonchus contortus. Extracts were tested at concentrations of 0.3, 0.6, 1.2, 2.5, 5.0, 10, 20, and 40 mg/mL. The larval exsheathment inhibition (LEI) results showed that G. sepium achieved the highest average inhibition of 91.2%, compared with 44.6% for P. dulce and 41.0% for L. leucocephala at a concentration of 40 mg/mL; the corresponding IC₅₀ values were 22.4, 41.7, and 43.3 mg/mL, respectively. The rates of egg hatching inhibition (EHI) at a concentration of 5 mg/mL were 99.5% for G. sepium, 64.2% for P. dulce, and 54% for L. leucocephala; the corresponding IC₅₀ values were 1.9 mg/mL for G. sepium, 3.9 mg/mL for P. dulce, and 4.3 mg/mL for L. leucocephala. The species extracts studied here were also analyzed by ultra-high performance liquid chromatography and Orbitrap high resolution mass spectrometry (UHPLC-Q/Orbitrap/MS/MS), resulting in the compounds' identification associated with AA. Glycosylated flavonoids and methoxyphenols were observed in all three species: fatty acids in G. sepium and P. dulce; phenylpropanoids, anthraquinone glycosides, amino acids and glycosylated phenolic acids in G. sepium; and flavonoids in L. leucocephala. Comparatively, G. sepium presented a greater diversity of compounds potentially active against the control of gastrointestinal nematodes, which was associated with the results obtained in the applied tests.

Plant-Based Natural Products for the Discovery and Development of Novel Anthelmintics against Nematodes

Intestinal parasitic nematodes infect approximately two billion people worldwide. In the absence of vaccines for human intestinal nematodes, control of infections currently relies mainly on chemotherapy, but resistance is an increasing problem. Thus, there is an urgent need for the discovery and development of new anthelmintic drugs, especially ones with novel mechanisms of action. Medicinal plants hold great promise as a source of effective treatments, including anthelmintic therapy. They have been used traditionally for centuries and are mostly safe (if not, their toxicity is well-known). However, in most medicinal plants the compounds active against nematodes have not been identified thus far. The free-living nematode C. elegans was demonstrated to be an excellent model system for the discovery of new anthelmintics and for characterizing their mechanism of action or resistance. The compounds discussed in this review are of botanical origin and were published since 2002. Most of them need further studies of their toxicity, mechanisms and structure-activity relationship to assess more fully their potential as drugs.

In vitro nematocidal activity of commercial fatty acids and β-sitosterol against Haemonchus contortus

Haemonchus contortus is a haematophagous gastrointestinal nematode (GIN) that causes severe anaemia and even death in small ruminants, negatively impacting the economic viability of farms. Traditionally, this parasite has been controlled with chemical compounds; however, inadequate use of these types of products has favoured the emergence of anthelmintic resistance. Therefore, it is necessary to search for alternatives for GIN control. Previous studies have reported the anthelmintic activity of edible mushroom extracts against H. contortus. A recent study reported that a fraction constituted of different fatty acids and β-sitosterol isolated from the basidiomata of the edible mushroom Pleurotus djamor ECS-123 has ovicidal and larvicidal activity against H. contortus. Thus, this study aimed to assess the anthelmintic activity of the pure molecules: pentadecanoic acid, palmitic acid, β-sitosterol, stearic acid and linoleic acid. For this purpose, an egg-hatching inhibition test was carried out in which the compounds were evaluated individually and in combination at a final concentration of 20 mg mL-1. Furthermore, larval mortality was assessed using a combination of the five commercial compounds previously mentioned at different concentrations (1.25-20 mg mL-1). Palmitic acid and stearic acid, in some combinations, inhibited H. contortus egg hatching by 100%. On the other hand, in the larval mortality test, the combination of the five compounds showed dose-dependent behaviour, and 100% mortality was obtained 24 h post-incubation. Pure molecules and their combinations have anthelmintic-like activity against the eggs and larvae of H. contortus.

In Vitro Anthelmintic Activity of Saponins from Medicago spp. Against Sheep Gastrointestinal Nematodes

Gastrointestinal strongyle nematodes (GIS) are included among the most important parasites of small ruminants. The widespread drug resistance and drug residues in products of animal origin have increased the interest in the search for natural compounds with anthelmintic activity as a valid alternative to current synthetic drugs. The aim of the present investigation was to test the ‘in vitro’ anthelmintic activity of saponins and prosapogenins from different Medicago species, selected for their importance as a forage crop worldwide for animal feeding. From these plants, saponin mixtures were extracted, purified and used at scalar concentrations to evaluate their anthelmintic activities against sheep gastrointestinal strongyles (GISs), by the egg hatch test. Treated and untreated controls were used as the comparison. Data were statistically analyzed, and EC₅₀ and EC₉₀ were also calculated. All saponins and prosapogenins showed inhibiting effects on GIS eggs in a concentration-dependent manner. At higher concentrations, most of them showed an efficacy comparable to the reference drug (Thiabendazole 3 µg/mL) (P < 0.001). With 1.72 mg/mL EC₅₀ and 3.84 mg/mL EC₉₀, saponin from M. polymorpha cultivars Anglona was the most active. Obtained results encourage further studies aimed at evaluating the efficacy ‘in vivo’ of saponins which resulted as most effective ‘in vitro’ in this study.