Ovicidal and larvicidal activity of extracts of Opuntia ficus-indica against gastrointestinal nematodes of naturally infected sheep

Molecular interaction analysis of the lignans from Piper cubeba in complex with Haemonchus contortus phosphomethyltransferase

In vitro larvicidal assays carried out previously by our research group with cubebin, dihydrocubebin and hinokinin, lignans extracted from the fruits of Piper cubeba, against Haemonchus contortus larvae showed strong action larvicidal these compounds. Hinokinin was the most active (EC50 = 0.34 µg/mL) with strong action on the cuticle of the larvae as observed by scanning electron microscopy of the L3 stage. Therefore, to understand the mechanism of action of these compounds in silico studies were carried out using the enzyme phosphomethyltransferase of Haemonchus contortus that contain PMT-1 and PMT-2 di-domains responsible for phosphocholine synthesis, which is one of the main lipids in nematodes. This pathway is not found in mammals, so this enzyme is an important biological target for the development of new anthelmintics. Results of molecular docking, molecular dynamic and a density functional theory calculations studies with the three lignans show few interactions with PMT-1. However, hinokinin has important interactions with PMT-2, that can deactivate the enzyme and interrupt the phosphocholine synthesis, which is an essential compound for the development and maintenance of the nematode cuticle and its survive. Therefore, the previous results of the in vitro assay allied with in silico results, now realized; suggest that hinokinin may be a possible selective target for the development of new anthelmintics against Haemonchus contortus since the PMT-2 domain is present in this nematode.

Blood biochemical parameters of lambs fed diets containing cactus cladodes

ABSTRACT This study aimed to evaluate the effects of partial replacement (750g/kg) of Tifton hay by two cactus cladodes (Nopalea or Opuntia) on the metabolic profile of lambs. Thirty-six uncastrated male Santa Inês lambs (22.0 ± 2.9kg initial body weight) were distributed in a completely randomized design, with three treatments and 12 repetitions. The animals were fed a control diet (Tifton hay as exclusive roughage), Miúda cactus cladodes-based diet or Orelha de Elefante Mexicana (O.E.M.) cactus cladodes-based diet. Blood samples were collected one day before (baseline) and 45 days after the introduction of the tested diets. The Miúda cactus cladodes caused an increase (P=0.055) in the serum activity of the gamma-glutamyl transferase enzyme (53.66U/L) and in the blood content of glucose and fructosamine. The O.E.M. cactus cladodes caused lower (P=0.038) serum cholesterol content (41.33mg/dL). Regardless of the variety, there was a decrease (P=0.001) in the serum content of indirect bilirubin, urea, and sodium, and increase in the serum magnesium concentration. The partial replacement of the Tifton hay by Miúda or O.E.M. cactus cladodes in lamb feeding increases the enzyme activity, indicating liver and/or kidney changes, but does not cause relevant damage to energy, protein, and mineral metabolism.

Kidney changes in lambs fed cactus pear varieties resistant to Dactylopius opuntiae as the only roughage

This study aimed to evaluate the effects of four varieties of cactus pear resistant to carmine cochineal as exclusive roughage for lambs on the biochemical, histopathological, and histomorphometric parameters of kidneys. Twenty-four castrated male crossbred lambs at eight months of age and an initial body weight of 21.0 ± 0.5 kg were distributed in a completely randomized design, with four treatments and six repetitions. The experimental treatments consisted of four diets containing Miúda cactus pear, IPA-Sertânia cactus pear, IPA-F21 cactus pear, or Orelha de Elefante Mexicana (OEM) cactus pear as the only roughage. Blood samples were collected every two weeks (14 d, 28 d, 42 d, and 56 d) to quantify serum urea and creatinine levels. After 72 days of the introduction of the tested diets, the animals were slaughtered and fragments of the kidneys were collected for histological analysis. The serum urea level was higher in animals fed a diet based on the Miúda variety (49.38 mg dL^-1), and the serum creatinine levels were lower in the last two collections (P = 0.009). The most frequent histopathological findings in the kidneys were calcification, congestion, glomerular atrophy, presence of luminal cellular debris, and nephrosis, regardless of the cactus pear variety. The Miúda cactus pear and OEM cactus pear varieties caused more severe damage to the nephron components, while the varieties IPA F-21 and IPA-Sertânia caused less significant injuries. The use of IPA-Sertânia and IPA F-21 cactus pear varieties is suggested in lamb's diets, due to the lower impact on the renal parenchyma. However, there was no expressive impairment of renal function, and there was no difference between the cactus pear varieties tested in this study on the weight gain of the animals, and they can all be used to feed feedlot sheep.

A Systematic Review on Comparative Analysis, Toxicology, and Pharmacology of Medicinal Plants Against Haemonchus contortus

Background:Haemonchus contortus is an important pathogenic nematode parasite and major economic constraint of small ruminants in tropics and subtropics regions. This review is an attempt to systematically address the; (a) efficacy of different plants against H. contortus by in vitro and in vivo proof; (b) toxicology, mechanism of action, and active phyto-compounds involve in anti-haemonchiasis activity; (c) and comparative analysis of plant species evaluated both in vitro and in vivo.

Methods: Online databases (Google Scholar, PubMed, Scopus, and ScienceDirect) were searched and published research articles (1980–2020) were gathered and reviewed.

Results: A total of 187 plant species were reported belonging to 59 families and 145 genera with Asteraceae and Fabaceae being frequently used. Out of the total plant species, 171 species were found to be evaluated in vitro and only 40 species in vivo. Twenty-four species were commonly evaluated for in vitro and in vivo anti-haemonchiasis activity. Among the reported assays, egg hatching test (EHT) and fecal egg count reduction (FECR) were the most widely used assays in vitro and in vivo, respectively. Moreover, sheep were the frequently used experimental model in vivo. After comparative analysis, Lachesiodendron viridiflorum, Corymbia citriodora, Calotropis procera, and Artemisia herba-alba were found highly effective both in vitro and in vivo. L. viridiflorum inhibited enzymatic activities and metabolic processes of the parasite and was found to be safe without toxic effects. C. citriodora was moderately toxic in vivo, however, the plant extract produced promising nematicidal effects by causing muscular disorganization and changes in the mitochondrial profile. Additionally, C. procera and A. herba-alba despite of their high anti-haemonchiasis activity were found to be highly toxic at the tested concentrations. C. procera caused perforation and tegumental disorganization along with adult worm paralysis. Nineteen compounds were reported, among which anethole and carvone completely inhibited egg hatching in vitro and significantly reduced fecal egg count, decreased male length, and reproductive capacity of female in vivo.

Conclusion: This review summarized different medicinal plants owing to nematicidal activities against H. contortus eggs, larvae, and adult worms. Plants like L. viridiflorum, C. citriodora, C. procera, and A. herba-alba, while compounds anethole and carvone having promising nematicidal activities and could be an alternative source for developing novel drugs after further investigation.

Nematicidal Effect and Histological Modifications Induced by Hydrolysable Tannin Extract on the Third-Stage Infective Larvae of Haemonchus contortus

Haemonchus contortus is the most frequent and most important nematode parasite in the ruminants production of tropical and subtropical regions. There are strains resistant to all families of available anthelmintics. Consequently, the conduction of research to find other resources that allow effective control of this parasitic disease, preferably focusing on green production, is necessary. The aim of this study was to evaluate the effect of hydrolysable tannin extract (HTE) on larvae 3 (L3) of H. contortus in vitro. L3 were exposed to different HTE concentrations and times. In addition, both light and scanning electron microscopy were used to explore physical damage on L3 subjected to HTE activity. After 72 h of incubation, the mean lethal concentration of HTE was 2 mg/mL; this concentration has been previously referred to as safe for consumption in cattle. Scanning electron microscopy revealed H. contortus L3 destruction, damage was evident by separation of the sheath mainly in the cervical and caudal regions of the larva and by rupture of the cuticle with larval evisceration. Our results suggest that hydrolysable tannin extract from chestnut could be considered as a green alternative for parasitic control in ruminants.

Anthelmintics in the future: current trends in the discovery and development of new drugs against gastrointestinal nematodes

The control of gastrointestinal nematodes (GINs), the most abundant and serious parasites of livestock, has become difficult because of the limited number of available drugs and fast development of drug resistance. Thus, considerable efforts have been devoted to developing new anthelmintics that are efficient against nematodes, especially resistant species. Here, we summarize the most recent results using various approaches: target-based or high-throughput screening (HTS) of compound libraries; the synthesis of new derivatives or new combinations of current anthelmintics; the repurposing of drugs currently approved for other indications; and lastly, the identification of active plant products. We also evaluate the advantages and disadvantages of each of these approaches.

In vitro anthelmintic activity of the crude hydroalcoholic extract of Piper cubeba fruits and isolated natural products against gastrointestinal nematodes in sheep

This study describes the in vitro anthelmintic activity of a hydroalcoholic extract from the fruit of Piper cubeba and its major isolated components against the eggs and larvae of gastrointestinal nematodes obtained from naturally-infected ovines. In vitro anthelmintic activity was evaluated using the egg hatch test (EHT), larval development test (LDT) and L3 migration inhibition test (LMT). The extract showed ovicidal and larvicidal activity, with an EC₅₀ of 200 μg/mL and 83.00 μg/mL in the EHT and LDT, respectively. The extract inhibited 100% of larval migration at the lowest tested concentration (95 μg/mL). The crude extract was purified using successive silica gel chromatographic columns, which revealed the lignans hinokinin, cubebin and dihydrocubebin as the major compounds that were present, which were then used in in vitro tests. Cubebin, dihydrocubebin and hinokinin showed higher activity than the crude extract, with an EC₅₀ for ovicidal activity of 150.00 μg/mL, 186.70 μg/mL and 68.38 μg/mL, respectively. In the LDT, cubebin presented an EC₅₀ of 14.89 μg/mL and dihydrocubebin of 30.75 μg/mL. Hinokinin inhibited 100% the larval development at all concentrations evaluated. In the LMT, dihydrocubebin inhibited 100% the larval migration in all concentrations evaluated while cubebin and hinokinin showed EC₅₀ values of 0.89 μg/mL and 0.34 μg/mL, respectively. P. cubeba extract is rich in several classes of active compounds, but here we demonstrate that the described anthelmintic activity may be related to the presence of these lignans, which are present in larger concentrations than other components of the extract. Our results demonstrate for first time the anthelmintic activity against gastrointestinal nematodes in sheep for this class of special metabolites that are present in P. cubeba fruit. However, future detailed studies are needed to evaluate the effectiveness of P. cubeba fruits extract and active lignans in in vivo tests.

Discovery of potential ovicidal natural products using metabolomics

Plant extracts are a potential source of new compounds for nematode control and may be an excellent alternative for the control gastrointestinal nematodes that are resistant to conventional anthelmintics. However, research involving natural products is a complex process. The main challenge is the identification of bioactive compounds. Online analytical techniques with universal detectors, such as high-performance liquid chromatography-mass spectrometry (HPLC-MS), together with metabolomics could enable the fast, accurate evaluation of a massive amount of data, constituting a viable option for the identification of active compounds in plant extracts. This study focused on the evaluation of the ovicidal activity of ethanol extracts from 17 plants collected from the Pantanal wetland in the state of Mato Grosso do Sul, Brazil, against eggs of Haemonchus placei using the egg hatchability test. The ethanol extracts were obtained using accelerated solvent extraction. The data on ovicidal activity, mass spectrometry and metabolomics were evaluated using HPLC-DAD-MS, partial least squares regression analysis (PLS-DA) and a correlation map (univariate correlation analyses) to detect compounds that have a positive correlation with biological activity. Among the ten metabolites with the best correlation coefficients, six were phenylpropanoids, two were triterpene saponins, one was a brevipolide, and one was a flavonoid. Combinations of metabolites with high ovicidal action were also identified, such as phenylpropanoids combined with the triterpene saponins and the flavonoid, flavonoids combined with iridoid and phenylpropanoids, and saponins combined with phenylpropanoid. The positive correlation between classes of compounds in plants belonging to different genera and biological activity (as previously identified in the literature) reinforces the robustness of the statistical data and demonstrates the efficacy of this method for the selection of bioactive compounds without the need for isolation and reevaluation. The proposed method also enables the determination of synergism among the classes, which would be impracticable using traditional methods. The present investigation demonstrates that the metabolomic technique was efficient at detecting secondary metabolites with ovicidal activity against H. placei. Thus, the use of metabolomics can be a tool to accelerate and simplify bioprospecting research with plant extracts in veterinary parasitology.

In vitro anthelmintic activity of grape pomace extract against gastrointestinal nematodes of naturally infected sheep

Grape pomace obtained as a byproduct of industrial processing of grapes retains nutrients and substances with anthelmintic potential such as saponins, tannins, and flavonoids. Therefore, this study evaluated the in vitro ovicidal and larvicidal activity of hydroalcoholic grape pomace extract against gastrointestinal nematodes of sheep. The anthelmintic evaluation was performed by in vitro assays with eggs and larvae of nematodes obtained from naturally infected donor sheep. The grape pomace extract showed high in vitro ovicidal and larvicidal activity with LD50 values of 0.30 mg/mL for egg hatching inhibition, 1.01 mg/mL for larval development inhibition and 100% efficacy in larval migration inhibition assays at all concentrations evaluated. The effect of tannins was evaluated by the addition of 50 mg/mL polyvinyl polypyrrolidone to grape pomace extract at the concentration of 12.5 mg/mL. The in vitro ovicidal activity of grape pomace was reduced by only 15% after polyvinyl polypyrrolidone addition, indicating that other phytochemicals also contribute to the ovicidal activity displayed by the extract. Our results demonstrate that grape pomace exhibits in vitro anthelmintic activity, suggesting that, beyond its nutritional potential, this pomace can also be an ally for gastrointestinal nematode control in sheep.

Chemical Characterization of Opuntia ficus-indica (L.) Mill. Hydroalcoholic Extract and Its Efficiency against Gastrointestinal Nematodes of Sheep

Opuntia ficus-indica (L.) Mill. is a xerophylous plant that originated in tropical and subtropical America. This plant is popularly known in Brazil as “palma forrageira” (cactus pear) and plays a fundamental role in animal nutrition, mainly in the Northeastern semi-arid region of the country. The plant has several uses since it presents bioactive compounds that confer biological and pharmacological properties. In this context, the cactus pear can also be considered a potential product to combat parasite infections. The objective of this study was to chemically characterize the O. ficus-indica hydroalcoholic extract (OFIEOH) and to determine its efficacy against gastrointestinal parasites using in vitro tests. Initially, the hydroalcoholic extract from cladode peels of O. ficus-indica was produced by maceration for 21 days. For the chemical characterization, colorimetric dosages were performed for carbohydrates, proteins, phenols and condensed tannins. Liquid chromatography coupled to mass spectrometry/electron spray ionization (LC-MS/ESI) was used to characterize the polyphenolic profile of the OFIEOH extract. Fifteen compounds were identified in the OFIEOH extract, such as methyl, glycosylated and aglycone quercetin derivatives and aglycone and glycosylated kaempferol derivatives. Tri-glycosylated methyl quercetin derivatives were the main compounds identified. In vitro egg hatch (EHT) and larval migration tests (LMT) were used in a range of concentrations of OFIEOH from 12.5 to 100 mg/mL for EHT and 12.5 to 200 mg/mL for LMT. In addition, the LMT was used to test ivermectin (IVM) (from 11.4 to 57.1 µM), associated with the inhibitory concentration of 50% (IC₅₀) for OFIEOH. The combination of OFIEOH (12.5 to 200 mg/mL) plus the IC₅₀ of IVM was also tested. The efficacy of OFIEOH alone varied from 19.33 to 90.0% using the EHT. The LMT revealed an efficacy of 5.78 to 77.26% for the extract. Both tests showed a concentration-dependence inhibitory effect. We found a drug-extract antagonistic neutralizing effect when doses of IVM were added to OFIEOH (maximum efficacy of 73.78%), while a positive additive effect was observed when OFIEOH was added to the IC₅₀ of IVM (IC₅₀ of 82.79 for OFIEOH alone against an IC₅₀ of 55.08 of OFIEOH + IVM). The data from this work indicate that OFIEOH alone may be considered as a suitable ecofriendly product to control gastrointestinal parasites of sheep, offering a more holistic approach to improve animal farming and welfare. The drug-extract interaction is also a promising therapeutic alternative, reducing the final dose to the host, with an optimum combination effect.

Assessment of anthelmintic activity and bio-guided chemical analysis of Persea americana seed extracts

The aim of this study was to characterize the extracts and fractions of Persea americana Mill. (Avocado) seeds and to determine the composition and the in vitro anthelmintic activity against third-stage larvae (L3) of Haemonchus contortus. The fresh (F) and dried (H) avocado seeds (PA) were subjected to extraction with hot water (W-PAF, W-PAH), ethanol (E-PAF, E-PAH) or methanol 70% (v/v), and partition with solvents of increasing polarity [n-hexane (H-PAF, H-PAH), chloroform (C-PAF, C-PAH), ethyl acetate (Ea-PAF, Ea-PAH), and n-butanol (B-PAF, B-PAH)], yielding a total of 14 extracts/fractions. After considering the yield, water solubility, and the preliminary results of the larval migration test (LMT), the E-PAF, E-PAH, H-PAF, and H-PAH were selected for further experiments. E-PAH presented an efficiency concentration of 50% (EC₅₀) of 36 μg/mL on the LMT. E-PAH showed the greatest efficiency when its EC₅₀ was compared to the other fractions (E-PAF = 147 μg/mL; H-PAF = 801 μg/mL; H-PAH = 77 μg/mL). After that, the E-PAH was chemically characterized, considering its quantitative polyphenolic and flavonoid contents by colorimetric and chromatographic techniques. E-PAH presented 50, 38, and 24 mg/g of dry matter of total phenol, condensed tannins (CT), and flavonoid contents, respectively. Using high performance liquid chromatography (HPLC) analysis, E-PAH had shown to have epicatechin (4.7 μg/mL), rutin (2.8 μg/mL), and chlorogenic acid (1.4 μg/mL) as its main constituents besides quercetin. These isolated compounds were evaluated using the LMT in order to relate the composition to the anthelmintic activity observed for E-PAH. Quercetin (EC₅₀ = 7.8 μg/mL) and epicatechin (EC₅₀ = 10 μg/mL) presented a higher efficiency than rutin (EC₅₀ = 30 μg/mL). Chlorogenic acid was also tested with the LMT but did not present a significant efficiency. According to the results, the phenolic composition of E-PAH and the EC₅₀ values obtained for the isolated phenols, it can be suggested that, besides the CT content, the presence of epicatechin and rutin contributed to the larvicidal activity of E-PAH. In conclusion, avocado seeds may be used as a source of polyphenols with promising anthelmintic applications.