Is there a negative association between the content of condensed tannins, total phenols, and total tannins of tropical plant extracts and in vitro anthelmintic activity against Haemonchus contortus eggs? (original) (raw)
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Journal of Helminthology, 2019
This study assessed the in vitro anthelmintic (AH) activity of methanol and acetone:water leaf extracts from Annona squamosa, A. muricata and A. reticulata against Haemonchus contortus eggs. The egg hatch test was used to determine the effective concentrations required to inhibit 50% of eggs hatching (EC50). The role of polyphenols on AH activity was measured through bioassays with and without polyvinylpolypyrrolidone (PVPP). Methanolic extracts mainly caused the death of eggs at the morula stage (ovicidal activity). Meanwhile, acetone:water extracts caused egg-hatching failure of developed larvae (larvae failing eclosion (LFE) activity). The lowest EC50 values against H. contortus eggs were observed for the methanolic extracts from A. reticulata and A. muricata (274.2 and 382.9 µg/ml, respectively). From the six extracts evaluated, the methanolic extracts of A. muricata, A. reticulata and A. squamosa showed the highest ovicidal activity, resulting in 98.9%, 92.8% and 95.1% egg mort...
Industrial Crops and Products, 2021
Due to high prevalence and large pathogenicity, Haemonchus contortus is the main gastrointestinal nematode in tropical and subtropical regions. This species is responsible for severe economic losses to sheep and goat breeders in Brazil. The control of this parasite is currently compromised, mainly, due to anthelmintic resistance. In the search for natural anthelmintic alternatives, Pterogyne nitens, a native Brazilian tree with potential ethnopharmacological activity, has been identified. The aim of this study was to evaluate the anthelmintic activity of ethanolic extracts and phenolic compounds from P. nitens, as well as two commercial flavonoids (chrysin and morin), to derive the chemical structure and anthelmintic activity. The ovicidal and larvicidal activity of ethanolic extracts from leaves (EEL) and fruits (EEFR), as well as natural compounds from P. nitens on H. contortus were evaluated through egg hatch assay (EHA) and larval development assay (LDA). The results showed that all extracts, especially the phenolic compounds were active in the EHA and LDA. The egg hatch inhibitory effects of EEL (EC 50 = 316 μg/mL) were more potent than EEFR (EC 50 = 512 μg/mL). However, larval development inhibitory effects of EEL (EC 50 = 47 μg/mL) and EEFR (EC 50 = 35 μg/mL) were similar. Among the compounds, the flavones (sorbifolin, pedalitin, and chrysin) did not have inhibitory effects on egg hatching but presented some activity against larval development of H. contortus. In contrast, the flavonols (quercetin, rutin, and morin) showed high activity in the EHA but were inactive in the LDA. The addition of at hydroxyl group and rutinose group to the flavonoid structure increased the ovicidal and larvicidal activity, respectively. The phenolic acids showed potent anthelmintic activity: caffeic acid, ferulic acid, and gallic acid had the highest anthelmintic effects, presenting EC 50 values of 1.48, 0.56, and 4.93 μg/mL in the EHA; and 31, 22, and 33 μg/mL in the LDA, respectively. These results suggest that P. nitens might be a source of effective alternative compounds to control H. contortus.
Veterinary Parasitology, 2012
The resistance of gastrointestinal nematodes to anthelmintics has increased the need to evaluate natural products that can replace or assist current strategies to control gastrointestinal nematodes. The objective of this study was to evaluate the effect of decoctions of Lantana camara (DLc), Alpinia zerumbet (DAz), Mentha villosa (DMv) and Tagetes minuta (DTm) on Haemonchus contortus by two in vitro tests. The effects of increasing concentrations of lyophilized decoctions (0.31 to 10 mg/ml) were assessed using the egg hatch test (EHT). The decoctions were then tested in the larval artificial exsheathment assay. H. contortus third stage larvae (L3) were exposed to 0.31 mg/ml A. zerumbet and M. villosa decoctions and 0.62 mg/ml T. minuta and L. camara decoctions for 3 h and then exsheathment procedure at 10 min intervals. An inhibitor of tannins, polyvinyl polypyrrolidone (PVPP), was used to study if tannins were responsible for the inhibitory effect on hatching and exsheathment of larvae. A. zerumbet, M. villosa and T. minuta showed a dose-dependent effect in the EHT, which did not disappear after the addition of PVPP. No effect was observed for L. camara in the EHT. However, the decoctions inhibited the process of larval exsheathment, which may be related to tannin action because the addition of PVPP reversed the inhibitory effect. A. zerumbet, M. villosa and T. minuta decoctions showed inhibitory activity on H. contortus larvae hatching and exsheathing. The decoctions of these plants could be used to control gastrointestinal nematodes following confirmation of their anthelmintic activity in vivo.
Medicina Veterinária (UFRPE), 2019
We evaluated the activity of Annona crassiflora leaves against Haemonchus contortus resistant to albendazol. Aqueous (AE), ethanolic (EE) and ethyl acetate (EAE) extracts were produced and the predominant presence of flavonoids was observed in HPLC-DAD chromatograms. Initially we evaluated the larval development inhibition (LDI) of dry A. crassiflora leaf powder or its AE directly in fecal quantitative cultures. The efficacies of the extracts, with or without tannins, on egg hatching inhibition (EHI) were investigated reveling that the EE was the most effective (LC90 = 8.96 mg/mL). However, after tannin removal, AE showed the highest activity (LC90 = 4.27 mg/mL). In the LDI test, the LC90 of AE was < 6.25 mg/g of fecal culture and to leaf powder of leaves was 69.14 mg/g. High efficacies of AE and EE for EHI were detected and the tannins were not the main active metabolites. The anthelmintic potential of this plant could be attributed to association between flavonoids and other ...
BMC Veterinary Research, 2013
Background: Helminthiasis is a major limitation to the livestock industry in Africa. Haemonchus contortus is the singular most important helminth responsible for major economic losses in small ruminants. The high cost of anthelmintics to small farmers, resistance to available anthelmintics and residue problems in meat and milk consumed by humans further complicates matters. The use of plants and plant extracts as a possible source of new anthelmintics has received more interest in the last decade. Our aim was not to confirm the traditional use, but rather to determine activity of extracts. Based on our past experience acetone was used as extractant. Because it is cheaper and more reproducible to evaluate the activity of plant extracts, than doing animal studies, the activity of acetone leaf extracts of thirteen plant species used traditionally in ethnoveterinary medicine in South Africa were determined using the egg hatch assay and the larval development test. Cytotoxicity of these extracts was also evaluated using the MTT cellular assay. Results: Extracts of three plant species i.e. Heteromorpha trifoliata, Maesa lanceolata and Leucosidea sericea had EC 50 values of 0.62 mg/ml, 0.72 mg/ml and 1.08 mg/ml respectively for the egg hatch assay. Clausena anisata; (1.08 mg/ml) and Clerodendrum glabrum; (1.48 mg/ml) extracts were also active. In the larval development assay the H. trifoliata extract was the most effective with an EC 50 of 0.64 mg/ml followed by L. sericea (1.27 mg/ml). The activities in the larval development test were generally lower in most plant species than the egg hatch assay. Based on the cytotoxicity results C. anisata was the least toxic with an LC 50 of 0.17 mg/ml, while Cyathea dregei was the most toxic plant with an LC 50 of 0.003 mg/ml. The C. anisata extract had the best selectivity index with a value of 0.10 and 0.08 for the two assays, followed by H. trifoliata and L. sericea with values of 0.07, 0.07 and 0.05, 0.04. The C. dregei extract had the worst selectivity index with a value of 0.00019 for both assays. Conclusion: The result of this study indicates which species should be further investigated in depth for isolation of compounds.
Anthelmintic activity of Jatropha curcas L. seeds on Haemonchus contortus
Veterinary Parasitology, 2011
The aim of this study was to evaluate the anthelmintic activity of hexane (HE), ethyl acetate (EA) and ethanol (EE) extracts obtained from the seeds of Jatropha curcas using the egg hatch inhibition assay (EHA) and the artificial larval exsheathment inhibition assay (LEIA). For the egg hatch assay, HE, EA and EE were used in concentrations of 3.12, 6.25, 12.5, 25 and 50 mg ml −1 , accompanied by a negative control (5% Tween 80) and a positive control (0.025 g ml −1 thiabendazole). In LEIA, the extracts were tested at a concentration of 1000 g ml −1 , accompanied by a negative control (PBS). To evaluate the effect of tannins, the extract with the greatest effect was incubated with polyvinyl polypyrrolidone (PVPP). The EE (50 mg ml −1 ) inhibited 99.8% of egg hatching. After the addition of PVPP, the ovicidal effectiveness of EE was reduced to 91.9%. Using the HE and EA, inhibition of egg hatching was 15.3% and 32.2%, respectively. In the LEIA, 18.9% of L3 incubated with EE were exsheathed (p < 0.01). The addition of PVPP to EE reversed the inhibitory effect on larval exsheathment. The percentage of exsheathment of L3 incubated with HE (99.6%) and EA (97.8%) did not differ from the control group (p > 0.05). The results show that the effects of EE on eggs are not solely due to the tannins. However, these secondary metabolites are implicated in blocking the larval exsheathment.
2017
It has been suggested that the anthelmintic (AH) activity of tannin-rich forages is related to their tannin content. However, reports on tropical fodders such as <i>Lysiloma latisiliquum</i> describe the same AH activity after the addition of tannin-blocking agents, suggesting that the activity either depends on the method of tannin blocking/removal or is due to other type of secondary metabolites. This study compared both the effect of the drying process of the plant material and the effect of different polyphenol removal methods on the AH activity of <i>L. latisiliquum</i> acetone-water extracts when tested against <i>Haemonchus contortus</i>. The results showed that the extraction of oven-dried (OD) leaves of <i>L. latisiliquum</i> yielded a CT-free extract with high AH activity. However, polyphenol-free fractions showed similar or lower AH activity levels as of those original OD extract. HPLC analysis confirmed that common polyphen...