In vitro anthelmintic activity of an R-carvone nanoemulsions towards multiresistant Haemonchus contortus.

This work aimed to evaluate the in vitro anthelmintic effect of carvone nanoemulsions on Haemonchus contortus. Three R-carvone nanoemulsions were prepared: uncoated R-carvone nanoemulsions homogenized in a sonicator (UNAlg-son) and homogenized in an ultrahomogenizer (UNAlg-ultra) and sodium alginate-coated R-carvone (CNAlg-ultra). The physicochemical characterizations of the nanoemulsions were carried out. The anthelmintic activity was evaluated using egg hatch test (EHT), larval development test (LDT) and adult worm motility test (AWMT). Changes in cuticle induced in adult H. contortus were evaluated by scanning electron microscopy (SEM). The results were subjected to analysis of variance and compared using the Tukey test (P < 0.05). The effective concentration to inhibit 50% (EC50) of egg hatching and larval development was calculated. The particle sizes were 281.1 nm (UNAlg-son), 152.7 nm (UNAlg-ultra) and 557.8 nm (CNAlg-ultra), and the zeta potentials were −15 mV (UNAlg-son), −10.8 mV (UNAlg-ultra) and −24.2 mV (CNAlg-ultra). The encapsulation efficiency was 99.84 ± 0.01%. SEM of the nanoemulsions showed an increase in size. In EHT, the EC50 values of UNAlg-son, UNAlg-ultra and CNAlg-ultra were 0.19, 0.02 and 0.17 mg mL−1, respectively. In LDT, they were 0.29, 0.31 and 0.95 mg mL−1 for UNAlg-son, UNAlg-ultra and CNAlg-ultra, respectively. The adult motility inhibition was 100% after 12 h of exposure to UNAlg-ultra and CNAlg-ultra, while for UNAlg-son, it was 79.16%. SEM showed changes in the buccal capsule and cuticular damage. It was concluded that R-carvone nanoemulsions showed antiparasitic action demonstrating promise for the control of infections caused by gastrointestinal nematodes in small ruminants.

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.

Anthelmintic activity of Eucalyptus citriodora essential oil and its major component, citronellal, on sheep gastrointestinal nematodes / Atividade anti-helmíntica do óleo essencial de Eucalyptus citriodora e seu componente majoritário, citronelal, sobre nematoides gastrintestinais de ovinos

Abstract This study aimed to evaluate the anthelmintic activity of Eucalyptus citriodora essential oil and citronellal on sheep gastrointestinal nematodes. Essential oil composition was determined by gas chromatography mass spectrometry. The substances were evaluated in vitro using adult worm motility test (AWMT) and transmission electron microscopy (TEM). The acute toxicity test in mice and the fecal egg count reduction test (FECRT) in sheep were performed. Citronellal was confirmed as the essential oil major constituent (63.9%). According to the AWMT, 2 mg/mL of essential oil and citronellal completely inhibited Haemonchus contortus motility at 6 h post exposure. H. contortus exposed to essential oil and citronellal exhibited internal ultrastructural modifications. The lethal dose 50 values in mice were 5,000 and 2,609 mg/kg for essential oil and citronellal, respectively. E. citriodora essential oil reduced sheep epg at 14 days post treatment by 69.5% (P<0.05). No significant differences were observed in epg between the citronellal and negative control groups (P>0.05). The interaction between citronellal and other constituents in the essential oil may be relevant for its in vivo anthelmintic activity. Thus, E. citriodora essential oil and citronellal pharmacokinetic studies may help elucidate the anthelmintic activity of these compounds.

Resumo Este trabalho objetivou avaliar a atividade anti-helmíntica do óleo essencial de Eucalyptus citriodora e citronelal sobre nematoides gastrintestinais de ovinos. A composição do óleo essencial foi determinada por cromatografia gasosa acoplada à espectrometria de massas. As substâncias foram avaliadas in vitro utilizando-se teste de motilidade de vermes adultos (AWMT) e microscopia eletrônica de transmissão (TEM). Teste de toxicidade aguda em camundongos e teste de redução da contagem de ovos fecais (FECRT) em ovinos foram realizados. Citronelal foi confirmado como componente majoritário do óleo essencial (63,9%). No AWMT, 2 mg/mL de óleo essencial e citronelal inibiram completamente a motilidade de H. contortus 6 h pós-exposição. H. contortus expostos ao óleo essencial e citronelal exibiram modificações ultraestruturais internas. Os valores da dose letal 50 em camundongos foram 5.000 e 2.609 mg/kg para óleo essencial e citronelal, respectivamente. Óleo essencial de E. citriodora reduziu opg de ovinos 14 dias pós-tratamento em 69,5% (P<0,05). Não houve diferença significativa de opg entre grupo controle negativo e citronelal (P>0,05). A interação entre citronelal e outros constituintes do óleo essencial pode ser relevante na atividade anti-helmíntica in vivo. Portanto, avaliação farmacocinética do óleo essencial de E. citriodora e citronelal pode auxiliar a elucidar a atividade anti-helmíntica desses compostos.