Efficacy of purified fractions of Artemisia ludoviciana Nutt. mexicana and ultraestructural damage to newly excysted juveniles of Fasciola hepatica in vitro.

The study aimed to evaluate the fasciolicidal efficacy of extracts and fractions of Artemisia ludoviciana and identify the active substance. Extracts from A. ludoviciana were obtained by using hexane, ethyl acetate and methanol. To test the extracts, newly excysted juveniles of Fasciola hepatica were artificially obtained. The extracts were tested at concentrations of 125, 250, 375 and 500 mg/L. In each test run, an untreated control group and control wells containing triclabendazole sulfoxide were also included. The flukes were examined at 24, 48 and 72 h after treatment. Ethyl acetate extract (ALEAE) showed 100 % efficacy at 48 h of exposure (P < 0.05). Then, this extract was fractionated by column chromatography (CC), and the obtained fractions were evaluated in vitro as previously mentioned. The results indicated that fraction 3 yielded 100 % efficacy at 48 h (P < 0.05). Subsequently, the purification of fraction 3 was performed. New fractions were obtained (A-L), with sub-fraction "J" exhibiting 100 % efficacy at 24 h (P < 0.05). These sub-fractions were submitted to phytochemical analysis, demonstrated the presence of sesquiterpene lactones. Likewise, were analyzed by HPLC/MS/DAD, and the results showed that artemisinin was the main compound. In addition, flukes treated were examined by scanning electron microscopy (SEM) showing areas of inflammation throughout the tegument.

Hybridization experiments indicate incomplete reproductive isolating mechanism between Fasciola hepatica and Fasciola gigantica.

Experiments on hybridization between Fasciola hepatica and Fasciola gigantica were carried out to clarify whether a reproductive isolating mechanism appears between the two Fasciola species. Molecular evidence for hybridization was based on the DNA sequence of the internal transcribed spacer 1 (ITS1) region in nuclear ribosomal DNA, which differs between the species. The results suggested that there were not pre-mating but post-mating isolating mechanisms between the two species. However, viable adults of the hybrids F1 and F2 were produced from both parental F. hepatica and F. gigantica. The hybrids inherited phenotypic characteristics such as ratio of body length and width and infectivity to rats from parental Fasciola hepatica and F. gigantica. These findings suggest that reproductive isolation is incomplete between Fasciola hepatica and F. gigantica. Adults of the hybrids F1 and F2 were completely different in mode of reproduction from aspermic Fasciola forms that occur in Asia and seem to be offspring originated from hybridization between F. hepatica and F. gigantica and to reproduce parthenogenetically.

The effect of the 5-chloro-2-methylthio-6-(1-naphtyloxy)-1H-benzimidazole on the tegument of immature Fasciola hepatica in their natural host.

The damage to the tegument of 3-week-old Fasciola hepatica was evaluated by scanning electron microscopy (SEM) following treatment with the 5-chloro-2-methylthio-6-(1-naphtyloxy)-1H-benzimidazole (called compound alpha) in its natural host. For the present study, flukes were raised in pelibuey sheep infected orally with metacercariae of F. hepatica; the parasites were recovered from the liver of the sacrificed sheep after 6, 12 and 24 h of treatment with compound alpha. At 6 h of treatment, the flukes showed some lesions on the ventral surface of the anterior region, such as a swollen tegument and blebs. At 12 h after treatment, the specimens showed structural disorganization and spine loss in the ventral anterior region. The tegument of the flukes treated for 24 h was completely lost in some areas of the ventral surface, leaving an exposed basal lamina. The tegument of immature F. hepatica might be a target organ for compound alpha to exert its fasciolicide effect.

Tegumental surface changes in adult Fasciola hepatica following treatment in vitro and in vivo with an experimental fasciolicide.

Our objective was to determine by scanning electron microscopy the structural changes in the tegument of adult Fasciola hepatica after treatment with 5-chloro-2-methylthio-6-(1-naphtyloxy)-1 H-benzimidazole, called compound alpha, and its active metabolite sulphoxide, under in vitro and in vivo conditions. For the in vitro studies, flukes from sheep were exposed to 40 mg/l of compound alpha-sulphoxide over different incubation times. Flukes for the in vivo studies were raised in sheep treated orally with compound alpha and killed at different times post-treatment. Non-treated controls were included for each time of incubation. The results showed lesions after 6 h of treatment, such as swelling and furrows. At 12 h, the spines appeared to be surrounded by the tegument. At 24 h the tegument in some areas showed an exposed basal lamina. These changes became more severe as the incubation periods of the treated flukes increased. Compound alpha exerts a significant effect on the tegument of F. hepatica.