Could beta-myrcene be an alternative to albendazole for the treatment of experimental cystic echinococcosis?

Echinococcus granulosus causes hydatidosis or cystic echinococcosis in humans and livestock. In humans, this disease can be managed with surgery, percutaneous treatment, chemotherapy and/or observation. The chemotherapeutic agents used and approved for treatment of hydatidosis are benzimidazoles. Because of the difficulties in achieving successful treatment, considerable efforts have been made to find new natural compounds against hydatid disease. Beta-myrcene is a monoterpene presented in the essential oils of different plants. It is the principal component of essential oil of Rosmarinus officinalis (rosemary). The goal of the present study was to evaluate the in vitro effects of beta-myrcene against germinal cells, protoscoleces and murine cyst of E. granulosus, as well also, investigate its chemoprophylactic activity in a murine model of cystic echinococcosis. For the in vitro assays, the parasites were incubated with beta-myrcene at 10, 5 and 1 µg/mL. The treatments were dose and time-dependent, and consistent with the observed morphological alterations. In the chemoprophylactic efficacy study, the effect of beta-myrcene was similar to albendazole, the reference drug for human echinococcosis treatment.

Chemoprophylactic and therapeutic efficacy of thymol in murine cystic echinococcosis.

Cystic echinococcosis is a zoonotic disease caused by the larval stage of the cestode Echinococcus granulosus. The drugs commonly used against cystic echinococcosis are benzimidazoles. Unfortunately, 20%-40% of cases do not respond favorably to such chemotherapy. Consequently, the search of new therapeutic alternatives such as the use of traditional medicinal plants has been increased. The aim of the current experimental work was to investigate the chemoprophylactic and clinical efficacy of thymol on mice infected with E. granulosus metacestodes. Thymol (40 mg/kg) was administered under two different therapeutic schemes: dosing every 24h over 20 days and treatment every 12h for 10 days. Thymol demonstrated efficacy against experimental murine cystic echinococcosis. The chemoprophylactic and therapeutic effects of thymol were comparable to that of albendazole. Due to the lack of toxicity observed in mice at the tested doses; we consider that thymol is a potential alternative to be applied for the treatment of human hydatid disease.

Efficacy of Essential Oils of Thymus vulgaris and Origanum vulgare on Echinococcus granulosus.

The aim of the present work was to determine the in vitro effect of T. vulgaris and O. vulgare essential oils against E. granulosus protoscoleces and cysts. Essential oils were added to the medium resulting in thymol final concentrations of 10 µg/mL. The essential oils had a time-dependent effect provoking the complete loss of protoscolex viability after 72 days of postincubation. The results were confirmed at the ultrastructure level. Loss of infectivity in protoscoleces incubated with O. vulgare after 60 days was observed. On the other hand, the weight of cysts recorded in mice inoculated with T. vulgaris treated protoscoleces was significantly lower than that obtained in control group. Gamma-glutamyl-transpeptidase activity was readily detected in the culture supernatant of protoscoleces treated either with the essential oils or thymol. T. vulgaris and O. vulgare essential oils and thymol can induce cell apoptosis of protoscoleces after short incubation times. The efficacy of T. vulgaris and O. vulgare essential oils was also demonstrated in vitro on E. granulosus murine cysts. Our data suggest that essential oils of T. vulgaris and O. vulgare have anthelmintic effect against protoscoleces and cysts of E. granulosus.

In vitro effect of 5-fluorouracil and paclitaxel on Echinococcus granulosus larvae and cells.

Human cystic echinococcosis is a zoonosis caused by the metacestode stage of the tapeworm Echinococcus granulosus. Although benzimidazole compounds such as albendazole and mebendazole have been the cornerstone of chemotherapy for the disease, there is often no complete recovery after treatment. Hence, in searching for novel treatment options, we examined the in vitro efficacies of 5-fluorouracil (5-FU) and paclitaxel (PTX) against E. granulosus germinal cells, protoscoleces and cysts. 5-FU or PTX inhibited the growth of E. granulosus cells in a time dependent manner. Although both treatments had a protoscolicidal effect, 5-FU had a considerably stronger effect than PTX. 5-FU produced a dose- and time-dependent effect, provoking the complete loss of viability after 24 days of incubation. Moreover, cysts did not develop following the inoculation of treated protoscoleces into mice. The loss of viability was slower in PTX treated protoscoleces, reaching to approximately 60% after 30 days. The results of the in vitro treatment with 5-FU and PTX were similar in secondary murine cysts. The employment of SEM and TEM allowed us to examine, at an ultrastructural level, the effects induced by 5-FU and PTX on E. granulosus germinal cells, protoscoleces and murine cysts. In conclusion, the data obtained clearly demonstrated that 5-FU and PTX at clinically achievable concentrations inhibit the survival of larval cells, protoscoleces and metacestodes. In vivo studies to test the antiparasitic activities of 5-FU and PTX are currently being undertaken on the murine model of cystic echinococcosis.