Antiparasitic Effects of Asteraceae Species Extracts on Echinococcus granulosus s.s.

Cystic echinococcosis is a zoonotic disease caused by the parasite Echinococcus granulosus sensu lato (s.l.), which is worldwide distributed and causes long-lasting infections in animals and humans. The existing treatment is limited to the use of benzimidazoles, mainly albendazole (ABZ). However, it has unwanted side effects and its efficacy is about 50%. The Asteraceae family includes plants that have therapeutic applications (medicinal species) and has an important role in new drug development. The species belonging to a different genus of this family show a wide range of anti-inflammatory, antimicrobial, antioxidant, hepatoprotective, and antiparasitic activities, among others. The aim of the present study was to evaluate the in vitro efficacy of extracts of four Asteraceae species against protoscoleces of E. granulosus sensu stricto (s.s.). On the other hand, the Stevia aristata extract was assessed on the murine cyst of E. granulosus (s.s.) and the efficacy of S. aristata extract was investigated in a murine model of CE. Stevia satureiifolia, S. aristata, Grindelia pulchella, and G. chiloensis extracts at 100 µg/mL caused a decrease in protoscoleces viability; however, S. aristata extract produced the greatest in vitro protoscolicidal effect. After 20 days of treatment with the highest concentration (100 µg/mL) of S. aristata extract, protoscoleces viability decreased to 0%. The tegumental changes observed by scanning electron microscopy were consistent with the reduction in vitality. The collapse of the germinal layer was registered in 60 ± 5.8% and 83.3 ± 12.0% of cysts treated during 4 days with 50 and 100 µg/ml, respectively. The half maximal effective concentration (EC50) value of the S. aristata extract against E. granulosus (s.s.) cysts was 47.86 µg/mL (96 h). The dosage of infected animals with the 50 mg kg-1 dose of S. aristata extract resulted in a significant reduction in cyst weight in comparison with the control group. In conclusion, S. aristata extract was demonstrated to exert a marked effect, both in vitro and in the murine model.

Anthelmintic activity of Stevia multiaristata extract against Echinococcus granulosus sensu stricto.

Cystic echinococcosis is a zoonotic disease caused by the larval stage of the parasite Echinococcus granulosus sensu lato. The available anti-parasitic treatment is mostly limited to a continuous administration of albendazole. However, due to its numerous side-effects and efficacy of around 50%, there is a need to find new drugs to improve the treatment for this disease. In the current study, the in vitro and in vivo efficacy of a Stevia multiaristata extract against E. granulosus sensu stricto (s.s.) was demonstrated. Stevia multiaristata extract (100 and 50 µg mL−1) caused a quick viability decrease on protoscoleces which was consistent with the observed tegumental alterations. Loss of turgidity was detected in 95 ± 3.4% of cysts incubated with S. multiaristata extract during 2 days (100 µg mL−1) and the collapse of the germinal layer was observed in 60 ± 9.3% of cysts treated with 100 µg mL−1 of the S. multiaristata extract during 4 days. The half maximal effective concentration value was 69.6 µg mL−1 and the selectivity index for E. granulosus s.s. cysts was 1.9. In this clinical efficacy study, the treatment of infected mice with the S. multiaristata extract (50 mg kg−1) caused a significant decrease in the weight of the cysts compared with the control group. These results coincided with the tissue damage observed in the cysts at the ultrastructural level. In conclusion, we observed high protoscolicidal and cysticidal effects, and significant reduction in the weight of the cysts in experimentally infected mice following treatment with the S. multiaristata extract.

In silico study of structural and geometrical requirements of natural sesquiterpene lactones with trypanocidal activity.

Chagas' disease, caused by the intracellular protozoan Trypanosoma cruzi, is one of the most serious health problems throughout South America. Despite the progress that has been made in the study of its biochemistry and physiology, more efficient chemotherapies to control this parasitic infection are still lacking. In this paper we report the trypanocidal and cytotoxic activities of a series of sesquiterpene lactones, isolated from Asteraceae medicinal plants. The significant trypanocidal activity and high selectivity indexes found for many of the compounds evaluated, prompted us to undertake a quantitative structure-activity relationship study. A model using 3D molecular descriptors allowed us to set up a high correlation of the observed activity and the atomic spatial arrangement of these sesquiterpene lactones closely related to steric parameters.

In Vitro Antiplasmodial Activity of Sesquiterpene Lactones from Ambrosia tenuifolia.

The in vitro antiplasmodial activity of Ambrosia tenuifolia organic extract and its isolated sesquiterpene lactones, psilostachyin and peruvin, has been evaluated against Plasmodium falciparum F32 and W2 strains. The cytotoxicity of both compounds was determined on lymphoid cells, and their corresponding selectivity indexes (SIs) were calculated. Peruvin was the most active compound on F32 strain of P. falciparum with a 50% inhibitory concentration value (IC(50)) of 0.3 µg/mL (1.1 µM) whereas psilostachyin showed activity on both strains (IC(50) = 0.6 (2.1 µM) and 1.8 µg/mL (6.4 µM)). Fifty percent cytotoxic concentration (CC(50)) values (48 h) were 6.8 µg/mL (24.3 µM) and 10.0 µg/mL (37.9 µM) for psilostachyin and peruvin, respectively.

In vitro evaluation of trypanocidal activity in plants used in Argentine traditional medicine.

Thirty-two organic and aqueous extracts, belonging to 12 Argentine medicinal plants were tested for their in vitro trypanocidal activity on epimastigote forms of Trypanosoma cruzi. Among the selected species, the organic extracts of Ambrosia scabra, Ambrosia tenuifolia, Baccharis spicata, Eupatorium buniifolium, Lippia integrifolia, Mulinum spinosum and Satureja parvifolia, and the aqueous extracts of E. buniifolium, L. integrifolia, M. spinosum and S. parvifolia showed trypanocidal activity with a percentage of growth inhibition higher than 70% at a concentration of 100 microg/ml.