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| Author(s): |
Claudineide Nascimento Fernandes de Oliveira
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Campinas, SP. |
| Institution: | Universidade Estadual de Campinas (UNICAMP). Instituto de Biologia |
| Defense date: | 2012-09-10 |
| Examining board members: |
Silmara Marques Allegretti;
Mara Cristina Pinto;
Marili Villa Nova Rodrigues;
Lizandra Guidi Magalhães;
Josué de Moraes
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| Advisor: | Silmara Marques Allegretti; Vera Lucia Garcia |
| Abstract | |
The dissemination of schistosomiasis and the threat of its causing agents becoming resistant to the drug of choice, i.e., praziquantel, have intensified the research with medicinal plants to promote the development of new schistosomicidal drugs. Phyllanthus amarus (stone-breaker) is a plant whose anti-inflammatory and hepatoprotective activities have already been attested, which is the reason why it was chosen for this study, as the main pathology of schistosomiasis is the formation of granulomas (inflammatory process) in the liver. The aim of this work was to carry out a bioguided fractionation of the ethanol extract of P. amarus by means of in vitro and in vivo assays in order to verify the schistosomicidal potential of that plant against S. mansoni, BH strain. To carry out the in vitro assays, the collected adult worms were incubated in plates containing RPMI 1640 medium, a pair of mating worms, and samples of crude ethanol extract, fractions of different polarities or isolated lignans at the concentrations of 200, 100, 50 and 25 ?g/mL. The worms were observed over a period of 72 hours, in which mortality rate, egg laying, mating, and tegumentary changes were evaluated. The best in vitro activity was provided by butanol fraction 2, as it proved lethal for 100% of the worms over 48 hours of observation, and so it was used in the in vivo assays. Butanol fraction 2 is mainly composed of lignans, and some of them (nirantin, filantin: nirantin, and filantin + filtetralin + nirtetralin), albeit not effective in the in vitro assays, were selected for in vivo evaluation. In the in vivo assays, Balb/c mice were treated orally 45 or 60 days following infection. On the 45th day following infection, the animals were treated with 100 and 200 mg/kg of butanol fraction 2, 100 mg/kg of filantina:nirantin and filantin + filtetralin + nirtetralin in a single dose, and 100 mg/kg of butanol fraction 2 distributed over 3 consecutive days. On the 60th day following infection, the treatment was carried out in a single dose with 100 mg/kg of butanol fraction 2, nirantin, filantina:nirantin, and filantin + filtetralin + nirtetralin. The in vivo activity was evaluated based on the following parameters: action on adult worms, eggs eliminated in the stool, egg counting, granulomatous reactions, and action on the tegument of the worms (using scanning electron microscopy (SEM). The most effective treatments on the 45th day were those carried out with 100 mg/kg of filantina:nirantin, and nirantin. The association of filantina:nirantin provided a reduction of 63.8% in the number of eggs, whereas nirantin achieved a reduction rate of 90.3%. The results for the other parameters (reduction in the total number of worms, number of females, and number of granulomas) were similar with reduction rates around 58%. In addition to such changes, images obtained by SEM showed extensive lesions on the tegument of male worms. On the 60th day following infection, the filantin + nirantin association and butanol fraction 2 at 100 mg/kg achieved the most significant xxiii reduction rates: 50.8% and 46.7% in the total number of worms, respectively; 47.2% and 42.7% in the number of females, respectively; 87.5% and 98.3% in the number of eggs, respectively; and 44% and 18% in the number of granulomas, respectively. Therefore, according to the biological parameters evaluated in this work, the association of the lignans filantina:nirantin at 100 mg/kg has a promising schistosomicidal activity, as it was effective over two periods of treatment (AU) | |
| FAPESP's process: | 09/10324-2 - Study of the activity of isolated compounds from Phyllanthus amarus L. ethanolic extract against Schistosoma mansoni BH strain. |
| Grantee: | Claudineide Nascimento Fernandes de Oliveira |
| Support Opportunities: | Scholarships in Brazil - Doctorate |