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Praziquantel is the drug of choice for the treatment of schistosomiasis. However, several strains of Schistosoma mansoni are resistant to praziquantel, making it necessary to discover new drugs that might be used for its treatment. With this in mind, the properties of a schistosomicidal ethanolic extract of Garcinia brasiliensis Mart. epicarp, the fractions obtained by partitioning this extract, including the hexane fractions, ethyl acetate fraction, and the aqueous fraction, and the isolated compounds 7-epiclusianone, a major component from these fractions, and fukugetin were tested in vitro on adult worms of S. mansoni. Mortality, damage to membranes, and excretory system activity were observed at 100.0, 50.0, 75.0, and 14.0 µg/mL for the ethanolic extract of G. brasiliensis Mart. epicarp, its hexane fractions, the ethyl acetate fraction, and 7-epiclusianone, respectively. For 7-epiclusianone, these data were confirmed by fluorescent probe Hoechst 33 258 and resorufin. Additionally, the biocidal effect of 7-epiclusianone was even higher than the hexane fractions. Moreover, an inhibitory effect of 7-epiclusianone on the egg laying of female adult S. mansoni worms was observed in cercariae and schistossomula. Thus, 7-epiclusianone is a promising schistosomicidal compound; however, more studies are needed to elucidate its mechanism of toxicity and to evaluate the in vivo activity of this compound.

Schistosomiasis is a neglected disease that affects approximately 200 million people worldwide. In order to reduce the parasite prevalence, further researches aiming new treatment methods is necessary. Once infected by Shistossoma mansoni, one can have no symptoms in the acute phase, however, chronic phase is characterized by marked egg-induced hepatic granulomatous inflammation. To prevent the disease, the main prophylactic method is environmental sanitation which decreases the entrance of eggs into water bodies. In addition to fighting the snail, treatment of population is important. Currently, for treatment of schistosomisasis, the most used drugs are Praziquantel (PZQ) and Oxamniquine, whereas PZQ is the drug of choice. Each drug has a specific mechanism of action aimed at the elimination of the parasite. However, any parasite treatment based on the use of a single drug poses serious concerns regarding the onset of resistance. The search for new therapeutic agents derived from medicinal plants for schistosomiasis has progressed significantly in the last decade. The aim of this paper is to provide an updated survey on medicinal plants that have significant therapeutic effects in animal models of schistosomiasis. A considerable number of herbal constituents with schistosomicidal effect have been well characterized and may be good candidates for prospective studies and investigations that may result in clinical usage. Key words: Schistosoma mansoni, schistosomicidal, medicinal plants.

We have been able to label the excretory system of cercariae and all forms of schistosomula, immature and adult worms with the highly fluorescent dye resorufin. We have shown that the accumulation of the resorufin into the excretory tubules and collecting ducts of the male adult worm depends on the presence of extracellular calcium and phosphate ions. In the adult male worms, praziquantel (PZQ) prevents this accumulation in RPMI medium and disperses resorufin from tubules which have been prelabelled. Female worms and all other developmental stages are much less affected either by the presence of calcium and phosphate ions, or the disruption caused by PZQ. The male can inhibit the excretory system in paired female. Fluorescent PZQ localises in the posterior gut (intestine) region of the male adult worm, but not in the excretory system, except for the anionic carboxy fluorescein derivative of PZQ, which may be excreted by this route. All stages of the parasite can recover from damage by PZQ treatment in vitro. The excretory system is highly sensitive to damage to the surface membrane and may be involved in vesicle movement and damage repair processes. In vivo the adult parasite does not recover from PZQ treatment, but what is inhibiting recovery is unknown, but likely to be related to immune effector molecules.

Federal University of Juiz de Fora. Institute of Biological Sciences. Department of Biochemistry. Bioactive Natural Products Laboratory. Juiz de Fora, MG, Brazil Federal University of Juiz de Fora. Institute of Biological Sciences. Department of Biochemistry. Bioactive Natural Products Laboratory. Juiz de Fora, MG, Brazil Federal University of Juiz de Fora. Institute of Biological Sciences. Department of Biochemistry. Bioactive Natural Products Laboratory. Juiz de Fora, MG, Brazil Federal University of Juiz de Fora. Institute of Biological Sciences. Department of Biochemistry. Bioactive Natural Products Laboratory. Juiz de Fora, MG, Brazil Fundação Oswaldo Cruz. Rene Rachou Research Center. Schistosomiasis Laboratory. Belo Horizonte, MG, Brazil Fundação Oswaldo Cruz. Rene Rachou Research Center. Schistosomiasis Laboratory. Belo Horizonte, MG, Brazil Federal University of Juiz de Fora. Institute of Biological Sciences. Department of Morphology. Juiz de Fora, MG, Brazil Federal University of Juiz de Fora. Institute of Biological Sciences. Department of Biochemistry. Protein Structure and Function Study Laboratory. Juiz de Fora, MG, Brazil Federal University of Juiz de Fora. Institute of Biological Sciences. Department of Biochemistry. Protein Structure and Function Study Laboratory. Juiz de Fora, MG, Brazil Federal University of Juiz de Fora. Institute of Biological Sciences. Department of Biochemistry. Bioactive Natural Products Laboratory. Juiz de Fora, MG, Brazil The aims of this work were to evaluate the in vitro and in vivo schistosomicidal properties of the methanolic extract of the aerial parts of Mitracarpus frigidus (MFM) and to determine its HPLC profile. For the in vitro experiment, four pairs of adult worms, obtained from infected mice, were exposed to different concentrations of MFM (100 to 400 g/mL) for 24 and 48 h and analyzed under an inverted microscope. For the in vivo experiment, mice were inoculated with cercariae and, 20 days after infection, MFM (100 and 300mg/kg) was administered orally for the following 25 days. Mice were euthanized after 60 days. MFM showed in vitro schistosomicidal activity, exhibiting the opening of the gynaecophoral canal of some male schistosomes, the presence of contorted muscles, vesicles, and the darkening of the paired worms skin. In vivo experiments showed that MFM treatments significantly reduced total wormcount, as praziquantel, showing a decrease in liver and spleen weight. Also, a significant reduction in granuloma density was observed. MFM treatment did not cause alterations in the liver function of either infected or noninfected mice. The HPLC chromatogram profile showed the presence of kaempferol-O-rutinoside, rutin, kaempferol, psychorubrin, and ursolic acid.

Schistosomiasis is a parasitic disease that, according to the World Health Organization, constitutes a major public health problem associated with severe morbidity, mostly children in preschool age. The administration of drugs in children always constitutes a difficult task, especially when formulations are not developed specifically for pediatric use, when high doses of drug are required and the drug has a bitter taste, as in the case of praziquantel. Polymer nanoparticles are promising systems for development of encapsulated drugs with low water solubility and bitter taste, due to the good physical and chemical stability, adequate biocompatibility and simple manufacturing processes. Moreover, they can enhance the bioavailability and reduce variability of treatment among patients. Poly(methyl methacrylate) doped with praziquantel was produced through a miniemulsion polymerization process to compose a pediatric pharmaceutical suspension. Nanoparticles were characterized in terms of physico-chemical properties, toxicological properties and biological activity in mice, being concluded that obtained results were satisfactory. The results were encapsulation rate around 90%, absence of chemical interaction drug - polymer and the presence of biological activity. A collaborative approach was used for this development, involving national partnerships and independent funding mechanisms, a powerful pathway for development of drugs for neglected diseases. A esquistossomose é uma doença parasitária que, segundo a Organização Mundial da Saúde, é um dos principais problemas de saúde pública associados à morbidade severa, sendo boa parte crianças. A administração de medicamentos em crianças constitui uma tarefa difícil, principalmente quando não há formulações pediátricas, quando altas doses de fármaco são requeridas e o fármaco apresenta um sabor amargo, como é o caso do praziquantel. Nanopartículas poliméricas são sistemas promissores para o desenvolvimento de fármacos com baixa hidrossolubilidade e gosto ruim, apresentam estabilidade físico-química, biocompatibilidade e fáceis processos de produção. Podem ainda proporcionar o aumento da biodisponibilidade e redução da variabilidade do tratamento entre pacientes. O polímero poli(metacrilato de metila) com o praziquantel encapsulado foi sintetizado pelo processo de polimerização em miniemulsão para compor uma suspensão farmacêutica pediátrica. As nanopartículas foram caracterizadas em termos das propriedades físico-químicas, toxicológicas e da atividade biológica em camundongos. Os resultados encontrados foram satisfatórios, taxa de encapsulamento de 90%, ausência de interação química fármaco - polímero e presença de atividade biológica. Uma abordagem colaborativa foi utilizada para este desenvolvimento, envolvendo parcerias nacionais e mecanismos de financiamento independentes, uma maneira nova e poderosa de desenvolver medicamentos para doenças negligenciadas.

A esquistossomose é uma doença parasitária que, segundo a Organização Mundial da Saúde, é um dos principais problemas de saúde pública associados à morbidade severa, sendo boa parte crianças. A administração de medicamentos em crianças constitui uma tarefa difícil, principalmente quando não há formulações pediátricas, quando altas doses de fármaco são requeridas e o fármaco apresenta um sabor amargo, como é o caso do praziquantel. Nanopartículas poliméricas são sistemas promissores para o desenvolvimento de fármacos com baixa hidrossolubilidade e gosto ruim, apresentam estabilidade físico-química, biocompatibilidade e fáceis processos de produção. Podem ainda proporcionar o aumento da biodisponibilidade e redução da variabilidade do tratamento entre pacientes. O polímero poli(metacrilato de metila) com o praziquantel encapsulado foi sintetizado pelo processo de polimerização em miniemulsão para compor uma suspensão farmacêutica pediátrica. As nanopartículas foram caracterizadas em termos das propriedades físico-químicas, toxicológicas e da atividade biológica em camundongos. Os resultados encontrados foram satisfatórios, taxa de encapsulamento de 90%, ausência de interação química fármaco - polímero e presença de atividade biológica. Uma abordagem colaborativa foi utilizada para este desenvolvimento, envolvendo parcerias nacionais e mecanismos de financiamento independentes, uma maneira nova e poderosa de desenvolver medicamentos para doenças negligenciadas.

To elucidate the mechanisms of antischistosoma resistance, drug-resistant Schistosoma mansoni laboratory isolates are essential. We developed a new method for inducing resistance to praziquantel (PZQ) using successive drug treatments of Biomphalaria glabrata snails infected with S. mansoni. Infected B. glabrata were treated three times with 100 mg/kg PZQ for five consecutive days with a one-week interval between them. After the treatment, the cercariae (LE-PZQ) produced from these snails and the LE strains (susceptible) were used to infect mice. Forty-five days after infection, mice were treated with 200, 400 or 800 mg/kg PZQ. Thirty days post-treatment, we observed that the mean number of worms recovered by perfusion was significantly higher in the group of mice infected with the LE-PZQ isolate treated with 200 and 400 mg/kg in comparison to the LE strain with the same treatment. Moreover, there was a significant difference between the ED50 (effective dose required to kill 50% of the worms) of the LE-PZQ isolate (362 mg/kg) and the LE strain (68 mg/kg). In the in vitro assays, the worms of the LE-PZQ isolate were also less susceptible to PZQ. Thus, the use of infected snails as an experimental model for development of resistance to S. mansoni is effective, fast, simple and cheap.

SUMMARYThe use of chemotherapy on a mass scale in endemic areas may lead to the appearance of resistant isolates through the mechanism of selective drug pressure. Studies have demonstrated that praziquantel (PZQ) is able to inhibit the excretory activity and to cause tegumental damage inSchistosoma mansoniadult worms. The use of the probe resorufin to evaluate excretory activity, as well as the probe Hoechst 33258 to detect tegumental damage in adult worms, may represent a method to identify resistant (or less susceptible) isolates. The purpose of the present work was to compare the changes caused by PZQ in the function of the excretory system and in the integrity of the tegument of adult worms from the LE isolate (susceptible to PZQ) and the LE-PZQ isolate (less susceptible to PZQ). Worms from the isolate LE-PZQ showed less severe tegumental lesions, in bothin vitroandin vivoexperiments, detected by labelling with Hoechst 33258 and continued to have a functional excretory system as shown by labelling with resorufinin vitro.

The antischistosomal activity of clonazepam, when administered alone or in association with oxamniquine and praziquantel, was experimentally evaluated in mice infected with Schistosoma mansoni. The animals were treated 45 days post-infection with a single dose, by oral route, according to three treatment schedules: clonazepam 25 mg/kg and sacrificed 15 min, 1h or 4 h after treatment; clonazepam 1.0, 2.5 or 10.0 mg/kg and sacrificed 15 days post-treatment or with the dose of 10 mg/kg in association with oxamniquine 50 mg/kg or praziquantel 200 mg/kg, single dose, orally, every schedule with a control group. The efficacy of the drugs in vivo was assessed by means of worm counts and their distribution in mesentery and liver, mortality and oogram changes. In the chemotherapeutic schedules used, clonazepam did not present antischistosomal activity and the result of the association of this drug with oxamniquine or praziquantel was not significantly different from the one obtained when these two last drugs were administered alone. In the in vitro experiments, the worms exposed to 0.6 mg/mL clonazepam remained motionless throughout the 8-day-period of observation, without egg-laying, whereas the worms of the control group showed normal movements, egg-laying and hatching of miracidia on the last day of observation. The results obtained in the present study confirm the action of clonazepam on S. mansoni adult worm, in vitro, causing total paralysis of males and females. However, no additive or synergistic effects were observed when clonazepam were used in association with oxamniquine or praziquantel.

The activity of lovastatin associated with oxamniquine or praziquantel against schistosomiasis mansoni was evaluated in mice infected with Schistosoma mansoni. Forty days after infection, mice were treated with lovastatin, 400 mg/kg for five consecutive days by oral route, and on the last day of this sequence with 50 mg/kg oxamniquine or with 200 mg/kg praziquantel, both by oral route, single dose. Fifteen days later, the animals were perfused in parallel with an untreated control group. Studies were carried out in vitro, using lovastatin in culture medium containing S. mansoni worms proceeding from experimentally infected mice. In the in vivo trials, the association of lovastatin with oxamniquine or praziquantel did not show any additive action, but there were oogram changes when lovastatin was associated with oxamniquine. In vitro lovastatin was able to interrupt the maturation of S. mansoni eggs, which remained at the 1st or 2nd stages, depending on the dose used. The total number of morphologically dead eggs found in culture of worms exposed to 2 microg/ml or 4 microg/ml concentrations of lovastatin was significantly higher than the number of viable eggs. Using the probe Hoescht 33258 it was observed that 70% of the eggs considered morphologically viable in the treated groups (against 16% in the control group) were labeled, indicating that the majority of the viable eggs had membrane permeability increased due to lovastatin action.

The activity of oxamniquine (OXA), praziquantel (PZQ), and a combination of both drugs was evaluated at the intramolluscan phase of Schistosoma mansoni. Biomphalaria glabrata snails infected with S. mansoni were treated with 500 mg/kg OXA, 1000 mg/kg PZQ or with 250 mg/kg OXA and 500 mg/kg PZQ, in association, at the pre-patent and patent phases of infection. The results showed that either treatments with OXA or PZQ, alone, at the pre-patent period, delayed the parasite's development, increasing the pre-patent period by approximately 10 days. At the same pre-patent period, treatment with a combination of OXA/PZQ delayed the parasite's development even more, extending the pre-patent period up to 56 days. At the patent period, treatment with OXA and PZQ, alone, interrupted cercarial shedding. When the snails were treated with 1000 mg/kg PZQ, the cercarial production was re-established 15 days after treatment, but in lower numbers than those obtained before treatment, whereas the snails treated with 500 mg/kg OXA were able to shed cercariae in similar quantities to those observed before treatment. The association 250 mg/kg OXA+500 mg/kg PZQ, at the patent period, not only discontinued cercarial shedding, but also led to the "cure" of the snails, showing a synergistic effect of this combination of drugs. These results suggest that this model will be useful for selection of resistant parasites, as well as for screening new antischistosomal drugs.