In vitro activity, ultrastructural analysis and in silico pharmacokinetic properties (ADMET) of thiazole compounds against adult worms of Schistosoma mansoni.

The present work aimed to carry out in vitro biological assays of thiazole compounds against adult worms of Schistosoma mansoni, as well as the in silico determination of pharmacokinetic parameters to predict the oral bioavailability of these compounds. In addition to presenting moderate to low cytotoxicity against mammalian cells, thiazole compounds are not considered hemolytic. All compounds were initially tested at concentrations ranging from 200 to 6.25 µM against adult worms of S. mansoni parasites. The results showed the best activity of PBT2 and PBT5 at a concentration of 200 µM, which caused 100% mortality after 3 h of incubation. While at 6 h of exposure, 100% mortality was observed at the concentration of 100 µM. Subsequent studies with these same compounds allowed classifying PBT5, PBT2, PBT6 and PBT3 compounds, which were considered active and PBT1 and PBT4 compounds, which were considered inactive. In the ultrastructural analysis the compounds PBT2 and PBT5 (200 µM) promoted integumentary changes with exposure of the muscles, formation of integumentary blisters, integuments with abnormal morphology and destruction of tubercles and spicules. Therefore, the compounds PBT2 and PBT5 are promising antiparasitics against S. mansoni.

Evaluation of ß-lapachone-methyl-ß-cyclodextrin inclusion complex prepared by spray drying and its application against different developmental stages of Schistosoma mansoni in murine model.

BACKGROUND: ß-lapachone (ß-lap) is a naphthoquinone widely found in species of vegetables. However, its poor aqueous solubility limits its systemic administration and clinical applications in vivo. To overcome this limitation, several studies have been carried out in order to investigate techniques that can enhance the solubility and dissolution rate of ß-lap, such as the use of inclusion complexes with cyclodextrin. PURPOSE: To evaluate the in vivo effect of ß-lap complexed in methyl-ß-cyclodextrin (MßCD) on the evolutionary stages of Schistosoma mansoni in a murine model. METHODS: The development and characterization of the physicochemical properties of the inclusion complex of ß-lap in ß-lap:MßCD was prepared by solubility and dissolution tests, FTIR, DSC, X-RD and SEM. The mice were infected and subsequently treated with ß-lap:MßCD orally with 50 mg/kg/day and 100 mg/kg/day for 5 consecutive days, starting therapy on the 1st (skin schistosomula), 14th (pulmonary schistosomula), 28th (young worms) and 45th (adult worms) days after infection. Control groups were also formed; one infected untreated, treated with MßCD, and the other treated with PZQ. RESULTS: The loss of the crystalline form of ß-lap in the ß-lap:MßCD complex obtained by spray drying was proven through physical-chemical characterization analyses. ß-lap:MßCD caused reduction in the number of worms of the 33.56%, 35.7%, 35.45% and 36.45%, when the dose was at 50 mg/kg, and 65.00%, 60.34%, 52.72% and 65.01%, in the dose 100 mg/kg; when treatment was started in the 1st, 14th, 28th and 45th days after infection, respectively. It was also possible to observe a significant reduction in the number of immature eggs and an increase in the number of ripe and dead eggs and, consequently, a reduction in the damage caused by the egg antigens to the host tissue, where we attributed the reduction in the average diameter of the granulomas to the ß-lap. CONCLUSION: The dissolved content of ß-lap:MßCD by spray drying reached almost 100%, serving for future formulations and delineation of the mechanisms of action of ß-lap against S. mansoni.

Effect of Bauhinia monandra Kurz Leaf Preparations on Embryonic Stages and Adult Snails of Biomphalaria glabrata (Say, 1818), Schistosoma mansoni Cercariae and Toxicity in Artemia salina.

Biomphalaria glabrata snails constitute the main vector of schistosomiasis in Brazil, and Bauhinia monandra Kurz, the leaves of which contain BmoLL lectin with biocidal action, is a plant widely found on continents in which the disease is endemic. This work describes the composition of B. monandra preparations and the effect on embryos and adult snails, their reproduction parameters and hemocytes. We also describe the results of a comet assay after B. glabrata exposure to sublethal concentrations of the preparations. Additionally, the effects of the preparations on S. mansoni cercariae and environmental monitoring with Artemia salina are described. In the chemical evaluation, cinnamic, flavonoid and saponin derivatives were detected in the two preparations assessed, namely the saline extract and the fraction. Both preparations were toxic to embryos in the blastula, gastrula, trochophore, veliger and hippo stages (LC50 of 0.042 and 0.0478; 0.0417 and 0.0419; 0.0897 and 0.1582; 0.3734 and 0.0974; 0.397 and 0.0970 mg/mL, respectively) and to adult snails (LC50 of 6.6 and 0.87 mg/mL, respectively), which were reproductively affected with decreased egg deposition. In blood cell analysis, characteristic cells for apoptosis, micronucleus and binucleation were detected, while for comet analysis, different degrees of nuclear damage were detected. The fraction was able to cause total mortality of the cercariae and did not present environmental toxicity. Therefore, B. monandra preparations are promising in combating schistosomiasis since they can control both the intermediate host and eliminate the infectious agent, besides being safe to the environment.

Schistosoma mansoni infection decreases IL-33-mRNA expression and increases CXCL9 and CXCL10 production by peripheral blood cells.

Schistosoma mansoni infections, particularly egg antigens, induce Th2-dominant granulomatous responses accompanied by remarkable immunoregulatory mechanisms that avoid intense fibrosis. Interleukin (IL)-33 is a cytokine that stimulates the early activation of Th2 responses, and its soluble ST2 receptor (sST2) avoids granulomatous response, as well as CXCL9 and CXCL10 chemokines that have antifibrotic activity. However, in schistosomiasis, these molecules have not been suitably studied. Therefore, this study aimed to measure IL-33 and sST2 RNA, cytokines, and chemokines in peripheral blood cultures from individuals living in schistosomiasis-endemic areas. Peripheral blood cells from individuals with S. mansoni (n = 34) and non-infected individuals (n = 31) were cultured under mitogen stimulation. Supernatant chemokines and cytokines were evaluated using a cytometric bead array, and IL-33 and sST2 mRNA expression was measured using qPCR. Infected individuals showed higher levels of CXCL8, CXCL9, CXCL10, IFN-γ, TNF-α, IL-6, IL-2, IL-4, and IL-10; there was a lower expression of IL-33 mRNA and similar expression of sST2mRNA in infected than non-infected individuals. In conclusion, for the first time, we demonstrated lower IL-33mRNA expression and high levels of the antifibrotic chemokines CXCL9 and CXCL10 in schistosomiasis mansoni, which could control exacerbations of the disease in individuals from endemic areas.

Toxic, cytotoxic and genotoxic effect of saline extract and fraction of Parkia pendula seeds in the developmental stages of Biomphalaria glabrata (Say 1818 - intermediate host) and cercaricide activity against the infectious agent of schistosomiasis.

This study describes for the first time the effect of saline extract and Parkia pendula seed fraction on Biomphalaria glabrata adult embryos and molluscs well as the reproductive parameters (fecundity and fertility) and survival, in addition to cytotoxicity and genotoxicity through the profile of blood cells after exposure to sublethal concentrations. Furthermore, we analyzed the action of both preparations against the cercariae of Schistosoma mansoni and their environmental safety using the bioindicator Artemia salina. The saline extract and fraction showed toxic effects for embryos (CL90 of 464.25, 479.62, 731.28, 643.28, 408.43 and 250.94, 318.03, 406.12, 635.64, 1.145 mg/mL, for blastula, gastrula, trocophore, veliger and hippo stage respectively), adult snails after 24 h of exposure (CL90 of 9.50 and 10.92 mg/mL, respectively) with increased mortality after 7 days of observation and significant decrease (p <0.05; p < 0.01 and p < 0.001) in egg mass deposition. At sublethal concentrations, an increase in quantitative and morphological changes in hemocytes was observed, and in the genotoxicity/comet assay analysis, varying degrees of nuclear damage were detected. In addition, the saline extract showed changes in the motility of the cercariae, while the fraction howed toxicity from a concentration of 1.0 mg/mL. The saline extract showed toxicity to A. salina at the highest concentrations (3.0, 4.0 and 5.0 mg/mL), while the fraction did not show ecotoxicity. Thus, the saline extract and fraction was promising in combating schistosomiasis by eliminating the intermediate host and causing alterations and/or mortality to the infectious agent.

The Natural Compound Hydrophobic Usnic Acid and Hydrophilic Potassium Usnate Derivative: Applications and Comparisons.

Usnic acid is the best-studied lichen metabolite, presenting several biological activities, such as antibacterial, immunostimulating, antiviral, antifungal, anti-inflammatory, and antiparasitic agents; despite these relevant properties, it is a hydrophobic and toxic molecule. In this context, scientific research has driven the development of innovative alternatives, considering usnic acid as a source of raw material in obtaining new molecules, allowing structural modifications (syntheses) from it. The purpose is to optimize biological activities and toxicity, with less concentration and/or response time. This work presents a literature review with an analogy of the hydrophobic molecule of usnic acid with its hydrophilic derivative of potassium usnate, emphasizing the elucidation and structural characteristics, biological activities, and toxicological aspects of both molecules, and the advantages of using the promising derivative hydrophilic in different in vitro and in vivo assays when compared to usnic acid.

Extract from Ascaris suum and N-acetyl-L-cysteine induces an immunosuppressant effect in model of autoimmune hepatitis.

BACKGROUND: Extract of adult Ascaris suum (ASC) worms attenuated the liver damage in experimental autoimmune hepatitis (EAH) with induction of Th2 immune response, but fibrosis occurred. N-acetyl-L-cysteine (NAC) has protective effects against liver fibrosis. OBJECTIVES: Evaluate the association ASC + NAC on the T- and B-cell activation, inflammation and fibrogenic markers in the liver in EAH. METHODS: Experimental autoimmune hepatitis was induced intravenously with concanavalin A in BALB/c mice. EAH + ASC+NAC group received NAC and ASC; EAH + ASC group received ASC; EAH group received PBS. Doubly labelled CD4+ T (CD28, CTLA-4, CD40L or IL-10) and CD45R+ B lymphocytes (IL-10) and CD4+ CD25+ FoxP3+ cells were evaluated, along with gene expression of Col1a1, α-SMA, Fizz1, Arg1 and PPAR-γ and histomorphometry. RESULTS: Experimental autoimmune hepatitis group showed high frequency of CD28+ and CD40L+  T lymphocytes, but not the EAH + ASC group. In relation to EAH group, the Fizz1 expression was lower in both groups treated, but Arg1 expression was lower in only EAH + ASC+NAC group. In the EAH + ASC+NAC group, there were higher frequencies of CD4+ IL-10+ and CD4+ CD25+ FoxP3+ cells, but not CD45R+ IL-10+ , along with mitigated inflammation and collagen production. CONCLUSIONS: Ascaris suum favoured immunosuppression in EAH limiting the T cells activation. However, association ASC and NAC was necessary for attenuating the inflammatory process and collagen production.

Gestation and breastfeeding in schistosomotic mice differentially alters the expression of histone deacetylases (HDACs) in adult offspring.

BACKGROUND: Breastfeeding or gestation in schistosomotic mothers can cause long-term alterations in the immune response of offspring. OBJECTIVES: Evaluate the expression of histone deacetylases (HDACs) (all classes), the production of cytokines by T and B lymphocytes and macrophages, and the frequency of CD4+CD25+FoxP3+-cells in adult offspring born and/or suckled by schistosomotic mothers. METHODS: We harvested splenocytes from offspring born to (BIM), suckled by (SIM), or born to/suckled by (BSIM) schistosomotic mothers and animals from noninfected mothers (Control) at seven-weeks old and cultured them with/without Concanavalin A. HDAC expression was evaluated by real-time quantitative polymerase chain reaction (qPCR), and cytokines and membrane markers were evaluated by fluorescence-activated cell sorting (FACS). FINDINGS: Compared to Control, BIM mice showed increased expression of HDAC9 and frequency of CD4+IL-10+-cells. The SIM group had increased expression of HDAC1, HDAC2, HDAC6, HDAC7, HDAC10, Sirt2, Sirt5, Sirt6, and Sirt7. The BSIM group only had increased HDAC10 expression. The SIM and BSIM groups exhibited decreased frequencies of CD4+IL-4+-cells and CD4+CD25+FoxP3+-cells, along with a higher frequency of CD14+IL-10+-cells and an increase in CD45R/B220+IL-10+-cells. The BSIM group also showed a high frequency of CD4+IL10+-cells. MAIN CONCLUSIONS: Breastfeeding induced the expression of HDACs from various classes involved in reducing inflammatory responses. However, gestation enhanced the expression of a single HDAC and breastfeeding or gestation appears to favour multiple IL-10-dependent pathways, but not cells with a regulatory phenotype.

Toxicological effects of Ramalina aspera (lichen) on Biomphalaria glabrata snails and Schistosoma mansoni cercariae.

In this study, the molluscicidal activities against Biomphalaria glabrata and cercaricidal activities against Schistosoma mansoni of the ether extract of Ramalina aspera were evaluated. Additionally, toxicity parameters were evaluated at sublethal doses in terms of the influence of the extract on the fertility and fecundity of snails, as well as morphological alterations and quantification of their immunological cells. A test with Artemia salina was also carried out, in order to verify the environmental toxicity of the compound. The ether extract of R. aspera, in which divaricatic acid was identified as the major compound, demonstrated molluscicidal activity at low concentrations against both embryos (LC90 of 22.78, 24.23, 16.63 and 16.03 µg mL-1 for the gastrula, blastula, trochophore and veliger, respectively) and against adult snails (LC90 of 8.66 µg mL-1), after 24 h of exposure. At the sublethal doses, it was possible to observe a decrease in fecundity and quantitative and morphological changes in the defense cells of the exposed snails. In addition, the extract of R. aspera showed a cercaricidal effect on S. mansoni from the concentration of 5.0 µg mL-1, while showing low toxicity to Artemia salina. The ether extract of R. aspera demonstrated effective molluscicidal activity on embryos and adult snails of the species B. glabrata, cercariae of S. mansoni, and presenting low toxicity on Artemia salina. In this way, it could be considered a promising compound in the development of future molluscicidal and cercaricidal agents, thus helping to combat schistosomiasis.

Gestation and breastfeeding in schistosomotic mice differentially alters the expression of histone deacetylases (HDACs) in adult offspring

BACKGROUND Breastfeeding or gestation in schistosomotic mothers can cause long-term alterations in the immune response of offspring. OBJECTIVES Evaluate the expression of histone deacetylases (HDACs) (all classes), the production of cytokines by T and B lymphocytes and macrophages, and the frequency of CD4+CD25+FoxP3+-cells in adult offspring born and/or suckled by schistosomotic mothers. METHODS We harvested splenocytes from offspring born to (BIM), suckled by (SIM), or born to/suckled by (BSIM) schistosomotic mothers and animals from noninfected mothers (Control) at seven-weeks old and cultured them with/without Concanavalin A. HDAC expression was evaluated by real-time quantitative polymerase chain reaction (qPCR), and cytokines and membrane markers were evaluated by fluorescence-activated cell sorting (FACS). FINDINGS Compared to Control, BIM mice showed increased expression of HDAC9 and frequency of CD4+IL-10+-cells. The SIM group had increased expression of HDAC1, HDAC2, HDAC6, HDAC7, HDAC10, Sirt2, Sirt5, Sirt6, and Sirt7. The BSIM group only had increased HDAC10 expression. The SIM and BSIM groups exhibited decreased frequencies of CD4+IL-4+-cells and CD4+CD25+FoxP3+-cells, along with a higher frequency of CD14+IL-10+-cells and an increase in CD45R/B220+IL-10+-cells. The BSIM group also showed a high frequency of CD4+IL10+-cells. MAIN CONCLUSIONS Breastfeeding induced the expression of HDACs from various classes involved in reducing inflammatory responses. However, gestation enhanced the expression of a single HDAC and breastfeeding or gestation appears to favour multiple IL-10-dependent pathways, but not cells with a regulatory phenotype.

Dataset on schistosomiasis control using potassium usnate against Biomphalaria glabrata at different developmental stage and Schistosoma mansoni cercariae.

This text presents complementary data corresponding to schistosomiasis mansoni׳s vector control and toxicity on Schistosoma mansoni cercariae using potassium usnate. This information support our research article "Potassium Usnate Toxicity Against Embryonic Stages of the Snail Biomphalaria glabrata and Schistosoma mansoni Cercariae" [1], and focuses on the analysis of the detailed data regarding the different concentrations of potassium usnate and their efficiency to B. glabrata mortality and non-viability and S. mansoni cercariae mortality etiologic agent of the disease.

Maternal schistosomiasis: IL-2, IL-10 and regulatory T lymphocytes to unrelated antigen in adult offspring mice.

INTRODUCTION: We evaluated IL-10, IL-2 and regulatory T cells (Treg), in response to ovalbumin (OA), in offspring from schistosomotic mouse mothers. METHODS: We used animals born (BIM) or suckled (SIM) from infected mothers; and mice born/suckled from infected (BSIM) or non-infected mothers (CONTROL). After OA+adjuvant immunization, spleen cells were cultured, with or without OA, and doubly marked for cytometry. RESULTS: BIM showed fewer CD4+/IL-2+ and more B220+/IL-10+ cells, whereas the SIM group showed increased Treg frequency. BSIM had fewer B220+/IL-10+ and Treg cells. CONCLUSIONS: Separately, gestation or nursing induced immunosuppressive cells in infected mothers, but improved anti-OA immunity when combined.

Maternal schistosomiasis: IL-2, IL-10 and regulatory T lymphocytes to unrelated antigen in adult offspring mice

Abstract INTRODUCTION: We evaluated IL-10, IL-2 and regulatory T cells (Treg), in response to ovalbumin (OA), in offspring from schistosomotic mouse mothers. METHODS: We used animals born (BIM) or suckled (SIM) from infected mothers; and mice born/suckled from infected (BSIM) or non-infected mothers (CONTROL). After OA+adjuvant immunization, spleen cells were cultured, with or without OA, and doubly marked for cytometry. RESULTS: BIM showed fewer CD4+/IL-2+ and more B220+/IL-10+ cells, whereas the SIM group showed increased Treg frequency. BSIM had fewer B220+/IL-10+ and Treg cells. CONCLUSIONS: Separately, gestation or nursing induced immunosuppressive cells in infected mothers, but improved anti-OA immunity when combined.

New 1,3-benzodioxole derivatives: Synthesis, evaluation of in vitro schistosomicidal activity and ultrastructural analysis.

Schistosomiasis is considered a serious public health problem in 78 countries and territories located in Africa, Asia and America and it is estimated in more than 249 million people infected by any of the species of Schistosoma. The exclusive use of praziquantel (PZQ), effective drug against all species of Schistosoma, has been the basis of the development of a possible resistance against the strains of this parasite. In addition, PZQ is not effective against young forms of worms. Thus, there is a need for the development of new drugs with schistosomicidal activity. The objective of this work was to synthesize and to evaluate the therapeutic potential of new benzodioxole derivatives (3-14) candidates for schistosomicidal drugs. All compounds synthesized showed in vitro schistosomicidal activity. The derivative 12 was considered the best compound, since it took 100% of worms to mortality in the first 72 h of exposure at the concentration of 100 µM and 83.3% at the concentration of 50 µM. Furthermore, male and female adult worms, incubated for 24 h with the compound 12 showed tegument damages characterized by extensive desquamation and edema, tuber destruction, bubble formation and exposure of the muscle layer. This compound has a restricted structure, where the thiazolidinone is attached to the 4-position of the 1,3-benzodioxol ring. The structural conformation of derivative 12 was probably responsible for the promising schistosomicidal activity, where the presence of an electron/conformational restriction of the thiazolidine ring, as well as the action of bromine as a bulk substitute, favored an increase in biological activity. In addition, tegumentary changes caused by derivative 12 may also have been responsible for the death of adult worms of Schistosoma mansoni. Therefore, we verified that the results obtained in this study make benzodioxole derivatives possible candidates for prototypes of new schistosomicidal drugs.

Barbatic Acid Offers a New Possibility for Control of Biomphalaria Glabrata and Schistosomiasis.

This study evaluated the biological activity of an ether extract and barbatic acid (BAR) from Cladia aggregata on embryos and adult mollusks of Biomphalaria glabrata, cercariae of Schistosoma mansoni and the microcrustacean Artemia salina. The ether extract and BAR were obtained by successive extractions with diethyl ether. The obtained extracts were analyzed using thin-layer chromatography (TLC), high-performance liquid chromatography (HPLC), proton nuclear magnetic resonance (¹H-NMR) and infrared (IR) spectroscopy. The results demonstrated that the ether extract exerted embryotoxic effects at 50 and 100 µg/mL and molluscicidal effects at 20 and 25 µg/mL. BAR exhibited no embryotoxicity, and its molluscicidal concentration was equal to that of the ether extract. However, after 60 min of exposure, 1 µg/mL BAR presented cercaricidal activity against the parasite S. mansoni at the second larval stage. Neither substance induced toxicity against A. salina. These results indicate the potential molluscicidal activities of the ether extract and BAR against B. glabrata and S. mansoni cercariae. In addition to these effects, there was a lack of toxicity against the aquatic environment and no damage to the biota, indicating the potential of these products for large-scale control and/or eradication of schistosomiasis.

Gestation and breastfeeding in schistosomotic mothers differently modulate the immune response of adult offspring to postnatal Schistosoma mansoni infection.

Schistosoma mansoni antigens in the early life alter homologous and heterologous immunity during postnatal infections. We evaluate the immunity to parasite antigens and ovalbumin (OA) in adult mice born/suckled by schistosomotic mothers. Newborns were divided into: born (BIM), suckled (SIM) or born/suckled (BSIM) in schistosomotic mothers, and animals from noninfected mothers (control). When adults, the mice were infected and compared the hepatic granuloma size and cellularity. Some animals were OA + adjuvant immunised. We evaluated hypersensitivity reactions (HR), antibodies levels (IgG1/IgG2a) anti-soluble egg antigen and anti-soluble worm antigen preparation, and anti-OA, cytokine production, and CD4+FoxP3+T-cells by splenocytes. Compared to control group, BIM mice showed a greater quantity of granulomas and collagen deposition, whereas SIM and BSIM presented smaller granulomas. BSIM group exhibited the lowest levels of anti-parasite antibodies. For anti-OA immunity, immediate HR was suppressed in all groups, with greater intensity in SIM mice accompanied of the remarkable level of basal CD4+FoxP3+T-cells. BIM and SIM groups produced less interleukin (IL)-4 and interferon (IFN)-g. In BSIM, there was higher production of IL-10 and IFN-g, but lower levels of IL-4 and CD4+FoxP3+T-cells. Thus, pregnancy in schistosomotic mothers intensified hepatic fibrosis, whereas breastfeeding diminished granulomas in descendants. Separately, pregnancy and breastfeeding could suppress heterologous immunity; however, when combined, the responses could be partially restored in infected descendants.

Gestation and breastfeeding in schistosomotic mothers differently modulate the immune response of adult offspring to postnatal Schistosoma mansoni infection

Schistosoma mansoni antigens in the early life alter homologous and heterologous immunity during postnatal infections. We evaluate the immunity to parasite antigens and ovalbumin (OA) in adult mice born/suckled by schistosomotic mothers. Newborns were divided into: born (BIM), suckled (SIM) or born/suckled (BSIM) in schistosomotic mothers, and animals from noninfected mothers (control). When adults, the mice were infected and compared the hepatic granuloma size and cellularity. Some animals were OA + adjuvant immunised. We evaluated hypersensitivity reactions (HR), antibodies levels (IgG1/IgG2a) anti-soluble egg antigen and anti-soluble worm antigen preparation, and anti-OA, cytokine production, and CD4+FoxP3+T-cells by splenocytes. Compared to control group, BIM mice showed a greater quantity of granulomas and collagen deposition, whereas SIM and BSIM presented smaller granulomas. BSIM group exhibited the lowest levels of anti-parasite antibodies. For anti-OA immunity, immediate HR was suppressed in all groups, with greater intensity in SIM mice accompanied of the remarkable level of basal CD4+FoxP3+T-cells. BIM and SIM groups produced less interleukin (IL)-4 and interferon (IFN)-g. In BSIM, there was higher production of IL-10 and IFN-g, but lower levels of IL-4 and CD4+FoxP3+T-cells. Thus, pregnancy in schistosomotic mothers intensified hepatic fibrosis, whereas breastfeeding diminished granulomas in descendants. Separately, pregnancy and breastfeeding could suppress heterologous immunity; however, when combined, the responses could be partially restored in infected descendants.

Ultrastructural analysis of ß-lapachone-induced surface membrane damage in male adult Schistosoma mansoni BH strain worms.

The present study provides, for the first time, conclusions on the in vitro schistosomicidal properties of ß-lap. Adult male Schistosoma mansoni worms of the BH strain were used for the study. Motility, mortality, cell viability and alterations in the tegument were employed as schistosomicidal parameters. Alterations in motility were observed 6h after incubation in concentrations of 50 and 100 µM. ß-lap decreased significantly the worm viability, reducing the formation of formazan in 17.7%, 27.4% and 54.8% at concentrations of 25, 50 and 100 µM, respectively. Mortality in concentrations of 50 and 100 µM was of 67% and 100%, respectively, after 24h. The death of the parasite was preceded by progressive surface membrane damage, characterized by tegument peeling, spine reduction and erosion, blister formation and rupture, and the emergence of holes. In addition to this, in the anterior portion, intense general edema, areas of cracking with a wrinkled surface, furrows and a fibrous appearance were also observed. The results of the present study thus provide a sound basis for further in-depth studies of the schistosomicidal properties of ß-lap, both in the laboratory and in the field.

ß-Lapachone: a naphthoquinone with promising antischistosomal properties in mice.

The activity of ß-lapachone (3,4-dihydro-2,2-dimethyl-2H-naphthol[1,2-b]pyran-5,6-dione, ß-lap) against different stages of Schistosoma mansoni was investigated in mice. Mice infected with 50 cercariae (BH strain) were intraperitoneally treated at a dose of 50 mg/kg for 5 consecutive days, starting on the 1st, 14th, 28th and 45th days after infection, to evaluate the effect of ß-lap on skin schistosomula, lung schistosomula, young worms (before oviposition) and adult worms (after oviposition), respectively. All animals were euthanized 60 days after infection. ß-Lap significantly reduced (p<0.001) the number of worms in 29.78%, 37.2%, 24.2% and 40.22% when administered during the phases of skin schistosomula, lung schistosomula, young worms and adult worms, respectively. Significant reduction was also achieved in terms of female burden. In all groups, there was significant reduction in the number of eggs and granulomas in the hepatic tissue. When the intervention was performed during the phase of adult worms, ß-lap reduced the size of hepatic granulomas and changed the oogram pattern, lowering the percentage of immature eggs and increasing the percentage of mature and dead eggs. Our data indicate that ß-lap has moderate antischistosomal properties. Its molecule may also be used as a prototype for synthesis of new naphthoquinone derivatives with potential schistosomicidal properties. Further studies with different formulations containing ß-lap are needed to clearly establish the best dose and route of administration and its mechanism of action against schistosomes.

Study of the activity of 3-benzyl-5-(4-chloro-arylazo)-4-thioxo-imidazolidin-2-one against Schistosomiasis mansoni in mice.

Previous studies conducted with the imidazolidinic derivative 3-benzyl-5-(4-chloro-arylazo)-4-thioxo-imidazolidin-2-one (LPSF-PT05) show outstanding activity against adult Schistosoma mansoni worms in vitro. In the first phase of this study, S. mansoni-infected mice were treated, orally, with 100 mg/Kg of the LPSF-PT05 in three formulations: Tween 80 and saline solution, oil/water (70 : 30) emulsion, and solid dispersion with polyethylene glycol (PEG). In the second phase, three other doses of the LPSF-PT05 in PEG were tested: 3, 10, 30 mg/kg. These treatment regimens significantly reduced the number of recovered worms due to increases in the solubility of the compound in this formulation; the greatest reduction (70.5%) was observed at the dose of 100 mg/kg. There was no changes in the pattern of mature egg compared to immature eggs; however there was a significant increase in the number of dead eggs. Histopathological analysis of liver tissue showed changes in morphological aspects of the hepatic parenchyma with decrease exudative-productive hepatic granuloma stages, although we found no significant differences in IFN-γ, IL-4, IL-10, or NO production in response to the specific antigen SEA. The results show the derivative LPSF-PT05 to be a potential candidate in the etiological treatment of schistosomiasis with a possible dampening effect of the granulomatous process.