André de Lima Aires

β-Lapachone: A naphthoquinone with promising antischistosomal properties in mice

The activity of β-lapachone (3,4-dihydro-2,2-dimethyl-2H-naphthol[1,2-b]pyran-5,6-dione, β-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 β-lap on skin schistosomula, lung schistosomula, young worms (before oviposition) and adult worms (after oviposition), respectively. All animals were euthanized 60 days after infection. β-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, β-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 β-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 β-lap are needed to clearly establish the best dose and route of administration and its mechanism of action against schistosomes.

Ultrastructural analysis of β-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 β-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. β-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 β-lap, both in the laboratory and in the field.

Analysis of Plasma Citrulline and Intestinal Morphometry in Mice with Hepatosplenic Schistosomiasis

BACKGROUND Portal hypertension in the mucosa of the intestine and the presence of granulomas in the wall of this organ can alter digestive function in patients with schistosomiasis. Citrulline is a potential marker of intestinal function in some diseases that affect the morphometry of the mucosa because of its close association with enterocytes. The aims of the present study were to determine serum citrulline concentrations in mice with hepatosplenic schistosomiasis, analyze the morphologic repercussions for the mucosa of the small intestine, correlate citrulline concentrations with morphometric changes in the intestinal mucosa, and evaluate the effect of splenectomy on citrulline concentration. METHODS After approval from the local ethics committee, 46 adult female albino Swiss mice were divided into two groups: Control (23 healthy mice) and experimental (23 mice with hepatosplenic schistosomiasis). Blood samples were collected for the analysis of plasma citrulline before and after splenectomy. A segment of the jejunum was resected for morphometric analysis. RESULTS The average body mass in the control group was greater than that in the experimental group (p = 0.00062). The average citrulline concentration in the control group was greater than that in the experimental group both before and after splenectomy (p < 0.001). In the experimental group, the villi had less height and area, and there was a smaller perimeter of the mucosal surface (p = 0.003, <0.001, and p = 0.001, respectively). There was a direct correlation between citrulline concentration and the height and area of the villi (p = 0.003 and 0.04, respectively). There was no correlation between citrulline concentration and the perimeter of the surface of the jejunal mucosa. After splenectomy, there was a reduction in the mean citrulline concentration in the experimental group (p = 0.009). CONCLUSIONS Serum citrulline concentrations were reduced in mice with schistosomiasis, and a direct correlation was found between the citrulline concentration and the morphometry of the jejunal villi. Moreover, there was a reduction in the plasma concentration of citrulline after splenectomy.

Laboratory assessment of divaricatic acid against Biomphalaria glabrata and Schistosoma mansoni cercariae

In this study, the molluscicidal and antiparasitic activities of divaricatic acid was evaluated, targeting the mollusc Biomphalaria glabrata and cercariae of the helminth Schistosoma mansoni. In addition, the environmental toxicity of divaricatic acid was assessed by bioassay using the microcrustacean Artemia salina. Divaricatic acid showed high toxicity against both adult snails (5μg/mL) and embryos (20μg/mL after 6h of exposure). Similar activity was observed in Schistosoma mansoni cercariae after only a short exposure time (10μg/mL after 30min of exposure). The divaricatic acid did not show toxicity in the acute test using Artemia salina at concentrations equal to or below 200μg/mL. The divaricatic acid proved to be a promising substance for the elimination of the snail Biomphalaria glabrata, an intermediate host of schistosomiasis, as well as the cercariae of the pathogen, while being non-toxic to the Artemia salina at the same concentrations. This is the first experimental observation of the molluscicidal and cercaricide activity of divaricatic acid.

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.

Solid dispersions to enhance the delivery of a potential drug candidate LPSF/FZ4 for the treatment of schistosomiasis

Abstract Drug candidate LPSF/FZ4 with promising schistosomicidal properties in vitro was previously synthesized. However, LPSF/FZ4 has limited aqueous solubility (<1 &mgr;g/mL), leading to ineffective dissolution and, therefore, no meaningful in vivo comparative studies could be pursued. This study was aimed to develop a proper amorphous solid dispersion (SD) to enhance the solubility and dissolution rate of LPSF/FZ4 such that its biological activity could be investigated. To better understand its physiological behavior, the pKa of LPSF/FZ4, a monoprotic weak acid with NH group at the imidazolidine ring, was first determined to be 8.13 using an automated SiriusT3. The development of SD systems for LPSF/FZ4 involved the evaluation of various water‐soluble polymer carriers such as PVP K‐29/32, PVP K‐90, HPMC K4M, PVPVA 64 and SOLUPLUS®. The most promising SD systems were selected through in vitro dissolution studies under nonsink conditions, together with physicochemical characterization as well as accelerated stability study. It was shown that SD of 10% LPSF/FZ4 in SOLUPLUS® and PVP K‐90 could significantly increase the area‐under‐the‐curve value of the nonsink dissolution profile (AUC values of the SD in SOLUPLUS® and PVP K‐90 were 1381.03 and 1342.34 &mgr;L/mL·min, respectively, and that of the pure crystalline drug was 0.02 &mgr;L/mL·min), a useful surrogate for the in vivo bioavailability. Cmax values for the SD in SOLUPLUS® (12.50 &mgr;L/mL) and PVP K‐90 (25.86 &mgr;L/mL) were also higher than the one of the crystalline drug (0.02 &mgr;L/mL). The SD system of LPSF/FZ4 in SOLUPLUS® showed a significant increase in schistosomicidal activity in an animal model as compared with the conventional treatment using crystalline drug, consistent with the AUC trend from the nonsink dissolution. Thus this SD system of LPSF/FZ4 could be useful as a potential formulation for treating schistosomiasis. Graphical abstract Figure. No caption available.

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.

Data set of the toxic effects of divaricatic acid depside on Biomphalaria glabrata and Schistosoma mansoni cercariae

In this study, the molluscicidal and antiparasitic activities of divaricatic acid was evaluated, targeting the mollusc Biomphalaria glabrata and cercariae of the helminth Schistosoma mansoni. Divaricatic acid showed high toxicity against both adult snails (5.5 μg/mL) and embryos (20 μg/mL after 6 h of exposure). Similar activity was observed in S. mansoni cercariae after only a short exposure time. The divaricatic acid proved to be a promising substance for the control of the snail B. glabrata, an intermediate host of schistosomiasis, as well as the cercariae of the pathogen.

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.

Potassium usnate toxicity against embryonic stages of the snail Biomphalaria glabrata and Schistosoma mansoni cercariae

The snail Biomphalaria glabrata is the most important vector for Schistosoma mansoni. Control of this vector to prevent the spread of schistosomiasis is currently performed with the application of a niclosamide molluscicide, which is highly toxic to the environment. Screening of substances that show embryotoxic molluscicidal potential as well as have detrimental effects on cercariae is very relevant for the control of schistosomiasis, as the efficacy of prevention of the disease is increased if it acts as a molluscicide as well as on the cercariae of S. mansoni. The aim of this work was to evaluate the effect of potassium usnate derived from usnic acid on different stages of embryonic development of B. glabrata and on S. mansoni cercariae. After 24 h of exposure, potassium usnate showed embryotoxic activity across all embryonic stages. The values obtained from the LC50 for the embryonic stages were the following: blastula 5.22 μg/mL, gastrula 3.21 μg/mL, trochophore 3.58 μg/mL, veliger 2.79, and hippo stage 2.52 μg/mL. Against S. mansoni cercariae, it had LC90 and 100% mortality at concentrations of 2.5 and 5 μg/mL in 2 h of exposure. In conclusion, this is the first report of potassium usnate toxicity on the embryonic stages of B. glabrata and cercariae of S. mansoni, and this study shows the potassium usnate as a promising agent for the control of mansoni schistosomiasis.