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Human cysticercosis caused by Taenia crassiceps is unusual; however, it is an useful experimental model for cysticercosis studies. Benzimidazole derivatives are important antihelminthic drugs widely used against helminths. A novel compound 6-chloro-5-(1-naphthyloxy) -2-(trifluoromethyl)-1H-benzimidazole (RCB20) is a benzimidazole derivative less polar and more lipophilic. The aim of this study was to detect the effect of the RCB20 on the in vitro energetic metabolism of T. crassiceps cysticerci. For this, products of the metabolism both produced and secreted/excreted (S/E) by the parasite were detected through spectrophotometry and high performance liquid chromatography after exposure to 6.5 and 13 μM of RCB20 and albendazole sulfoxide (ABZSO). There was a gradual increase in the concentrations of glucose not uptaken by parasites exposed to both concentrations RCB20 and ABZSO. There was a higher concentration of all the organic acids related to the tricarboxilic acid cycle int the parasites exposed to RCB20. The structural differences between RCB20 and ABZSO result in different targets within the parasite and in a greater induction of the energetic pathways, such as the glycolysis and the TCA cycle. RCB20 is a good candidate as a substitute for anthelminthic benzimidazoles due to a differentiated site of action with similar outcome., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Biochemical studies of benzimidazole derivatives are important to determine their mode of action and activity against parasites. The lack of antihelminthic alternatives to treat parasitic infections and albendazole resistance cases make the search for new antiparasitary drugs of utmost importance. The 6-chloro-5-(1-naphthyloxy)-2-(trifluoromethyl)-1H-benzimidazole (RCB20) is a benzimidazole derivative with promising effect. This study evaluated the effect of different concentrations of RCB20 in the alternative energetic pathway of in vitro Taenia crassiceps cysticerci. The parasites were in vitro exposed to 6.5 and 13 µM of RCB20 and albendazole sulfoxide (ABZSO). The quantification of acetate, acetoacetate, β-hydroxybutyrate, fumarate and propionate was performed by high-performance liquid chromatography. The quantification of urea, creatinine and total proteins was performed by spectrophotometry. The increase in β-hydroxybutyrate reflects the enhancement of the fatty acid oxidation in the treated groups. Volatile fatty acids secretion, acetate and propionate, was increased in the treated groups. The secretion mechanisms of the treated parasites were impaired due to organic acids increased concentrations in the cysticerci. It is possible to conclude that the metabolic effect on alternative energetic pathways is slightly increased in the parasites treated with RCB20 than the ones treated with ABZSO.

Using a murine model of cysticercosis caused by the Taenia crassiceps ORF strain, we developed a fluorescent quantitative evaluation of the action of two well known anti-helminthic drugs: albendazole sulfoxide and praziquantel. The fluorescence emitted by a biotransformed CellTracker Probe known as CellTracker Green CMFDA in the vesicular fluids of cysticerci was estimated, and the results were compared with macroscopic observations of the parasites. The pharmacological EC(50) value of each drug and changes in the level of biotransformation of the fluorescent tracker caused by the drugs could be easily calculated. These drug-induced changes in biotransformation could be related to changes in the GSH/GSSG ratio of parasites. Both the cysticercosis murine model and the CMFDA biotransformation assay could be used as an in vitro screening method to evaluate potential or well known cysticidal drugs., (Copyright © 2010 Elsevier Inc. All rights reserved.)