In Vitro Effects of Albendazole Sulfoxide and Praziquantel against Taenia solium and Taenia crassiceps Cysts

Abstract

We investigated the minimum exposure times of prazicuantel (PZQ) and albendazole sulfoxide (ABZSO) required for their activities against Taenia cysts in vitro as well as the 50 and 99% effective concentrations. The results showed that although the effects of both drugs are time and concentration dependent, ABZSO acts much slower and is less potent than PZQ.Several studies (3,8) have evaluated the effects of praziquantel (PZQ) and albendazole sulfoxide (ABZSO) against different species of metacestodes, but this study is the first to evaluate the minimum exposure times required for activity and the effective concentrations of PZQ and ABZSO against Taenia solium and Taenia crassiceps cysts.T. crassiceps cysts (ORF strain) were obtained from experimentally infected male BALB/c mice (age, 2 months). The mice were killed by cervical dislocation, and the metacestodes were removed from the peritoneal cavity. T. solium cysts were obtained from the skeletal muscle of naturally infected pigs. The parasites were washed with sterile 0.9% saline solution, and only those which exhibited an intact bladder surface were used for the experiments.Stock solutions of ABZSO and PZQ were prepared in dimethyl sulfoxide (DMSO) and ethanol, respectively. Working solutions of the drugs were prepared with culture medium to obtain PZQ concentrations from 0.001 to 0.3 g/ml and ABZSO concentrations from 0.0125 to 2.5 g/ml. Culture media containing 0.25% DMSO or 0.05% ethanol were prepared as controls. Each cell culture flask contained 25 cysts in 5 ml of culture medium and was incubated at 37°C with 5% CO 2 . The parasites were observed with an inverted light microscope (Reichert 569). The criteria used to assess cyst mortality in vitro were total paralysis of the membrane and cyst collapse. In order to determine the exposure time required for activity for PZQ, the cysts were observed each 15 min for 6 h; after this time, observations were made each 24 h for 11 days. For ABZSO, the parasites were observed each 24 h for 11 days. The culture medium was changed every day. Each experiment was performed in quadruplicate.The effective concentrations that killed 50 and 99% of the parasites (EC 50 s and EC 99 s, respectively) were determined at 4 and 6 h and 11 days for PZQ and at 11 days for ABZSO. Each experiment was performed in triplicate. Data were analyzed by logistic regression by using SPSS software (version 9.0).When the cysts were exposed to the drugs, an immediate contraction of the membrane was found; extensive vacuolization of the teguments and evagination were also observed. Figure 1A shows the loss of the cystic fluid of T. solium cysts after treatment with PZQ, and Fig. 1B shows the loss of the integrity of the membrane when the T. crassiceps cysts were exposed to the drugs.The maximum effects on T. crassiceps and T. solium cysts were observed after 4 and 6 h, respectively, when the concentrations of PZQ were in the range of 0.012 to 0.1 g/ml. When the effects of PZQ against T. crassiceps cysts were evaluated at lower concentrations (0...

In Vitro Analysis of Albendazole Sulfoxide Enantiomers Shows that (+)-( R )-Albendazole Sulfoxide Is the Active Enantiomer against Taenia solium

“…Even at low doses, the effect of (ϩ)-(R)-ABZSO at 72 h was comparable to that of PZQ at 24 h, which suggests a similar effect taking longer to occur. This is consistent with the observed slower effect of ABZSO on cysts, as seen with AP secretion and in previous studies (16,22).…”

“…Using AP inhibition as a marker of drug effect, changes associated with ABZSO and each of its enantiomers were detected as early as 3 days after drug exposure and at 10, 100, and 500 ng/ml (Fig. 2ii to iv), in contrast to previous reports on T. solium and T. crassiceps, where the ABZSO effect could be seen only after 11 days with doses between 65 and 556 ng/ml (22).…”

Sensitive In Vitro System To Assess Morphological and Biochemical Effects of Praziquantel and Albendazole on Taenia solium Cysts

“…Studies using T. solium cysts are difficult because many infected pigs are required, harvesting cysts individually is laborious and time-consuming, and culturing and maintaining cysts in the laboratory is difficult. For these reasons, cysts of a related parasite of the same genus as T. solium, Taenia crassiceps, have been commonly used instead of T. solium cysts for in vitro studies of drug effects and parasite biology (16,17,32). However, it is not known whether any or all of the conclusions from these studies can be applied to T. solium.…”

“…Traditionally, the effects of drugs on taeniid cysts have been assessed by visual examination of cysts for morphological and histopathological changes on light or electron microscopy suggesting damage (16,17). Although these approaches have demonstrated effects of the commonly used anthelmintics for treatment of T. solium (17) and other cestodes (7,11), the techniques require experienced personnel and equipment and are time-consuming for routine use and analysis. We were interested in investigating alternative, potentially more sensitive methods for detection of damage to parasites that had the potential for testing new drugs rapidly and inexpensively.…”

Quantitative Screening for Anticestode Drugs Based on Changes in Baseline Enzyme Secretion by Taenia crassiceps

“…The low values precluded the use of OD ratios as a reliable measure of enzyme release. Previous studies, by aggregating the enzyme released over the whole period of culture, avoided this issue and may have thereby allowed detection of ABZSO effects (17,18), although we believe that the rate of accumulation provides additional useful information about the effects of drugs on the parasite.…”