Molecular & Biochemical Parasitology 185 (2012) 151–153 Contents lists available at SciVerse ScienceDirect Molecular & Biochemical Parasitology Short communication Increase of carboxylesterase activity in Fasciola hepatica recovered from triclabendazole treated sheep S. Scarcella a,∗ , E. Miranda-Miranda b , R. Cossío-Bayúgar b , L. Ceballos a , V. Fernandez a , H. Solana a a CIVETAN-CONICET, Facultad de Cs. Veterinarias, U.N.C. P.B.A., 7000 Tandil, Argentina b CENID PAVET, INIFAP, 62550 Jiutepec, México, Mexico a r t i c l e i n f o Article history: Received 12 December 2011 Received in revised form 6 July 2012 Accepted 7 July 2012 Available online 16 July 2012 Keywords: Fasciola hepatica Triclabendazole Zymogram Carboxylesterase activity a b s t r a c t In the present work, we evaluate in vivo the activity of carboxylesterase of Fasciola hepatica exposed to triclabendazole. We observed a statistically significant increase in enzyme activity at 24 and 48 h post treatment (P < 0.01 and P < 0.001, respectively). The zymogram of cytosolic fractions identified a protein of 170 kDa containing the carboxylesterase activity. The densitograms of the zymograms confirmed the phe- nomenon of enzyme induction under the experimental conditions of the assay. These results provide not only the understanding of the importance of this metabolic pathway in flukes but carboxylesterase would also be an enzyme that could participate more actively in the development of anthelmintic resistance at TCBZ. © 2012 Elsevier B.V. All rights reserved. Development of drug resistance in parasitic helminthes is facil- itated by the action of xenobiotic metabolizing enzymes (XMEs) [1], which are found in most metazoan organisms and confer an enzymatic defense against the potential toxic action of nat- ural xenobiotics compounds [1]. In general, parasitic helminthes exhibit an efficient XME array [2], which may introduce or unmask new functions of xenobiotic compounds [1]. Parasitic helminthes XMEs include: cytochrome P450, flavin-containing monooxyge- nases, alcohol and aldehyde dehydrogenases and carboxylesterases [3]. XMEs biochemically transform exogenous and endogenous chemical radicals into hydrophilic derivatives through reactions collectively known as biotransformation [1]. It is well recognized that species-related differences in XME expression may affect not only the persistence in the body of drugs and poisons, but also susceptibility to them. Fasciolosis is a world-wide parasitic zoono- sis [4] produced by the parasite Fasciola hepatica which affects mainly sheep, cattle, goats, swine, horses, other herbivores and, accidentally, man [4]. Treatment of liver fluke-infested livestock is mainly based on the use of triclabendazole (TCBZ), a halogenated benzimidazole-thiol derivative which showed efficiency against juvenile and adult stages. In the trematode, TCBZ is metabolized through phase I enzymes. In search for a scientific explanation for the liver fluke anthelmintic metabolism; the majority of this studies ∗ Corresponding author at: Facultad de Cs. Veterinarias, U.N.C. P.B.A., Campus Uni- versitario, 7000 Tandil, Argentina. Tel.: +54 249 4439850x234; fax: +54 249 4439850. E-mail address: silvanas@vet.unicen.edu.ar (S. Scarcella). have concentrated on cytochrome P 450 [5], flavin monooxygenase (FMO) systems [6] or both [2]. The indiscriminate use of TCBZ has favored the manifestation of anthelmintic resistance [7]. This situation leads to the need to expand knowledge of other detox- ification pathways that would have the fluke F. hepatica against TCBZ. Carboxylesterases (CEs) are XMEs complex enzymes that cat- alyze Phase I biotransformation, so producing hydrolytic reactions of carboxylic ester, phosphate esters, amides and thioesters among other chemical compounds [8], playing an important role in endo- biotic and xenobiotic metabolism in metazoans. Carboxylesterases are traditionally regarded as metabolizing enzymes that hydrolyze esterifies xenobiotics to alcohol and carboxylic acid products. Eight different CEs isoenzymes were distinguishable in F. hepatica, the most active of which was an organophosphate-resistant type [9]. In general, parasites defense mechanisms against chemical treat- ments, include detoxifying and anti-oxidant enzymes that would suppress toxic chemical actions [10]. The metabolic interactions of anthelmintics with the flukes XMEs complex may drastically affect the disposition kinetics of different drug [2]. Hence, increased knowledge of enzymatic detoxification and XME-mediated resis- tance mechanisms in F. hepatica is needed. The increased activity of the FMO (XME phase I) [2] and the glutathione-S-transferase (GST) (XME phase II) [11] in the flukes TCBZ resistant (Sligo) pro- vides an understanding of the phenomenon of resistance and adds information to the knowledge of the response that the parasites have exposure to different xenobiotic. This overexpression con- firms that manifestation of the phenomenon of resistance at TCBZ in F. hepatica is a multienzymatic response involving more than one metabolic pathway [11]. At present it is unknown if the CEs are 0166-6851/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.molbiopara.2012.07.001