Three superoxide dismutase isoenzymes of different cellular location were detected in an homogenate of Thrichuris ovis. Each of these molecular forms was purified by differential centrifugation and precipitation with ammonium sulphate, followed by chromatography on DEAE-cellulose and Sephadex G-75 columns. The activity levels of the two molecular forms detected in the mitochondrial (one cyanide sensitive Cu-Zn-SOD and the other cyanide intensitive Mn-Sod were higher than that of the superoxide dismutase detected in the cytoplasmic fraction (cyanid sensitive Cu-Zn-SOD). All the mollecular forms present evident differences to the SODs contained in the host liver. Molecular mass and some of the physical and chemical aproperties of the enzyme was determined for all three molecular forms. An inhibitory effect on the SOD of the parasite an the host was detected with a series of compounds, some of wich markedly inhibited parasite ensyme but not host enzyme.

The inhibitor effect on the Glycogen synthetase (E.C.2.4.1.11) activity by four anthelmintics: Mebendazole, Parbendazole, Albendazole and Thiabendazole was determinated. The most inhibitor effect of Parbendazole on A. suum, F. hepatica and M. expansa, was observed. The lowest inhibitor effect of Thiabendazole, on all cases, was also observed. The aim of our study, and further studies on the same line, are to provide new reports about the unknown locus of actuation of these anthelmintics.

Se ha determinado el effecto inhibidor sobre la actividad Glucogeno sintetasa (E.C.2.41.11) por parte de cuatro antihelminticos: Albendazol, Mebendazol, Parbendazol y Tiabendazol. Observandose que en todos los casos, es el Parbendazol quien ha demostrado un mayor poder inhibidor sobre la glucógeno sintetasa de Ascaris suum, Fasciola hepatica y Moniezia expansa. El Tiabendazol es el anti-helmintico que menor efecto inhibidor ha presentado sobre la enzima en los tres parasitos objeto de nuestro estudio. Con el presente trabajo y otros previstos en la misma linea, se pretende aportar nuevos datos acerca del aun desconocido locus de acción de estos antihelminticos.