Albendazole (ABZ), ricobendazole (RBZ) and eprinomectin (EPM) are commonly used antiparasitic drugs in cattle, sheep and goats. ABZ is oxidized in the liver and converted to its active metabolite RBZ. In this study, the effects of ABZ, RBZ and EPM were investigated on the cytosolic β-glucosidase activity of the liver enzymes. For this purpose, cytosolic β-glucosidase from lamb liver was purified. Purification was performed in two phases by ammonium sulfate precipitation and hydrophobic interaction chromatography methods. At the end of the procedures, it was calculated that the enzyme was purified 26.7 folds with a yield of 10.7%. The purified enzyme was visualized on SDS-PAGE as a single band at about 55kDa.

In vitro effects of ABZ, RBZ, EPM on purified lamb liver β-glucosidase with using p/o-NPG substrates were determined. % activity against drug concentration chart was used to determine the inhibitory effects of drugs. ABZ did not change the enzyme activity as determined with both substrates. EPM decreased the enzyme activity but its inhibition effect was not strong. RBZ was determined that it inhibite the enzyme. It was determined RBZ concentration reducing by half the enzyme activity for the substrates p/o-NPG were 4.8 and 5.9 mM, respectively. It was determined that RBZ had competitive inhibition both against p/o-NPG substrates, and Ki values were calculated as 3.9x10^-5±0.3x10^-5 and 1.5x10^-5±0.1x10^-5mM, respectively.

In this study, RBZ inhbited the enzyme while ABZ and EPM did not inhbit lamb liver cytosolic β-glucosidase. However ABZ also be metabolized very rapidly to RBZ in vivo is thought to ABZ indirectly affect the enzyme activity adversely.