Abstract
Avermectins are effective agricultural pesticides and antiparasitic agents that are widely employed in the agricultural, veterinary and medical fields. The aim of this study was to investigate the inhibitory effects of selected avermectins including abamectin, doramectin, emamectin, eprinomectin, ivermectin and moxidectin that are used as drugs against a wide variety of internal and external mammalian parasites, on the carbonic anhydrase enzyme (CA, EC 4.2.1.1.) purified from fresh bovine erythrocyte. CA catalyses the rapid interconversion of carbon dioxide (CO
2
) and water (H
2
O) to bicarbonate (
) and protons (H
+
) and regulate the acidity of the local tissues. Bovine erythrocyte CA (bCA) enzyme was purified by Sepharose-4B affinity chromatography with a yield of 21.96% and 262.7-fold purification. The inhibition results obtained from this study showed K
i
values of 9.73, 17.39, 20.43, 13.39, 16.44 and 17.73 nM for abamectin, doramectin, emamectin, eprinomectin, ivermectin and moxidectin, respectively. However, acetazolamide, well-known clinically established CA inhibitor, possessed a K
i
value of 27.68 nM.