Effect of some pesticides/weedicides on cathepsin B activity and lysosomal membrane

The in vitro inhibitory effects of various weedicides and pesticides on goat brain cathepsin B and their labilizing potency on the lysosomal membrane were quantitated. Endosulfan an organochlorine insecticide inhibited the enzymic activity to approximately 50% at 7 mM concentration followed by methyl parathion, aldrin, melathion and benzene hexachloride (BHC) in that order. Among the weedicides, butachlor was found to be most inhibitory (approximately 50% activity was lost at 6 mM) followed by isoproturone (28%) and anilophos (19%). When the labilizing/stabilizing potency of all these drugs was observed on lysosomal membrane it was found that none of these was capable of stabilizing the membrane. At 40 degrees C and 1 mM drug concentration, aldrin, endosulfan, melathion and anilophos were found to be strong labilizers of the lysosomal membrane. Others like isoproturone, BHC and methyl parathion had moderate labilizing effect. The labilization potency of the drugs was temperature dependent and was less pronounced at 25 degrees C as compared to 40 degrees C.