Avaliação do efeito inibitório do metribuzin na atividade de catalase hepática de Prochilodus argenteus

Abstract

The widespread use of herbicides in Brazil raises questions about the possible damage they may cause to the environment and the beings that live in it due to the aerial dispersal of the herbicide, by leaching or hauling, affecting aquatic animals that suffer directly from the impacts. of these applications. Metribuzin is a leaching herbicide that is widely used to eliminate weeds from crops such as soybeans, cotton and especially sugar cane. Given this, there is a need to gauge the impact of this substance on the watercourses and individuals living there, so we opted for an aquatic species taking into account its sensitivity or tolerance to various types of changes in its habitat. The sentinel species used was Curimatã Pacu (Prochilodus argenteus), endemic to the São Francisco River and of importance to the riverside subsistence, as well as local trade. Thinking about these impacts, this work aims to evaluate liver catalase activity and total protein concentration after exposure to metribuzin and to analyze the enzymatic kinetics of this same enzyme in healthy fish. The fish were subjected to an experiment correlating concentration over a period of time, where metribuzin concentrations were 37.32, 74.65, and 111.97 mg.L-1 over 24 and 96h. It was found a significant decrease (according to Tukey's statistical test) of catalase activity with the highest concentration (111.97 mg.L-1) when compared to control at 24 and 96h, with inhibition respectively 64.41 % and 78.91%. Total protein concentration decreased 36.83% in 24h and 35.94% in 96h. For the enzymatic kinetics H2O2 concentrations between 0.5 and 24.26 mM were used to obtain the kinetic constants Km (80.58 ± 12.83 M), Vmax (2.06 ± 0.2486 M.min-1). The activity and total protein decay show the toxic potential of metribuzin, the kinetics performed showed that the catalase does not follow the model proposed by Michaelis-Menten and the kinetic constants were obtained by estimation of values.