The Effects of the Fungicide Myclobutanil on Soil Enzyme Activity

Abstract

(1) Background: The use of pesticides, although needed to protect crops and increase production, represents an environmental and human health issue. Therefore, measures must be taken in order to develop a better understanding of the risks involved in the overuse of these compounds. Myclobutanil is a chiral triazole fungicide widely used for the protection of crops against fungal diseases. Published data have shown that, although effective in preventing fungal infections, high doses of myclobutanil can affect the soil environment. The aim of this study was to evaluate the effect of different doses of myclobutanil on soil enzyme activity, as well as the possible specificity of the interactions of the two stereoisomers of myclobutanil with these enzymes. (2) Methods: A combination of experimental and computational approaches was considered. An experimental method was applied in order to assess the effect of different doses of myclobutanil on the activity of dehydrogenase, phosphatase, catalase, urease and protease. The computational approach was based on the molecular docking of the two enantiomers of myclobutanil with the above-mentioned enzymes to assess the possible enantioselectivity of the interactions. (3) Results: High doses of myclobutanil significantly affected the enzymatic activity of dehydrogenase and led to a slight increase in the activity of catalase. Molecular docking data showed that both enantiomers of myclobutanil were able to bind to the active sites of dehydrogenase, phsosphatase and protease, with higher interacting energies observed for (S)-myclobutanil, the enantiomer known to be less active against target organisms but have a higher toxicity against non-target organisms. (4) Conclusions: The results of our study confirm the need to implement better management practices regarding the use of myclobutanil (and of pesticides in general) by using the enantiomer that is most effective on target organisms and less toxic to non-target organisms.

Keywords

• triazole fungicides
• soil enzyme activity
• stereoisomers of myclobutanil
• enantioselectivity