Prospecção de inibidores de ureases promissores para otimização de fertilizante nitrogenado.

Abstract

Urea is the most widely used nitrogen fertilizer in agriculture. However, losses due to ammonia volatilization, resulting from the action of the urease enzyme, cause economic and environmental problems. One of the strategies to prevent this loss is the use of urease inhibitors, with N-(butyl) thiophosphoric triamide (NBPT) being the most commercially used inhibitor. However, NBPT has important limitations, such as low stability at high temperatures, less efficiency in acid soils and, as it is an imported product, it burdens Brazilian agricultural production, leading to the need to develop new urease inhibitors. In this work, two Schiff bases, 3B4 and 3D6, and an amine derived from the substance 3B4, were better studied with the aim of obtaining a formulation capable of carrying these inhibitors. Solubility studies were conducted and showed that the proposed urease inhibitors are practically insoluble in water, requiring the aid of solvents and co-solvents for solubilization. A safe formulation was developed to verify the safety of these substances in phytotoxicity studies using lettuce seeds (Lactuca sativa L.). Evaluation of inhibition of antiureolytic activity in soil was conducted and showed that substance 3B4 (55 ± 4%) was the most promising urease inhibitor compared to substance 3D6 (39 ± 7%) and 3B4a (28 ± 11%), with no statistical difference from the NBPT (50 ± 1%, p> 0.05). However, in the in vitro urease inhibition study, no statistical difference was observed between substance 3B4 (23 ± 7%) and its amine (3B4a, 24 ± 10%); and the molecular docking study showed that the interaction between the 3B4a substance and the urease enzyme resulted in a more stable complex. The evaluation of the interaction of the 3B4:urea (1:1) and 3B4a:urea (1:1) mixtures using Fourier transform infrared spectroscopy showed no evidence of interactions at times 0, 24 and 48h. The data set provide indications that Schiff base 3B4 and its amine (3B4a) are promising candidates for additives for further studies as urease inhibitors.