Extrato pirolenhoso: caracterização, identificação dos componentes principais e efeitos sobre a atividade ureolítica de urease

Abstract

The increase in food production to meet the growing global population's demand is largely dependent on the efficiency of fertilizers. Developing low-cost and more environmentally friendly urease inhibitors is a challenge for the agricultural sector. Pyroligneous acid (PA), a by-product of the charcoal industry, has proven to be an ally to agricultural practices by providing benefits to both plants and soil. While many of its effects have been reported, the compounds and mechanisms involved are still relatively unknown, primarily due to the complex chemical composition of PA. Therefore, this study aimed to characterize and evaluate the potential use of PA as a urease inhibitor. Four samples of PA obtained from the carbonization of different biomass sources (eucalyptus, black wattle, and coconut husk) and in different production processes (metal kilns and brick ovens) were characterized and evaluated. In vitro results of urease inhibition in Canavalia ensiformis (Jack Bean) showed that the PAs exhibited varying inhibitory activities, which depended on the biomass source and production process. The eucalyptus PA produced in a metal kiln (1.EPCE) exhibited the highest activity, followed by the coconut husk PA (3.EPCC), also produced in a metal kiln, and finally, the black wattle (4.EPAN) and eucalyptus (2.EPAE) PAs produced in brick ovens. The 1.EPCE underwent sequential extraction with different solvents to facilitate the identification of the main compounds involved in urease inhibition. Among the evaluated compounds, 4-methylcatechol (MC) and pyrocatechol (PC) showed the greatest urease inhibition, and molecular docking was performed to elucidate the inhibitory activity of these compounds. Both eucalyptus PAs (metal kiln and brick oven) as well as PC and MC were also evaluated for their ability to inhibit the ammonia volatilization emitted by urea in the soil in a closed system with continuous airflow. The 1.EPCE performed similarly to NBPT, the most successful urease inhibitor in the market, with no statistically significant difference in the percentage of accumulated nitrogen lost. The results appear promising regarding urease inhibition by the PA samples, primarily due to their low cost, biodegradability, non-toxicity, high water solubility, and beneficial effects on plant development.