Pesticides of natural origin as safer alternatives to synthetic pesticides: Identification of hinokitiol, tebuconazole and 2,4-D metabolites and evaluation of their impact on cereals

Abstract

The persistence of synthetic pesticides in ecosystems and the accumulation of their metabolites, which may have unknown toxicological properties, pose significant ecological and health risks. These compounds disrupt key plant metabolic pathways, affecting the synthesis of amino acids, secondary metabolites, and phytohormones, ultimately influencing plant growth, development, and food quality. Natural allelochemical compounds, such as hinokitiol (β-thujaplicin), present promising alternatives due to their biopesticidal properties and lower environmental persistence. This study, for the first time, verifies the hypothesis that pesticides of natural origin are metabolized more rapidly and cause less disruption to plant metabolism compared to synthetic pesticides, thereby reducing ecological and health risks. This study evaluated the metabolic effects of applying hinokitiol, and synthetic pesticides, 2,4-dichlorophenoxyacetic acid and tebuconazole (1-(4-chlorophenyl)-4,4-dimethyl-3-(1H-1,2,4-triazol-1-ylmethyl)pentan-3-ol), to wheat and barley under controlled conditions. A metabolic fingerprinting liquid chromatography–mass spectrometry (LC-MS)/MS approach was applied to comprehensively assess the global metabolic response of the plants to both natural and synthetic pesticides. High-resolution LC-Full-MS/ddMS² was employed to identify pesticide metabolites and track their degradation kinetics over a four-week period. This study evaluated the influence of biopesticides on the biosynthesis of amino acids, L-phenylalanine, L-tyrosine, and L-tryptophan, in treated plants. Hinokitiol induced modest changes in biogenic amine profiles (up to 50 % alterations), in contrast to the significant modifications observed with tebuconazole, which led to changes up to 270 % relative to the blank control. This research highlights a breakthrough in sustainable crop protection by demonstrating the lower ecological footprint and metabolic impact of natural pesticides compared to synthetic ones.