Assessing the Effects of Alloxydim Phototransformation Products by QSAR Models and a Phytotoxicity Study

Abstract

Once applied, an herbicide first makes contact with leaves and soil. It is known that photolysis can be one of the most important processes of dissipation of herbicides in the field. However, degradation does not guarantee detoxification and can give rise to byproducts that could be more toxic and/or persistent than the active substance. In this work, the photodegradation of alloxydim herbicide in soil and leaf cuticle surrogates was studied and a detailed study on the phytotoxicity of the main byproduct on sugar beet, tomato, and rotational crops was performed. Quantitative structure–activity relationship (QSAR) models were used to obtain a first approximation of the possible ecotoxicological and environmental implications of the alloxydim and its degradation product. The results show that alloxydim is rapidly degraded on carnauba and sandy loam soil surfaces, two difficult matrices to analyze and not previously studied with alloxydim. Two transformation products that formed in both matrices were identified: alloxydim Z-isomer and imine derivative (mixture of two tautomers). The phytotoxicity of alloxydim and the major byproduct shows that tomato possesses high sensitivity to the imine byproduct, while wheat crops are inhibited by the parent compound. This paper demonstrates the need to further investigate the behavior of herbicide degradation products on target and nontarget species to determine the adequate use of herbicidal products to maximize productivity in the context of sustainable agriculture.

Combined 2D-QSAR, Principal Component Analysis and Sensitivity Analysis Studies on Fluoroquinolones’ Genotoxicity

“…The 2D-QSAR model analysis method uses the physicochemical parameters or structural parameter variables related to the compound to study the relationship between chemical substances and biological activity/toxicity by mathematical statistics; this method explains the changes in the physical and chemical properties of the compound caused by structural changes and how the biological activity of the compound is altered by these changes [26,27]. In this study, the genetic toxicity data (pLOEC) of FQs were selected as the dependent variable, and the geometric parameters, electronic parameters, physical and chemical parameters, and spectral parameters of FQs calculated using Gaussian 2009 software and Chemdraw12.0 software were used as the independent variables.…”

Herbicide Residues in Agroecosystems: Fate, Detection, and Effect on Non-Target Plants

“…Kandel et al [63] reported that applying different post-emergence herbicides resulted in higher phytotoxicity at different soybean growth stages than non-treated control. Villaverde et al [54] studied the phytotoxicity of alloxydim herbicide and reported high sensitivity of tomato to this herbicide and its major byproduct. Mehdizadeh et al [42] reported that root and shoot biomass of oilseed rape (Brassica napus L.) was severely affected by metribuzin residues in soil.…”

Novel Mechanism and Kinetics of Tetramethrin Degradation Using an Indigenous Gordonia cholesterolivorans A16

“…The study of metabolic pathways is crucial to the analysis of the biodegradation potential of microorganisms. Sometimes, the intermediate metabolite is more toxic than the parent compound [61][62][63]. These intermediates are ephemeral, in low concentrations, and are readily converted to smaller molecular compounds by oxidation and hydrolysis [64][65][66].…”