Influence of an iron-rich amendment on chemical lability and plant (Raphanus sativus L.) availability of two metallic elements (As and Pb) on mine-impacted agricultural soils

Influence of nitisinone and its metabolites on l-tyrosine metabolism in a model system

Nitisinone (NTBC) is currently used for the treatment of tyrosinemia type 1, a rare disease. It also exhibits potential in the treatment of other orphan diseases as well as nervous system disorders - this is however limited by its side effects. In all living organisms, NTBC inhibits 4-hydroxyphenylpyruvate dioxygenase activity, thereby affecting l-tyrosine (L-TYR) catabolism, which results in the therapeutic effect. The NTBC metabolites formed in patient's body is one of the causes of its side effects. The influence of NTBC and its metabolites; 2-amino-4-(trifluoromethyl)benzoic acid, 2-nitro-4-(trifluoromethyl)benzoic acid, and cyclohexane-1,3-dione on L-TYR catabolism was investigated in Raphanus sativus var. longipinnatus. Based on targeted LC-MS/MS analysis the concentration of NTBC and its metabolites in exposed plant tissues was determined. Based on non-targeted LC-MS/MS analysis the concentrations of products of L-TYR catabolism: levodopa, epinephrine, norepinephrine, normetanephrine, dopamine, tyramine and vitamins C, B5 and B6, additionally leucine and valine were identified as influenced by the NTBC or its metabolites. NTBC and its metabolites influenced L-TYR catabolism differently. Particularly significant changes were found in the content of epinephrine and normetanephrine: in the plant tissues exposed to NTBC, an increase in the content of these neurotransmitters was found (+42%), whereas in the plant treated with 2-amino-4-(trifluoromethyl)benzoic acid or 2-nitro-4-(trifluoromethyl)benzoic acid a decrease in concentration (-39% and 55%, respectively) was observed. Cyclohexane-1,3-dione does not influence epinephrine and normetanephrine concentration. The conclusions of this study provide a platform for expanded research on the causes of side effects of NTBC treatment.

Metabolic profiles and non-targeted LC-MS/MS approach as a complementary tool to targeted analysis in assessment of plant exposure to pesticides

Liquid chromatography coupled with tandem mass spectrometry was employed for the detection of pesticides (thiamethoxam, lambda-cyhalothrin, deltamethrin, and metalaxyl) and their metabolites in Raphanus sativus var. longipinnatus exposed to these compounds under experimental conditions. Metalaxyl (0.008 mg/kg), metalaxyl acid (0.009 mg/kg), and (+)-trans-chrysanthemic acid (0.098 mg/kg) were identified in the plants exposed to the individual pesticides and their metabolites. Non-targeted analysis revealed the presence of thiamethoxam, lambda-cyhalothrin, and deltamethrin metabolites in plants exposed to these substances, despite the fact that the pesticide concentrations were below the analytical method's limit of quantification (0.005-0.006 mg/kg). Based on the non-targeted screening, non-specific (leucine and tyramine) and specific (epinephrine, dopamine, tryptamine, and serotonin) markers of plant exposure to the mentioned stress-inducing compounds were detected. These findings prove that non-targeted analysis is an indispensable tool for determining plants' exposure to pesticides, even when the parent compound has been completely metabolized.

Phosphate-modified ferric-based material remediates lead and arsenic co-contaminated soil and enhances maize seedling growth

Soil heavy metal pollution, especially lead (Pb) and arsenic (As), is a global issue that requires urgent attention. In the present study, phosphate-modified ferric-based material (PFM) was used to remedy Pb and As co-contaminated soil. The remediation potential of PFM on Pb and As co-contaminated soil was studied by static culture experiments, and the effect on maize (Zea mays L.) seedling growth was studied using pot experiments. The results showed that the bioavailability of Pb and As in the soil and their accumulation in the seedlings were reduced when PFM was added to the soil. At 2-6 wt% PFM, the remediation rates of Pb and As reached 57%-82% and 62%-76%, respectively, and their accumulation in the seedlings decreased by 27.8%-68% and 55.6%-70%. The optimal amount of PFM was 4 wt% of the soil. There was a linear correlation between the amount of DTPA-extractable Pb or NaHCO₃-extractable As in the soil and the amount of Pb or As accumulated by the seedlings. The correlation coefficients of Pb and As reached 0.7690-0.8166 and 0.9982-0.9779. Seedling growth was also promoted. Compared with the controls, the seedling emergence rate increased by 1.4%-4%, plant height increased by 4.1%-12.4%, plant weight increased by 29.6%-37%, and the root length increased by 5%-52%. In summary, PFM offers an environmentally friendly approach with excellent potential for the remediation of Pb and As co-contaminated soil.