Identification of Azoxystrobin Glutathione Conjugate Metabolites in Maize Roots by LC-MS

AOP Report: Glutathione Conjugation Leading to Reproductive Dysfunction via Oxidative Stress

We propose an adverse outcome pathway (AOP) for reproductive dysfunction via oxidative stress (OS). The AOP was developed based on Organisation for Economic Co-operation and Development (OECD) Guidance Document 184 and on the specific considerations of the OECD users' handbook supplement to the guidance document for developing and assessing AOPs (no. 233). According to the qualitative and quantitative experimental data evaluation, glutathione (GSH) conjugation is the first upstream key event (KE) of this AOP to reproductive dysfunction triggering OS. This event causes depletion of GSH basal levels (KE2 ). Consequently, this drop of free GSH induces an increase of reactive oxygen species (KE3 ) generated by the natural cellular metabolic processes (cellular respiration) of the organism. Increased levels of these reactive species, in turn, induce an increase of lipid peroxidation (KE4 ). This KE consequently leads to a rise in the amount of toxic substances, such as malondialdehyde and hydroxynonenal, which are associated with decreased quality and competence of gamete cell division, consequently impairing fertility (KE5 and adverse outcome). The overall assessment of the general biological plausibility, the empirical support, and the essentiality of KE relationships was considered as high for this AOP. We conclude that GSH conjugation is able to lead to reproductive disorder in fishes and mammals, via OS, but that the amount of stressor needed to trigger the AOP differs between stressors. Environ Toxicol Chem 2023;42:2519-2528. © 2023 SETAC.

Non-targeted screening of pyranosides in Rhodiola crenulata using an all ion fragmentation-exact neutral loss strategy combined with liquid chromatography-quadrupole time-of-flight mass spectrometry

INTRODUCTION

Pyranosides as one kind of natural glycosides contain a pyran ring linked to an aglycone in the structure. They occur widely in plants and possess diverse biological activities. The discovery of new pyranosides not only contributes to research on natural products but also may promote pharmaceutical development.

OBJECTIVES

A non-targeted liquid chromatography-quadrupole time-of-flight mass spectrometry method coupled with an all ion fragmentation-exact neutral loss (AIF-ENL) strategy was developed for the screening of pyranosides in plants.

METHODS

Pyranosides in various types were collected as a model. The AIF-ENL strategy comprised three steps: AIF spectrum acquisition and generation, ENL-based searching and identification, and confirmation of structural type using target second-stage mass spectrometry (MS/MS). The strategy was systematically evaluated based on the matrix effects, fragmentation stability, scan rate and screening efficiency and finally applied to Rhodiola crenulata (Hook. f. et Thoms) H. Ohba.

RESULTS

The method was proved to be an efficient tool for the screening of pyranosides. When it was applied to R. crenulata, a total of 24 pyranoside candidates were detected. Among them, six were tentatively identified on the basis of the agreement of their elemental composition with the reported. The other 18 were detected in R. crenulata for the first time.

CONCLUSION

The method offers a new platform for discovering pyranosides. In addition, the developed non-targeted strategy can also be used for other natural products, such as flavonoids and coumarins, as long as there is a common fragmentation behaviour in their MS/MS to generate characteristic neutral losses or fragments.

Effects of Radix Scrophulariae on Hyperthyroidism Assessed by Metabonomics and Network Pharmacology

Radix Scrophulariae (Chinese name: Xuanshen), a traditional Chinese herb, is used for the treatment of hyperthyroidism, and in this study, its mechanisms were evaluated by metabonomics and system pharmacology. To study the anti-hyperthyroidism effects of R. Scrophulariae, a male SD rat (180–220 g) model of hyperthyroidism induced by Euthyrox was used. Thirty rats were randomly distributed into three groups: the Model group, the R. Scrophulariae treatment group (RS group) and the healthy Control group. Using the UHPLC/Q-TOF-MS metabolomics approach, 44 metabolites were found to be profoundly altered in the model group, and the levels of these biomarkers were significantly decreased after treatment with R. Scrophulariae. Forty-four metabolites and 13 signaling pathways related to R. Scrophulariae, including the biosynthesis of unsaturated fatty acids, primary bile acid biosynthesis and sphingolipid metabolism, were explored, and linoleic acid metabolism and sphingolipid metabolism were identified as the most relevant metabolic pathways. In addition, the system pharmacology paradigm revealed that R. Scrophulariae contains 83 active ingredients and is related to 795 genes, and 804 disease genes are related to hyperthyroidism. The construction of the R. Scrophulariaceae-chemical composition-target-hyperthyroidism network identified a total of 112 intersection genes. The enriched gene targets were analyzed, and five pathways were found to be enriched. Among them pathways, the HIF signaling pathway had the highest enrichment score, which indicated that this pathway might be the main signaling pathway related to the treatment of hyperthyroidism by R. Scrophulariae.The integrated approach involving metabolomics and network pharmacology revealed that R. Scrophulariae might play a role in the treatment of hyperthyroidism by regulating the “IL6-APOA1-cholesterol” pathway and disturbing the HIF signaling pathway. The results demonstrate that the combination of metabolomics and network pharmacology could be used to reflect the effects of R. Scrophulariae on the biological network and metabolic state of hyperthyroidism and to evaluate the drug efficacy of R. Scrophulariaceae and its related mechanisms.

Assessment of Environmental Pollution and Human Exposure to Pesticides by Wastewater Analysis in a Seven-Year Study in Athens, Greece

Pesticides have been used in large amounts around the world for decades and are responsible for environmental pollution and various adverse effects on human health. Analysis of untreated wastewater can deliver useful information on pesticides’ use in a particular area and allow the assessment of human exposure to certain substances. A wide-scope screening method, based on liquid chromatography coupled to quadrupole-time-of-flight mass spectrometry, was applied, using both target and suspect screening methodologies. Daily composite influent wastewater samples were collected for seven or eight consecutive days in Athens between 2014 and 2020 and analyzed for 756 pesticides, their environmental transformation products and their human metabolites. Forty pesticides were quantified at mean concentrations up to 4.9 µg/L (tralkoxydim). The most abundant class was fungicides followed by herbicides, insect repellents, insecticides and plant growth regulators. In addition, pesticide transformation products and/or metabolites were detected with high frequency, indicating that research should be focused on them. Human exposure was evaluated using the wastewater-based epidemiology (WBE) approach and 3-ethyl-carbamoyl benzoic acid and cis-1,2,3,6-tetrahydrophthalimide were proposed as potential WBE biomarkers. Wastewater analysis revealed the presence of unapproved pesticides and indicated that there is an urgent need to include more transformation products in target databases.

S-Adenosyl-l-Methionine Promotes Metabolism of Fungicides in Cabernet Sauvignon (Vitis vinifera L.) Berries

Fungicides are commonly used to prevent and treat grape (Vitis vinifera L.) diseases; however, they are potentially toxic to humans. Herein, we show that the application of S-adenosyl-l-methionine (SAM) accelerated the metabolism of various fungicides in Cabernet Sauvignon berries. The substances and enzymes involved in the metabolism of fungicides were analyzed to elucidate the effects of SAM. Results showed that SAM improved the production rate of superoxide anion, the hydrogen peroxide content, and the activities of superoxide dismutase, catalase, and peroxidase in azoxystrobin-treated berries. Additionally, SAM had a positive effect on the content of reduced glutathione and on the activities of glutathione S-transferase, glutathione reductase, and glutathione peroxidase. Importantly, the stimulatory effect of SAM on fungicide metabolism was also observed for metalaxyl and thiophanate-methyl. These results suggest that SAM can be used to improve food safety.