Mechanistic Understanding of the Synergistic Potential of Azole Fungicides in the Aquatic Invertebrate Gammarus pulex.
Andrea RöschMichele GottardiCaroline VignetNina CedergreenJuliane HollenderPublished in: Environmental science & technology (2017)
Azole fungicides are known inhibitors of the important enzyme class cytochrome P450 monooxygenases (CYPs), thereby influencing the detoxification of co-occurring substances via biotransformation. This synergism in mixtures containing an azole has mostly been studied by effect measurements, while the underlying mechanism has been less well investigated. In this study, six azole fungicides (cyproconazole, epoxiconazole, ketoconazole, prochloraz, propiconazole, and tebuconazole) were selected to investigate their synergistic potential and their CYP inhibition strength in the aquatic invertebrate Gammarus pulex. The strobilurin fungicide azoxystrobin was chosen as co-occurring substrate, and the synergistic potential was measured in terms of internal concentrations of azoxystrobin and associated biotransformation products (BTPs). Azoxystrobin is biotransformed by various reactions, and 18 BTPs were identified. By measuring internal concentrations of azoxystrobin and its BTPs with high-resolution tandem mass spectrometry in the presence and absence of azole fungicides followed by toxicokinetic modeling, we showed that the inhibition of CYP-catalyzed biotransformation reactions indeed played a role for the observed synergism. However, synergism was only observed for prochloraz at environmentally realistic concentrations. Increased uptake rate constants, an increase in the total internal concentration of azoxystrobin and its BTPs, in vivo assays for measuring CYP activities, and G. pulex video-tracking suggested that the 2-fold increase in bioaccumulation, and, thereby, the raised toxicity of azoxystrobin in the presence of prochloraz is not only caused by inhibited biotransformation but even more by increased azoxystrobin uptake induced by hyperactivity.
Keyphrases
- candida albicans
- tandem mass spectrometry
- high resolution
- human health
- risk assessment
- ultra high performance liquid chromatography
- high performance liquid chromatography
- liquid chromatography
- cancer therapy
- simultaneous determination
- gas chromatography
- mass spectrometry
- oxidative stress
- drinking water
- drug delivery
- solid phase extraction
- high throughput
- health risk
- room temperature
- climate change
- single cell
- oxide nanoparticles