Trichloroethylene metabolism in vitro: an EPR/SPIN trapping study

Area of Science:

• Toxicology
• Biochemistry
• Spectroscopy

Background:

• Trichloroethylene (TCE) is a common industrial solvent with known hepatotoxicity.
• The mechanism of TCE-induced liver injury is not fully understood but may involve oxidative stress.
• Free radical formation is a potential pathway for TCE toxicity.

Purpose of the Study:

• To investigate the role of free radical formation in Trichloroethylene (TCE) toxicity using electron paramagnetic resonance (EPR) spectroscopy.
• To quantify the relationship between TCE concentration and free radical generation in liver tissue.
• To assess the impact of free radicals on lipid peroxidation in liver slices.

Main Methods:

• Precision-cut liver slices were incubated with Trichloroethylene (TCE) and the spin trap alpha-phenyl tert-butyl nitrone (PBN).
• Free radicals were detected and characterized using electron paramagnetic resonance (EPR) spectroscopy, measuring hyperfine coupling constants.
• Conjugated diene levels, a marker of lipid peroxidation, were measured in liver slices.

Main Results:

• EPR spectroscopy detected free radicals in liver slices exposed to TCE, with characteristic hyperfine coupling constants (aN = 1.61 mT, aH = 0.325 mT).
• A dose-dependent, linear increase in detected free radicals was observed with increasing headspace TCE concentrations (2500-10000 p.p.m.).
• Incubation with PBN reduced conjugated diene levels compared to slices incubated without PBN, suggesting PBN scavenges radicals and inhibits lipid peroxidation.

Conclusions:

• Trichloroethylene (TCE) exposure induces free radical formation in liver slices.
• The generated free radicals are associated with increased lipid peroxidation, potentially contributing to TCE-induced liver pathology.
• Electron paramagnetic resonance (EPR) spectroscopy with spin trapping is a valuable tool for detecting TCE-mediated oxidative stress.