Biochem/physiol Actions DL-Ethionine is a racemic mixture of the anti-methylation agent L-Ethionine and its enantiomer D-Ethionine. DL-Ethionine is used as a dietary supplement to accelerate cholangiocarcinogenesis in vivo. DL-Ethionine is used to induce oxidative stress in liver to study the levels and activities of anti-oxidative enzymes and compounds such as glutathione.